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Classifications

ISDS Skeletal Nosology

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Inheritance

1

Autosomal dominant HP:0000006

GDD segregates as an autosomal dominant trait in multigeneration kindreds and also arises de novo; affected individuals are heterozygous for an ANO5 missense variant. This is the inheritance mode that distinguishes GDD from the autosomal recessive ANO5 muscular dystrophies.

Autosomal dominant inheritance Penetrance: UNKNOWN Expressivity: VARIABLE

Show evidence (3 references)

PMID:40861765 SUPPORT Human Clinical

"with autosomal dominant inheritance, with high penetrance"

The only penetrance statement in the GDD literature, describing the founding Akasaka kindred. `penetrance` is nonetheless recorded as UNKNOWN rather than COMPLETE because this is a historical pedigree impression rather than a measured estimate, and no quantitative penetrance study exists; support is PARTIAL for that reason. `expressivity: VARIABLE` is the better-supported claim - the same p.Cys356Tyr allele spans mild jaw lesions to severe multi-quadrant gigantiform disease, bone mass runs in opposite directions between families, and one p.Thr513Ile kindred adds a muscle phenotype absent from every other GDD family.

PMID:28176803 SUPPORT Human Clinical

"Gnathodiaphyseal dysplasia (GDD; MIM#166260) is an autosomal dominant syndrome with characteristic cemento-osseous lesions of jawbones, bone fragility, and diaphyseal sclerosis of tubular bones."

States the autosomal dominant inheritance mode alongside the defining triad.

PMID:38922934 SUPPORT Human Clinical

"Genetic testing revealed two de novo variants of the ANO5 gene, confirming the diagnosis."

Documents de novo occurrence of the dominant ANO5 allele, so a negative family history does not exclude GDD.

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Mechanistic Hypotheses

2

Gain-of-function scramblase model

gof_scramblase_model CANONICAL

Evidence balance 2 support

The prevailing model: heterozygous GDD missense alleles confer constitutive, calcium-independent phospholipid scrambling on TMEM16E, and that aberrant activity - not a shortfall of ANO5 - disturbs bone-cell behaviour. Its two supports are the dominant inheritance with a restricted missense spectrum, and the head-to-head functional comparison showing GDD and muscular-dystrophy alleles moving in opposite directions in the same assay. Its weakness is that the step from scrambling to a bone lesion, and above all to a jaw-restricted lesion, has not been demonstrated in bone tissue.

Pathograph links

Altered Calcium-Activated Phospholipid Scrambling by TMEM16E -> Pro-Osteogenic Signalling Dysregulation in Osteoblasts INDIRECT UNKNOWN INTERMEDIATES Route to the osteoblast arm. Candidate intermediates are now identified in mouse models, but the step from altered TMEM16E scrambling to those signalling changes has not been demonstrated in patient bone.

Altered Calcium-Activated Phospholipid Scrambling by TMEM16E -> Osteoclast Differentiation Blockade and Apoptosis INDIRECT UNKNOWN INTERMEDIATES Route to the osteoclast arm, evidenced in the same model systems and subject to the same caveat.

Dysregulated Osteoblast and Osteoclast Differentiation -> High-Turnover Skeletal Remodelling Imbalance DIRECT A coordinated disturbance of osteoblast and osteoclast behaviour is what produces the paradoxical combination of sclerotic, thickened bone that nevertheless fractures. This edge is claimed by BOTH mechanistic hypotheses, and that is the point: they disagree about the SIGN of the remodelling change - the gain-of-function model predicts increased indices and high bone mass, the sub-entity model predicts decreased indices and osteopenia for loss-of-function alleles - while agreeing that the cellular imbalance is what produces the skeletal phenotype.

Show evidence (2 references)

PMID:32112655 SUPPORT In Vitro

"Previous studies have demonstrated that TMEM16E/ANO5 is a Ca2+ -activated phospholipid scramblase and that the mutation c.1538C>T (p.Thr513Ile) causing GDD leads to a gain-of-function phenotype."

States the gain-of-function characterization that this hypothesis group is built on.

PMID:38922934 SUPPORT Other

"GDD is a rare but frequently inherited cause of bone fragility and jaw lesions characterized by a gain-of-function variant within the ANO5 gene."

Shows the gain-of-function reading has been adopted as the working model in the contemporary clinical literature. Classified OTHER rather than HUMAN_CLINICAL because the sentence is a literature-review characterization, not an observation the authors made in their own patients.

Variant-class-stratified GOF/LOF sub-entity model

ano5_deficiency_model EMERGING

Evidence balance 5 support 1 refute

A reading that does not compete with the gain-of-function model so much as subsume it, and that changes what a curator should record about bone mass. Li et al. propose that GDD comprises two sub-entities assigned by variant class rather than by clinical convention: gain-of-function alleles produce a HIGH-bone-mass phenotype through hyperactive phospholipid scrambling with increased osteoblast and osteoclast indices, while loss-of-function alleles produce a LOW-bone-mass, osteopenic phenotype through impaired calcium oscillations with decreased indices. The supporting observations are that Ano5-knockout mice replicate several cardinal GDD traits, and that a GDD family carrying a frameshift insertion with reduced TMEM16E presented with osteopenia rather than osteosclerosis. One frequently cited finding is NOT support for this model and should not be listed as such: reduced ANO5 in osteoblast precursors INCREASES osteoblastogenesis and mineralization, which runs opposite to the decreased-indices arm proposed here - Li et al. name that result themselves as partly contradicting their own conclusions. Li et al. further argue ANO5 is dosage-sensitive and that their heterozygous frameshift causes only PARTIAL loss of function, partly compensated by the normal allele - which is how a reduced-activity allele can be dominant without being a simple haploinsufficiency. The practical curation consequence is that this entry deliberately does NOT put a single INCREASED or DECREASED modifier on bone mineral density, because either would be wrong for one of the two sub-entities.

Pathograph links

Altered Calcium-Activated Phospholipid Scrambling by TMEM16E -> Pro-Osteogenic Signalling Dysregulation in Osteoblasts INDIRECT UNKNOWN INTERMEDIATES Route to the osteoblast arm. Candidate intermediates are now identified in mouse models, but the step from altered TMEM16E scrambling to those signalling changes has not been demonstrated in patient bone.

Altered Calcium-Activated Phospholipid Scrambling by TMEM16E -> Osteoclast Differentiation Blockade and Apoptosis INDIRECT UNKNOWN INTERMEDIATES Route to the osteoclast arm, evidenced in the same model systems and subject to the same caveat.

Dysregulated Osteoblast and Osteoclast Differentiation -> High-Turnover Skeletal Remodelling Imbalance DIRECT A coordinated disturbance of osteoblast and osteoclast behaviour is what produces the paradoxical combination of sclerotic, thickened bone that nevertheless fractures. This edge is claimed by BOTH mechanistic hypotheses, and that is the point: they disagree about the SIGN of the remodelling change - the gain-of-function model predicts increased indices and high bone mass, the sub-entity model predicts decreased indices and osteopenia for loss-of-function alleles - while agreeing that the cellular imbalance is what produces the skeletal phenotype.

Show evidence (6 references)

PMID:35982081 SUPPORT In Vitro

"Overall, our results suggest the existence of GDD-sub-entities with high and low BMD phenotypes due to different GOF and LOF mutations and functions."

The authors' explicit statement of the two-sub-entity model that this hypothesis group records.

PMID:35982081 SUPPORT In Vitro

"Thus, our results suggest that ANO5 is dosage-sensitive and that LOF of the TMEM16E protein caused by the heterozygous ANO5 mutation in one allele is partly compensated by another normally functional allele."

Supplies the dosage-sensitivity argument that lets a partial-loss-of-function allele be dominant without implying that a full null allele would be.

PMID:30712070 SUPPORT Model Organism

"Homozygous Ano5 knockout mice (Ano5-/-) replicate some typical traits of human GDD including massive jawbones, bowing tibia, sclerosis and cortical thickening of femoral and tibial diaphyses."

A pure loss-of-function genotype reproducing GDD-like bone traits, which is the central difficulty for a strict gain-of-function-only account.

+ 3 more references

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Discussions and Knowledge Gaps

4

Why does a heterozygous missense change in ANO5, a broadly expressed endoplasmic-reticulum phospholipid scramblase, produce focal expansile cemento-osseous lesions that are essentially confined to the tooth-bearing jaws, while the rest of the skeleton shows a diffuse high-turnover sclerosing phenotype instead?

KNOWLEDGE GAP OPEN gdd_jaw_selectivity_gap

Attached to

pathophysiology#Jaw Cemento-Osseous Fibrous Lesion Formation

This is the central unexplained feature of GDD and the reason the causal edge into the jaw lesion node is marked INDIRECT_UNKNOWN_INTERMEDIATES rather than DIRECT. The gnathic and extragnathic lesions are not the same pathology in two locations - jaw lesions are fibro-osseous and specifically lack the osteosclerosis that defines the long-bone lesion - so the disorder needs an account of tissue selectivity, not merely of bone-cell dysfunction. Candidate explanations include a neural-crest-derived versus mesoderm-derived skeletal origin, the distinct periodontal-ligament and cementoblast populations of the gnathic skeleton (ANO5 is expressed in periodontal ligament cells), and the continuous remodelling demand of tooth-bearing bone. None has been tested. Filling this gap with a plausible-sounding chain would misrepresent the state of the evidence.

Proposed experiments

Lineage-resolved conditional ANO5 GDD-allele expression

gdd_lineage_conditional_knockin

Express a GDD knock-in allele conditionally in neural-crest-derived versus mesoderm-derived skeletal lineages in mouse and ask whether jaw lesion formation tracks lineage rather than anatomical site.

Single-cell profiling of human GDD jaw lesion tissue

gdd_jaw_lesion_single_cell

Single-cell or spatial transcriptomic profiling of resected GDD gnathic lesions against uninvolved bone from the same patient, to identify the cell population that expands and whether it is cementoblast or periodontal-ligament derived.

Distinct from the mechanism-direction dispute recorded in `gdd_gof_vs_lof_dispute`: even if the gain-of-function reading is correct, the tissue-selectivity question remains open.

Is the GDD skeletal phenotype driven by gain of ANO5 function, or can reduced ANO5 activity produce it too - and if the latter, why do heterozygous ANO5 null carriers (the parents of LGMDR12 patients) not develop bone disease?

KNOWLEDGE GAP OPEN gdd_gof_vs_lof_dispute

Attached to

pathophysiology#Altered Calcium-Activated Phospholipid Scrambling by TMEM16E

The gain-of-function reading rests on strong but indirect grounds - dominant inheritance with a clustered missense spectrum, plus heterologous-expression assays in HEK293 cells showing GDD and muscular-dystrophy alleles moving in opposite directions. Three findings sit awkwardly with it. First, Ano5-knockout mice reproduce several cardinal GDD traits, which a strict gain-of-function model does not predict. Second, canonical GDD missense alleles reduce steady-state ANO5 protein in overexpression studies, so they are not purely hyperactive. Third, a GDD family has been reported with a frameshift insertion and reduced TMEM16E expression. The observation that obligate heterozygous null carriers of LGMDR12 alleles are not reported with bone disease remains the strongest argument against simple haploinsufficiency, but it is an argument from absence in a population that has not been systematically skeletally phenotyped, and that limitation should be stated rather than glossed.

Proposed experiments

Skeletal phenotyping of obligate ANO5 null heterozygotes

gdd_null_carrier_skeletal_phenotyping

Systematic dental panoramic imaging, long-bone radiography and bone-turnover marker assessment in obligate heterozygous carriers of ANO5 truncating alleles ascertained through LGMDR12 probands, to convert an argument from absence into a measured negative.

Allelic series knock-in comparison in a single genetic background

gdd_allelic_series_knockin

Compare knock-in of a GDD missense allele, a heterozygous null allele, and a homozygous null allele in one mouse background with identical skeletal phenotyping, to separate dosage effects from allele-specific activity.

Show evidence (1 reference)

PMID:30712070 SUPPORT Model Organism

"Here we generated Ano5-knockout (KO) mice using a CRISPR/Cas 9 approach to study loss of function aspects of GDD mutations."

Frames the loss-of-function investigation whose positive skeletal result is the main tension with the gain-of-function model.

How absolute is the separation between the ANO5 bone and muscle phenotypes, given a dominant kindred in which the functionally characterized GDD allele p.Thr513Ile produced both cemento-osseous jaw lesions and recurrent rhabdomyolysis with hyperCKemia?

KNOWLEDGE GAP OPEN gdd_phenotypic_dichotomy_challenged

Attached to

pathophysiology#Heterozygous ANO5 Missense Variant

The clean dichotomy - dominant missense to bone, recessive null to muscle - is the framing that motivates this entry, and it is largely right, but it is not absolute and the entry should not assert more than the literature supports. An 11-member kindred carrying p.Thr513Ile showed recurrent rhabdomyolysis, muscle cramps, hyperCKemia and muscle hypertrophy alongside the mandibular cemento-osseous lesions, and the authors explicitly framed this as a challenge to the proposed dichotomy. If a single dominant allele can produce both tissue phenotypes, then allele class and tissue are not in one-to-one correspondence, and the gain-of-function versus loss-of-function assignment explains the inheritance pattern better than it explains the tissue distribution.

Proposed experiments

Prospective neuromuscular assessment of GDD cohorts

gdd_prospective_neuromuscular_assessment

Systematic CK measurement, muscle imaging and exertional-symptom history in genotyped GDD patients stratified by allele, to establish whether subclinical muscle involvement is specific to p.Thr513Ile or general to GDD.

Show evidence (2 references)

PMID:34291158 SUPPORT Human Clinical

"This report described the coexistence of muscle and bone phenotypes in the same patients with ANO5-related disorder."

Documents the coexistence directly, which is what makes the dichotomy a curated question rather than a settled fact.

PMID:34291158 SUPPORT Human Clinical

"Our data challenge recent results that suggested complete dichotomy of these phenotypes and the proposed loss-of-function and gain-of-function mechanisms for the skeletal and muscle phenotypes, respectively."

The authors' explicit statement that they are challenging the dichotomy this entry otherwise adopts as its organizing frame. Reader caution, since the quote is reproduced verbatim and must not be altered: the trailing "respectively" pairs loss-of-function with the SKELETAL phenotype and gain-of-function with the MUSCLE phenotype, which is the reverse of the assignment made everywhere else in this entry and in the functional literature (PMID:29124309, PMID:32112655, and this paper's own discussion). Treat the sentence as evidence that the dichotomy is being challenged, not as a source for which direction goes with which tissue.

Do the existing mouse models faithfully represent human GDD, given that a knock-in of the murine equivalent of a human GDD missense allele produced no skeletal phenotype at all, while Ano5 knockout - the genotype that in humans causes myopathy rather than bone disease - does produce GDD-like bone changes?

HUMAN MODEL MISMATCH OPEN gdd_mouse_model_mismatch

Attached to

pathophysiology#Heterozygous ANO5 Missense Variant pathophysiology#Altered Calcium-Activated Phospholipid Scrambling by TMEM16E

The mouse evidence is internally inconsistent in a way that inverts the human genotype-phenotype relationship, so no mouse result about GDD mechanism can currently be transferred to human disease without argument. A p.T491F knock-in - the murine equivalent of the human p.Ser500Phe GDD allele, taken from a thoroughly characterized patient - showed no alteration of skeletal microarchitecture or mandible morphology in heterozygotes or homozygotes, assessed at two ages in males with the result confirmed in females and in an independent clone. Meanwhile Ano5 knockout mice, and a separate p.Cys360Tyr knock-in, do develop GDD-like massive jawbones, tibial bowing and diaphyseal cortical thickening. Worse, the two null lines disagree with EACH OTHER. Wang's knockout gave osteosclerosis and hypermineralized matrix; Li's knockout gave low bone volume with defective osteoblast and osteoclast differentiation. Li et al. state the non-replication plainly. So the model evidence is not merely positive-versus-negative: three independent lines carrying ANO5 lesions produce three different skeletal directions, and two of them share a genotype. Together with the null-models-a-missense-disease problem, this means the mouse literature cannot presently arbitrate the gain- versus loss-of-function question it is most often invoked to settle. There is at least one concrete, testable explanation for the negative knock-in rather than a bare species hand-wave: Li et al. point out the residue is not conserved - the human change is Ser to Phe while the murine equivalent is Ter to Phe - so the mouse allele may simply not be the same lesion, and they also argue the animals were phenotyped too late. That is an argument about construct validity, and it is why the negative result is recorded here as a mismatch to be resolved rather than as a refutation of the human mechanism.

Proposed experiments

Harmonized multi-allele skeletal phenotyping

gdd_harmonized_multiallele_phenotyping

Phenotype p.T491F, p.Cys360Tyr and null Ano5 alleles in one genetic background with a single harmonized imaging and histomorphometry protocol, to determine whether the discrepancy is allele-specific biology or protocol and background variation.

Human osteoblast and cementoblast models of GDD alleles

gdd_human_osteoblast_cementoblast_models

Patient-derived or isogenic iPSC-derived human osteoblasts and periodontal-ligament or cementoblast cultures carrying GDD alleles, to test the mechanism in human cells rather than relying on mouse models that disagree.

Show evidence (5 references)

PMID:32455153 SUPPORT Model Organism

"These mice did not display alterations of skeletal microarchitecture or mandible morphology."

The negative knock-in result: the murine equivalent of a human GDD allele produced no skeletal phenotype.

PMID:32455153 SUPPORT Model Organism

"Therefore, our results indicate that Ano5 is dispensable for bone homeostasis in mice, at least under unchallenged conditions, and that these animals may not present the most adequate model to study the physiological role of Anoctamin 5."

The authors' own conclusion that the mouse is not an adequate model, which is the substance of this mismatch.

PMID:34841576 SUPPORT Model Organism

"Homozygous Ano5 knock-in mice (Ano5KI/KI ) replicated GDD-like skeletal features, including massive jawbones, bowing tibia, bone fragility, sclerosis, and cortical thickening of the femoral and tibial diaphysis."

The contradicting positive knock-in result, in a different GDD allele, that makes the model evidence inconsistent rather than merely negative.

+ 2 more references

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Pathophysiology

9

Heterozygous ANO5 Missense Variant

GDD is caused by a heterozygous missense variant in ANO5 (TMEM16E), the gene originally designated GDD1. The reported alleles are strikingly clustered: the founding Japanese and African American families carried substitutions at the evolutionarily conserved cysteine 356 (p.Cys356Arg, p.Cys356Gly, and later p.Cys356Tyr), and subsequent families added p.Cys360Tyr, p.Arg215Gly, p.Ser500Phe, p.Thr513Ile and p.Gly518Glu. All map either to the extracellular loop following the first transmembrane domain or to the fourth putative transmembrane domain, which is what makes a simple gene-dosage explanation implausible: a haploinsufficiency mechanism would tolerate nonsense and frameshift alleles anywhere in the gene, and those alleles instead produce a recessive myopathy.

Genetic context ANO5 hgnc:27337 allele_type: Missense substitution clustered at ANO5 residues 215, 356, 360, 500, 513 and 518 variant_origin: GERMLINE zygosity: HETEROZYGOUS functional_impact_category: GAIN_OF_FUNCTION

Heterozygous germline ANO5 missense allele. `functional_impact_category` is set to GAIN_OF_FUNCTION rather than LOSS_OF_FUNCTION on two converging grounds: the dominant inheritance with a restricted missense spectrum, and functional assay data. Note the scope of that assay evidence precisely - the calcium-independent-scrambling demonstration is for p.Thr513Ile specifically (PMID:29124309), and the class-level claim that GDD alleles gain function while muscular-dystrophy alleles lose it comes from a separate head-to-head comparison (PMID:32112655) that did not name every allele it tested. It is NOT established that every GDD allele behaves this way; the two commonest, p.Cys356Tyr and p.Cys360Tyr, have published *reduced* steady-state protein in overexpression. The category is therefore an allele-class judgement, and the competing loss-of-function reading is not dismissed - see the mechanistic hypotheses and the `gdd_gof_vs_lof_dispute` discussion.

Downstream

Altered Calcium-Activated Phospholipid Scrambling by TMEM16E The missense substitution acts on the protein's own transport behaviour; this is the step demonstrated directly in heterologous expression.

Show evidence (2 references)

PMID:15124103 SUPPORT Human Clinical

"Two missense mutations (C356R and C356G) of GDD1 were identified in the two families with GDD (the original Japanese family and a new African American family), and both missense mutations occur at the cysteine residue at amino acid 356, which is evolutionarily conserved among human, mouse,..."

The founding gene-identification study, establishing GDD1/ANO5 missense change at a single conserved cysteine as the cause of GDD.

PMID:28176803 SUPPORT Human Clinical

"It appears that all GDD mutations known so far locate in an extracellular domain following the first transmembrane domain or in the 4th putative transmembrane domain."

Documents the tight positional clustering of GDD alleles, which is difficult to reconcile with simple haploinsufficiency.

Altered Calcium-Activated Phospholipid Scrambling by TMEM16E

ANO5 encodes TMEM16E/anoctamin-5, a member of the TMEM16 family that behaves as a calcium-activated phospholipid scramblase and a poorly selective ion conduit, and that localizes predominantly to the endoplasmic reticulum rather than the plasma membrane. In heterologous expression, the GDD-associated p.Thr513Ile protein scrambles phospholipid and carries large currents even at very low cytosolic calcium, i.e. it is uncoupled from its normal calcium gating rather than inactivated. When GDD alleles and muscular-dystrophy alleles were compared side by side in the same assay system, they moved in opposite directions - GDD towards gain of function, muscular dystrophy towards loss of function. This is the node at which the two ANO5 diseases separate, and it is why bone disease is not simply "less ANO5".

Gain-of-function scramblase model Variant-class-stratified GOF/LOF sub-entity model

calcium activated phospholipid scrambling GO:0061588 ⇑ GAIN OF FUNCTION endoplasmic reticulum calcium ion homeostasis GO:0032469 ↕ DYSREGULATED

phospholipid scramblase activity GO:0017128 ⇑ GAIN OF FUNCTION

Downstream

Pro-Osteogenic Signalling Dysregulation in Osteoblasts Route to the osteoblast arm. Candidate intermediates are now identified in mouse models, but the step from altered TMEM16E scrambling to those signalling changes has not been demonstrated in patient bone.

Osteoclast Differentiation Blockade and Apoptosis Route to the osteoclast arm, evidenced in the same model systems and subject to the same caveat.

Show evidence (3 references)

PMID:29124309 SUPPORT In Vitro

"While the activity of wild-type TMEM16E depended on elevated cytosolic Ca2+ levels, a mutant form carrying the GDD-causing T513I substitution showed PLS and large time-dependent ion currents even at low cytosolic Ca2+ concentrations."

Direct demonstration that a GDD allele uncouples TMEM16E scrambling from its normal calcium requirement - constitutive activity, not absent activity.

PMID:32112655 SUPPORT In Vitro

"Our results collectively demonstrate that, on the level of protein function, MD mutations are associated to loss-of-function and GDD mutations to gain-of-function phenotypes, confirming conjectures made on the basis of inheritance modes."

The head-to-head comparison establishing the allelic dichotomy at the level of protein function, and explicitly grounding it in the opposite inheritance modes.

PMID:15124103 SUPPORT In Vitro

"Cellular localization to the endoplasmic reticulum suggests a role for GDD1 in the regulation of intracellular calcium homeostasis."

Establishes the ER localization that constrains where the scrambling defect can act; the calcium-regulation role is inferred rather than measured here, hence PARTIAL.

Pro-Osteogenic Signalling Dysregulation in Osteoblasts

The osteoblast-side intermediate between the ANO5 defect and the remodelling imbalance. Four convergent mouse studies identify signalling routes by which perturbed ANO5 drives excess bone formation: AMPK phosphorylation rises and accelerates glycolysis and PGC1a-dependent mitochondrial respiration; AMPK in turn upregulates ATG9A and activates autophagy, which is required for the excess osteogenesis; miR-34c-5p falls, de-repressing KLF4 and activating canonical Wnt/beta-catenin; and Akt phosphorylation falls, with Akt re-activation suppressing mineralization. Each arm has a pharmacological or genetic rescue. READ THE GENOTYPES BEFORE TRANSFERRING ANY OF THIS TO HUMAN GDD. The AMPK and Akt arms come from the Ano5 p.Cys360Tyr knock-in, which carries an actual human GDD allele. The autophagy/ATG9A, miR-34c-5p/KLF4 and NF-kB arms come from Ano5-null mice - a genotype that in humans causes myopathy, not bone disease. So this node is better evidenced than the bare "unknown intermediates" it replaces, but it is not thereby established for human GDD, and the two model classes are not interchangeable. See `gdd_mouse_model_mismatch`.

osteoblast CL:0000062

AMPK-driven glycolytic shift GO:0006096 ↑ INCREASED autophagy (ATG9A-dependent) GO:0006914 ↑ INCREASED canonical Wnt/beta-catenin signalling via KLF4 GO:0060070 ↑ INCREASED PI3K/Akt signalling in osteoblasts GO:0043491 ↓ DECREASED

AMP-activated protein kinase activity GO:0004679 ↑ INCREASED

Animal models

Ano5 p.Cys360Tyr knock-in mouse Mouse rescues The AMPK inhibitor Compound C reverses the skeletal phenotype in this genotype-matched knock-in, restraining formation and restoring osteoclastogenesis by suppressing PGC1a and promoting PGC1b.

Ano5 knockout mouse Mouse rescues Two independent in vivo rescues of the osteogenic excess in Ano5-null mice: the autophagy inhibitor 3-methyladenine alleviates the bone phenotype, and miR-34c-5p delivered by AAV rescues the abnormally thickened cortical bone, improves biomechanics and lowers serum P1NP. Both establish their arm as causal rather than correlative.

Downstream

Dysregulated Osteoblast and Osteoclast Differentiation These signalling changes are what the differentiation phenotype is measured as; each arm's rescue reverses the osteogenic excess.

Show evidence (4 references)

PMID:40067389 SUPPORT Model Organism

"Further analysis revealed that Ano5 deficiency upregulated the expression of ATG9A, and silencing ATG9A significantly reduced both autophagy and osteogenic activity in Ano5-/- mCOBs."

Establishes ATG9A-dependent autophagy as a required intermediate for the excess osteogenesis, with the silencing experiment supplying the causal direction.

PMID:41717545 SUPPORT Model Organism

"Furthermore, ANO5 mutation promoted the phosphorylation of AMPK, the classical sensor of energy metabolism."

Places AMPK activation downstream of a genotype-matched GDD knock-in allele (p.Cys360Tyr), not merely of Ano5 loss.

PMID:40508076 SUPPORT Model Organism

"In this study, we found that Ano5 deficiency notably inhibited miR-34c-5p expression. Krüppel-Like Factor 4 (Klf4), a target gene of miR-34c-5p confirmed by dual luciferase reporter assay, was up-regulated in Ano5-/- mCOBs, accompanied by activated downstream canonical Wnt/β-catenin signaling..."

Supplies the miR-34c-5p/KLF4/beta-catenin arm with a validated target relationship.

+ 1 more reference

Osteoclast Differentiation Blockade and Apoptosis

The osteoclast-side intermediate. Perturbed ANO5 suppresses RANKL-induced early signalling and the NF-kB pathway, reducing NFATc1, c-Fos and the osteoclast effector programme and leaving disrupted actin rings with impaired mineral resorption. Separately, calcium dyshomeostasis in Ano5-null osteoclasts drives an overactivated endoplasmic-reticulum stress response and CHOP-mediated apoptosis, so osteoclasts are both under-differentiated and actively lost. Akt is the third arm: it is reduced in the knock-in, and the Akt activator SC79 restores multinucleated osteoclast formation. The same genotype caveat as the osteoblast node applies - the NF-kB and ER-stress arms are null-mouse work.

osteoclast CL:0000092

canonical NF-kappaB signalling in osteoclast precursors GO:0007249 ↓ DECREASED response to endoplasmic reticulum stress GO:0034976 ↑ INCREASED osteoclast apoptosis GO:0006915 ↑ INCREASED

Animal models

Ano5 p.Cys360Tyr knock-in mouse Mouse rescues The Akt activator SC79 restores osteoclast formation in this genotype-matched knock-in - multinucleated TRAP-positive osteoclasts and actin rings reappear with the osteoclast effector programme re-expressed - while the mirror experiment in osteoblasts suppresses mineralization. One intervention corrects both arms.

Ano5 knockout mouse Mouse recapitulates Reproduces the osteoclast blockade with suppressed RANKL/NF-kB signalling, disrupted actin rings and reduced resorption, plus ER-stress/CHOP-driven osteoclast apoptosis.

Downstream

Dysregulated Osteoblast and Osteoclast Differentiation Reduced osteoclast differentiation and increased osteoclast apoptosis are the resorption-side half of the remodelling imbalance.

Show evidence (3 references)

PMID:36989132 SUPPORT Model Organism

"RANKL-induced early signaling pathways were suppressed in Ano5-/- osteoclasts and Ano5 knockdown RAW264.7 cells. Moreover, the inhibitory effects of NF-κB signalling pathway on osteoclastogenesis were partially attenuated with NF-κB signalling activator."

Establishes suppressed RANKL/NF-kB signalling as the osteoclast intermediate, with partial pharmacological reversal supplying the causal direction.

PMID:40049314 SUPPORT Model Organism

"In addition, the endoplasmic reticulum stress (ERS) response was significantly enhanced in Ano5-/- osteoclasts, possibly because of calcium dyshomeostasis, which leading to the increased proportion of apoptotic osteoclasts via the activation of the C/EBP homologous protein (CHOP) signalling pathway"

Supplies the ER-stress/CHOP apoptosis arm and ties it back to calcium dyshomeostasis, connecting this node to the upstream ER calcium claim.

PMID:39866532 SUPPORT Model Organism

"Akt activation promoted the generation of TRAP-positive multinucleated osteoclasts and the formation of actin rings in Ano5 KI/KI BMMs cultures"

The Akt arm in the genotype-matched knock-in, with rescue of both multinucleation and the actin ring defect noted elsewhere in this entry.

Dysregulated Osteoblast and Osteoclast Differentiation

ANO5 is expressed in osteoblasts and periodontal ligament cells, and manipulating it in cell culture perturbs both arms of bone remodelling. Knockdown in osteoblast precursors raises osteoblast marker expression and mineral nodule formation, while ANO5 supports RANKL-driven osteoclast differentiation through Akt-NFATc1 signalling and its loss impairs osteoclastogenesis and actin-ring formation. The direction of effect is not consistent across systems - which is itself informative, and is the reason the cellular arm is curated as a hypothesis-tagged step rather than a settled mechanism. Both processes therefore carry `modifier: DYSREGULATED` rather than a direction: knockdown in MC3T3-E1 precursors increased osteoblast markers and mineralization, ANO5 downregulation in another system did not affect osteoblast differentiation at all, and the Ano5-null osteoblasts of a third study showed decreased indices. Asserting INCREASED here would pick a winner among three published directions.

Gain-of-function scramblase model Variant-class-stratified GOF/LOF sub-entity model

osteoblast CL:0000062 osteoclast CL:0000092

osteoblast differentiation GO:0001649 ↕ DYSREGULATED osteoclast differentiation GO:0030316 ↕ DYSREGULATED

Animal models

Ano5 p.Cys360Tyr knock-in mouse Mouse recapitulates Directly measures the two-lineage remodelling disturbance, with increased osteoblastogenesis and decreased osteoclastogenesis in primary cultures.

Ano5 knockout mouse (Li et al., low-bone-mass line) Mouse recapitulates Measures the two-lineage remodelling disturbance and ties it to calcium oscillations, WNT/beta-catenin and RANKL-NFATc1 signalling.

Downstream

High-Turnover Skeletal Remodelling Imbalance A coordinated disturbance of osteoblast and osteoclast behaviour is what produces the paradoxical combination of sclerotic, thickened bone that nevertheless fractures. This edge is claimed by BOTH mechanistic hypotheses, and that is the point: they disagree about the SIGN of the remodelling change - the gain-of-function model predicts increased indices and high bone mass, the sub-entity model predicts decreased indices and osteopenia for loss-of-function alleles - while agreeing that the cellular imbalance is what produces the skeletal phenotype.

Jaw Cemento-Osseous Fibrous Lesion Formation The jaw-selective step. Why a systemically expressed ER scramblase produces focal, expansile fibro-osseous masses confined to the gnathic skeleton is unexplained; see the knowledge-gap discussion. The expanding cell population on that node is deliberately left as free text rather than bound to CL:0000061 cementoblast, because which lineage expands is precisely what `gdd_jaw_selectivity_gap` records as untested.

Show evidence (3 references)

PMID:28176803 SUPPORT In Vitro

"After Ano5 gene knock-down with shRNA in MC3T3-E1 osteoblast precursors we saw elevated expression of osteoblast-related genes such as Col1a1, osteocalcin, osterix and Runx2 as well as increased mineral nodule formation in differentiating cells."

Links ANO5 perturbation to an osteoblast differentiation and mineralization phenotype in an osteoblast precursor line.

PMID:30557634 SUPPORT In Vitro

"Furthermore, Ano5-mediated Akt phosphorylation resulted in nuclear factor of activated T-cells c1 (NFATc1) activation, indicating that Ano5 regulates osteoclast differentiation through activation of the Akt-NFATc1 signaling pathway."

Places ANO5 in the RANKL-Akt-NFATc1 osteoclast differentiation axis, the osteoclast arm of the remodelling imbalance.

PMID:30557634 SUPPORT In Vitro

"Downregulation of Ano5 expression did not affect osteoblast differentiation and mineralization, while ectopic expression of Ano5 significantly enhanced receptor activator of nuclear factor kappa B ligand (RANKL)-induced osteoclast differentiation."

A directly contrary result on the osteoblast arm - no effect, where another system reported an increase - which is why the osteoblast process carries DYSREGULATED rather than a direction. Also shows the osteoclast effect runs the opposite way from the knock-in mouse.

High-Turnover Skeletal Remodelling Imbalance

Full osteological assessment of a GDD patient carrying p.Ser500Phe showed increased trabecular bone mass with elevated serum markers of both bone formation and bone resorption, and an iliac crest biopsy with markedly increased osteoblast and osteoclast indices. GDD is therefore not a low-turnover sclerosing disease: bone is being both laid down and resorbed faster than normal, and the resulting tissue is sclerotic in the diaphyses yet mechanically inadequate. Elevated serum alkaline phosphatase is the usual laboratory correlate of this high-turnover presentation, but it is not universal across GDD: the osteopenic sub-entity has been reported with low bone-formation markers, and individual patients with normal ALP are documented.

bone mineralization GO:0030282 ↑ INCREASED

diaphysis UBERON:0004769

Animal models

Ano5 knockout mouse (Li et al., low-bone-mass line) Mouse rescues Osteoanabolic parathyroid hormone restored bone strength in the null mouse - the only pharmacological rescue reported for any ANO5 bone model, and the origin of the osteoanabolic option recorded under treatments.

Downstream

Diaphyseal Sclerosis and Bone Fragility Accelerated, poorly coordinated remodelling yields thickened sclerotic diaphyses whose material quality does not match their apparent density.

Show evidence (2 references)

PMID:27541832 SUPPORT Human Clinical

"We thereby identified increased trabecular bone mass accompanied by elevated serum markers of bone formation and bone resorption."

Establishes the high-turnover character of the skeletal phenotype in a genetically confirmed GDD patient.

PMID:27541832 SUPPORT Human Clinical

"The high turnover bone pathology was further confirmed through the analysis of an iliac crest biopsy, where osteoblast and osteoclast indices were remarkably increased."

Histomorphometric confirmation that both cell lineages are hyperactive, tying the tissue phenotype back to the cellular node.

Jaw Cemento-Osseous Fibrous Lesion Formation

The gnathic component of GDD is a multi-quadrant fibro-osseous lesion of the mandible and maxilla - cementum-like calcified deposits scattered in a fibroblastic stroma - that expands, deforms the face, and frequently becomes secondarily infected. It has been variously reported as florid cemento-osseous dysplasia, cemento-ossifying fibroma, or familial gigantiform cementoma, and ANO5 p.Cys356Tyr has since been found in familial gigantiform cementoma kindreds, suggesting that entity is an atypical variant of GDD rather than a separate disease. Notably, osteosclerosis - the hallmark of the long-bone lesion - is not a feature of the jaw lesion, so the two components of GDD are not the same pathology in two places.

cementoblast or periodontal ligament cell (lineage unresolved)

mandible UBERON:0001684

Downstream

Mandibular Osteomyelitis and Facial Deformity Expansile avascular fibro-osseous masses in tooth-bearing bone deform the face and provide a nidus for purulent infection.

Show evidence (2 references)

PMID:37649308 SUPPORT Human Clinical

"Results showed that all three patients harbored the heterozygous mutation c.1067G > A (p.Cys356Tyr) in the ANO5 gene."

Ties the recurrent GDD allele to expansile multi-quadrant gnathic fibro-osseous disease, supporting a shared lesion biology.

PMID:37649308 SUPPORT Human Clinical

"Our findings indicate that FGC may be an atypical variant of GDD, providing evidence for the feasibility of ANO5 gene testing as an auxiliary diagnostic method for complex cases with multiple quadrants."

Supports treating familial gigantiform cementoma as within the GDD spectrum rather than as a differential to be excluded.

Diaphyseal Sclerosis and Bone Fragility

The extragnathic skeletal phenotype: sclerosis and cortical thickening of the diaphyses of the tubular bones, bowing of the lower limbs, and recurrent fractures that typically begin around puberty but may present prenatally as bone bowing. The combination of radiographically dense bone with a high fracture rate is the feature that historically caused GDD to be misfiled as osteogenesis imperfecta.

diaphysis UBERON:0004769

Animal models

Ano5 p.Cys360Tyr knock-in mouse Mouse recapitulates Reproduces the cardinal long-bone features of GDD - sclerosis, cortical thickening, bowing and fragility - in a genotype matched to a human GDD allele.

Ano5 p.T491F knock-in mouse Mouse fails to recapitulate A genotype-matched GDD allele that produces no bone phenotype in mouse, in direct conflict with the human disease and with the p.Cys360Tyr knock-in.

Ano5 knockout mouse Mouse partially recapitulates Reproduces GDD-like jawbone enlargement, tibial bowing and diaphyseal sclerosis with cortical thickening, but from a genotype that does not correspond to human GDD.

Show evidence (3 references)

PMID:28176803 SUPPORT Human Clinical

"One Caucasian family with seven affected members exhibited frequent bone fractures and florid osseous dysplasia (p.Cys356Tyr), while one Chinese family with two affected members suffered from cementoma and purulent osteomyelitis (p.Cys360Tyr)."

Documents the co-occurrence of fractures with gnathic fibro-osseous disease in genotyped families.

PMID:27541832 SUPPORT Human Clinical

"Gnathodiaphyseal dysplasia (GDD) is a rare skeletal syndrome that involves an osteopetrosis-like sclerosis of the long bones and fibrous dysplasia-like cemento-osseous lesions of the jawbone."

Substantiates the sclerosis half of this node, which the fracture-focused evidence above does not address.

PMID:28176803 SUPPORT Human Clinical

"his radiographs showed gross thickening of the diaphyseal cortices of long bones with narrow medullary canals"

Human radiographic evidence for the cortical-thickening component of this node.

Mandibular Osteomyelitis and Facial Deformity

Jaw lesions enlarge through adolescence and adult life, producing maxillofacial deformity and malocclusion that may require orthognathic or reconstructive surgery, and are susceptible to purulent osteomyelitis. This was a defining feature of the original Japanese kindred.

mandible UBERON:0001684

Show evidence (1 reference)

PMID:28176803 SUPPORT Human Clinical

"first described in a large Japanese family including 21 patients exhibiting frequent bone fractures in adolescence and purulent osteomyelitis of the jaws during adult life"

Establishes the age-staged pattern of adolescent fractures followed by adult jaw osteomyelitis in the founding kindred.

✶

Histopathology

1

Jaw fibro-osseous lesion histology

Cementum-like calcified deposits scattered within a fibroblastic stroma, with psammomatoid bodies and abundant mineralization of vessel walls. Riminucci et al. used precisely this histology to separate the entity from the sclerosing disorders, since osteosclerosis is NOT a feature of the jaw lesion even though it defines the long-bone lesion. Psammomatoid bodies are characteristic but not invariable, so their absence does not exclude the diagnosis.

Show evidence (1 reference)

PMID:37649308 SUPPORT Human Clinical

"Riminucci et al. have described the histopathological features of jaw lesions, including cementum‐ossifying fibroma, psammomatoid bodies, and abundant mineralization in the vessel wall, and refined the name of this disease entity to gnathodiaphyseal dysplasia, as osteosclerosis is not a feature..."

Gives the defining histological features and the explicit statement that the jaw lesion is not osteosclerotic - which is why this entry models the gnathic and diaphyseal components as separate nodes rather than one pathology in two sites.

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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

10

Head and Neck 2

Abnormality of the dentition HP:0000164

Show evidence (1 reference)

PMID:38922934 SUPPORT Human Clinical

"Clinical manifestations range from recurrent dental infections with mild jaw lesions to severe bone fragility with several fractures associated with large jaw lesions requiring disfiguring surgeries."

Places recurrent dental infection at the mild end of the GDD clinical spectrum, establishing dental involvement as a disease manifestation.

Abnormal mandible morphology HP:0000277

Show evidence (1 reference)

PMID:41193275 SUPPORT Human Clinical

"Patients typically present with pathological fractures, muscle weakness, and jawbone deformities."

States jawbone deformity as a typical GDD presentation.

Musculoskeletal 2

Recurrent fractures HP:0002757

Show evidence (1 reference)

PMID:28176803 SUPPORT Human Clinical

"One Caucasian family with seven affected members exhibited frequent bone fractures and florid osseous dysplasia (p.Cys356Tyr), while one Chinese family with two affected members suffered from cementoma and purulent osteomyelitis (p.Cys360Tyr)."

Reports frequent bone fractures in a genotyped seven-member GDD family.

Osteopenia HP:0000938

Show evidence (1 reference)

PMID:35982081 SUPPORT Human Clinical

"First, our GDD family with the mutation did not have a history of severe bone fractures, although it presented decreased BMD throughout the body."

Documents the low-bone-mass GDD presentation, which is the counterpart of the high-bone-mass presentation cited on the diaphyseal-sclerosis phenotype.

Other 6

Diaphyseal sclerosis HP:0003034

Show evidence (1 reference)

PMID:27541832 SUPPORT Human Clinical

"Gnathodiaphyseal dysplasia (GDD) is a rare skeletal syndrome that involves an osteopetrosis-like sclerosis of the long bones and fibrous dysplasia-like cemento-osseous lesions of the jawbone."

Describes the long-bone sclerosis that defines the diaphyseal half of the disease name.

Cortical thickening of long bone diaphyses HP:0005791

Show evidence (2 references)

PMID:34841576 SUPPORT Model Organism

"Homozygous Ano5 knock-in mice (Ano5KI/KI ) replicated GDD-like skeletal features, including massive jawbones, bowing tibia, bone fragility, sclerosis, and cortical thickening of the femoral and tibial diaphysis."

Model-organism corroboration of diaphyseal cortical thickening; the human evidence is the accompanying PMID:28176803 item, which is what actually substantiates the phenotype.

PMID:28176803 SUPPORT Human Clinical

"his radiographs showed gross thickening of the diaphyseal cortices of long bones with narrow medullary canals"

Direct human radiographic documentation of diaphyseal cortical thickening in a genotyped GDD patient, so this phenotype does not rest on mouse data alone.

Cementoma HP:0012328

Show evidence (1 reference)

PMID:28176803 SUPPORT Human Clinical

"One Caucasian family with seven affected members exhibited frequent bone fractures and florid osseous dysplasia (p.Cys356Tyr), while one Chinese family with two affected members suffered from cementoma and purulent osteomyelitis (p.Cys360Tyr)."

Documents cementoma in a genotyped GDD family.

Mandibular osteomyelitis HP:0007626

Show evidence (1 reference)

PMID:28176803 SUPPORT Human Clinical

"first described in a large Japanese family including 21 patients exhibiting frequent bone fractures in adolescence and purulent osteomyelitis of the jaws during adult life"

Documents purulent jaw osteomyelitis as an adult-onset feature of GDD.

Bowing of the legs HP:0002979

Show evidence (1 reference)

PMID:38922934 SUPPORT Human Clinical

"The cases involved two fetuses exhibiting bone bowing, which led to the diagnosis of GDD."

Establishes bone bowing as a recognized, and potentially prenatal, GDD presentation.

Elevated circulating alkaline phosphatase concentration HP:0003155

Show evidence (2 references)

PMID:34841576 SUPPORT Model Organism

"Serum alkaline phosphatase (ALP) levels were elevated in Ano5KI/KI mice as in GDD patients with p.Cys360Tyr mutation."

Reports elevated ALP in the knock-in mouse and states the same finding in the corresponding human patients; paired below with direct human evidence so this phenotype does not rest on mouse data alone.

PMID:37649308 SUPPORT Human Clinical

"There was a slight increase in alkaline phosphatase levels in the blood before the last surgery."

Human ALP elevation in an ANO5 p.Cys356Tyr patient. PARTIAL because it is a single case and the rise is described as slight; the same paper records another patient whose ALP was normal, so this is not a constant finding.

🧬

Genetic Associations

1

ANO5

Gene: ANO5 hgnc:27337 relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (3 references)

PMID:15124103 SUPPORT Human Clinical

"By linkage analysis of a large Japanese family with GDD, we previously mapped the GDD locus to chromosome 11p14.3-15.1."

Establishes the GDD locus subsequently shown to contain ANO5.

PMID:32112655 SUPPORT In Vitro

"Mutations in the human TMEM16E/ANO5 gene are causative for gnathodiaphyseal dysplasia (GDD), a rare bone malformation and fragility disorder, and for two types of muscular dystrophy (MD)."

States the two-disease allelic architecture of ANO5 that this entry contrasts against the LGMD entry.

PMID:28176803 SUPPORT Human Clinical

"absent in dbSNP, 1000Genomes, the Exome Variant Server (~6500 exomes) and the ExAC database"

Population-database absence of the GDD alleles, supporting pathogenicity and relevant to the allelic contrast: ANO5 truncating alleles are by comparison common enough in the population to sustain a recessive disease.

Variants (9)

ANO5 p.Cys356Tyr Pathogenic

Gene: ANO5 hgnc:27337

The most frequently recurring GDD allele, seen in unrelated GDD kindreds and in familial gigantiform cementoma.

Show evidence (1 reference)

PMID:37649308 SUPPORT Human Clinical

"Results showed that all three patients harbored the heterozygous mutation c.1067G > A (p.Cys356Tyr) in the ANO5 gene."

Documents the recurrent heterozygous p.Cys356Tyr allele in gnathic fibro-osseous disease.

ANO5 p.Thr513Ile Pathogenic

Gene: ANO5 hgnc:27337

The GDD allele with the most direct functional characterization: it confers calcium-independent phospholipid scrambling in heterologous expression. It is also the allele reported in a dominant kindred with combined muscle and bone involvement, so it is the pivot point for both the gain-of-function argument and the challenge to a clean phenotypic dichotomy.

Show evidence (1 reference)

PMID:34291158 SUPPORT Human Clinical

"Molecular testing revealed a missense variant in anoctamin 5 (ANO5) designated as c.1538C>T; p.Thr513Ile, which was previously described in a large kindred with GDD."

Identifies the recurrent p.Thr513Ile allele and its prior association with GDD.

ANO5 p.Cys356Arg and p.Cys356Gly Pathogenic

Gene: ANO5 hgnc:27337

The two founding GDD alleles, at the evolutionarily conserved cysteine 356.

Show evidence (1 reference)

PMID:15124103 SUPPORT Human Clinical

"Two missense mutations (C356R and C356G) of GDD1 were identified in the two families with GDD (the original Japanese family and a new African American family)"

The founding allele identifications in two independent GDD kindreds.

ANO5 p.Cys360Tyr Pathogenic

Gene: ANO5 hgnc:27337

A recurrent GDD allele, reported with cementoma and purulent osteomyelitis, and the allele modelled by the p.Cys360Tyr knock-in mouse.

Show evidence (1 reference)

PMID:28176803 SUPPORT Human Clinical

"while one Chinese family with two affected members suffered from cementoma and purulent osteomyelitis (p.Cys360Tyr)"

Ties p.Cys360Tyr to a genotyped GDD family with the gnathic phenotype.

ANO5 p.Cys360Arg Pathogenic

Gene: ANO5 hgnc:27337

A variant at the second recurrently affected cysteine, segregating with disease in a large Iranian kindred - useful because segregation across an extended pedigree is stronger evidence of pathogenicity than a single proband.

Show evidence (1 reference)

PMID:35758145 SUPPORT Human Clinical

"Sanger sequencing was performed to confirm the detected pathogenic variant in DNA samples of the entire family (except deceased individuals), which segregated with the disease within the family."

Reports co-segregation of the p.Cys360Arg allele with GDD across a large pedigree.

ANO5 p.Cys356Phe Pathogenic

Gene: ANO5 hgnc:27337

A third substitution at cysteine 356, found by genome sequencing in a large family first diagnosed as cherubism - the allele that makes the cherubism differential concrete rather than theoretical.

Show evidence (1 reference)

PMID:30554457 SUPPORT Human Clinical

"Through WGS, we identified a novel mutation c.1067G>T (p.C356F) in ANO5, and bioinformatics analyses and structural modeling showed that the mutation was deleterious."

Identifies the p.Cys356Phe allele and the in silico support for its deleteriousness.

ANO5 p.Arg215Gly Pathogenic

Gene: ANO5 hgnc:27337

A sporadic GDD allele lying in the extracellular loop after the first transmembrane domain - the more N-terminal of the two mutational clusters.

Show evidence (1 reference)

PMID:28176803 SUPPORT Human Clinical

"In addition, two different novel mutations (p.Gly518Glu and p.Arg215Gly) were identified in sporadic patients without family history."

Reports p.Arg215Gly and p.Gly518Glu as sporadic GDD alleles, extending the spectrum beyond the familial cysteine cluster.

ANO5 p.Leu370_Ala371insDYWRLNSTCL Pathogenic

Gene: ANO5 hgnc:27337

The de novo in-frame insertion that anchors the low-bone-mass argument. Unlike every other allele curated here it is not a missense substitution, it reduces TMEM16E expression, and the family presented with osteopenia rather than osteosclerosis - which is why this entry curates two bone-mass directions and an EMERGING sub-entity hypothesis rather than a single phenotype.

Show evidence (2 references)

PMID:35982081 SUPPORT Human Clinical

"we report a de novo pathogenic ANO5 frameshift insertion mutation (c.1080_1081insGATTATTGGAGACTAAATAGTACGTGTTTG, p.L370_A371insDYWRLNSTCL)"

Identifies the insertion allele at nucleotide resolution in the osteopenic GDD family.

PMID:35982081 SUPPORT In Vitro

"Our results also confirm that the mutation resulted in partial instead of complete LOF of the TMEM16E protein."

Establishes the allele as a PARTIAL loss of function, which is how a reduced-activity allele can be dominant without implying a full null would be.

ANO5 p.Ser500Phe Pathogenic

Gene: ANO5 hgnc:27337

A de novo GDD allele in a patient with recurrent femoral diaphyseal fractures, whose full osteological workup established the high-turnover osteosclerotic phenotype. Its murine equivalent is the knock-in that failed to reproduce GDD.

Show evidence (1 reference)

PMID:27541832 SUPPORT Human Clinical

"We report a new case of GDD in a 13-year-old boy with recurrent diaphyseal fractures of the femur, in whom we identified a novel de novo missense mutation in the ANO5 gene, causing a p.Ser500Phe substitution at the protein level."

Identifies the de novo p.Ser500Phe allele and the clinical context in which it was characterized.

💊

Medical Actions

4

Bisphosphonate Therapy (Pamidronate)

Action: Pharmacotherapy NCIT:C15986

Agent: pamidronate CHEBI:7903

Intravenous pamidronate has been given to GDD patients with low bone mass and fractures. The evidence is case-level - a child treated with seven infusions from 15 months of age, and a separate patient whose osteopenia was managed with pamidronate - and no controlled data exist. The mechanistic caveat is the important part and follows directly from the sub-entity split this entry curates. An antiresorptive suppresses bone resorption, which is coherent for the low-bone-mass, osteopenic GDD sub-entity, but is the wrong direction for the high-turnover osteosclerotic sub-entity, where trabecular bone mass is already increased. Bone mass and turnover markers should therefore be established before an antiresorptive is chosen, rather than inferring from the diagnosis alone.

Mechanism Target:

INHIBITS High-Turnover Skeletal Remodelling Imbalance — Suppresses the osteoclastic resorption arm of the remodelling imbalance. Directionally appropriate only for the low-bone-mass sub-entity.

Show evidence (2 references)

PMID:29175271 SUPPORT Human Clinical

"We assessed his response to a total of 7 pamidronate infusions commencing at age 15months"

Documents pamidronate exposure in a GDD patient. PARTIAL because it is a single case and the snippet records that a response was assessed, not that a particular benefit was established.

PMID:28176803 SUPPORT Human Clinical

"The osteopenia is being treated with pamidronate."

A second, independent report of pamidronate use, and notably in an OSTEOPENIC patient - the sub-entity for which an antiresorptive is directionally appropriate.

Osteoanabolic Therapy (Parathyroid Hormone) - Preclinical Only

Action: Pharmacotherapy NCIT:C15986

Parathyroid hormone enhanced bone strength in Ano5-knockout mice. This is a mouse result in a genotype that does not correspond to human GDD, and no human GDD patient has been reported treated with an osteoanabolic. It is curated because it is the only pharmacological rescue reported for any ANO5 bone model, and because it is the directional complement of the bisphosphonate entry: osteoanabolic for low bone mass, antiresorptive for high turnover. This is NOT a clinical recommendation. No `therapeutic_agent` is bound, deliberately. The source says "parathyroid hormone" without naming an analogue. Teriparatide has both CHEBI and NCIT identities and would be the obvious binding, but it is specifically PTH 1-34, and asserting it would attribute an agent the paper does not specify; neither ontology offers a plain "parathyroid hormone" therapeutic term. Left unbound rather than made precise beyond the evidence.

Mechanism Target:

MODULATES High-Turnover Skeletal Remodelling Imbalance — Shifts the remodelling balance towards formation; demonstrated only in the low-bone-mass null mouse.

Show evidence (1 reference)

PMID:35982081 SUPPORT Model Organism

"Osteoanabolic treatment of parathyroid hormone was effective in enhancing bone strength in Ano5 KO mice."

Model-organism evidence only, in a null genotype unlike human GDD, hence PARTIAL and explicitly not a treatment recommendation.

Orthognathic and Reconstructive Jaw Surgery

Action: orthopedic surgical procedure Ontology label: Orthopedic Surgical Procedure NCIT:C16186

Surgical management of the expansile gnathic lesions and the resulting malocclusion and facial deformity. Orthognathic surgery (Le Fort I advancement with bilateral sagittal split osteotomy) has been performed safely in a GDD patient with stable two-year occlusal follow-up, but the evidence base is single case reports and best practices are not established. This is anatomical correction, not disease modification; no therapy targeting the ANO5 mechanism exists.

Mechanism Target:

MODULATES Mandibular Osteomyelitis and Facial Deformity — Alters the anatomical outcome node - the deformity and malocclusion produced by the jaw lesions - without acting on any upstream mechanism node.

Show evidence (2 references)

PMID:41193275 SUPPORT Human Clinical

"He was treated with LeFort 1 advancement and Bilateral Sagittal Split Osteotomy of the mandible with setback procedures. No complications were seen and 2-year follow-up showed stable dental occlusion."

Documents the orthognathic procedure and its two-year outcome in a GDD patient.

PMID:41193275 SUPPORT Human Clinical

"Other procedures are possible, but more research is needed to develop best practices for this disorder."

The authors' own statement that the surgical evidence base is not yet sufficient to define standard management.

Fracture Fixation and Orthopedic Management

Action: orthopedic surgical procedure Ontology label: Orthopedic Surgical Procedure NCIT:C16186

Operative fixation of pathological diaphyseal fractures. Sclerotic, thickened cortices make instrumentation technically demanding, and the reported experience is case-level.

Mechanism Target:

MODULATES Diaphyseal Sclerosis and Bone Fragility — Symptomatic management of the fracture burden at the outcome node; it does not act on the ANO5 mechanism.

Show evidence (2 references)

PMID:33826556 SUPPORT Human Clinical

"Internal fixation with the Ender nail was effective for the tubular bone with deformity. Callus formation was observed without delay."

Reports the outcome of operative fixation in a GDD diaphyseal fracture, including the observation that callus formation was not delayed - relevant because sclerotic GDD bone might be expected to heal poorly.

PMID:33826556 SUPPORT Human Clinical

"This is the first report describing the treatment of fracture in an adult patient with gnathodiaphyseal dysplasia."

Establishes how thin the evidence base is - a single adult case at the time of publication - which is why this treatment is not presented as standard practice.

🔬

Biochemical Markers

1

Bone turnover markers

Show evidence (2 references)

PMID:27541832 SUPPORT Human Clinical

"We thereby identified increased trabecular bone mass accompanied by elevated serum markers of bone formation and bone resorption."

Documents the elevated-marker, high-turnover pattern in a genetically confirmed patient.

PMID:35982081 SUPPORT Human Clinical

"First, our GDD family with the mutation did not have a history of severe bone fractures, although it presented decreased BMD throughout the body."

The contrasting low-bone-mass presentation, which is why marker direction is recorded as sub-entity-dependent rather than fixed.

🔬

Diagnosis

4

Recognition and misdiagnosis

GDD is substantially under-recognized. Two thirds of molecularly confirmed cases were initially given another diagnosis, most often osteogenesis imperfecta or fibrous dysplasia, and clinicians continue to manage it as an OI variant. The diagnostic combination that should prompt ANO5 testing is the one that makes no sense under either alternative: recurrent fractures together with expansile cemento-osseous jaw lesions, with diaphyseal sclerosis and cortical thickening on radiographs rather than the osteopenia expected in OI.

Show evidence (1 reference)

PMID:30554457 SUPPORT Human Clinical

"67% of GDD cases confirmed by molecular testing were initially misdiagnosed."

Quantifies the misdiagnosis rate, which is the practical reason this entry exists as a distinct disease rather than as a note on osteogenesis imperfecta.

Osteological assessment (densitometry, HR-pQCT, turnover markers)

Because GDD's bone-mass direction is not uniform, densitometry plus high-resolution peripheral quantitative CT plus serum turnover markers together establish which presentation a given patient has - and that determines whether an antiresorptive or an osteoanabolic is directionally appropriate. This combination is what established the high-turnover osteosclerotic phenotype in the p.Ser500Phe patient; iliac crest biopsy added histomorphometric confirmation.

dual-energy X-ray absorptiometry with HR-pQCT and bone turnover markers NCIT:C48789

Show evidence (1 reference)

PMID:27541832 SUPPORT Human Clinical

"we focused on a full osteologic assessment using dual-energy X-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT), and serum analyses"

Names the modality combination used to characterize GDD bone status. The same paper opens by stating there is still no established consensus regarding the bone status of GDD patients, which is why this assessment is informative rather than routine.

Radiographic jaw and long-bone surveillance

Radiography carries the diagnosis and tracks it over decades: the jaw lesion by dental and panoramic imaging, the long bones by plain films. A patient followed from age one to over forty showed diaphyseal cortical widening at three years, sclerosis adjacent to the permanent tooth roots at nine, and a clearly denser mass once the secondary dentition completed at fourteen. Because the diaphyseal change precedes the jaw lesion, imaging both compartments is what makes the combination recognizable before it is obvious.

serial radiography of the jaws and long bones NCIT:C16502

Show evidence (1 reference)

PMID:40861765 SUPPORT Human Clinical

"This report describes the long-term radiographic follow-up study of jaw lesions in a GDD-affected woman of >40 years of age from the age of one onward."

Establishes serial radiography as the modality by which GDD jaw lesions are detected and followed over time.

Molecular confirmation

Diagnosis is confirmed molecularly. Because the GDD allele spectrum is tightly clustered, targeted ANO5 sequencing is informative; exome or genome sequencing is used when the presentation is atypical or the differential is broad, and was how the two reported prenatal cases were resolved.

Show evidence (1 reference)

PMID:38922934 SUPPORT Human Clinical

"Diagnostic techniques depend on the context and include targeted genetic testing of ANO5, untargeted molecular analysis with whole-exome sequencing, or whole-genome sequencing."

States the molecular diagnostic strategies and that the choice is context-dependent.

📈

Progression

2

Early childhood - long bones first, jaws silent

Age: 1-8 years

The two components of GDD do not begin together. In a woman followed radiographically from age one to over forty, widening of the diaphyseal cortices of the femur and radius was already present at three years old while the jawbones were still asymptomatic. The long-bone lesion is therefore the earlier finding, which matters diagnostically: a child with unexplained diaphyseal cortical thickening and fractures may not yet show the gnathic lesion that makes the diagnosis obvious.

Show evidence (1 reference)

PMID:40861765 SUPPORT Human Clinical

"At three years of age, widening of the diaphyseal cortices in the femur and radius was observed, although no symptoms were observed in the jawbones."

Establishes that the diaphyseal change precedes any jaw involvement in this long-followed patient.

Mixed dentition onward - jaw lesion appears and grows

Age: 9 years to adulthood

The gnathic lesion emerges around the mixed-dentition stage and then enlarges with age rather than remaining static. Sclerosis appeared adjacent to the permanent tooth roots at nine years, became a clearly denser mass once the secondary dentition was complete at fourteen, and continued to develop over four decades. The association with the erupting permanent dentition is a suggestive - though untested - hint towards the tissue-selectivity question recorded in `gdd_jaw_selectivity_gap`.

Show evidence (2 references)

PMID:40861765 SUPPORT Human Clinical

"At nine years of age, we observed a slightly sclerotic appearance in the alveolar and jawbones adjacent to the permanent tooth roots. After completion of the secondary dentition at 14 years of age, increased density of the sclerotic mass was clearly observed."

Dates the appearance of the jaw lesion to the mixed-dentition period and ties its progression to completion of the secondary dentition.

PMID:40861765 SUPPORT Human Clinical

"this study observed that the onset of the jawbone lesion had already appeared after the mixed dentition stage, and the sclerotic mass developed with age"

The authors' summary that the lesion is progressive rather than static across four decades of follow-up.

📊

Prevalence

1

Worldwide

Unknown Ultra Rare

No population-based estimate exists. The literature consistently describes GDD as rare or ultra-rare, and the qualitative class is recorded here rather than a fabricated rate; `rate_per_100000` is deliberately left unset. The largest aggregation is a literature review of about 108 clinically diagnosed individuals across 25 families, which is a case count, not a denominator.

Show evidence (1 reference)

PMID:29175271 SUPPORT Human Clinical

"Gnathodiaphyseal dysplasia (GDD; OMIM #166260) is an ultra-rare autosomal dominant disorder caused by heterozygous mutation in the anoctamin 5 (ANO5) gene"

Supports the qualitative ULTRA_RARE class, in a sentence that also states the heterozygous-mutation mechanism. No quantitative rate is asserted because none is reported anywhere in the literature.

🔀

Differential Diagnoses

4

Conditions with similar clinical presentations that must be differentiated from Gnathodiaphyseal Dysplasia:

Osteogenesis imperfecta

Overlapping Features The historical misdiagnosis, and still the commonest one. GDD was originally named "osteogenesis imperfecta with unusual skeletal lesions"; both cause recurrent fractures, but GDD adds diaphyseal sclerosis with cortical thickening and gnathic fibro-osseous lesions, whereas OI bone is typically osteopenic.

Show evidence (1 reference)

PMID:41193275 SUPPORT Human Clinical

"However, clinicians are still largely unaware of this entity and continue to label and treat it as a variation of Osteogenesis Imperfecta."

States that GDD continues to be misclassified as osteogenesis imperfecta in practice.

Cherubism

Overlapping Features Also presents with fibro-osseous lesions of the jawbones, and is a documented misdiagnosis: one family was initially diagnosed as cherubism, found to have no pathogenic SH3BP2 variant, and resolved to a novel ANO5 p.Cys356Phe allele by genome sequencing. A negative SH3BP2 result in a jaw fibro-osseous kindred should prompt ANO5 testing.

Show evidence (1 reference)

PMID:30554457 SUPPORT Human Clinical

"A family with patients with fibro-osseous lesions of the jawbones were initially diagnosed with cherubism. Sequencing of SH3BP2, which is the causal gene of cherubism, revealed no pathogenic mutation."

Documents cherubism as a real-world GDD misdiagnosis and the SH3BP2-negative result that redirected the workup to ANO5.

Fibrous dysplasia and McCune-Albright syndrome

Overlapping Features Share fibro-osseous jaw lesions, but are caused by activating GNAS1 mutations and are mosaic or somatic rather than germline dominant.

Show evidence (1 reference)

PMID:28176803 SUPPORT Human Clinical

"GDD shares clinical and pathological features of syndromes involving fibro-osseous jaw lesions, most notably fibrous dysplasia (FD) and McCune-Albright syndrome (MAS)."

Names the fibro-osseous differentials and, in the same passage, the distinct GNAS1 basis that separates them.

🐁

Animal Models

4

Ano5 p.Cys360Tyr knock-in mouse

The first knock-in mouse carrying a human GDD missense allele. Homozygotes reproduce massive jawbones, tibial bowing, bone fragility, diaphyseal sclerosis and cortical thickening, and elevated serum ALP, together with increased osteoblastogenesis and decreased osteoclastogenesis with disrupted osteoclast actin rings.

Species

Mouse

Genotype

Ano5 knock-in homozygous for the murine equivalent of human ANO5 p.Cys360Tyr

Publication

PMID:34841576

Pathograph links

Diaphyseal Sclerosis and Bone Fragility recapitulates fidelity: moderate Reproduces the cardinal long-bone features of GDD - sclerosis, cortical thickening, bowing and fragility - in a genotype matched to a human GDD allele.

Limitations: The phenotype is reported in homozygotes, whereas human GDD is heterozygous, so the model does not test dominance. A knock-in of a different human GDD allele (p.Ser500Phe, murine p.T491F) in an independent study produced no skeletal phenotype at all, so mouse results for GDD alleles are not consistent across alleles.

Readouts

Femoral and tibial diaphyseal cortical thickness and sclerosis

Direction: INCREASED

Interpretation: Structural correlate of the human diaphyseal sclerosis phenotype.

Show evidence (1 reference)

PMID:34841576 SUPPORT Model Organism

"Homozygous Ano5 knock-in mice (Ano5KI/KI ) replicated GDD-like skeletal features, including massive jawbones, bowing tibia, bone fragility, sclerosis, and cortical thickening of the femoral and tibial diaphysis."

Reports the diaphyseal sclerosis and cortical thickening measurement.

Show evidence (1 reference)

PMID:34841576 SUPPORT Model Organism

"Here, we generated the first knock-in mouse model for GDD with the expression of human mutation p.Cys360Tyr in ANO5."

Establishes that the model carries a human GDD allele, making it informative for the skeletal node.

Dysregulated Osteoblast and Osteoclast Differentiation recapitulates fidelity: moderate Directly measures the two-lineage remodelling disturbance, with increased osteoblastogenesis and decreased osteoclastogenesis in primary cultures.

Limitations: Cultured calvarial osteoblasts and bone-marrow-derived macrophages are ex vivo readouts; the direction of the osteoclast effect is opposite to that reported for ANO5 overexpression in human cell systems.

Readouts

Calvaria-derived osteoblast mineralization and osteoblastogenesis

Direction: INCREASED

Interpretation: Cellular correlate of the increased-osteoblast arm of the imbalance.

Show evidence (1 reference)

PMID:34841576 SUPPORT Model Organism

"Calvaria-derived Ano5KI/KI osteoblast cultures showed increased osteoblastogenesis, including hypermineralized bone matrix and enhanced bone formation-related factors expression."

Reports the osteoblastogenesis and mineralization measurement.

Bone-marrow-derived osteoclastogenesis and actin ring formation

Direction: DECREASED

Interpretation: Cellular correlate of the osteoclast arm of the imbalance.

Show evidence (1 reference)

PMID:34841576 SUPPORT Model Organism

"Interestingly, Ano5KI/KI bone marrow-derived macrophage cultures showed decreased osteoclastogenesis, and Ano5KI/KI osteoclasts exhibited disrupted actin ring formation, which may be associated with some signaling pathways."

Reports the osteoclastogenesis and actin-ring measurements.

Show evidence (1 reference)

PMID:34841576 SUPPORT Model Organism

"Calvaria-derived Ano5KI/KI osteoblast cultures showed increased osteoblastogenesis, including hypermineralized bone matrix and enhanced bone formation-related factors expression."

A measured result in the knock-in model on both arms of the remodelling node, which is what makes this model informative for it.

Osteoclast Differentiation Blockade and Apoptosis rescues fidelity: moderate The Akt activator SC79 restores osteoclast formation in this genotype-matched knock-in - multinucleated TRAP-positive osteoclasts and actin rings reappear with the osteoclast effector programme re-expressed - while the mirror experiment in osteoblasts suppresses mineralization. One intervention corrects both arms.

Limitations: Ex vivo BMM and calvarial osteoblast cultures from homozygous knock-in mice, with no in vivo skeletal endpoint and no human data. SC79 is a research tool compound, not a therapeutic, which is why this is curated here and not under `treatments`.

Readouts

TRAP-positive multinucleated osteoclast and actin ring formation after SC79

Direction: RESTORED

Interpretation: Pharmacological reversal of the osteoclast blockade, which is what establishes Akt as a causal intermediate rather than a correlate.

Show evidence (1 reference)

PMID:39866532 SUPPORT Model Organism

"Akt activation promoted the generation of TRAP-positive multinucleated osteoclasts and the formation of actin rings in Ano5 KI/KI BMMs cultures, accompanied by increased expression of Nfatc1, Trap, Dc-stamp, Mmp9, Ctsk, and Atp6v0d2."

Reports the SC79 rescue measurements on the osteoclast arm.

Show evidence (1 reference)

PMID:39866532 SUPPORT Model Organism

"Akt activation by SC79 stimulation can obviously rescue abnormal increased osteogenesis and decreased osteoclastogenesis in Ano5 KI/KI mouse model"

The authors' summary that a single intervention rescues both arms, which is what makes this model informative for the signalling nodes.

Pro-Osteogenic Signalling Dysregulation in Osteoblasts rescues fidelity: moderate The AMPK inhibitor Compound C reverses the skeletal phenotype in this genotype-matched knock-in, restraining formation and restoring osteoclastogenesis by suppressing PGC1a and promoting PGC1b.

Limitations: Compound C is a non-selective research tool with well-documented off-target activity, and the result is mouse-only. Not curated as a treatment.

Readouts

Bone phenotype after AMPK inhibition

Direction: RESTORED

Interpretation: Reversal of the remodelling imbalance by blocking the AMPK arm.

Show evidence (1 reference)

PMID:41717545 SUPPORT Model Organism

"AMPK inhibitor reversed the bone phenotype of GDD by restraining bone formation and restoring osteoclastogenesis."

Reports the Compound C rescue of the skeletal phenotype.

Show evidence (1 reference)

PMID:41717545 SUPPORT Model Organism

"Inhibiting AMPK reduced glycolysis in osteoblast and maintained the mitochondrial homeostasis between osteoblast and osteoclast by suppressing PGC1a and promoting PGC1b respectively, to restrain bone formation and restore osteoclastogenesis."

Gives the mechanism by which the AMPK arm is corrected, tying the rescue to the glycolytic and mitochondrial changes curated on that node.

Ano5 p.T491F knock-in mouse

A knock-in of the murine equivalent of a human GDD-causing allele taken from a thoroughly phenotyped patient. Despite radiography, micro-CT and undecalcified histomorphometry at two ages in males, with confirmation in females and in a second independent clone, no skeletal or mandibular phenotype was found.

Species

Mouse

Genotype

Ano5 p.T491F knock-in (murine equivalent of human ANO5 p.Ser500Phe), heterozygous and homozygous

Publication

PMID:32455153

Pathograph links

Diaphyseal Sclerosis and Bone Fragility fails to recapitulate fidelity: low A genotype-matched GDD allele that produces no bone phenotype in mouse, in direct conflict with the human disease and with the p.Cys360Tyr knock-in.

Limitations: Mice were assessed only under unchallenged conditions and only to 24 weeks, so a late or stress-dependent phenotype is not excluded; the authors nonetheless conclude Ano5 is dispensable for murine bone homeostasis. Construct validity is the more specific concern: the mutated residue is not conserved, so the human Ser-to-Phe change corresponds to a Ter-to-Phe change in mouse, and the knock-in may therefore not model the human lesion at all.

Show evidence (1 reference)

PMID:32455153 SUPPORT Model Organism

"These mice did not display alterations of skeletal microarchitecture or mandible morphology. The results were confirmed in female mice and animals derived from a second, independent clone."

The negative result, with the replication that makes it a substantive negative claim rather than an underpowered one.

Ano5 knockout mouse

Complete Ano5 loss of function in mouse. Homozygous null animals develop several cardinal GDD traits with elevated serum ALP and increased osteoblastogenesis - which is mechanistically awkward, since in humans it is biallelic loss of function that causes myopathy rather than bone disease.

Species

Mouse

Genotype

Ano5 homozygous knockout (CRISPR/Cas9)

Publication

PMID:30712070

Pathograph links

Diaphyseal Sclerosis and Bone Fragility partially recapitulates fidelity: low Reproduces GDD-like jawbone enlargement, tibial bowing and diaphyseal sclerosis with cortical thickening, but from a genotype that does not correspond to human GDD.

Limitations: The genotype is a homozygous null, whereas human GDD is heterozygous missense and human biallelic ANO5 null alleles cause muscular dystrophy, not bone disease. Its GDD-like readout therefore cannot be read as validating a loss-of-function mechanism for human GDD; it is evidence that murine and human ANO5 skeletal requirements differ.

Readouts

Mandibular size, tibial bowing and diaphyseal sclerosis

Direction: INCREASED

Interpretation: GDD-like skeletal changes arising from a null genotype, the observation that drives the alternative deficiency hypothesis.

Show evidence (1 reference)

PMID:30712070 SUPPORT Model Organism

"Homozygous Ano5 knockout mice (Ano5-/-) replicate some typical traits of human GDD including massive jawbones, bowing tibia, sclerosis and cortical thickening of femoral and tibial diaphyses."

Reports the skeletal measurements in the null mouse.

Show evidence (1 reference)

PMID:30712070 SUPPORT Model Organism

"Bone matrix is hypermineralized, and the expression of bone formation-related factors is enhanced in Ano5-/- mice, suggesting that the osteogenic anomaly arises from a genetic disruption of Ano5."

Supports the model as informative about ANO5 and bone, while the genotype mismatch keeps the support partial.

Pro-Osteogenic Signalling Dysregulation in Osteoblasts rescues fidelity: low Two independent in vivo rescues of the osteogenic excess in Ano5-null mice: the autophagy inhibitor 3-methyladenine alleviates the bone phenotype, and miR-34c-5p delivered by AAV rescues the abnormally thickened cortical bone, improves biomechanics and lowers serum P1NP. Both establish their arm as causal rather than correlative.

Limitations: Fidelity is LOW for a specific reason, not a generic one: these rescues are in a homozygous NULL, and human GDD is heterozygous missense while human biallelic ANO5 null alleles cause muscular dystrophy rather than bone disease. A rescue that works in this genotype does not establish the arm is operating in human GDD. 3-MA is also a non-selective autophagy inhibitor.

Readouts

Cortical thickness, biomechanics and serum P1NP after miR-34c-5p AAV

Direction: RESTORED

Interpretation: In vivo reversal of the cortical phenotype through the miR-34c-5p/KLF4/ beta-catenin arm, with a serum bone-formation marker moving in the same direction.

Show evidence (1 reference)

PMID:40508076 SUPPORT Model Organism

"Furthermore, miR-34c-5p adeno-associated virus (AAV) treatment in vivo rescued the abnormally thickened cortical bone and enhanced biomechanical properties in Ano5-/- mice."

Reports the in vivo AAV rescue measurements.

Bone phenotype after 3-methyladenine

Direction: RESTORED

Interpretation: In vivo reversal through the autophagy arm.

Show evidence (1 reference)

PMID:40067389 SUPPORT Model Organism

"Moreover, in vivo experiments confirmed that treatment with 3-MA alleviated the bone phenotype abnormalities in Ano5-/- mice."

Reports the in vivo 3-MA rescue.

Show evidence (1 reference)

PMID:40067389 SUPPORT Model Organism

"The application of 3-methyladenine (3-MA) and chloroquine (CQ) reversed the excessive osteogenesis observed in Ano5-/- mCOBs."

Two independent autophagy inhibitors reversing the phenotype, which is what makes this model informative for the osteoblast signalling node.

Osteoclast Differentiation Blockade and Apoptosis recapitulates fidelity: low Reproduces the osteoclast blockade with suppressed RANKL/NF-kB signalling, disrupted actin rings and reduced resorption, plus ER-stress/CHOP-driven osteoclast apoptosis.

Limitations: Homozygous null genotype, not corresponding to human GDD; see the note on the other link from this model.

Readouts

Osteoclast marker expression and resorption

Direction: DECREASED

Interpretation: The osteoclast-side deficit in the null mouse.

Show evidence (1 reference)

PMID:36989132 SUPPORT Model Organism

"Ano5-/- osteoclasts manifested disrupted actin ring and less mineral resorption."

Reports the actin-ring and resorption measurements.

Show evidence (1 reference)

PMID:40049314 SUPPORT Model Organism

"In summary, Ano5 deficiency impairs the function of osteoclasts by increasing osteoclast apoptosis, which is induced by an overactivated ERS response via calcium dyshomeostasis."

Summarizes the ER-stress/apoptosis mechanism this model evidences for the osteoclast node.

Ano5 knockout mouse (Li et al., low-bone-mass line)

A second, independent Ano5-null line that reports the OPPOSITE skeletal direction from the Wang knockout: low bone volume, defective osteoblast and osteoclast differentiation, and diminished intracellular calcium oscillations, modelling the low-bone-mass GDD sub-entity rather than the osteosclerotic one. Heterozygotes show a milder version of the homozygous phenotype, which is the basis of the dosage-sensitivity argument. Parathyroid hormone rescued bone strength.

Species

Mouse

Genotype

Ano5 homozygous and heterozygous knockout

Publication

PMID:35982081

Pathograph links

Dysregulated Osteoblast and Osteoclast Differentiation recapitulates fidelity: moderate Measures the two-lineage remodelling disturbance and ties it to calcium oscillations, WNT/beta-catenin and RANKL-NFATc1 signalling.

Limitations: A null genotype, whereas human GDD is heterozygous missense. Its direction of effect on osteoblasts is opposite to both the Wang null and the p.Cys360Tyr knock-in, so the three lines cannot all be describing the same biology.

Readouts

Trabecular bone volume and osteoblast/osteoclast differentiation

Direction: DECREASED

Interpretation: The low-bone-mass arm of the proposed sub-entity split, opposite in sign to the other two mouse lines.

Show evidence (1 reference)

PMID:35982081 SUPPORT Model Organism

"Moreover, using Ano5 knockout (KO) mice, we found that they exhibited low bone volume, abnormal calcium deposits, and defective osteoblast and osteoclast differentiation."

Reports the bone-volume and differentiation measurements.

Show evidence (1 reference)

PMID:35982081 SUPPORT Model Organism

"Here, we show that ablation of Ano5 reduced intracellular calcium transients, leading to defects in osteogenesis and osteoclastogenesis and thus bone dysplasia."

Establishes the mechanism this line is informative about at the cellular node.

High-Turnover Skeletal Remodelling Imbalance rescues fidelity: low Osteoanabolic parathyroid hormone restored bone strength in the null mouse - the only pharmacological rescue reported for any ANO5 bone model, and the origin of the osteoanabolic option recorded under treatments.

Limitations: Mouse only, in a null genotype that does not correspond to human GDD, and it rescues the low-bone-mass phenotype - so it says nothing about, and would be mechanistically wrong for, the osteosclerotic high-turnover sub-entity.

Readouts

Bone strength after parathyroid hormone treatment

Direction: RESTORED

Interpretation: Pharmacological reversal of the low-bone-mass phenotype.

Show evidence (1 reference)

PMID:35982081 SUPPORT Model Organism

"Osteoanabolic treatment of parathyroid hormone was effective in enhancing bone strength in Ano5 KO mice."

Reports the PTH rescue measurement.

Show evidence (1 reference)

PMID:35982081 SUPPORT Model Organism

"Osteoanabolic treatment of parathyroid hormone was effective in enhancing bone strength in Ano5 KO mice."

The rescue is real but in a non-corresponding genotype, so it is partial support for treating this node as pharmacologically addressable.

{ }

Source YAML

click to show

name: Gnathodiaphyseal Dysplasia
creation_date: "2026-08-21T00:00:00Z"
category: Mendelian
disease_term:
  preferred_term: gnathodiaphyseal dysplasia
  term:
    id: MONDO:0008151
    label: gnathodiaphyseal dysplasia
synonyms:
- GDD
- gnathodiaphyseal sclerosis
- osteogenesis imperfecta with unusual skeletal lesions
- osteogenesis imperfecta Levin type
description: >-
  Gnathodiaphyseal dysplasia (GDD) is a rare autosomal dominant skeletal disorder
  caused by heterozygous missense variants in ANO5 (TMEM16E, originally GDD1). It
  couples two lesions that rarely travel together: expansile cemento-osseous
  fibrous lesions of the jaws, and diaphyseal sclerosis with cortical thickening
  and bowing of the tubular bones accompanied by bone fragility. Patients
  therefore present with both recurrent long-bone fractures and progressive
  mandibular or maxillary swelling, and the jaw lesions are prone to purulent
  osteomyelitis in adult life. GDD was long mistaken for osteogenesis imperfecta
  or fibrous dysplasia; the 2004 identification of ANO5 established it as a
  distinct entity.

  The entry's mechanistic focus is allelic. ANO5 carries two essentially separate
  disease programmes: heterozygous missense variants clustered at a few residues
  (p.Cys356Tyr/Arg/Gly, p.Cys360Tyr, p.Ser500Phe, p.Thr513Ile, p.Gly518Glu,
  p.Arg215Gly) cause this dominant skeletal disease, whereas biallelic
  loss-of-function variants cause limb-girdle muscular dystrophy R12 and
  Miyoshi-like distal myopathy, curated separately in
  Autosomal_Recessive_Limb-Girdle_Muscular_Dystrophy. That opposite inheritance
  is itself an argument against haploinsufficiency here - the obligate
  heterozygous null carriers who are the parents of LGMDR12 patients are not
  reported with bone disease, though they have never been systematically
  skeletally phenotyped, so this is an argument from absence rather than a
  measured negative. What does bear the gain-of-function reading out directly is
  heterologous expression, where GDD alleles and muscular-dystrophy alleles
  compared in one assay system move in opposite directions.

  Three things stop that story being tidier than the evidence, and all three are
  curated rather than smoothed over. The bone-mass direction is not uniform: a
  proposed sub-entity split assigns high bone mass to gain-of-function alleles and
  osteopenia to loss-of-function ones, which is why this entry curates both
  diaphyseal sclerosis and osteopenia and puts no single direction on bone mineral
  density. The bone/muscle separation is not absolute either: one dominant kindred
  carrying p.Thr513Ile - the very allele the gain-of-function assay characterized -
  had rhabdomyolysis and hyperCKemia alongside its jaw lesions, and those authors
  explicitly challenged the dichotomy. And the mouse models disagree with each other
  and invert the human genotype-phenotype relation. Finally, how altered scramblase
  activity in an ER protein produces jaw-selective fibro-osseous lesions is simply
  not known, and is recorded as an open knowledge gap rather than filled in with a
  plausible chain.

parents:
- Skeletal Dysplasias

references:
- reference: PMID:15124103
  title: "The novel gene encoding a putative transmembrane protein is mutated in gnathodiaphyseal dysplasia (GDD)."
- reference: PMID:32112655
  title: "TMEM16E/ANO5 mutations related to bone dysplasia or muscular dystrophy cause opposite effects on lipid scrambling."

classifications:
  isds_skeletal_category:
  - classification_value: osteogenesis_imperfecta_and_decreased_bone_density
    notes: >-
      ISDS Nosology of Genetic Skeletal Disorders, 2023 revision (PMID:36779427),
      group 26 "Osteogenesis Imperfecta and bone fragility group", which explicitly
      lists "gnathodiaphyseal dysplasia (ANO5)" among the non-OI bone-fragility
      conditions. This agrees with the MONDO parent of MONDO:0008151
      (MONDO:0800064, the osteogenesis-imperfecta/reduced-bone-mineral-density
      grouping). Note the placement is by bone fragility, not by the diaphyseal
      sclerosis, which would otherwise suggest group 25.

inheritance:
- name: Autosomal dominant
  description: >-
    GDD segregates as an autosomal dominant trait in multigeneration kindreds and
    also arises de novo; affected individuals are heterozygous for an ANO5 missense
    variant. This is the inheritance mode that distinguishes GDD from the
    autosomal recessive ANO5 muscular dystrophies.
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  penetrance: UNKNOWN
  expressivity: VARIABLE
  evidence:
  - reference: PMID:40861765
    reference_title: "A Long-Term (41 Years) Radiographic Follow-Up Study of the Onset and Development of a Jawbone Lesion in a Patient With Gnathodiaphyseal Dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      with autosomal dominant inheritance, with high penetrance
    explanation: >-
      The only penetrance statement in the GDD literature, describing the founding
      Akasaka kindred. `penetrance` is nonetheless recorded as UNKNOWN rather than
      COMPLETE because this is a historical pedigree impression rather than a measured
      estimate, and no quantitative penetrance study exists; support is PARTIAL for that
      reason. `expressivity: VARIABLE` is the better-supported claim - the same
      p.Cys356Tyr allele spans mild jaw lesions to severe multi-quadrant gigantiform
      disease, bone mass runs in opposite directions between families, and one
      p.Thr513Ile kindred adds a muscle phenotype absent from every other GDD family.
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Gnathodiaphyseal dysplasia (GDD; MIM#166260) is an autosomal dominant syndrome
      with characteristic cemento-osseous lesions of jawbones, bone fragility, and
      diaphyseal sclerosis of tubular bones.
    explanation: >-
      States the autosomal dominant inheritance mode alongside the defining triad.
  - reference: PMID:38922934
    reference_title: "Gnathodiaphyseal dysplasia: Diagnostic clues from two fetal cases and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Genetic testing revealed two de novo variants of the ANO5 gene, confirming the
      diagnosis.
    explanation: >-
      Documents de novo occurrence of the dominant ANO5 allele, so a negative family
      history does not exclude GDD.

progression:
- phase: Early childhood - long bones first, jaws silent
  age_range: 1-8 years
  notes: >-
    The two components of GDD do not begin together. In a woman followed
    radiographically from age one to over forty, widening of the diaphyseal
    cortices of the femur and radius was already present at three years old while
    the jawbones were still asymptomatic. The long-bone lesion is therefore the
    earlier finding, which matters diagnostically: a child with unexplained
    diaphyseal cortical thickening and fractures may not yet show the gnathic
    lesion that makes the diagnosis obvious.
  evidence:
  - reference: PMID:40861765
    reference_title: "A Long-Term (41 Years) Radiographic Follow-Up Study of the Onset and Development of a Jawbone Lesion in a Patient With Gnathodiaphyseal Dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      At three years of age, widening of the diaphyseal cortices in the femur and
      radius was observed, although no symptoms were observed in the jawbones.
    explanation: >-
      Establishes that the diaphyseal change precedes any jaw involvement in this
      long-followed patient.
- phase: Mixed dentition onward - jaw lesion appears and grows
  age_range: 9 years to adulthood
  notes: >-
    The gnathic lesion emerges around the mixed-dentition stage and then enlarges
    with age rather than remaining static. Sclerosis appeared adjacent to the
    permanent tooth roots at nine years, became a clearly denser mass once the
    secondary dentition was complete at fourteen, and continued to develop over
    four decades. The association with the erupting permanent dentition is a
    suggestive - though untested - hint towards the tissue-selectivity question
    recorded in `gdd_jaw_selectivity_gap`.
  evidence:
  - reference: PMID:40861765
    reference_title: "A Long-Term (41 Years) Radiographic Follow-Up Study of the Onset and Development of a Jawbone Lesion in a Patient With Gnathodiaphyseal Dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      At nine years of age, we observed a slightly sclerotic appearance in the
      alveolar and jawbones adjacent to the permanent tooth roots. After completion
      of the secondary dentition at 14 years of age, increased density of the
      sclerotic mass was clearly observed.
    explanation: >-
      Dates the appearance of the jaw lesion to the mixed-dentition period and ties
      its progression to completion of the secondary dentition.
  - reference: PMID:40861765
    reference_title: "A Long-Term (41 Years) Radiographic Follow-Up Study of the Onset and Development of a Jawbone Lesion in a Patient With Gnathodiaphyseal Dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      this study observed that the onset of the jawbone lesion had already appeared
      after the mixed dentition stage, and the sclerotic mass developed with age
    explanation: >-
      The authors' summary that the lesion is progressive rather than static across
      four decades of follow-up.

prevalence:
- population: Worldwide
  measure_type: UNKNOWN
  prevalence_class: ULTRA_RARE
  notes: >-
    No population-based estimate exists. The literature consistently describes GDD as
    rare or ultra-rare, and the qualitative class is recorded here rather than a
    fabricated rate; `rate_per_100000` is deliberately left unset. The largest
    aggregation is a literature review of about 108 clinically diagnosed individuals
    across 25 families, which is a case count, not a denominator.
  evidence:
  - reference: PMID:29175271
    reference_title: "Gnathodiaphyseal dysplasia: Severe atypical presentation with novel heterozygous mutation of the anoctamin gene (ANO5)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Gnathodiaphyseal dysplasia (GDD; OMIM #166260) is an ultra-rare autosomal
      dominant disorder caused by heterozygous mutation in the anoctamin 5 (ANO5) gene
    explanation: >-
      Supports the qualitative ULTRA_RARE class, in a sentence that also states the
      heterozygous-mutation mechanism. No quantitative rate is asserted because none is
      reported anywhere in the literature.

pathophysiology:
- name: Heterozygous ANO5 Missense Variant
  biological_scale: MOLECULAR
  role: trigger
  description: >-
    GDD is caused by a heterozygous missense variant in ANO5 (TMEM16E), the gene
    originally designated GDD1. The reported alleles are strikingly clustered: the
    founding Japanese and African American families carried substitutions at the
    evolutionarily conserved cysteine 356 (p.Cys356Arg, p.Cys356Gly, and later
    p.Cys356Tyr), and subsequent families added p.Cys360Tyr, p.Arg215Gly,
    p.Ser500Phe, p.Thr513Ile and p.Gly518Glu. All map either to the extracellular
    loop following the first transmembrane domain or to the fourth putative
    transmembrane domain, which is what makes a simple gene-dosage explanation
    implausible: a haploinsufficiency mechanism would tolerate nonsense and
    frameshift alleles anywhere in the gene, and those alleles instead produce a
    recessive myopathy.
  genetic_context:
    gene:
      preferred_term: ANO5
      term:
        id: hgnc:27337
        label: ANO5
    allele_type: Missense substitution clustered at ANO5 residues 215, 356, 360, 500, 513 and 518
    variant_origin: GERMLINE
    zygosity: HETEROZYGOUS
    functional_impact_category: GAIN_OF_FUNCTION
    description: >-
      Heterozygous germline ANO5 missense allele. `functional_impact_category` is
      set to GAIN_OF_FUNCTION rather than LOSS_OF_FUNCTION on two converging
      grounds: the dominant inheritance with a restricted missense spectrum, and
      functional assay data. Note the scope of that assay evidence precisely - the
      calcium-independent-scrambling demonstration is for p.Thr513Ile specifically
      (PMID:29124309), and the class-level claim that GDD alleles gain function while
      muscular-dystrophy alleles lose it comes from a separate head-to-head comparison
      (PMID:32112655) that did not name every allele it tested. It is NOT established
      that every GDD allele behaves this way; the two commonest, p.Cys356Tyr and
      p.Cys360Tyr, have published *reduced* steady-state protein in overexpression.
      The category is therefore an allele-class judgement, and the competing
      loss-of-function reading is not dismissed - see the mechanistic hypotheses and
      the `gdd_gof_vs_lof_dispute` discussion.
  evidence:
  - reference: PMID:15124103
    reference_title: "The novel gene encoding a putative transmembrane protein is mutated in gnathodiaphyseal dysplasia (GDD)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Two missense mutations (C356R and C356G) of GDD1 were identified in the two
      families with GDD (the original Japanese family and a new African American
      family), and both missense mutations occur at the cysteine residue at amino
      acid 356, which is evolutionarily conserved among human, mouse, zebrafish,
      fruit fly, and mosquito.
    explanation: >-
      The founding gene-identification study, establishing GDD1/ANO5 missense change
      at a single conserved cysteine as the cause of GDD.
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It appears that all GDD mutations known so far locate in an extracellular
      domain following the first transmembrane domain or in the 4th putative
      transmembrane domain.
    explanation: >-
      Documents the tight positional clustering of GDD alleles, which is difficult to
      reconcile with simple haploinsufficiency.
  downstream:
  - target: Altered Calcium-Activated Phospholipid Scrambling by TMEM16E
    causal_link_type: DIRECT
    description: >-
      The missense substitution acts on the protein's own transport behaviour; this is
      the step demonstrated directly in heterologous expression.

- name: Altered Calcium-Activated Phospholipid Scrambling by TMEM16E
  biological_scale: MOLECULAR
  role: central_effector
  description: >-
    ANO5 encodes TMEM16E/anoctamin-5, a member of the TMEM16 family that behaves as
    a calcium-activated phospholipid scramblase and a poorly selective ion conduit,
    and that localizes predominantly to the endoplasmic reticulum rather than the
    plasma membrane. In heterologous expression, the GDD-associated p.Thr513Ile
    protein scrambles phospholipid and carries large currents even at very low
    cytosolic calcium, i.e. it is uncoupled from its normal calcium gating rather
    than inactivated. When GDD alleles and muscular-dystrophy alleles were compared
    side by side in the same assay system, they moved in opposite directions - GDD
    towards gain of function, muscular dystrophy towards loss of function. This is
    the node at which the two ANO5 diseases separate, and it is why bone disease is
    not simply "less ANO5".
  molecular_functions:
  - preferred_term: phospholipid scramblase activity
    term:
      id: GO:0017128
      label: phospholipid scramblase activity
    modifier: GAIN_OF_FUNCTION
  biological_processes:
  - preferred_term: calcium activated phospholipid scrambling
    term:
      id: GO:0061588
      label: calcium activated phospholipid scrambling
    modifier: GAIN_OF_FUNCTION
  - preferred_term: endoplasmic reticulum calcium ion homeostasis
    term:
      id: GO:0032469
      label: endoplasmic reticulum calcium ion homeostasis
    modifier: DYSREGULATED
  evidence:
  - reference: PMID:29124309
    reference_title: "Gain of function of TMEM16E/ANO5 scrambling activity caused by a mutation associated with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      While the activity of wild-type TMEM16E depended on elevated cytosolic Ca2+
      levels, a mutant form carrying the GDD-causing T513I substitution showed PLS and
      large time-dependent ion currents even at low cytosolic Ca2+ concentrations.
    explanation: >-
      Direct demonstration that a GDD allele uncouples TMEM16E scrambling from its
      normal calcium requirement - constitutive activity, not absent activity.
  - reference: PMID:32112655
    reference_title: "TMEM16E/ANO5 mutations related to bone dysplasia or muscular dystrophy cause opposite effects on lipid scrambling."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Our results collectively demonstrate that, on the level of protein function, MD
      mutations are associated to loss-of-function and GDD mutations to
      gain-of-function phenotypes, confirming conjectures made on the basis of
      inheritance modes.
    explanation: >-
      The head-to-head comparison establishing the allelic dichotomy at the level of
      protein function, and explicitly grounding it in the opposite inheritance modes.
  - reference: PMID:15124103
    reference_title: "The novel gene encoding a putative transmembrane protein is mutated in gnathodiaphyseal dysplasia (GDD)."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Cellular localization to the endoplasmic reticulum suggests a role for GDD1 in
      the regulation of intracellular calcium homeostasis.
    explanation: >-
      Establishes the ER localization that constrains where the scrambling defect can
      act; the calcium-regulation role is inferred rather than measured here, hence
      PARTIAL.
  downstream:
  - target: Pro-Osteogenic Signalling Dysregulation in Osteoblasts
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Route to the osteoblast arm. Candidate intermediates are now identified in mouse
      models, but the step from altered TMEM16E scrambling to those signalling changes
      has not been demonstrated in patient bone.
    hypothesis_groups:
    - gof_scramblase_model
    - ano5_deficiency_model
  - target: Osteoclast Differentiation Blockade and Apoptosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Route to the osteoclast arm, evidenced in the same model systems and subject to
      the same caveat.
    hypothesis_groups:
    - gof_scramblase_model
    - ano5_deficiency_model

- name: Pro-Osteogenic Signalling Dysregulation in Osteoblasts
  biological_scale: CELLULAR
  description: >-
    The osteoblast-side intermediate between the ANO5 defect and the remodelling
    imbalance. Four convergent mouse studies identify signalling routes by which
    perturbed ANO5 drives excess bone formation: AMPK phosphorylation rises and
    accelerates glycolysis and PGC1a-dependent mitochondrial respiration; AMPK in turn
    upregulates ATG9A and activates autophagy, which is required for the excess
    osteogenesis; miR-34c-5p falls, de-repressing KLF4 and activating canonical
    Wnt/beta-catenin; and Akt phosphorylation falls, with Akt re-activation suppressing
    mineralization. Each arm has a pharmacological or genetic rescue.

    READ THE GENOTYPES BEFORE TRANSFERRING ANY OF THIS TO HUMAN GDD. The AMPK and Akt
    arms come from the Ano5 p.Cys360Tyr knock-in, which carries an actual human GDD
    allele. The autophagy/ATG9A, miR-34c-5p/KLF4 and NF-kB arms come from Ano5-null
    mice - a genotype that in humans causes myopathy, not bone disease. So this node is
    better evidenced than the bare "unknown intermediates" it replaces, but it is not
    thereby established for human GDD, and the two model classes are not
    interchangeable. See `gdd_mouse_model_mismatch`.
  cell_types:
  - preferred_term: osteoblast
    term:
      id: CL:0000062
      label: osteoblast
  biological_processes:
  - preferred_term: AMPK-driven glycolytic shift
    term:
      id: GO:0006096
      label: glycolytic process
    modifier: INCREASED
  - preferred_term: autophagy (ATG9A-dependent)
    term:
      id: GO:0006914
      label: autophagy
    modifier: INCREASED
  - preferred_term: canonical Wnt/beta-catenin signalling via KLF4
    term:
      id: GO:0060070
      label: canonical Wnt signaling pathway
    modifier: INCREASED
  - preferred_term: PI3K/Akt signalling in osteoblasts
    term:
      id: GO:0043491
      label: phosphatidylinositol 3-kinase/protein kinase B signal transduction
    modifier: DECREASED
  molecular_functions:
  - preferred_term: AMP-activated protein kinase activity
    term:
      id: GO:0004679
      label: AMP-activated protein kinase activity
    modifier: INCREASED
  evidence:
  - reference: PMID:40067389
    reference_title: "Anoctamin-5 deficiency enhances ATG9A-dependent autophagy, inducing osteogenesis and gnathodiaphyseal dysplasia-like bone formation."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Further analysis revealed that Ano5 deficiency upregulated the expression of
      ATG9A, and silencing ATG9A significantly reduced both autophagy and osteogenic
      activity in Ano5-/- mCOBs.
    explanation: >-
      Establishes ATG9A-dependent autophagy as a required intermediate for the excess
      osteogenesis, with the silencing experiment supplying the causal direction.
  - reference: PMID:41717545
    reference_title: "Anoctamin 5 mutation leads to abnormal bone homeostasis of GDD by regulating AMPK-dependent glucose metabolism."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Furthermore, ANO5 mutation promoted the phosphorylation of AMPK, the classical
      sensor of energy metabolism.
    explanation: >-
      Places AMPK activation downstream of a genotype-matched GDD knock-in allele
      (p.Cys360Tyr), not merely of Ano5 loss.
  - reference: PMID:40508076
    reference_title: "Ano5 Deficiency Leads to Abnormal Bone Formation via miR-34c-5p/KLF4/beta-Catenin in Gnathodiaphyseal Dysplasia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      In this study, we found that Ano5 deficiency notably inhibited miR-34c-5p
      expression. Krüppel-Like Factor 4 (Klf4), a target gene of miR-34c-5p confirmed
      by dual luciferase reporter assay, was up-regulated in Ano5-/- mCOBs, accompanied
      by activated downstream canonical Wnt/β-catenin signaling and increased
      expression of β-catenin.
    explanation: >-
      Supplies the miR-34c-5p/KLF4/beta-catenin arm with a validated target
      relationship.
  - reference: PMID:39866532
    reference_title: "Ano5(Cys360Tyr) mutation leads to bone dysfunction of gnathodiaphyseal dysplasia via disturbing Akt signaling."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Additionally, Ano5 Cys360Tyr mutation down-regulated the Akt phosphorylation
      level in osteoblast.
    explanation: >-
      The Akt arm, again in the genotype-matched knock-in. Note the direction: Akt is
      DECREASED, and it is Akt re-activation that suppresses the excess mineralization.
  downstream:
  - target: Dysregulated Osteoblast and Osteoclast Differentiation
    causal_link_type: DIRECT
    description: >-
      These signalling changes are what the differentiation phenotype is measured as;
      each arm's rescue reverses the osteogenic excess.

- name: Osteoclast Differentiation Blockade and Apoptosis
  biological_scale: CELLULAR
  description: >-
    The osteoclast-side intermediate. Perturbed ANO5 suppresses RANKL-induced early
    signalling and the NF-kB pathway, reducing NFATc1, c-Fos and the osteoclast
    effector programme and leaving disrupted actin rings with impaired mineral
    resorption. Separately, calcium dyshomeostasis in Ano5-null osteoclasts drives an
    overactivated endoplasmic-reticulum stress response and CHOP-mediated apoptosis, so
    osteoclasts are both under-differentiated and actively lost. Akt is the third arm:
    it is reduced in the knock-in, and the Akt activator SC79 restores multinucleated
    osteoclast formation.

    The same genotype caveat as the osteoblast node applies - the NF-kB and ER-stress
    arms are null-mouse work.
  cell_types:
  - preferred_term: osteoclast
    term:
      id: CL:0000092
      label: osteoclast
  biological_processes:
  - preferred_term: canonical NF-kappaB signalling in osteoclast precursors
    term:
      id: GO:0007249
      label: canonical NF-kappaB signal transduction
    modifier: DECREASED
  - preferred_term: response to endoplasmic reticulum stress
    term:
      id: GO:0034976
      label: response to endoplasmic reticulum stress
    modifier: INCREASED
  - preferred_term: osteoclast apoptosis
    term:
      id: GO:0006915
      label: apoptotic process
    modifier: INCREASED
  evidence:
  - reference: PMID:36989132
    reference_title: "Genetic disruption of Ano5 leads to impaired osteoclastogenesis for gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      RANKL-induced early signaling pathways were suppressed in Ano5-/- osteoclasts and
      Ano5 knockdown RAW264.7 cells. Moreover, the inhibitory effects of NF-κB
      signalling pathway on osteoclastogenesis were partially attenuated with NF-κB
      signalling activator.
    explanation: >-
      Establishes suppressed RANKL/NF-kB signalling as the osteoclast intermediate, with
      partial pharmacological reversal supplying the causal direction.
  - reference: PMID:40049314
    reference_title: "Ano5 deficiency disturbed bone formation by inducing osteoclast apoptosis in Gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      In addition, the endoplasmic reticulum stress (ERS) response was significantly
      enhanced in Ano5-/- osteoclasts, possibly because of calcium dyshomeostasis, which
      leading to the increased proportion of apoptotic osteoclasts via the activation of
      the C/EBP homologous protein (CHOP) signalling pathway
    explanation: >-
      Supplies the ER-stress/CHOP apoptosis arm and ties it back to calcium
      dyshomeostasis, connecting this node to the upstream ER calcium claim.
  - reference: PMID:39866532
    reference_title: "Ano5(Cys360Tyr) mutation leads to bone dysfunction of gnathodiaphyseal dysplasia via disturbing Akt signaling."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Akt activation promoted the generation of TRAP-positive multinucleated osteoclasts
      and the formation of actin rings in Ano5 KI/KI BMMs cultures
    explanation: >-
      The Akt arm in the genotype-matched knock-in, with rescue of both multinucleation
      and the actin ring defect noted elsewhere in this entry.
  downstream:
  - target: Dysregulated Osteoblast and Osteoclast Differentiation
    causal_link_type: DIRECT
    description: >-
      Reduced osteoclast differentiation and increased osteoclast apoptosis are the
      resorption-side half of the remodelling imbalance.

- name: Dysregulated Osteoblast and Osteoclast Differentiation
  biological_scale: CELLULAR
  description: >-
    ANO5 is expressed in osteoblasts and periodontal ligament cells, and
    manipulating it in cell culture perturbs both arms of bone remodelling.
    Knockdown in osteoblast precursors raises osteoblast marker expression and
    mineral nodule formation, while ANO5 supports RANKL-driven osteoclast
    differentiation through Akt-NFATc1 signalling and its loss impairs
    osteoclastogenesis and actin-ring formation. The direction of effect is not
    consistent across systems - which is itself informative, and is the reason the
    cellular arm is curated as a hypothesis-tagged step rather than a settled
    mechanism. Both processes therefore carry `modifier: DYSREGULATED` rather than a
    direction: knockdown in MC3T3-E1 precursors increased osteoblast markers and
    mineralization, ANO5 downregulation in another system did not affect osteoblast
    differentiation at all, and the Ano5-null osteoblasts of a third study showed
    decreased indices. Asserting INCREASED here would pick a winner among three
    published directions.
  cell_types:
  - preferred_term: osteoblast
    term:
      id: CL:0000062
      label: osteoblast
  - preferred_term: osteoclast
    term:
      id: CL:0000092
      label: osteoclast
  biological_processes:
  - preferred_term: osteoblast differentiation
    term:
      id: GO:0001649
      label: osteoblast differentiation
    modifier: DYSREGULATED
  - preferred_term: osteoclast differentiation
    term:
      id: GO:0030316
      label: osteoclast differentiation
    modifier: DYSREGULATED
  evidence:
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      After Ano5 gene knock-down with shRNA in MC3T3-E1 osteoblast precursors we saw
      elevated expression of osteoblast-related genes such as Col1a1, osteocalcin,
      osterix and Runx2 as well as increased mineral nodule formation in
      differentiating cells.
    explanation: >-
      Links ANO5 perturbation to an osteoblast differentiation and mineralization
      phenotype in an osteoblast precursor line.
  - reference: PMID:30557634
    reference_title: "Role of anoctamin 5, a gene associated with gnathodiaphyseal dysplasia, in osteoblast and osteoclast differentiation."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Furthermore, Ano5-mediated Akt phosphorylation resulted in nuclear factor of
      activated T-cells c1 (NFATc1) activation, indicating that Ano5 regulates
      osteoclast differentiation through activation of the Akt-NFATc1 signaling
      pathway.
    explanation: >-
      Places ANO5 in the RANKL-Akt-NFATc1 osteoclast differentiation axis, the
      osteoclast arm of the remodelling imbalance.
  - reference: PMID:30557634
    reference_title: "Role of anoctamin 5, a gene associated with gnathodiaphyseal dysplasia, in osteoblast and osteoclast differentiation."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Downregulation of Ano5 expression did not affect osteoblast differentiation and
      mineralization, while ectopic expression of Ano5 significantly enhanced receptor
      activator of nuclear factor kappa B ligand (RANKL)-induced osteoclast
      differentiation.
    explanation: >-
      A directly contrary result on the osteoblast arm - no effect, where another
      system reported an increase - which is why the osteoblast process carries
      DYSREGULATED rather than a direction. Also shows the osteoclast effect runs the
      opposite way from the knock-in mouse.
  downstream:
  - target: High-Turnover Skeletal Remodelling Imbalance
    causal_link_type: DIRECT
    description: >-
      A coordinated disturbance of osteoblast and osteoclast behaviour is what
      produces the paradoxical combination of sclerotic, thickened bone that
      nevertheless fractures. This edge is claimed by BOTH mechanistic hypotheses, and
      that is the point: they disagree about the SIGN of the remodelling change - the
      gain-of-function model predicts increased indices and high bone mass, the
      sub-entity model predicts decreased indices and osteopenia for loss-of-function
      alleles - while agreeing that the cellular imbalance is what produces the
      skeletal phenotype.
    hypothesis_groups:
    - gof_scramblase_model
    - ano5_deficiency_model
  - target: Jaw Cemento-Osseous Fibrous Lesion Formation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The jaw-selective step. Why a systemically expressed ER scramblase produces
      focal, expansile fibro-osseous masses confined to the gnathic skeleton is
      unexplained; see the knowledge-gap discussion. The expanding cell population on
      that node is deliberately left as free text rather than bound to CL:0000061
      cementoblast, because which lineage expands is precisely what
      `gdd_jaw_selectivity_gap` records as untested.

- name: High-Turnover Skeletal Remodelling Imbalance
  biological_scale: TISSUE
  description: >-
    Full osteological assessment of a GDD patient carrying p.Ser500Phe showed
    increased trabecular bone mass with elevated serum markers of both bone
    formation and bone resorption, and an iliac crest biopsy with markedly
    increased osteoblast and osteoclast indices. GDD is therefore not a low-turnover
    sclerosing disease: bone is being both laid down and resorbed faster than
    normal, and the resulting tissue is sclerotic in the diaphyses yet mechanically
    inadequate. Elevated serum alkaline phosphatase is the usual laboratory correlate
    of this high-turnover presentation, but it is not universal across GDD: the
    osteopenic sub-entity has been reported with low bone-formation markers, and
    individual patients with normal ALP are documented.
  biological_processes:
  - preferred_term: bone mineralization
    term:
      id: GO:0030282
      label: bone mineralization
    modifier: INCREASED
  locations:
  - preferred_term: diaphysis
    term:
      id: UBERON:0004769
      label: diaphysis
  evidence:
  - reference: PMID:27541832
    reference_title: "A Novel ANO5 Mutation Causing Gnathodiaphyseal Dysplasia With High Bone Turnover Osteosclerosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We thereby identified increased trabecular bone mass accompanied by elevated
      serum markers of bone formation and bone resorption.
    explanation: >-
      Establishes the high-turnover character of the skeletal phenotype in a
      genetically confirmed GDD patient.
  - reference: PMID:27541832
    reference_title: "A Novel ANO5 Mutation Causing Gnathodiaphyseal Dysplasia With High Bone Turnover Osteosclerosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The high turnover bone pathology was further confirmed through the analysis of
      an iliac crest biopsy, where osteoblast and osteoclast indices were remarkably
      increased.
    explanation: >-
      Histomorphometric confirmation that both cell lineages are hyperactive, tying the
      tissue phenotype back to the cellular node.
  downstream:
  - target: Diaphyseal Sclerosis and Bone Fragility
    causal_link_type: DIRECT
    description: >-
      Accelerated, poorly coordinated remodelling yields thickened sclerotic
      diaphyses whose material quality does not match their apparent density.

- name: Jaw Cemento-Osseous Fibrous Lesion Formation
  biological_scale: TISSUE
  description: >-
    The gnathic component of GDD is a multi-quadrant fibro-osseous lesion of the
    mandible and maxilla - cementum-like calcified deposits scattered in a
    fibroblastic stroma - that expands, deforms the face, and frequently becomes
    secondarily infected. It has been variously reported as florid cemento-osseous
    dysplasia, cemento-ossifying fibroma, or familial gigantiform cementoma, and
    ANO5 p.Cys356Tyr has since been found in familial gigantiform cementoma
    kindreds, suggesting that entity is an atypical variant of GDD rather than a
    separate disease. Notably, osteosclerosis - the hallmark of the long-bone
    lesion - is not a feature of the jaw lesion, so the two components of GDD are
    not the same pathology in two places.
  cell_types:
  - preferred_term: cementoblast or periodontal ligament cell (lineage unresolved)
  locations:
  - preferred_term: mandible
    term:
      id: UBERON:0001684
      label: mandible
  evidence:
  - reference: PMID:37649308
    reference_title: "Familial gigantiform cementoma with recurrent ANO5 p.Cys356Tyr mutations: Clinicopathological and genetic study with literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Results showed that all three patients harbored the heterozygous mutation
      c.1067G > A (p.Cys356Tyr) in the ANO5 gene.
    explanation: >-
      Ties the recurrent GDD allele to expansile multi-quadrant gnathic fibro-osseous
      disease, supporting a shared lesion biology.
  - reference: PMID:37649308
    reference_title: "Familial gigantiform cementoma with recurrent ANO5 p.Cys356Tyr mutations: Clinicopathological and genetic study with literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our findings indicate that FGC may be an atypical variant of GDD, providing
      evidence for the feasibility of ANO5 gene testing as an auxiliary diagnostic
      method for complex cases with multiple quadrants.
    explanation: >-
      Supports treating familial gigantiform cementoma as within the GDD spectrum
      rather than as a differential to be excluded.
  downstream:
  - target: Mandibular Osteomyelitis and Facial Deformity
    causal_link_type: DIRECT
    description: >-
      Expansile avascular fibro-osseous masses in tooth-bearing bone deform the face
      and provide a nidus for purulent infection.

- name: Diaphyseal Sclerosis and Bone Fragility
  biological_scale: ORGANISM
  role: outcome
  description: >-
    The extragnathic skeletal phenotype: sclerosis and cortical thickening of the
    diaphyses of the tubular bones, bowing of the lower limbs, and recurrent
    fractures that typically begin around puberty but may present prenatally as
    bone bowing. The combination of radiographically dense bone with a high
    fracture rate is the feature that historically caused GDD to be misfiled as
    osteogenesis imperfecta.
  locations:
  - preferred_term: diaphysis
    term:
      id: UBERON:0004769
      label: diaphysis
  evidence:
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      One Caucasian family with seven affected members exhibited frequent bone
      fractures and florid osseous dysplasia (p.Cys356Tyr), while one Chinese family
      with two affected members suffered from cementoma and purulent osteomyelitis
      (p.Cys360Tyr).
    explanation: >-
      Documents the co-occurrence of fractures with gnathic fibro-osseous disease in
      genotyped families.
  - reference: PMID:27541832
    reference_title: "A Novel ANO5 Mutation Causing Gnathodiaphyseal Dysplasia With High Bone Turnover Osteosclerosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Gnathodiaphyseal dysplasia (GDD) is a rare skeletal syndrome that involves an
      osteopetrosis-like sclerosis of the long bones and fibrous dysplasia-like
      cemento-osseous lesions of the jawbone.
    explanation: >-
      Substantiates the sclerosis half of this node, which the fracture-focused
      evidence above does not address.
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      his radiographs showed gross thickening of the diaphyseal cortices of long bones
      with narrow medullary canals
    explanation: >-
      Human radiographic evidence for the cortical-thickening component of this node.

- name: Mandibular Osteomyelitis and Facial Deformity
  biological_scale: ORGANISM
  role: outcome
  description: >-
    Jaw lesions enlarge through adolescence and adult life, producing maxillofacial
    deformity and malocclusion that may require orthognathic or reconstructive
    surgery, and are susceptible to purulent osteomyelitis. This was a defining
    feature of the original Japanese kindred.
  locations:
  - preferred_term: mandible
    term:
      id: UBERON:0001684
      label: mandible
  evidence:
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      first described in a large Japanese family including 21 patients exhibiting
      frequent bone fractures in adolescence and purulent osteomyelitis of the jaws
      during adult life
    explanation: >-
      Establishes the age-staged pattern of adolescent fractures followed by adult jaw
      osteomyelitis in the founding kindred.

mechanistic_hypotheses:
- hypothesis_group_id: gof_scramblase_model
  hypothesis_label: Gain-of-function scramblase model
  status: CANONICAL
  description: >-
    The prevailing model: heterozygous GDD missense alleles confer constitutive,
    calcium-independent phospholipid scrambling on TMEM16E, and that aberrant
    activity - not a shortfall of ANO5 - disturbs bone-cell behaviour. Its two
    supports are the dominant inheritance with a restricted missense spectrum, and
    the head-to-head functional comparison showing GDD and muscular-dystrophy
    alleles moving in opposite directions in the same assay. Its weakness is that
    the step from scrambling to a bone lesion, and above all to a jaw-restricted
    lesion, has not been demonstrated in bone tissue.
  evidence:
  - reference: PMID:32112655
    reference_title: "TMEM16E/ANO5 mutations related to bone dysplasia or muscular dystrophy cause opposite effects on lipid scrambling."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Previous studies have demonstrated that TMEM16E/ANO5 is a Ca2+ -activated
      phospholipid scramblase and that the mutation c.1538C>T (p.Thr513Ile) causing
      GDD leads to a gain-of-function phenotype.
    explanation: >-
      States the gain-of-function characterization that this hypothesis group is built
      on.
  - reference: PMID:38922934
    reference_title: "Gnathodiaphyseal dysplasia: Diagnostic clues from two fetal cases and literature review."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      GDD is a rare but frequently inherited cause of bone fragility and jaw lesions
      characterized by a gain-of-function variant within the ANO5 gene.
    explanation: >-
      Shows the gain-of-function reading has been adopted as the working model in the
      contemporary clinical literature. Classified OTHER rather than HUMAN_CLINICAL
      because the sentence is a literature-review characterization, not an observation
      the authors made in their own patients.

- hypothesis_group_id: ano5_deficiency_model
  hypothesis_label: Variant-class-stratified GOF/LOF sub-entity model
  status: EMERGING
  description: >-
    A reading that does not compete with the gain-of-function model so much as
    subsume it, and that changes what a curator should record about bone mass.
    Li et al. propose that GDD comprises two sub-entities assigned by variant class
    rather than by clinical convention: gain-of-function alleles produce a
    HIGH-bone-mass phenotype through hyperactive phospholipid scrambling with
    increased osteoblast and osteoclast indices, while loss-of-function alleles
    produce a LOW-bone-mass, osteopenic phenotype through impaired calcium
    oscillations with decreased indices. The supporting observations are that
    Ano5-knockout mice replicate several cardinal GDD traits, and that a GDD family
    carrying a frameshift insertion with reduced TMEM16E presented with osteopenia
    rather than osteosclerosis. One frequently cited finding is NOT support for this
    model and should not be listed as such: reduced ANO5 in osteoblast precursors
    INCREASES osteoblastogenesis and mineralization, which runs opposite to the
    decreased-indices arm proposed here - Li et al. name that result themselves as
    partly contradicting their own conclusions. Li et al. further argue ANO5 is
    dosage-sensitive and
    that their heterozygous frameshift causes only PARTIAL loss of function, partly
    compensated by the normal allele - which is how a reduced-activity allele can be
    dominant without being a simple haploinsufficiency. The practical curation
    consequence is that this entry deliberately does NOT put a single INCREASED or
    DECREASED modifier on bone mineral density, because either would be wrong for one
    of the two sub-entities.
  evidence:
  - reference: PMID:35982081
    reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Overall, our results suggest the existence of GDD-sub-entities with high and low
      BMD phenotypes due to different GOF and LOF mutations and functions.
    explanation: >-
      The authors' explicit statement of the two-sub-entity model that this hypothesis
      group records.
  - reference: PMID:35982081
    reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Thus, our results suggest that ANO5 is dosage-sensitive and that LOF of the
      TMEM16E protein caused by the heterozygous ANO5 mutation in one allele is partly
      compensated by another normally functional allele.
    explanation: >-
      Supplies the dosage-sensitivity argument that lets a partial-loss-of-function
      allele be dominant without implying that a full null allele would be.
  - reference: PMID:30712070
    reference_title: "Genetic Disruption of Anoctamin 5 in Mice Replicates Human Gnathodiaphyseal Dysplasia (GDD)."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Homozygous Ano5 knockout mice (Ano5-/-) replicate some typical traits of human
      GDD including massive jawbones, bowing tibia, sclerosis and cortical thickening
      of femoral and tibial diaphyses.
    explanation: >-
      A pure loss-of-function genotype reproducing GDD-like bone traits, which is the
      central difficulty for a strict gain-of-function-only account.
  - reference: PMID:35982081
    reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We found a causative de novo ANO5 frameshift insertion mutation
      (p.L370_A371insDYWRLNSTCL) in a GDD family with osteopenia, accompanied by a
      decrease in TMEM16E expression
    explanation: >-
      Reports a GDD family whose allele is not a canonical missense change and is
      associated with reduced TMEM16E, supporting a reduced-activity route.
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      In vitro studies overexpressing GDD mutations (p.Cys356Tyr and p.Cys360Tyr)
      showed significantly reduced ANO5 protein.
    explanation: >-
      Shows canonical GDD missense alleles reduce steady-state protein, a partial
      bridge between the two models rather than a decisive result for either. Note the
      measurement is made in an overexpression system, as the snippet itself states,
      so it does not establish the protein level in patient bone.
  - reference: PMID:35982081
    reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
    supports: REFUTE
    evidence_source: MODEL_ORGANISM
    snippet: >-
      The authors also noticed that calvaria-derived Ano5−/− and Ano5KI/KI osteoblasts
      show increased mineralization and osteoblastogenesis, which partly contradicts
      our conclusions
    explanation: >-
      The authors' own acknowledgement that the increased osteoblastogenesis seen in
      Ano5-deficient osteoblasts runs against the decreased-indices arm of their
      sub-entity model. Recorded as REFUTE so the contradiction is visible in the
      entry rather than only in the prose.

genetic:
- name: ANO5
  gene_term:
    preferred_term: ANO5
    term:
      id: hgnc:27337
      label: ANO5
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  notes: >-
    ANO5 (TMEM16E; originally GDD1) at 11p14.3-15.1 is the sole gene known to cause
    GDD. The GDD allele class is heterozygous missense; the same gene's biallelic
    truncating and loss-of-function alleles cause limb-girdle muscular dystrophy R12
    and Miyoshi-like distal myopathy, curated in
    Autosomal_Recessive_Limb-Girdle_Muscular_Dystrophy. Obligate heterozygous
    carriers of those null alleles - the parents of affected LGMDR12 individuals -
    are not reported to develop the GDD skeletal phenotype, which is the clinical
    observation that argues against haploinsufficiency as the GDD mechanism.
  evidence:
  - reference: PMID:15124103
    reference_title: "The novel gene encoding a putative transmembrane protein is mutated in gnathodiaphyseal dysplasia (GDD)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      By linkage analysis of a large Japanese family with GDD, we previously mapped
      the GDD locus to chromosome 11p14.3-15.1.
    explanation: >-
      Establishes the GDD locus subsequently shown to contain ANO5.
  - reference: PMID:32112655
    reference_title: "TMEM16E/ANO5 mutations related to bone dysplasia or muscular dystrophy cause opposite effects on lipid scrambling."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Mutations in the human TMEM16E/ANO5 gene are causative for gnathodiaphyseal
      dysplasia (GDD), a rare bone malformation and fragility disorder, and for two
      types of muscular dystrophy (MD).
    explanation: >-
      States the two-disease allelic architecture of ANO5 that this entry contrasts
      against the LGMD entry.
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      absent in dbSNP, 1000Genomes, the Exome Variant Server (~6500 exomes) and the
      ExAC database
    explanation: >-
      Population-database absence of the GDD alleles, supporting pathogenicity and
      relevant to the allelic contrast: ANO5 truncating alleles are by comparison
      common enough in the population to sustain a recessive disease.
  variants:
  - name: ANO5 p.Cys356Tyr
    description: >-
      The most frequently recurring GDD allele, seen in unrelated GDD kindreds and in
      familial gigantiform cementoma.
    gene:
      preferred_term: ANO5
      term:
        id: hgnc:27337
        label: ANO5
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:37649308
      reference_title: "Familial gigantiform cementoma with recurrent ANO5 p.Cys356Tyr mutations: Clinicopathological and genetic study with literature review."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Results showed that all three patients harbored the heterozygous mutation
        c.1067G > A (p.Cys356Tyr) in the ANO5 gene.
      explanation: >-
        Documents the recurrent heterozygous p.Cys356Tyr allele in gnathic
        fibro-osseous disease.
  - name: ANO5 p.Thr513Ile
    description: >-
      The GDD allele with the most direct functional characterization: it confers
      calcium-independent phospholipid scrambling in heterologous expression. It is
      also the allele reported in a dominant kindred with combined muscle and bone
      involvement, so it is the pivot point for both the gain-of-function argument
      and the challenge to a clean phenotypic dichotomy.
    gene:
      preferred_term: ANO5
      term:
        id: hgnc:27337
        label: ANO5
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:34291158
      reference_title: "Autosomal Dominant ANO5-Related Disorder Associated With Myopathy and Gnathodiaphyseal Dysplasia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Molecular testing revealed a missense variant in anoctamin 5 (ANO5) designated
        as c.1538C>T; p.Thr513Ile, which was previously described in a large kindred
        with GDD.
      explanation: >-
        Identifies the recurrent p.Thr513Ile allele and its prior association with GDD.
  - name: ANO5 p.Cys356Arg and p.Cys356Gly
    description: >-
      The two founding GDD alleles, at the evolutionarily conserved cysteine 356.
    gene:
      preferred_term: ANO5
      term:
        id: hgnc:27337
        label: ANO5
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:15124103
      reference_title: "The novel gene encoding a putative transmembrane protein is mutated in gnathodiaphyseal dysplasia (GDD)."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Two missense mutations (C356R and C356G) of GDD1 were identified in the two
        families with GDD (the original Japanese family and a new African American
        family)
      explanation: >-
        The founding allele identifications in two independent GDD kindreds.
  - name: ANO5 p.Cys360Tyr
    description: >-
      A recurrent GDD allele, reported with cementoma and purulent osteomyelitis, and
      the allele modelled by the p.Cys360Tyr knock-in mouse.
    gene:
      preferred_term: ANO5
      term:
        id: hgnc:27337
        label: ANO5
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:28176803
      reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        while one Chinese family with two affected members suffered from cementoma and
        purulent osteomyelitis (p.Cys360Tyr)
      explanation: >-
        Ties p.Cys360Tyr to a genotyped GDD family with the gnathic phenotype.
  - name: ANO5 p.Cys360Arg
    description: >-
      A variant at the second recurrently affected cysteine, segregating with disease
      in a large Iranian kindred - useful because segregation across an extended
      pedigree is stronger evidence of pathogenicity than a single proband.
    gene:
      preferred_term: ANO5
      term:
        id: hgnc:27337
        label: ANO5
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:35758145
      reference_title: "Gnathodiaphyseal dysplasia with a novel genetic variant in a large family from Iran."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Sanger sequencing was performed to confirm the detected pathogenic variant in
        DNA samples of the entire family (except deceased individuals), which
        segregated with the disease within the family.
      explanation: >-
        Reports co-segregation of the p.Cys360Arg allele with GDD across a large
        pedigree.
  - name: ANO5 p.Cys356Phe
    description: >-
      A third substitution at cysteine 356, found by genome sequencing in a large family
      first diagnosed as cherubism - the allele that makes the cherubism differential
      concrete rather than theoretical.
    gene:
      preferred_term: ANO5
      term:
        id: hgnc:27337
        label: ANO5
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:30554457
      reference_title: "Novel ANO5 mutation c.1067G>T (p.C356F) identified by whole genome sequencing in a big family with atypical gnathodiaphyseal dysplasia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Through WGS, we identified a novel mutation c.1067G>T (p.C356F) in ANO5, and
        bioinformatics analyses and structural modeling showed that the mutation was
        deleterious.
      explanation: >-
        Identifies the p.Cys356Phe allele and the in silico support for its
        deleteriousness.
  - name: ANO5 p.Arg215Gly
    description: >-
      A sporadic GDD allele lying in the extracellular loop after the first
      transmembrane domain - the more N-terminal of the two mutational clusters.
    gene:
      preferred_term: ANO5
      term:
        id: hgnc:27337
        label: ANO5
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:28176803
      reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        In addition, two different novel mutations (p.Gly518Glu and p.Arg215Gly) were
        identified in sporadic patients without family history.
      explanation: >-
        Reports p.Arg215Gly and p.Gly518Glu as sporadic GDD alleles, extending the
        spectrum beyond the familial cysteine cluster.
  - name: ANO5 p.Leu370_Ala371insDYWRLNSTCL
    description: >-
      The de novo in-frame insertion that anchors the low-bone-mass argument. Unlike
      every other allele curated here it is not a missense substitution, it reduces
      TMEM16E expression, and the family presented with osteopenia rather than
      osteosclerosis - which is why this entry curates two bone-mass directions and an
      EMERGING sub-entity hypothesis rather than a single phenotype.
    gene:
      preferred_term: ANO5
      term:
        id: hgnc:27337
        label: ANO5
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:35982081
      reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        we report a de novo pathogenic ANO5 frameshift insertion mutation
        (c.1080_1081insGATTATTGGAGACTAAATAGTACGTGTTTG, p.L370_A371insDYWRLNSTCL)
      explanation: >-
        Identifies the insertion allele at nucleotide resolution in the osteopenic GDD
        family.
    - reference: PMID:35982081
      reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Our results also confirm that the mutation resulted in partial instead of
        complete LOF of the TMEM16E protein.
      explanation: >-
        Establishes the allele as a PARTIAL loss of function, which is how a
        reduced-activity allele can be dominant without implying a full null would be.
  - name: ANO5 p.Ser500Phe
    description: >-
      A de novo GDD allele in a patient with recurrent femoral diaphyseal fractures,
      whose full osteological workup established the high-turnover osteosclerotic
      phenotype. Its murine equivalent is the knock-in that failed to reproduce GDD.
    gene:
      preferred_term: ANO5
      term:
        id: hgnc:27337
        label: ANO5
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:27541832
      reference_title: "A Novel ANO5 Mutation Causing Gnathodiaphyseal Dysplasia With High Bone Turnover Osteosclerosis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We report a new case of GDD in a 13-year-old boy with recurrent diaphyseal
        fractures of the femur, in whom we identified a novel de novo missense mutation
        in the ANO5 gene, causing a p.Ser500Phe substitution at the protein level.
      explanation: >-
        Identifies the de novo p.Ser500Phe allele and the clinical context in which it
        was characterized.

phenotypes:
- category: Skeletal
  name: Recurrent fractures
  description: >-
    Recurrent long-bone fractures, characteristically beginning around puberty,
    occurring despite radiographically dense and thickened diaphyses.
  phenotype_term:
    preferred_term: Recurrent fractures
    term:
      id: HP:0002757
      label: Recurrent fractures
  evidence:
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      One Caucasian family with seven affected members exhibited frequent bone
      fractures and florid osseous dysplasia (p.Cys356Tyr), while one Chinese family
      with two affected members suffered from cementoma and purulent osteomyelitis
      (p.Cys360Tyr).
    explanation: >-
      Reports frequent bone fractures in a genotyped seven-member GDD family.

- category: Skeletal
  name: Diaphyseal sclerosis
  description: >-
    Sclerosis of the diaphyses of the tubular bones, an osteopetrosis-like
    radiographic appearance that coexists paradoxically with fragility.
  phenotype_term:
    preferred_term: Diaphyseal sclerosis
    term:
      id: HP:0003034
      label: Diaphyseal sclerosis
  evidence:
  - reference: PMID:27541832
    reference_title: "A Novel ANO5 Mutation Causing Gnathodiaphyseal Dysplasia With High Bone Turnover Osteosclerosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Gnathodiaphyseal dysplasia (GDD) is a rare skeletal syndrome that involves an
      osteopetrosis-like sclerosis of the long bones and fibrous dysplasia-like
      cemento-osseous lesions of the jawbone.
    explanation: >-
      Describes the long-bone sclerosis that defines the diaphyseal half of the
      disease name.

- category: Skeletal
  name: Osteopenia
  description: >-
    Reduced bone mineral density. This is NOT a universal GDD feature and is the
    reason bone mass is curated as a variant-class-stratified split rather than a
    single direction: a family carrying the p.L370_A371insDYWRLNSTCL frameshift
    presented with osteopenia and decreased BMD throughout the body, while the
    p.Ser500Phe patient assessed by DXA and HR-pQCT had increased trabecular bone
    mass. Both are GDD. See the `ano5_deficiency_model` hypothesis group.
  phenotype_term:
    preferred_term: Osteopenia
    term:
      id: HP:0000938
      label: Osteopenia
  evidence:
  - reference: PMID:35982081
    reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      First, our GDD family with the mutation did not have a history of severe bone
      fractures, although it presented decreased BMD throughout the body.
    explanation: >-
      Documents the low-bone-mass GDD presentation, which is the counterpart of the
      high-bone-mass presentation cited on the diaphyseal-sclerosis phenotype.

- category: Skeletal
  name: Cortical thickening of long bone diaphyses
  description: >-
    Cortical thickening of the femoral and tibial diaphyses, recapitulated in both
    the Ano5 knockout and the p.Cys360Tyr knock-in mouse.
  phenotype_term:
    preferred_term: Cortical thickening of long bone diaphyses
    term:
      id: HP:0005791
      label: Cortical thickening of long bone diaphyses
  evidence:
  - reference: PMID:34841576
    reference_title: "Introduction of a Cys360Tyr Mutation in ANO5 Creates a Mouse Model for Gnathodiaphyseal Dysplasia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Homozygous Ano5 knock-in mice (Ano5KI/KI ) replicated GDD-like skeletal features,
      including massive jawbones, bowing tibia, bone fragility, sclerosis, and cortical
      thickening of the femoral and tibial diaphysis.
    explanation: >-
      Model-organism corroboration of diaphyseal cortical thickening; the human
      evidence is the accompanying PMID:28176803 item, which is what actually
      substantiates the phenotype.
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      his radiographs showed gross thickening of the diaphyseal cortices of long bones
      with narrow medullary canals
    explanation: >-
      Direct human radiographic documentation of diaphyseal cortical thickening in a
      genotyped GDD patient, so this phenotype does not rest on mouse data alone.

- category: Skeletal
  name: Cementoma
  description: >-
    Expansile cemento-osseous fibrous lesions of the mandible and maxilla,
    histologically cementum-like calcified deposits in a fibroblastic stroma, often
    multi-quadrant.
  phenotype_term:
    preferred_term: Cementoma
    term:
      id: HP:0012328
      label: Cementoma
  evidence:
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      One Caucasian family with seven affected members exhibited frequent bone
      fractures and florid osseous dysplasia (p.Cys356Tyr), while one Chinese family
      with two affected members suffered from cementoma and purulent osteomyelitis
      (p.Cys360Tyr).
    explanation: >-
      Documents cementoma in a genotyped GDD family.

- category: Skeletal
  name: Mandibular osteomyelitis
  description: >-
    Purulent osteomyelitis of the jaws, characteristically emerging in adult life and
    a major source of morbidity in the founding kindred.
  phenotype_term:
    preferred_term: Mandibular osteomyelitis
    term:
      id: HP:0007626
      label: Mandibular osteomyelitis
  evidence:
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      first described in a large Japanese family including 21 patients exhibiting
      frequent bone fractures in adolescence and purulent osteomyelitis of the jaws
      during adult life
    explanation: >-
      Documents purulent jaw osteomyelitis as an adult-onset feature of GDD.

- category: Skeletal
  name: Bowing of the legs
  description: >-
    Bowing of the lower limbs, which can be the presenting prenatal sign - two fetal
    GDD cases came to diagnosis through bone bowing on antenatal imaging.
  phenotype_term:
    preferred_term: Bowing of the legs
    term:
      id: HP:0002979
      label: Bowing of the legs
  evidence:
  - reference: PMID:38922934
    reference_title: "Gnathodiaphyseal dysplasia: Diagnostic clues from two fetal cases and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The cases involved two fetuses exhibiting bone bowing, which led to the diagnosis
      of GDD.
    explanation: >-
      Establishes bone bowing as a recognized, and potentially prenatal, GDD
      presentation.

- category: Laboratory
  name: Elevated circulating alkaline phosphatase concentration
  description: >-
    Elevated serum alkaline phosphatase, reflecting the high-turnover state, is
    reported in GDD patients and reproduced in both the knockout and knock-in mouse
    models.
  phenotype_term:
    preferred_term: Elevated circulating alkaline phosphatase concentration
    term:
      id: HP:0003155
      label: Elevated circulating alkaline phosphatase concentration
  evidence:
  - reference: PMID:34841576
    reference_title: "Introduction of a Cys360Tyr Mutation in ANO5 Creates a Mouse Model for Gnathodiaphyseal Dysplasia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Serum alkaline phosphatase (ALP) levels were elevated in Ano5KI/KI mice as in GDD
      patients with p.Cys360Tyr mutation.
    explanation: >-
      Reports elevated ALP in the knock-in mouse and states the same finding in the
      corresponding human patients; paired below with direct human evidence so this
      phenotype does not rest on mouse data alone.
  - reference: PMID:37649308
    reference_title: "Familial gigantiform cementoma with recurrent ANO5 p.Cys356Tyr mutations: Clinicopathological and genetic study with literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There was a slight increase in alkaline phosphatase levels in the blood before
      the last surgery.
    explanation: >-
      Human ALP elevation in an ANO5 p.Cys356Tyr patient. PARTIAL because it is a
      single case and the rise is described as slight; the same paper records another
      patient whose ALP was normal, so this is not a constant finding.

- category: Craniofacial
  name: Abnormality of the dentition
  description: >-
    Dental involvement is a common and often presenting feature: recurrent dental
    infections, tooth displacement by the expanding jaw lesions, failed extraction
    healing and tooth loss. It is curated without a `frequency:` band - aggregated
    literature percentages exist but are not stated in any cached abstract, and they
    are ascertainment-biased because most GDD patients reach diagnosis through a
    maxillofacial or dental route in the first place.
  phenotype_term:
    preferred_term: Abnormality of the dentition
    term:
      id: HP:0000164
      label: Abnormality of the dentition
  evidence:
  - reference: PMID:38922934
    reference_title: "Gnathodiaphyseal dysplasia: Diagnostic clues from two fetal cases and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical manifestations range from recurrent dental infections with mild jaw
      lesions to severe bone fragility with several fractures associated with large jaw
      lesions requiring disfiguring surgeries.
    explanation: >-
      Places recurrent dental infection at the mild end of the GDD clinical spectrum,
      establishing dental involvement as a disease manifestation.

- category: Craniofacial
  name: Abnormal mandible morphology
  description: >-
    Progressive expansion and deformity of the mandible and maxilla from the
    fibro-osseous lesions, producing maxillofacial disfigurement and malocclusion.
  phenotype_term:
    preferred_term: Abnormal mandible morphology
    term:
      id: HP:0000277
      label: Abnormal mandible morphology
  evidence:
  - reference: PMID:41193275
    reference_title: "Double jaw surgery for a patient with Gnathodiaphyseal dysplasia (GDD): A case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patients typically present with pathological fractures, muscle weakness, and
      jawbone deformities.
    explanation: >-
      States jawbone deformity as a typical GDD presentation.

histopathology:
- name: Jaw fibro-osseous lesion histology
  description: >-
    Cementum-like calcified deposits scattered within a fibroblastic stroma, with
    psammomatoid bodies and abundant mineralization of vessel walls. Riminucci et al.
    used precisely this histology to separate the entity from the sclerosing
    disorders, since osteosclerosis is NOT a feature of the jaw lesion even though it
    defines the long-bone lesion. Psammomatoid bodies are characteristic but not
    invariable, so their absence does not exclude the diagnosis.
  diagnostic: true
  evidence:
  - reference: PMID:37649308
    reference_title: "Familial gigantiform cementoma with recurrent ANO5 p.Cys356Tyr mutations: Clinicopathological and genetic study with literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Riminucci et al. have described the histopathological features of jaw lesions,
      including cementum‐ossifying fibroma, psammomatoid bodies, and abundant
      mineralization in the vessel wall, and refined the name of this disease entity to
      gnathodiaphyseal dysplasia, as osteosclerosis is not a feature of the jaw lesions
      in this syndrome
    explanation: >-
      Gives the defining histological features and the explicit statement that the jaw
      lesion is not osteosclerotic - which is why this entry models the gnathic and
      diaphyseal components as separate nodes rather than one pathology in two sites.

diagnosis:
- name: Recognition and misdiagnosis
  description: >-
    GDD is substantially under-recognized. Two thirds of molecularly confirmed cases
    were initially given another diagnosis, most often osteogenesis imperfecta or
    fibrous dysplasia, and clinicians continue to manage it as an OI variant. The
    diagnostic combination that should prompt ANO5 testing is the one that makes no
    sense under either alternative: recurrent fractures together with expansile
    cemento-osseous jaw lesions, with diaphyseal sclerosis and cortical thickening on
    radiographs rather than the osteopenia expected in OI.
  evidence:
  - reference: PMID:30554457
    reference_title: "Novel ANO5 mutation c.1067G>T (p.C356F) identified by whole genome sequencing in a big family with atypical gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      67% of GDD cases confirmed by molecular testing were initially misdiagnosed.
    explanation: >-
      Quantifies the misdiagnosis rate, which is the practical reason this entry exists
      as a distinct disease rather than as a note on osteogenesis imperfecta.
- name: Osteological assessment (densitometry, HR-pQCT, turnover markers)
  description: >-
    Because GDD's bone-mass direction is not uniform, densitometry plus
    high-resolution peripheral quantitative CT plus serum turnover markers together
    establish which presentation a given patient has - and that determines whether an
    antiresorptive or an osteoanabolic is directionally appropriate. This combination is
    what established the high-turnover osteosclerotic phenotype in the p.Ser500Phe
    patient; iliac crest biopsy added histomorphometric confirmation.
  diagnosis_term:
    preferred_term: dual-energy X-ray absorptiometry with HR-pQCT and bone turnover markers
    term:
      id: NCIT:C48789
      label: Dual X-ray Absorptiometry
  evidence:
  - reference: PMID:27541832
    reference_title: "A Novel ANO5 Mutation Causing Gnathodiaphyseal Dysplasia With High Bone Turnover Osteosclerosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we focused on a full osteologic assessment using dual-energy X-ray absorptiometry
      (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT), and
      serum analyses
    explanation: >-
      Names the modality combination used to characterize GDD bone status. The same paper
      opens by stating there is still no established consensus regarding the bone status
      of GDD patients, which is why this assessment is informative rather than routine.

- name: Radiographic jaw and long-bone surveillance
  description: >-
    Radiography carries the diagnosis and tracks it over decades: the jaw lesion by
    dental and panoramic imaging, the long bones by plain films. A patient followed from
    age one to over forty showed diaphyseal cortical widening at three years, sclerosis
    adjacent to the permanent tooth roots at nine, and a clearly denser mass once the
    secondary dentition completed at fourteen. Because the diaphyseal change precedes the
    jaw lesion, imaging both compartments is what makes the combination recognizable
    before it is obvious.
  diagnosis_term:
    preferred_term: serial radiography of the jaws and long bones
    term:
      id: NCIT:C16502
      label: Diagnostic Imaging Testing
  evidence:
  - reference: PMID:40861765
    reference_title: "A Long-Term (41 Years) Radiographic Follow-Up Study of the Onset and Development of a Jawbone Lesion in a Patient With Gnathodiaphyseal Dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This report describes the long-term radiographic follow-up study of jaw lesions in
      a GDD-affected woman of >40 years of age from the age of one onward.
    explanation: >-
      Establishes serial radiography as the modality by which GDD jaw lesions are
      detected and followed over time.

- name: Molecular confirmation
  description: >-
    Diagnosis is confirmed molecularly. Because the GDD allele spectrum is tightly
    clustered, targeted ANO5 sequencing is informative; exome or genome sequencing is
    used when the presentation is atypical or the differential is broad, and was how
    the two reported prenatal cases were resolved.
  evidence:
  - reference: PMID:38922934
    reference_title: "Gnathodiaphyseal dysplasia: Diagnostic clues from two fetal cases and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Diagnostic techniques depend on the context and include targeted genetic testing
      of ANO5, untargeted molecular analysis with whole-exome sequencing, or
      whole-genome sequencing.
    explanation: >-
      States the molecular diagnostic strategies and that the choice is
      context-dependent.

biochemical:
- name: Bone turnover markers
  notes: >-
    Serum markers of bone formation and resorption. Their DIRECTION is
    sub-entity-dependent and must not be curated as a single expectation: the
    high-turnover osteosclerotic presentation shows elevated formation and resorption
    markers with markedly increased osteoblast and osteoclast indices on iliac crest
    biopsy, whereas the osteopenic presentation has been reported with decreased bone
    mineral density. Alkaline phosphatase is the routinely available marker and is
    curated separately as a phenotype.
  evidence:
  - reference: PMID:27541832
    reference_title: "A Novel ANO5 Mutation Causing Gnathodiaphyseal Dysplasia With High Bone Turnover Osteosclerosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We thereby identified increased trabecular bone mass accompanied by elevated
      serum markers of bone formation and bone resorption.
    explanation: >-
      Documents the elevated-marker, high-turnover pattern in a genetically confirmed
      patient.
  - reference: PMID:35982081
    reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      First, our GDD family with the mutation did not have a history of severe bone
      fractures, although it presented decreased BMD throughout the body.
    explanation: >-
      The contrasting low-bone-mass presentation, which is why marker direction is
      recorded as sub-entity-dependent rather than fixed.

differential_diagnoses:
- name: Osteogenesis imperfecta
  description: >-
    The historical misdiagnosis, and still the commonest one. GDD was originally
    named "osteogenesis imperfecta with unusual skeletal lesions"; both cause
    recurrent fractures, but GDD adds diaphyseal sclerosis with cortical thickening
    and gnathic fibro-osseous lesions, whereas OI bone is typically osteopenic.
  evidence:
  - reference: PMID:41193275
    reference_title: "Double jaw surgery for a patient with Gnathodiaphyseal dysplasia (GDD): A case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      However, clinicians are still largely unaware of this entity and continue to
      label and treat it as a variation of Osteogenesis Imperfecta.
    explanation: >-
      States that GDD continues to be misclassified as osteogenesis imperfecta in
      practice.
- name: Cherubism
  description: >-
    Also presents with fibro-osseous lesions of the jawbones, and is a documented
    misdiagnosis: one family was initially diagnosed as cherubism, found to have no
    pathogenic SH3BP2 variant, and resolved to a novel ANO5 p.Cys356Phe allele by
    genome sequencing. A negative SH3BP2 result in a jaw fibro-osseous kindred should
    prompt ANO5 testing.
  evidence:
  - reference: PMID:30554457
    reference_title: "Novel ANO5 mutation c.1067G>T (p.C356F) identified by whole genome sequencing in a big family with atypical gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A family with patients with fibro-osseous lesions of the jawbones were initially
      diagnosed with cherubism. Sequencing of SH3BP2, which is the causal gene of
      cherubism, revealed no pathogenic mutation.
    explanation: >-
      Documents cherubism as a real-world GDD misdiagnosis and the SH3BP2-negative
      result that redirected the workup to ANO5.
- name: Fibrous dysplasia and McCune-Albright syndrome
  description: >-
    Share fibro-osseous jaw lesions, but are caused by activating GNAS1 mutations
    and are mosaic or somatic rather than germline dominant.
  evidence:
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      GDD shares clinical and pathological features of syndromes involving fibro-osseous
      jaw lesions, most notably fibrous dysplasia (FD) and McCune-Albright syndrome
      (MAS).
    explanation: >-
      Names the fibro-osseous differentials and, in the same passage, the distinct GNAS1
      basis that separates them.
- name: ANO5-related limb-girdle muscular dystrophy R12
  description: >-
    The allelic recessive myopathy, curated as
    Autosomal_Recessive_Limb-Girdle_Muscular_Dystrophy. Same gene, biallelic
    loss-of-function alleles, adult-onset proximal weakness with high CK, and no
    skeletal dysplasia. It is a differential only in the sense that an ANO5 variant
    report must be interpreted against zygosity and allele class before a phenotype
    is assigned.
  evidence:
  - reference: PMID:32112655
    reference_title: "TMEM16E/ANO5 mutations related to bone dysplasia or muscular dystrophy cause opposite effects on lipid scrambling."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Mutations in the human TMEM16E/ANO5 gene are causative for gnathodiaphyseal
      dysplasia (GDD), a rare bone malformation and fragility disorder, and for two
      types of muscular dystrophy (MD).
    explanation: >-
      Establishes that the two disorders are allelic at ANO5, which is what makes
      zygosity and allele class the discriminating information.

treatments:
- name: Bisphosphonate Therapy (Pamidronate)
  description: >-
    Intravenous pamidronate has been given to GDD patients with low bone mass and
    fractures. The evidence is case-level - a child treated with seven infusions from
    15 months of age, and a separate patient whose osteopenia was managed with
    pamidronate - and no controlled data exist.

    The mechanistic caveat is the important part and follows directly from the
    sub-entity split this entry curates. An antiresorptive suppresses bone resorption,
    which is coherent for the low-bone-mass, osteopenic GDD sub-entity, but is the
    wrong direction for the high-turnover osteosclerotic sub-entity, where trabecular
    bone mass is already increased. Bone mass and turnover markers should therefore be
    established before an antiresorptive is chosen, rather than inferring from the
    diagnosis alone.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: pamidronate
      term:
        id: CHEBI:7903
        label: pamidronate
  target_mechanisms:
  - target: High-Turnover Skeletal Remodelling Imbalance
    treatment_effect: INHIBITS
    description: >-
      Suppresses the osteoclastic resorption arm of the remodelling imbalance.
      Directionally appropriate only for the low-bone-mass sub-entity.
  evidence:
  - reference: PMID:29175271
    reference_title: "Gnathodiaphyseal dysplasia: Severe atypical presentation with novel heterozygous mutation of the anoctamin gene (ANO5)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We assessed his response to a total of 7 pamidronate infusions commencing at age
      15months
    explanation: >-
      Documents pamidronate exposure in a GDD patient. PARTIAL because it is a single
      case and the snippet records that a response was assessed, not that a particular
      benefit was established.
  - reference: PMID:28176803
    reference_title: "Three novel ANO5 missense mutations in Caucasian and Chinese families and sporadic cases with gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The osteopenia is being treated with pamidronate.
    explanation: >-
      A second, independent report of pamidronate use, and notably in an OSTEOPENIC
      patient - the sub-entity for which an antiresorptive is directionally
      appropriate.

- name: Osteoanabolic Therapy (Parathyroid Hormone) - Preclinical Only
  description: >-
    Parathyroid hormone enhanced bone strength in Ano5-knockout mice. This is a mouse
    result in a genotype that does not correspond to human GDD, and no human GDD
    patient has been reported treated with an osteoanabolic. It is curated because it
    is the only pharmacological rescue reported for any ANO5 bone model, and because
    it is the directional complement of the bisphosphonate entry: osteoanabolic for
    low bone mass, antiresorptive for high turnover. This is NOT a clinical
    recommendation.

    No `therapeutic_agent` is bound, deliberately. The source says "parathyroid
    hormone" without naming an analogue. Teriparatide has both CHEBI and NCIT
    identities and would be the obvious binding, but it is specifically PTH 1-34, and
    asserting it would attribute an agent the paper does not specify; neither ontology
    offers a plain "parathyroid hormone" therapeutic term. Left unbound rather than
    made precise beyond the evidence.
  therapeutic_modality: PEPTIDE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: High-Turnover Skeletal Remodelling Imbalance
    treatment_effect: MODULATES
    description: >-
      Shifts the remodelling balance towards formation; demonstrated only in the
      low-bone-mass null mouse.
  evidence:
  - reference: PMID:35982081
    reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Osteoanabolic treatment of parathyroid hormone was effective in enhancing bone
      strength in Ano5 KO mice.
    explanation: >-
      Model-organism evidence only, in a null genotype unlike human GDD, hence PARTIAL
      and explicitly not a treatment recommendation.

- name: Orthognathic and Reconstructive Jaw Surgery
  description: >-
    Surgical management of the expansile gnathic lesions and the resulting
    malocclusion and facial deformity. Orthognathic surgery (Le Fort I advancement
    with bilateral sagittal split osteotomy) has been performed safely in a GDD
    patient with stable two-year occlusal follow-up, but the evidence base is single
    case reports and best practices are not established. This is anatomical
    correction, not disease modification; no therapy targeting the ANO5 mechanism
    exists.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: orthopedic surgical procedure
    term:
      id: NCIT:C16186
      label: Orthopedic Surgical Procedure
  target_mechanisms:
  - target: Mandibular Osteomyelitis and Facial Deformity
    treatment_effect: MODULATES
    description: >-
      Alters the anatomical outcome node - the deformity and malocclusion produced by
      the jaw lesions - without acting on any upstream mechanism node.
  evidence:
  - reference: PMID:41193275
    reference_title: "Double jaw surgery for a patient with Gnathodiaphyseal dysplasia (GDD): A case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      He was treated with LeFort 1 advancement and Bilateral Sagittal Split Osteotomy of
      the mandible with setback procedures. No complications were seen and 2-year
      follow-up showed stable dental occlusion.
    explanation: >-
      Documents the orthognathic procedure and its two-year outcome in a GDD patient.
  - reference: PMID:41193275
    reference_title: "Double jaw surgery for a patient with Gnathodiaphyseal dysplasia (GDD): A case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other procedures are possible, but more research is needed to develop best
      practices for this disorder.
    explanation: >-
      The authors' own statement that the surgical evidence base is not yet sufficient
      to define standard management.

- name: Fracture Fixation and Orthopedic Management
  description: >-
    Operative fixation of pathological diaphyseal fractures. Sclerotic, thickened
    cortices make instrumentation technically demanding, and the reported experience
    is case-level.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: orthopedic surgical procedure
    term:
      id: NCIT:C16186
      label: Orthopedic Surgical Procedure
  target_mechanisms:
  - target: Diaphyseal Sclerosis and Bone Fragility
    treatment_effect: MODULATES
    description: >-
      Symptomatic management of the fracture burden at the outcome node; it does not
      act on the ANO5 mechanism.
  evidence:
  - reference: PMID:33826556
    reference_title: "Surgical Treatment of Pathological Tibial Shaft Fracture in Adult Patient With Gnathodiaphyseal Dysplasia: A Case Report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Internal fixation with the Ender nail was effective for the tubular bone with
      deformity. Callus formation was observed without delay.
    explanation: >-
      Reports the outcome of operative fixation in a GDD diaphyseal fracture,
      including the observation that callus formation was not delayed - relevant
      because sclerotic GDD bone might be expected to heal poorly.
  - reference: PMID:33826556
    reference_title: "Surgical Treatment of Pathological Tibial Shaft Fracture in Adult Patient With Gnathodiaphyseal Dysplasia: A Case Report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This is the first report describing the treatment of fracture in an adult
      patient with gnathodiaphyseal dysplasia.
    explanation: >-
      Establishes how thin the evidence base is - a single adult case at the time of
      publication - which is why this treatment is not presented as standard practice.

animal_models:
- name: Ano5 p.Cys360Tyr knock-in mouse
  species: Mouse
  genotype: Ano5 knock-in homozygous for the murine equivalent of human ANO5 p.Cys360Tyr
  publication: PMID:34841576
  description: >-
    The first knock-in mouse carrying a human GDD missense allele. Homozygotes
    reproduce massive jawbones, tibial bowing, bone fragility, diaphyseal sclerosis
    and cortical thickening, and elevated serum ALP, together with increased
    osteoblastogenesis and decreased osteoclastogenesis with disrupted osteoclast
    actin rings.
  modeled_mechanisms:
  - target: Diaphyseal Sclerosis and Bone Fragility
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Reproduces the cardinal long-bone features of GDD - sclerosis, cortical
      thickening, bowing and fragility - in a genotype matched to a human GDD allele.
    limitations: >-
      The phenotype is reported in homozygotes, whereas human GDD is heterozygous, so
      the model does not test dominance. A knock-in of a different human GDD allele
      (p.Ser500Phe, murine p.T491F) in an independent study produced no skeletal
      phenotype at all, so mouse results for GDD alleles are not consistent across
      alleles.
    readouts:
    - name: Femoral and tibial diaphyseal cortical thickness and sclerosis
      target: Diaphyseal Sclerosis and Bone Fragility
      direction: INCREASED
      interpretation: Structural correlate of the human diaphyseal sclerosis phenotype.
      evidence:
      - reference: PMID:34841576
        reference_title: "Introduction of a Cys360Tyr Mutation in ANO5 Creates a Mouse Model for Gnathodiaphyseal Dysplasia."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Homozygous Ano5 knock-in mice (Ano5KI/KI ) replicated GDD-like skeletal
          features, including massive jawbones, bowing tibia, bone fragility, sclerosis,
          and cortical thickening of the femoral and tibial diaphysis.
        explanation: Reports the diaphyseal sclerosis and cortical thickening measurement.
    evidence:
    - reference: PMID:34841576
      reference_title: "Introduction of a Cys360Tyr Mutation in ANO5 Creates a Mouse Model for Gnathodiaphyseal Dysplasia."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Here, we generated the first knock-in mouse model for GDD with the expression of
        human mutation p.Cys360Tyr in ANO5.
      explanation: >-
        Establishes that the model carries a human GDD allele, making it informative for
        the skeletal node.
  - target: Dysregulated Osteoblast and Osteoclast Differentiation
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Directly measures the two-lineage remodelling disturbance, with increased
      osteoblastogenesis and decreased osteoclastogenesis in primary cultures.
    limitations: >-
      Cultured calvarial osteoblasts and bone-marrow-derived macrophages are ex vivo
      readouts; the direction of the osteoclast effect is opposite to that reported for
      ANO5 overexpression in human cell systems.
    readouts:
    - name: Calvaria-derived osteoblast mineralization and osteoblastogenesis
      target: Dysregulated Osteoblast and Osteoclast Differentiation
      direction: INCREASED
      interpretation: Cellular correlate of the increased-osteoblast arm of the imbalance.
      evidence:
      - reference: PMID:34841576
        reference_title: "Introduction of a Cys360Tyr Mutation in ANO5 Creates a Mouse Model for Gnathodiaphyseal Dysplasia."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Calvaria-derived Ano5KI/KI osteoblast cultures showed increased
          osteoblastogenesis, including hypermineralized bone matrix and enhanced bone
          formation-related factors expression.
        explanation: Reports the osteoblastogenesis and mineralization measurement.
    - name: Bone-marrow-derived osteoclastogenesis and actin ring formation
      target: Dysregulated Osteoblast and Osteoclast Differentiation
      direction: DECREASED
      interpretation: Cellular correlate of the osteoclast arm of the imbalance.
      evidence:
      - reference: PMID:34841576
        reference_title: "Introduction of a Cys360Tyr Mutation in ANO5 Creates a Mouse Model for Gnathodiaphyseal Dysplasia."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Interestingly, Ano5KI/KI bone marrow-derived macrophage cultures showed
          decreased osteoclastogenesis, and Ano5KI/KI osteoclasts exhibited disrupted
          actin ring formation, which may be associated with some signaling pathways.
        explanation: Reports the osteoclastogenesis and actin-ring measurements.
    evidence:
    - reference: PMID:34841576
      reference_title: "Introduction of a Cys360Tyr Mutation in ANO5 Creates a Mouse Model for Gnathodiaphyseal Dysplasia."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Calvaria-derived Ano5KI/KI osteoblast cultures showed increased
        osteoblastogenesis, including hypermineralized bone matrix and enhanced bone
        formation-related factors expression.
      explanation: >-
        A measured result in the knock-in model on both arms of the remodelling node,
        which is what makes this model informative for it.
  - target: Osteoclast Differentiation Blockade and Apoptosis
    relationship: RESCUES
    fidelity: MODERATE
    description: >-
      The Akt activator SC79 restores osteoclast formation in this genotype-matched
      knock-in - multinucleated TRAP-positive osteoclasts and actin rings reappear with
      the osteoclast effector programme re-expressed - while the mirror experiment in
      osteoblasts suppresses mineralization. One intervention corrects both arms.
    limitations: >-
      Ex vivo BMM and calvarial osteoblast cultures from homozygous knock-in mice, with
      no in vivo skeletal endpoint and no human data. SC79 is a research tool compound,
      not a therapeutic, which is why this is curated here and not under `treatments`.
    readouts:
    - name: TRAP-positive multinucleated osteoclast and actin ring formation after SC79
      target: Osteoclast Differentiation Blockade and Apoptosis
      direction: RESTORED
      interpretation: >-
        Pharmacological reversal of the osteoclast blockade, which is what establishes
        Akt as a causal intermediate rather than a correlate.
      evidence:
      - reference: PMID:39866532
        reference_title: "Ano5(Cys360Tyr) mutation leads to bone dysfunction of gnathodiaphyseal dysplasia via disturbing Akt signaling."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Akt activation promoted the generation of TRAP-positive multinucleated
          osteoclasts and the formation of actin rings in Ano5 KI/KI BMMs cultures,
          accompanied by increased expression of Nfatc1, Trap, Dc-stamp, Mmp9, Ctsk, and
          Atp6v0d2.
        explanation: Reports the SC79 rescue measurements on the osteoclast arm.
    evidence:
    - reference: PMID:39866532
      reference_title: "Ano5(Cys360Tyr) mutation leads to bone dysfunction of gnathodiaphyseal dysplasia via disturbing Akt signaling."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Akt activation by SC79 stimulation can obviously rescue abnormal increased
        osteogenesis and decreased osteoclastogenesis in Ano5 KI/KI mouse model
      explanation: >-
        The authors' summary that a single intervention rescues both arms, which is what
        makes this model informative for the signalling nodes.
  - target: Pro-Osteogenic Signalling Dysregulation in Osteoblasts
    relationship: RESCUES
    fidelity: MODERATE
    description: >-
      The AMPK inhibitor Compound C reverses the skeletal phenotype in this
      genotype-matched knock-in, restraining formation and restoring osteoclastogenesis
      by suppressing PGC1a and promoting PGC1b.
    limitations: >-
      Compound C is a non-selective research tool with well-documented off-target
      activity, and the result is mouse-only. Not curated as a treatment.
    readouts:
    - name: Bone phenotype after AMPK inhibition
      target: Pro-Osteogenic Signalling Dysregulation in Osteoblasts
      direction: RESTORED
      interpretation: Reversal of the remodelling imbalance by blocking the AMPK arm.
      evidence:
      - reference: PMID:41717545
        reference_title: "Anoctamin 5 mutation leads to abnormal bone homeostasis of GDD by regulating AMPK-dependent glucose metabolism."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          AMPK inhibitor reversed the bone phenotype of GDD by restraining bone formation
          and restoring osteoclastogenesis.
        explanation: Reports the Compound C rescue of the skeletal phenotype.
    evidence:
    - reference: PMID:41717545
      reference_title: "Anoctamin 5 mutation leads to abnormal bone homeostasis of GDD by regulating AMPK-dependent glucose metabolism."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Inhibiting AMPK reduced glycolysis in osteoblast and maintained the mitochondrial
        homeostasis between osteoblast and osteoclast by suppressing PGC1a and promoting
        PGC1b respectively, to restrain bone formation and restore osteoclastogenesis.
      explanation: >-
        Gives the mechanism by which the AMPK arm is corrected, tying the rescue to the
        glycolytic and mitochondrial changes curated on that node.

- name: Ano5 p.T491F knock-in mouse
  species: Mouse
  genotype: Ano5 p.T491F knock-in (murine equivalent of human ANO5 p.Ser500Phe), heterozygous and homozygous
  publication: PMID:32455153
  description: >-
    A knock-in of the murine equivalent of a human GDD-causing allele taken from a
    thoroughly phenotyped patient. Despite radiography, micro-CT and undecalcified
    histomorphometry at two ages in males, with confirmation in females and in a
    second independent clone, no skeletal or mandibular phenotype was found.
  modeled_mechanisms:
  - target: Diaphyseal Sclerosis and Bone Fragility
    relationship: FAILS_TO_RECAPITULATE
    fidelity: LOW
    description: >-
      A genotype-matched GDD allele that produces no bone phenotype in mouse, in
      direct conflict with the human disease and with the p.Cys360Tyr knock-in.
    limitations: >-
      Mice were assessed only under unchallenged conditions and only to 24 weeks, so a
      late or stress-dependent phenotype is not excluded; the authors nonetheless
      conclude Ano5 is dispensable for murine bone homeostasis. Construct validity is
      the more specific concern: the mutated residue is not conserved, so the human
      Ser-to-Phe change corresponds to a Ter-to-Phe change in mouse, and the knock-in
      may therefore not model the human lesion at all.
    evidence:
    - reference: PMID:32455153
      reference_title: "Gnathodiaphyseal dysplasia is not recapitulated in a respective mouse model carrying a mutation of the Ano5 gene."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        These mice did not display alterations of skeletal microarchitecture or mandible
        morphology. The results were confirmed in female mice and animals derived from a
        second, independent clone.
      explanation: >-
        The negative result, with the replication that makes it a substantive negative
        claim rather than an underpowered one.

- name: Ano5 knockout mouse
  species: Mouse
  genotype: Ano5 homozygous knockout (CRISPR/Cas9)
  publication: PMID:30712070
  description: >-
    Complete Ano5 loss of function in mouse. Homozygous null animals develop several
    cardinal GDD traits with elevated serum ALP and increased osteoblastogenesis -
    which is mechanistically awkward, since in humans it is biallelic loss of
    function that causes myopathy rather than bone disease.
  modeled_mechanisms:
  - target: Diaphyseal Sclerosis and Bone Fragility
    relationship: PARTIALLY_RECAPITULATES
    fidelity: LOW
    description: >-
      Reproduces GDD-like jawbone enlargement, tibial bowing and diaphyseal sclerosis
      with cortical thickening, but from a genotype that does not correspond to human
      GDD.
    limitations: >-
      The genotype is a homozygous null, whereas human GDD is heterozygous missense and
      human biallelic ANO5 null alleles cause muscular dystrophy, not bone disease. Its
      GDD-like readout therefore cannot be read as validating a loss-of-function
      mechanism for human GDD; it is evidence that murine and human ANO5 skeletal
      requirements differ.
    readouts:
    - name: Mandibular size, tibial bowing and diaphyseal sclerosis
      target: Diaphyseal Sclerosis and Bone Fragility
      direction: INCREASED
      interpretation: >-
        GDD-like skeletal changes arising from a null genotype, the observation that
        drives the alternative deficiency hypothesis.
      evidence:
      - reference: PMID:30712070
        reference_title: "Genetic Disruption of Anoctamin 5 in Mice Replicates Human Gnathodiaphyseal Dysplasia (GDD)."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Homozygous Ano5 knockout mice (Ano5-/-) replicate some typical traits of human
          GDD including massive jawbones, bowing tibia, sclerosis and cortical thickening
          of femoral and tibial diaphyses.
        explanation: Reports the skeletal measurements in the null mouse.
    evidence:
    - reference: PMID:30712070
      reference_title: "Genetic Disruption of Anoctamin 5 in Mice Replicates Human Gnathodiaphyseal Dysplasia (GDD)."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Bone matrix is hypermineralized, and the expression of bone formation-related
        factors is enhanced in Ano5-/- mice, suggesting that the osteogenic anomaly
        arises from a genetic disruption of Ano5.
      explanation: >-
        Supports the model as informative about ANO5 and bone, while the genotype
        mismatch keeps the support partial.
  - target: Pro-Osteogenic Signalling Dysregulation in Osteoblasts
    relationship: RESCUES
    fidelity: LOW
    description: >-
      Two independent in vivo rescues of the osteogenic excess in Ano5-null mice: the
      autophagy inhibitor 3-methyladenine alleviates the bone phenotype, and miR-34c-5p
      delivered by AAV rescues the abnormally thickened cortical bone, improves
      biomechanics and lowers serum P1NP. Both establish their arm as causal rather than
      correlative.
    limitations: >-
      Fidelity is LOW for a specific reason, not a generic one: these rescues are in a
      homozygous NULL, and human GDD is heterozygous missense while human biallelic ANO5
      null alleles cause muscular dystrophy rather than bone disease. A rescue that works
      in this genotype does not establish the arm is operating in human GDD. 3-MA is
      also a non-selective autophagy inhibitor.
    readouts:
    - name: Cortical thickness, biomechanics and serum P1NP after miR-34c-5p AAV
      target: Pro-Osteogenic Signalling Dysregulation in Osteoblasts
      direction: RESTORED
      interpretation: >-
        In vivo reversal of the cortical phenotype through the miR-34c-5p/KLF4/
        beta-catenin arm, with a serum bone-formation marker moving in the same
        direction.
      evidence:
      - reference: PMID:40508076
        reference_title: "Ano5 Deficiency Leads to Abnormal Bone Formation via miR-34c-5p/KLF4/beta-Catenin in Gnathodiaphyseal Dysplasia."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Furthermore, miR-34c-5p adeno-associated virus (AAV) treatment in vivo rescued
          the abnormally thickened cortical bone and enhanced biomechanical properties in
          Ano5-/- mice.
        explanation: Reports the in vivo AAV rescue measurements.
    - name: Bone phenotype after 3-methyladenine
      target: Pro-Osteogenic Signalling Dysregulation in Osteoblasts
      direction: RESTORED
      interpretation: In vivo reversal through the autophagy arm.
      evidence:
      - reference: PMID:40067389
        reference_title: "Anoctamin-5 deficiency enhances ATG9A-dependent autophagy, inducing osteogenesis and gnathodiaphyseal dysplasia-like bone formation."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Moreover, in vivo experiments confirmed that treatment with 3-MA alleviated the
          bone phenotype abnormalities in Ano5-/- mice.
        explanation: Reports the in vivo 3-MA rescue.
    evidence:
    - reference: PMID:40067389
      reference_title: "Anoctamin-5 deficiency enhances ATG9A-dependent autophagy, inducing osteogenesis and gnathodiaphyseal dysplasia-like bone formation."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        The application of 3-methyladenine (3-MA) and chloroquine (CQ) reversed the
        excessive osteogenesis observed in Ano5-/- mCOBs.
      explanation: >-
        Two independent autophagy inhibitors reversing the phenotype, which is what makes
        this model informative for the osteoblast signalling node.
  - target: Osteoclast Differentiation Blockade and Apoptosis
    relationship: RECAPITULATES
    fidelity: LOW
    description: >-
      Reproduces the osteoclast blockade with suppressed RANKL/NF-kB signalling,
      disrupted actin rings and reduced resorption, plus ER-stress/CHOP-driven osteoclast
      apoptosis.
    limitations: >-
      Homozygous null genotype, not corresponding to human GDD; see the note on the other
      link from this model.
    readouts:
    - name: Osteoclast marker expression and resorption
      target: Osteoclast Differentiation Blockade and Apoptosis
      direction: DECREASED
      interpretation: The osteoclast-side deficit in the null mouse.
      evidence:
      - reference: PMID:36989132
        reference_title: "Genetic disruption of Ano5 leads to impaired osteoclastogenesis for gnathodiaphyseal dysplasia."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Ano5-/- osteoclasts manifested disrupted actin ring and less mineral resorption.
        explanation: Reports the actin-ring and resorption measurements.
    evidence:
    - reference: PMID:40049314
      reference_title: "Ano5 deficiency disturbed bone formation by inducing osteoclast apoptosis in Gnathodiaphyseal dysplasia."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        In summary, Ano5 deficiency impairs the function of osteoclasts by increasing
        osteoclast apoptosis, which is induced by an overactivated ERS response via
        calcium dyshomeostasis.
      explanation: >-
        Summarizes the ER-stress/apoptosis mechanism this model evidences for the
        osteoclast node.

- name: Ano5 knockout mouse (Li et al., low-bone-mass line)
  species: Mouse
  genotype: Ano5 homozygous and heterozygous knockout
  publication: PMID:35982081
  description: >-
    A second, independent Ano5-null line that reports the OPPOSITE skeletal direction
    from the Wang knockout: low bone volume, defective osteoblast and osteoclast
    differentiation, and diminished intracellular calcium oscillations, modelling the
    low-bone-mass GDD sub-entity rather than the osteosclerotic one. Heterozygotes
    show a milder version of the homozygous phenotype, which is the basis of the
    dosage-sensitivity argument. Parathyroid hormone rescued bone strength.
  modeled_mechanisms:
  - target: Dysregulated Osteoblast and Osteoclast Differentiation
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Measures the two-lineage remodelling disturbance and ties it to calcium
      oscillations, WNT/beta-catenin and RANKL-NFATc1 signalling.
    limitations: >-
      A null genotype, whereas human GDD is heterozygous missense. Its direction of
      effect on osteoblasts is opposite to both the Wang null and the p.Cys360Tyr
      knock-in, so the three lines cannot all be describing the same biology.
    readouts:
    - name: Trabecular bone volume and osteoblast/osteoclast differentiation
      target: Dysregulated Osteoblast and Osteoclast Differentiation
      direction: DECREASED
      interpretation: >-
        The low-bone-mass arm of the proposed sub-entity split, opposite in sign to the
        other two mouse lines.
      evidence:
      - reference: PMID:35982081
        reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Moreover, using Ano5 knockout (KO) mice, we found that they exhibited low bone
          volume, abnormal calcium deposits, and defective osteoblast and osteoclast
          differentiation.
        explanation: Reports the bone-volume and differentiation measurements.
    evidence:
    - reference: PMID:35982081
      reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Here, we show that ablation of Ano5 reduced intracellular calcium transients,
        leading to defects in osteogenesis and osteoclastogenesis and thus bone
        dysplasia.
      explanation: >-
        Establishes the mechanism this line is informative about at the cellular node.
  - target: High-Turnover Skeletal Remodelling Imbalance
    relationship: RESCUES
    fidelity: LOW
    description: >-
      Osteoanabolic parathyroid hormone restored bone strength in the null mouse - the
      only pharmacological rescue reported for any ANO5 bone model, and the origin of
      the osteoanabolic option recorded under treatments.
    limitations: >-
      Mouse only, in a null genotype that does not correspond to human GDD, and it
      rescues the low-bone-mass phenotype - so it says nothing about, and would be
      mechanistically wrong for, the osteosclerotic high-turnover sub-entity.
    readouts:
    - name: Bone strength after parathyroid hormone treatment
      target: High-Turnover Skeletal Remodelling Imbalance
      direction: RESTORED
      interpretation: Pharmacological reversal of the low-bone-mass phenotype.
      evidence:
      - reference: PMID:35982081
        reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Osteoanabolic treatment of parathyroid hormone was effective in enhancing bone
          strength in Ano5 KO mice.
        explanation: Reports the PTH rescue measurement.
    evidence:
    - reference: PMID:35982081
      reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Osteoanabolic treatment of parathyroid hormone was effective in enhancing bone
        strength in Ano5 KO mice.
      explanation: >-
        The rescue is real but in a non-corresponding genotype, so it is partial support
        for treating this node as pharmacologically addressable.

discussions:
- discussion_id: gdd_jaw_selectivity_gap
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Why does a heterozygous missense change in ANO5, a broadly expressed
    endoplasmic-reticulum phospholipid scramblase, produce focal expansile
    cemento-osseous lesions that are essentially confined to the tooth-bearing
    jaws, while the rest of the skeleton shows a diffuse high-turnover sclerosing
    phenotype instead?
  attaches_to:
  - pathophysiology#Jaw Cemento-Osseous Fibrous Lesion Formation
  rationale: >-
    This is the central unexplained feature of GDD and the reason the causal edge
    into the jaw lesion node is marked INDIRECT_UNKNOWN_INTERMEDIATES rather than
    DIRECT. The gnathic and extragnathic lesions are not the same pathology in two
    locations - jaw lesions are fibro-osseous and specifically lack the
    osteosclerosis that defines the long-bone lesion - so the disorder needs an
    account of tissue selectivity, not merely of bone-cell dysfunction. Candidate
    explanations include a neural-crest-derived versus mesoderm-derived skeletal
    origin, the distinct periodontal-ligament and cementoblast populations of the
    gnathic skeleton (ANO5 is expressed in periodontal ligament cells), and the
    continuous remodelling demand of tooth-bearing bone. None has been tested.
    Filling this gap with a plausible-sounding chain would misrepresent the state of
    the evidence.
  proposed_experiments:
  - experiment_id: gdd_lineage_conditional_knockin
    name: Lineage-resolved conditional ANO5 GDD-allele expression
    description: >-
      Express a GDD knock-in allele conditionally in neural-crest-derived versus
      mesoderm-derived skeletal lineages in mouse and ask whether jaw lesion
      formation tracks lineage rather than anatomical site.
  - experiment_id: gdd_jaw_lesion_single_cell
    name: Single-cell profiling of human GDD jaw lesion tissue
    description: >-
      Single-cell or spatial transcriptomic profiling of resected GDD gnathic lesions
      against uninvolved bone from the same patient, to identify the cell population
      that expands and whether it is cementoblast or periodontal-ligament derived.
  notes: >-
    Distinct from the mechanism-direction dispute recorded in
    `gdd_gof_vs_lof_dispute`: even if the gain-of-function reading is correct, the
    tissue-selectivity question remains open.

- discussion_id: gdd_gof_vs_lof_dispute
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Is the GDD skeletal phenotype driven by gain of ANO5 function, or can reduced
    ANO5 activity produce it too - and if the latter, why do heterozygous ANO5 null
    carriers (the parents of LGMDR12 patients) not develop bone disease?
  attaches_to:
  - pathophysiology#Altered Calcium-Activated Phospholipid Scrambling by TMEM16E
  rationale: >-
    The gain-of-function reading rests on strong but indirect grounds - dominant
    inheritance with a clustered missense spectrum, plus heterologous-expression
    assays in HEK293 cells showing GDD and muscular-dystrophy alleles moving in
    opposite directions. Three findings sit awkwardly with it. First, Ano5-knockout
    mice reproduce several cardinal GDD traits, which a strict gain-of-function
    model does not predict. Second, canonical GDD missense alleles reduce
    steady-state ANO5 protein in overexpression studies, so they are not purely
    hyperactive. Third, a GDD family has been reported with a frameshift insertion
    and reduced TMEM16E expression. The observation that obligate heterozygous null
    carriers of LGMDR12 alleles are not reported with bone disease remains the
    strongest argument against simple haploinsufficiency, but it is an argument from
    absence in a population that has not been systematically skeletally phenotyped,
    and that limitation should be stated rather than glossed.
  proposed_experiments:
  - experiment_id: gdd_null_carrier_skeletal_phenotyping
    name: Skeletal phenotyping of obligate ANO5 null heterozygotes
    description: >-
      Systematic dental panoramic imaging, long-bone radiography and bone-turnover
      marker assessment in obligate heterozygous carriers of ANO5 truncating alleles
      ascertained through LGMDR12 probands, to convert an argument from absence into a
      measured negative.
  - experiment_id: gdd_allelic_series_knockin
    name: Allelic series knock-in comparison in a single genetic background
    description: >-
      Compare knock-in of a GDD missense allele, a heterozygous null allele, and a
      homozygous null allele in one mouse background with identical skeletal
      phenotyping, to separate dosage effects from allele-specific activity.
  evidence:
  - reference: PMID:30712070
    reference_title: "Genetic Disruption of Anoctamin 5 in Mice Replicates Human Gnathodiaphyseal Dysplasia (GDD)."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Here we generated Ano5-knockout (KO) mice using a CRISPR/Cas 9 approach to study
      loss of function aspects of GDD mutations.
    explanation: >-
      Frames the loss-of-function investigation whose positive skeletal result is the
      main tension with the gain-of-function model.

- discussion_id: gdd_phenotypic_dichotomy_challenged
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    How absolute is the separation between the ANO5 bone and muscle phenotypes,
    given a dominant kindred in which the functionally characterized GDD allele
    p.Thr513Ile produced both cemento-osseous jaw lesions and recurrent
    rhabdomyolysis with hyperCKemia?
  attaches_to:
  - pathophysiology#Heterozygous ANO5 Missense Variant
  rationale: >-
    The clean dichotomy - dominant missense to bone, recessive null to muscle - is
    the framing that motivates this entry, and it is largely right, but it is not
    absolute and the entry should not assert more than the literature supports. An
    11-member kindred carrying p.Thr513Ile showed recurrent rhabdomyolysis, muscle
    cramps, hyperCKemia and muscle hypertrophy alongside the mandibular
    cemento-osseous lesions, and the authors explicitly framed this as a challenge to
    the proposed dichotomy. If a single dominant allele can produce both tissue
    phenotypes, then allele class and tissue are not in one-to-one correspondence,
    and the gain-of-function versus loss-of-function assignment explains the
    inheritance pattern better than it explains the tissue distribution.
  proposed_experiments:
  - experiment_id: gdd_prospective_neuromuscular_assessment
    name: Prospective neuromuscular assessment of GDD cohorts
    description: >-
      Systematic CK measurement, muscle imaging and exertional-symptom history in
      genotyped GDD patients stratified by allele, to establish whether subclinical
      muscle involvement is specific to p.Thr513Ile or general to GDD.
  evidence:
  - reference: PMID:34291158
    reference_title: "Autosomal Dominant ANO5-Related Disorder Associated With Myopathy and Gnathodiaphyseal Dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This report described the coexistence of muscle and bone phenotypes in the same
      patients with ANO5-related disorder.
    explanation: >-
      Documents the coexistence directly, which is what makes the dichotomy a curated
      question rather than a settled fact.
  - reference: PMID:34291158
    reference_title: "Autosomal Dominant ANO5-Related Disorder Associated With Myopathy and Gnathodiaphyseal Dysplasia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our data challenge recent results that suggested complete dichotomy of these
      phenotypes and the proposed loss-of-function and gain-of-function mechanisms for
      the skeletal and muscle phenotypes, respectively.
    explanation: >-
      The authors' explicit statement that they are challenging the dichotomy this
      entry otherwise adopts as its organizing frame. Reader caution, since the quote
      is reproduced verbatim and must not be altered: the trailing "respectively"
      pairs loss-of-function with the SKELETAL phenotype and gain-of-function with the
      MUSCLE phenotype, which is the reverse of the assignment made everywhere else in
      this entry and in the functional literature (PMID:29124309, PMID:32112655, and
      this paper's own discussion). Treat the sentence as evidence that the dichotomy
      is being challenged, not as a source for which direction goes with which tissue.

- discussion_id: gdd_mouse_model_mismatch
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: >-
    Do the existing mouse models faithfully represent human GDD, given that a
    knock-in of the murine equivalent of a human GDD missense allele produced no
    skeletal phenotype at all, while Ano5 knockout - the genotype that in humans
    causes myopathy rather than bone disease - does produce GDD-like bone changes?
  attaches_to:
  - pathophysiology#Heterozygous ANO5 Missense Variant
  - pathophysiology#Altered Calcium-Activated Phospholipid Scrambling by TMEM16E
  rationale: >-
    The mouse evidence is internally inconsistent in a way that inverts the human
    genotype-phenotype relationship, so no mouse result about GDD mechanism can
    currently be transferred to human disease without argument. A p.T491F knock-in -
    the murine equivalent of the human p.Ser500Phe GDD allele, taken from a
    thoroughly characterized patient - showed no alteration of skeletal
    microarchitecture or mandible morphology in heterozygotes or homozygotes, assessed
    at two ages in males with the result confirmed in females and in an independent
    clone. Meanwhile Ano5 knockout mice, and a separate p.Cys360Tyr knock-in, do
    develop GDD-like massive jawbones, tibial bowing and diaphyseal cortical
    thickening.

    Worse, the two null lines disagree with EACH OTHER. Wang's knockout gave
    osteosclerosis and hypermineralized matrix; Li's knockout gave low bone volume
    with defective osteoblast and osteoclast differentiation. Li et al. state the
    non-replication plainly. So the model evidence is not merely
    positive-versus-negative: three independent lines carrying ANO5 lesions produce
    three different skeletal directions, and two of them share a genotype. Together
    with the null-models-a-missense-disease problem, this means the mouse literature
    cannot presently arbitrate the gain- versus loss-of-function question it is most
    often invoked to settle. There is at least one concrete, testable explanation for the negative
    knock-in rather than a bare species hand-wave: Li et al. point out the residue is
    not conserved - the human change is Ser to Phe while the murine equivalent is Ter
    to Phe - so the mouse allele may simply not be the same lesion, and they also
    argue the animals were phenotyped too late. That is an argument about construct
    validity, and it is why the negative result is recorded here as a mismatch to be
    resolved rather than as a refutation of the human mechanism.
  proposed_experiments:
  - experiment_id: gdd_harmonized_multiallele_phenotyping
    name: Harmonized multi-allele skeletal phenotyping
    description: >-
      Phenotype p.T491F, p.Cys360Tyr and null Ano5 alleles in one genetic background
      with a single harmonized imaging and histomorphometry protocol, to determine
      whether the discrepancy is allele-specific biology or protocol and background
      variation.
  - experiment_id: gdd_human_osteoblast_cementoblast_models
    name: Human osteoblast and cementoblast models of GDD alleles
    description: >-
      Patient-derived or isogenic iPSC-derived human osteoblasts and
      periodontal-ligament or cementoblast cultures carrying GDD alleles, to test the
      mechanism in human cells rather than relying on mouse models that disagree.
  evidence:
  - reference: PMID:32455153
    reference_title: "Gnathodiaphyseal dysplasia is not recapitulated in a respective mouse model carrying a mutation of the Ano5 gene."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      These mice did not display alterations of skeletal microarchitecture or mandible
      morphology.
    explanation: >-
      The negative knock-in result: the murine equivalent of a human GDD allele
      produced no skeletal phenotype.
  - reference: PMID:32455153
    reference_title: "Gnathodiaphyseal dysplasia is not recapitulated in a respective mouse model carrying a mutation of the Ano5 gene."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Therefore, our results indicate that Ano5 is dispensable for bone homeostasis in
      mice, at least under unchallenged conditions, and that these animals may not
      present the most adequate model to study the physiological role of Anoctamin 5.
    explanation: >-
      The authors' own conclusion that the mouse is not an adequate model, which is the
      substance of this mismatch.
  - reference: PMID:34841576
    reference_title: "Introduction of a Cys360Tyr Mutation in ANO5 Creates a Mouse Model for Gnathodiaphyseal Dysplasia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Homozygous Ano5 knock-in mice (Ano5KI/KI ) replicated GDD-like skeletal features,
      including massive jawbones, bowing tibia, bone fragility, sclerosis, and cortical
      thickening of the femoral and tibial diaphysis.
    explanation: >-
      The contradicting positive knock-in result, in a different GDD allele, that makes
      the model evidence inconsistent rather than merely negative.
  - reference: PMID:35982081
    reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Moreover, the amino acid sequence is not conserved between humans and mice at
      that mutation site, where Ser is mutated to Phe in humans while Ter is mutated to
      Phe in mice.
    explanation: >-
      Supplies a specific construct-validity explanation for the negative knock-in - the
      mouse allele is not the homologous lesion - which converts an unexplained species
      discrepancy into a testable one.
  - reference: PMID:35982081
    reference_title: "Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      however, a similar skeletal phenotype could not be produced in another study
    explanation: >-
      Records the knockout-versus-knockout non-replication in the authors' own words -
      the sharpest form of the mismatch, since the same null genotype yields opposite
      bone-mass directions across laboratories. The clause immediately preceding this
      one in the source describes the increased BMD and bone matrix mineralization
      reported in the other Ano5 knockout; it is not quoted here only because an inline
      citation marker sits mid-sentence and would break verbatim matching.

notes: >-
  Entry-type decision (issue #9198): curated as a `DISEASE` in `kb/disorders/`.
  MONDO:0008151 has no MONDO descendants, so there is nothing to group; it is not a
  subtype of an existing dismech entry (its MONDO parent, MONDO:0800064, is an
  osteogenesis-imperfecta/reduced-bone-mineral-density grouping term that dismech
  does not curate as an entry); and it carries a single causal gene with a
  well-defined allele class, so it is neither a grouping nor out of scope.

  Deliberately NOT modelled here: the mechanism of the ANO5 muscular dystrophies.
  That belongs to `Autosomal_Recessive_Limb-Girdle_Muscular_Dystrophy`, which
  already curates ANO5/LGMDR12 as a subtype and as a `genetic:` entry. This entry
  references that mechanism only where the contrast does mechanistic work - the
  argument that GDD is not haploinsufficiency.

  No GeneReviews chapter exists for gnathodiaphyseal dysplasia (PubMed searches for
  `gnathodiaphyseal dysplasia GeneReviews` returned no results on 2026-08-21), so
  the GeneReviews phenotype baseline step was not applicable. A GeneReviews chapter
  does exist for ANO5 *muscle* disease, which is the allelic disorder curated
  elsewhere, not this one.

  Prevalence is curated only as the qualitative class ULTRA_RARE, with
  `rate_per_100000` deliberately unset. No population-based estimate for GDD exists,
  and the Orphanet bulk XML was not available in this worktree to cite an Orphanet
  prevalence band; asserting a numeric rate would be fabrication.

  No `mappings:` block. OMIM #166260 (the phenotype) and *608662 (the gene) are stated
  in several cited abstracts, and ORPHA:53697 exists, but `DiseaseMappings` provides
  only `icd10cm_mappings`, `icd11f_mappings`, `mondo_mappings` and `ncit_mappings` -
  there is no OMIM or ORPHA slot - and no cached source in this worktree states an
  ICD-10-CM or NCIT code for GDD. A mapping is an assertion like any other, so none is
  made rather than one guessed from a plausible-looking code.

  No `frequency:` band on ANY phenotype, entry-wide and deliberately. Aggregated
  percentages do exist - a literature review of 108 individuals across 25 families
  gives roughly 67% jaw lesions, 48% tooth anomalies, 45% fractures, 19% bowing, 16%
  diaphyseal thickening, 10% osteopenia. Two reasons they are not curated. First, the
  numbers are not stated in any cached abstract, so a `frequency:` value would carry a
  snippet that does not support it, which is exactly the failure the frequency-evidence
  SOP warns about. Second, they are literature-derived and biased in opposing
  directions - jaw lesions are over-counted because most patients reach diagnosis
  through a maxillofacial route, while mildly affected relatives inside reported
  pedigrees are systematically under-phenotyped. If the full text is later cached, these
  become curatable with the ascertainment caveat attached.

  `has_subtypes` decision: NOT split, deliberately, and this is the closest call in the
  entry. The high-bone-mass and low-bone-mass presentations are a real candidate split
  and have been proposed as GDD sub-entities assigned by variant class. They are not
  curated as `has_subtypes` because the split currently rests on two contrasting
  reports - one p.Ser500Phe patient with increased trabecular mass and one
  p.L370_A371ins family with osteopenia - plus a mechanistic model, and the allele-class
  rule that would assign a new patient to a subtype is precisely what is unproven.
  Creating subtypes now would harden a hypothesis into structure and force every
  downstream annotation to pick a side. Instead the split is carried where it can be
  revised: an EMERGING `mechanistic_hypotheses` entry, both phenotypes curated with no
  direction on bone mineral density, and a treatment caveat that the two directions
  imply opposite drug choices. Revisit if a cohort demonstrates the allele-class rule.

  Muscle phenotypes (rhabdomyolysis, hyperCKemia, muscle hypertrophy) are deliberately
  NOT curated as `phenotypes:` even though a GDD kindred exhibits them. They are
  reported in a single p.Thr513Ile family, and the whole point of this entry is that
  ANO5 muscle disease is the allelic recessive disorder curated elsewhere; promoting
  them to disease-level phenotypes of GDD would blur the distinction the entry exists to
  draw. They are instead recorded in `gdd_phenotypic_dichotomy_challenged`, which is the
  honest location for a documented exception.

  No `conforms_to` declared, deliberately. `osteoporosis_bone_resorption` was
  considered and declined: that module models net bone LOSS through increased
  osteoclastic resorption, whereas GDD's bone-mass direction is contested and
  variant-class-dependent, with the better-characterized presentations showing
  INCREASED trabecular bone mass. Declaring conformance would assert exactly the
  direction this entry records as unresolved. It should be revisited if the
  low-bone-mass sub-entity is confirmed as a distinct, separately curatable entity.
  Two other modules were checked and also declined: `defective_skeletal_mineralization`
  is the wrong shape, since GDD produces HYPERmineralized matrix and sclerosis rather
  than a failure to mineralize, and its three trigger arms (calciopenic, phosphopenic,
  inhibitor-excess) are all absent here; and `loss_of_proteostasis` is
  aggregate-centred, whereas the ANO5 defect is a membrane-transport activity change,
  not an aggregation or degradation-capacity problem, notwithstanding that GDD missense
  alleles reduce steady-state protein in overexpression. The KB has no sclerosing
  bone dysplasia / increased-bone-mass module; GDD plus the existing autosomal dominant
  osteopetrosis entry could seed one, which is a better follow-up than forcing a fit.

  Lump/split on familial gigantiform cementoma and familial florid cemento-osseous
  dysplasia: these are curated here as within the GDD spectrum rather than as separate
  entries or differentials, following the finding of recurrent ANO5 p.Cys356Tyr in FGC
  kindreds and the authors' conclusion that FGC may be an atypical GDD variant. They
  are not given `has_subtypes` entries because the evidence is three probands and the
  nosology is explicitly unsettled in the source.

  Follow-up worth a separate issue, deliberately not attempted here: a
  `kb/groupings/` entry over the fibro-osseous and giant-cell lesions of the jaws.
  dismech already curates Cherubism and Fibrous_Dysplasia; heterozygous ANO5 variants
  are now also reported in florid cemento-osseous dysplasia WITHOUT the
  diaphyseal/fragility component, which would make ANO5 a shared-mechanism thread
  through part of that family. A grouping needs its members curated first, and the
  FCOD reports are not yet curated as entries, so this is a pointer rather than a
  half-built union.

  HPO/HPOA coverage gap, recorded because it affects what can be annotated rather
  than being a defect in this entry: the HPOA annotations on OMIM:166260 carry the
  diaphyseal, bowing, fracture, osteopenia, osteomyelitis, onset and inheritance
  features but include NO jaw-lesion annotation at all - the defining feature of the
  disease. `HP:0012328` Cementoma exists and is used here with a more specific
  `preferred_term`; there is no HPO term for a fibro-osseous lesion as such. Both the
  missing annotation and the missing term are upstream issues.

📚

References & Deep Research

References

2

PMID:15124103

The novel gene encoding a putative transmembrane protein is mutated in gnathodiaphyseal dysplasia (GDD).

No top-level findings curated for this source.

PMID:32112655

TMEM16E/ANO5 mutations related to bone dysplasia or muscular dystrophy cause opposite effects on lipid scrambling.

No top-level findings curated for this source.

Deep Research

1

Claude Code ▸

Gnathodiaphyseal Dysplasia (GDD) — Comprehensive Research Report

claude-haiku-4-5-20251001, claude-opus-5 9 citations 2026-08-21T21:02:01.867199

Gnathodiaphyseal Dysplasia (GDD) — Comprehensive Research Report

Prepared: 21 August 2026 · Target: Gnathodiaphyseal dysplasia · MONDO:0008151 · Category: Mendelian (autosomal dominant, monogenic — ANO5)

Evidence-quality note up front. GDD is an ultra-rare disorder with roughly 100–110 clinically described individuals in the entire literature. Almost all clinical content below rests on case reports and small pedigrees; there are no cohort studies, no clinical trials, no registry data, and no natural-history study. Mechanistic content rests almost entirely on mouse models and heterologous cell expression — and, as detailed in §6 and §15, the mouse models actively disagree with one another. Sections where the honest answer is "not available" are marked as such rather than filled with inference.

1. Disease Information

Overview

Gnathodiaphyseal dysplasia is a rare autosomal dominant generalized skeletal syndrome defined by the co-occurrence of three features: fibro-osseous (cemento-osseous) lesions of the jawbones, generalized bone fragility with recurrent fractures, and bowing plus diaphyseal cortical thickening/sclerosis of the tubular bones. Riminucci et al. established it as a discrete nosological entity in 2001, distinguishing it from polyostotic fibrous dysplasia; the jaw lesions are cemento-ossifying fibromas with a prominent psammomatoid body component, and — importantly for the name — osteosclerosis is not a feature of the jaw lesions themselves, which is why the entity was renamed from "gnathodiaphyseal sclerosis" (PMID:11547842).

The canonical description from the gene-discovery paper: "Gnathodiaphyseal dysplasia (GDD) is a rare skeletal syndrome characterized by bone fragility, sclerosis of tubular bones, and cemento-osseous lesions of the jawbone." (Tsutsumi et al., Am J Hum Genet 2004; PMID:15124103, DOI 10.1086/421527)

A defining and clinically underappreciated feature is susceptibility to purulent osteomyelitis of the jaws, typically emerging in adult life, often after dental extraction, with purulent discharge from gums, tooth mobility, tooth loss, and poor extraction-site healing (PMID:28176803).

Key identifiers

Resource	Identifier
MONDO	MONDO:0008151 (`gnathodiaphyseal dysplasia`) — verified against local ontology cache
OMIM (phenotype)	#166260 GNATHODIAPHYSEAL DYSPLASIA; GDD
OMIM (gene)	*608662 ANO5 / TMEM16E / GDD1
Orphanet	ORPHA:53697
ICD-10	M85.8 (per Orphanet mapping)
ICD-11	LD24.2Y (per Orphanet mapping)
UMLS / GTR / MedGen	C1833736
Disease Ontology	DOID:0111533
HGNC (causal gene)	hgnc:27337 (`ANO5`) — verified against local cache
MeSH	No dedicated descriptor. PubMed indexes GDD papers under Osteogenesis Imperfecta/genetics plus Jaw Abnormalities/genetics and Anoctamins/genetics — a legacy of GDD's historical classification as an OI variant (visible in the MeSH keyword lists of PMID:15124103, PMID:28176803, PMID:34841576). This is a real ontology gap worth flagging in any KB entry.

Synonyms and alternative names

GDD (standard abbreviation)
Gnathodiaphyseal sclerosis / hereditary gnathodiaphyseal sclerosis (historical; abandoned because jaw lesions are not sclerotic)
Osteogenesis imperfecta with unusual skeletal lesions (historical; how the original Japanese family was labelled)
Osteogenesis imperfecta, Levin type / Levin syndrome 2
Familial gigantiform cementoma (FGC) and familial florid cemento-osseous dysplasia (FFCOD) — see §10; these are increasingly regarded as allelic/atypical variants of GDD rather than separate entities (PMID:37649308, PMID:27216912, PMID:42361776)

Data provenance

All information below is disease-level, derived from published case reports, pedigrees, and functional studies. There is no EHR-derived, registry-derived, or claims-derived data on GDD. The largest structured clinical dataset in existence is the literature aggregation in Cuvelier et al. 2024 (PMID:38922934): 108 clinically diagnosed individuals across 25 families, of whom 67 individuals from 21 families had molecular confirmation.

2. Etiology

Disease causal factors

GDD is monogenic and fully genetic. It is caused by heterozygous (monoallelic) variants in ANO5 (anoctamin-5 / TMEM16E / GDD1) at chromosome 11p14.3. There is no known environmental, infectious, or multifactorial contribution to disease causation.

Historical trail of causal establishment: 1. Linkage — Tsutsumi et al. mapped the locus to an 8.7 cM interval at 11p14.3–15.1 in a four-generation Japanese family, establishing GDD "as a new and distinct disease entity from other systemic bone diseases" (J Bone Miner Res 2003; PMID:12619924). 2. Gene identification — "In the critical region determined by recombination mapping, we identified a novel gene (GDD1) that encodes a 913-amino-acid protein containing eight putative transmembrane-spanning domains. Two missense mutations (C356R and C356G) of GDD1 were identified in the two families with GDD..." (PMID:15124103)

Genetic risk factors

Causal variants: heterozygous ANO5 missense variants (and rare in-frame indels/frameshifts), concentrated in exons 7, 11, 15, and 16. See §4 for the full variant catalogue.
Susceptibility loci / GWAS: none. No GWAS has been or realistically could be performed on a disease this rare.
Modifier genes: Essentially unstudied. One tentative report suggested COL5A1 variants as potential modifiers in two affected siblings with divergent severity (cited in PMID:28176803). A COL6A3 variant (c.4604G>A; p.Arg1535His) found in one proband with combined myopathy+GDD was explicitly excluded as contributory, because it was absent in other affected family members (PMID:34291158). Treat "modifier genes" as an open question, not an established finding.

Environmental risk factors

None established for disease causation. However, several environmental/behavioural factors clearly act as precipitants or exacerbators of specific manifestations and should be modeled as such rather than as risk factors for the disease:

Minimal trauma precipitates fractures — one patient sustained "five fractures, all occurring as a result of minimal trauma" (PMID:28176803).
Dental extraction and oral surgery precipitate jaw osteomyelitis and non-healing extraction sites (PMID:28176803, PMID:29518808).
Physical exertion precipitates rhabdomyolysis and compartment syndrome in the rare combined muscle+bone phenotype (PMID:34291158).
Vitamin D deficiency was documented in most members of one Chinese GDD pedigree and is plausibly an aggravating cofactor for the low-bone-mass subtype (PMID:35982081).

Protective factors

No genetic or environmental protective factors have been identified. No protective ANO5 alleles are described. gnomAD/ExAC data are informative only in the negative direction: GDD-causing variants are absent from population databases (see §4).

Gene–environment interactions

Two interactions have functional support:

Mechanical/membrane challenge unmasks Ano5 dependency. Rolvien et al. found no skeletal or muscular phenotype in Ano5 knock-in or knockout mice under homeostatic conditions and reasoned: "it is conceivable that the function of Ano5 is only required, if there is cell membrane damage. Potentially, a challenge, such as muscular training, is required to induce an observable phenotype that is not present under homeostatic conditions." (PMID:32455153) — this is a genotype × mechanical-challenge interaction hypothesis, not yet demonstrated in bone.
Age × genotype. Li et al. argued that mouse studies using 12–24-week-old animals mask the phenotype because "the onset of GDD occurs at a very young age, mostly in juveniles between 10 and 16 years old," and that osteoporosis-like signals are obscured by murine ageing changes (PMID:35982081). Human data support an age effect in the other direction: elderly GDD patients maintain normal-to-increased bone mass because their low osteoclast activity protects against age-related bone loss (PMID:35982081).

3. Phenotypes

3a. Frequency data — the single best source

The only quantitative frequency data for GDD come from the systematic literature aggregation of 108 clinically diagnosed individuals in 25 families (67 molecularly confirmed, 21 families) in Cuvelier et al., Prenatal Diagnosis 2024 (PMID:38922934; DOI 10.1002/pd.6631):

Manifestation	Frequency	Suggested HPO term
Jaw lesions (cemento-osseous / fibro-osseous)	~67% — "most requiring at least one surgery"	`HP:0030791` Abnormal jaw morphology ✓
Tooth anomalies (infection, displacement)	48%	`HP:0000164` Abnormality of the dentition ✓; `HP:0000692` Tooth malposition ✓
Fractures	45% — from prenatal to age 42, most in childhood	`HP:0002659` Increased susceptibility to fractures ✓; `HP:0002757` Recurrent fractures ✓
Bowing of long bones	19%	`HP:0006487` Bowing of the long bones ✓; `HP:0002979` Bowing of the legs ✓; `HP:0002980` Femoral bowing ✓
Diaphyseal thickening	16%	`HP:0003103` Abnormal cortical bone morphology ✓
Generalized osteopenia	10%	`HP:0000938` Osteopenia ✓
Bowing, prenatal cases only	100% of 3 prenatal cases	as above
Fractures, prenatal cases only	33% of 3 prenatal cases	as above

✓ = HPO label verified against the repository's local cache/hp/terms.csv.

Caution on interpreting these percentages. They are literature-derived, so they are ascertainment-biased in two opposing directions: jaw lesions are over-represented because most patients reach diagnosis through a maxillofacial surgeon, while mild/asymptomatic carriers within reported pedigrees are systematically under-phenotyped. They should be recorded with evidence_source: HUMAN_CLINICAL and a note that they are aggregated case-report frequencies, not cohort frequencies.

3b. Craniofacial / gnathic phenotypes

Cemento-osseous jaw lesions are the disease's signature. Radiographically they present as "multiple lobular or amorphous radiopacities in the tooth-bearing segments of the maxilla and mandible, and a cotton-wool-like pattern in the alveolar regions" (PMID:28176803). Histologically: "Histopathological descriptions of tissue from GDD lesions note fibrous tissue with irregular acellular mineralized masses and small rounded spherical mineralized bodies (psammomatoid bodies)" (PMID:28176803).

Severity: highly variable — from asymptomatic radiographic findings to a 7.1 × 5.6 × 5.5 cm anterior mandibular mass requiring angle-to-angle segmental mandibular resection in a 15-year-old (PMID:28176803).
Progression: progressive and recurrent. One 4-year-old showed "symmetric anterior-posterior expansion of the maxilla from 2.8 to 5.1 cm over 4 months" and by age 1 year "was no longer able to close his mouth" (PMID:28176803). Recurrence after incomplete resection is characteristic (PMID:37649308).
Onset: the 41-year radiographic follow-up study (PMID:40861765) is the best natural-history document available: no jawbone symptoms at age 3 despite already-visible diaphyseal cortical widening; slight alveolar sclerosis at age 9; clearly increased sclerotic-mass density after completion of secondary dentition at 14. Conclusion: "the onset of the jawbone lesion had already appeared after the mixed dentition stage, and the sclerotic mass developed with age."
Related terms: HP:0000326 Abnormal maxilla morphology ✓; HP:0000324 Facial asymmetry ✓; HP:0002797 Osteolysis ✓

Jaw osteomyelitis — HP:0007626 Mandibular osteomyelitis ✓ / HP:0002754 Osteomyelitis ✓. "A number of GDD patients develop osteomyelitis in the oral cavity with an increased propensity for bacterial infections, resulting in the secretion of purulent exudate (pus) from infected lesions" (PMID:28176803). Typically adult-onset; the Chinese proband had "a more than 30-year history of propensity for jaw infections."

Tooth loss, impaction, and displacement. In one pedigree, patients had "multiple impacted teeth in the nasal side of the maxillary sinus and the inferior margin of the mandible," and impacted teeth were the presenting sign in two children aged 7–8 (PMID:35982081).

3c. Appendicular / axial skeletal phenotypes

Bone fragility with recurrent fractures. Onset "appears to be more common in the second decade of life," but the range is extraordinary: prenatal (bilateral femur fractures at 20 weeks gestation, PMID:28176803; multiple diaphyseal fractures of femurs, tibias, upper extremities, ribs and clavicle on fetal autopsy, PMID:38922934), neonatal, childhood, or as late as age 42 (PMID:28176803, PMID:38922934). One proband had "8 fractures in his left forearm and 1 fracture in left femur" between ages 7 and 17 (PMID:34291158).
Diaphyseal cortical thickening and sclerosis with narrowed medullary canals — "gross thickening of the diaphyseal cortices of long bones with narrow medullary canals" (PMID:28176803). Suggested HP:0005045 Diaphyseal cortical sclerosis (HPO API-sourced; not present in the local term cache — verify with OAK before use).
Bowing of tibiae/fibulae, femora.
Vertebral involvement: compression fractures of lumbar vertebrae in infancy (PMID:28176803); "severe osteopenia in cervical spine" (PMID:34291158); "thin and short" vertebral bodies on fetal imaging (PMID:38922934).
Calvarial involvement: "lacunar skull deformity (Lueckenschaedel)" in one infant (PMID:28176803); calvarial doughnut lesions in an Asian Indian patient, an explicit phenotype expansion (PMID:32902009).
Bone pain — HP:0002653 ✓; genu varum — HP:0002970 ✓.

3d. The bone-density paradox — two mechanistically distinct subtypes

This is the most important phenotypic subtlety in GDD and is easily mis-curated. Different ANO5 variants produce opposite bone-mass phenotypes:

Subtype	Bone mass	Turnover	Example variant	Reference
High-bone-mass / high-turnover	Increased trabecular bone mass; `HP:0011001` Increased bone mineral density ✓	Elevated formation and resorption markers; osteoblast and osteoclast indices "remarkably increased" on iliac crest biopsy	p.Ser500Phe	PMID:27541832
Low-bone-mass / osteopenic	Low BMD, low T- and Z-scores at lumbar spine and femoral neck; frank osteoporosis in two children	Low P1NP, low N-MID, low β-CTx	p.Leu370_Ala371insDYWRLNSTCL	PMID:35982081

Li et al. state the framework explicitly: "GOF of TMEM16E protein results in high-bone-mass phenotype GDD by hyperfunction of PLS with increased osteoblast and osteoclast indices, while LOF of TMEM16E protein causes low-bone-mass phenotype GDD by impaired function of calcium oscillations with decreased osteoblast and osteoclast indices... our results suggest the existence of GDD-sub-entities with high and low BMD phenotypes due to different GOF and LOF mutations and functions." (PMID:35982081)

Curation implication: a KB entry that records a single INCREASED or DECREASED modifier on bone mineral density will be wrong for half of patients. This is a genuine has_subtypes situation, and the assignment is by variant class, not by clinical convention.

3e. Laboratory abnormalities

Elevated serum alkaline phosphatase (ALP) — documented in GDD patients and reproduced in both Ano5^−/− and Ano5^KI/KI (Cys360Tyr) mice: "Serum alkaline phosphatase (ALP) levels were elevated in Ano5-/- mice as in GDD patients" (PMID:30712070); "Serum ALP levels were elevated in Ano5KI/KI mice as in GDD patients with p.Cys360Tyr mutation" (PMID:34841576). "A slight increase in alkaline phosphatase levels in the blood" was seen in an FGC patient (PMID:37649308). (No HPO label for elevated ALP was found in the local cache — look up "Elevated circulating alkaline phosphatase concentration" with OAK before binding.)
Bone turnover markers: direction is subtype-dependent — see §3d. Markers used: P1NP, N-MID osteocalcin, β-CTx (PMID:35982081).
25-OH vitamin D deficiency in most members of one pedigree (PMID:35982081).
Elevated creatine kinase — HP:0003236 ✓ — only in the rare combined muscle+bone phenotype; peak CK values of 8,000, 6,000, and 25,000 IU/L in three members of one kindred (PMID:34291158).

3f. Muscle phenotypes — a genuinely contested boundary

The textbook position is that ANO5 bone and muscle diseases are non-overlapping: "Pathogenic ANO5 variants cause 2 distinct disorders with no overlapping features." (PMID:34291158, intro). Shaibani et al. then broke that rule in the same paper, reporting a large kindred (11 affected) in which the known GDD variant p.Thr513Ile segregated with both phenotypes:

"The unique clinical presentation of recurrent episodes of rhabdomyolysis associated with muscle cramps, hyperCKemia, muscle hypertrophy, with absent or mild muscle weakness, as well as cemento-osseous lesions of the mandible, with or without bone fractures and other skeletal abnormalities... Our data challenge recent results that suggested complete dichotomy of these phenotypes and the proposed loss-of-function and gain-of-function mechanisms for the skeletal and muscle phenotypes, respectively." (PMID:34291158)

Features in that kindred: rhabdomyolysis (HP:0003201 ✓) 3–5×/year lasting 5–7 days, muscle cramps, muscle hypertrophy, and — novel for ANO5 disease — compartment syndrome requiring fasciotomy (four episodes in one 20-year-old, one causing peroneal nerve injury).

3g. Quality of life

No formal QoL instrument (EQ-5D, SF-36, PROMIS) has ever been applied to GDD. Documented functional impacts, per-manifestation:

Manifestation	Documented functional impact
Jaw mass	Inability to close the mouth; interference with feeding and speech; "severe facial disfigurement" (PMID:28176803, PMID:29175271, PMID:35982081)
Jaw osteomyelitis	Purulent gum discharge, tooth loss, failed extraction healing; 30-year symptom duration (PMID:28176803)
Fractures	Non-union with skin necrosis leading to below-knee amputation in one patient (PMID:28176803); post-traumatic femoral length discrepancy (PMID:32455153)
Muscle cramps/rhabdomyolysis	Episodes "disrupted his daily life activities" (PMID:34291158)
Dentition	Long-term prosthodontic dependence with repeated adjustment (PMID:29518808)
Overall	At least one death: "The patient died from complications related to GDD" (PMID:28176803)

4. Genetic / Molecular Information

Causal gene

ANO5 (anoctamin 5), also TMEM16E, historically GDD1. - HGNC: hgnc:27337 · NCBI Gene: 203859 · OMIM: 608662 - Locus: 11p14.3; 22 exons (PMID:36292621) - Reference transcript: NM_213599.3 - Protein: 913 amino acids, ~107 kDa; UniProt Q75V66 - Topology: classically described as 8 transmembrane domains with cytoplasmic N- and C-termini (PMID:15124103); revised to 10 membrane-spanning helices following the nhTMEM16 crystal structure (PMID:29124309, PMID:35982081) - Domains: one DUF590 / anoctamin domain; a 35-aa scrambling domain (SCRD); three calcium-binding sites (PMID:36292621, PMID:35982081) - Eight cysteines at positions 342, 353, 356, 360, 369, 601, 606, 804* in the putative extracellular loops are conserved from human to insect and are thought to form intrachain disulfide bonds critical to folding (PMID:28176803)

Catalogue of reported GDD-causing ANO5 variants

All are heterozygous, germline, and predominantly missense. Coordinates on NM_213599.3.

Protein change	cDNA	Exon	Population / context	Reference
p.Arg215Gly	c.643A>G	7	Sporadic (severe infantile; died of GDD complications)	PMID:28176803
p.Cys356Arg	c.1066T>C	11	Original Japanese family	PMID:15124103
p.Cys356Gly	c.1066T>G	11	African American family	PMID:15124103
p.Cys356Tyr	c.1067G>A	11	Caucasian family; also FGC ×3	PMID:28176803, PMID:37649308
p.Cys356Phe	c.1067G>T	11	Chinese family, atypical (jaw only, no fractures)	PMID:30554457
p.Cys356Trp	—	11	Familial florid cemento-osseous dysplasia (FFCOD)	Lv et al., cited in PMID:37649308
p.Cys360Tyr	c.1079G>A	11	Chinese family (cementoma + osteomyelitis)	PMID:28176803
p.Cys360Arg	c.1078T>C	11	Large Iranian family	PMID:35758145
p.Leu370_Ala371insDYWRLNSTCL	c.1080_1081ins30	11	De novo, Chinese family — low-bone-mass subtype	PMID:35982081
p.Ala492Val	c.1475C>T	15	De novo, fetal case	PMID:38922934
p.Ser500Phe	c.1499C>T	15	De novo, 13-year-old — high-turnover osteosclerosis	PMID:27541832
p.(Gln_Ile512insMet)	c.1533_1535dup	15	De novo, fetal case (in-frame duplication)	PMID:38922934
p.Thr513Ile	c.1538C>T	15	Italian pedigree; also the combined muscle+bone kindred	PMID:23047743, PMID:34291158
p.Gly518Glu	c.1553G>A	15	Sporadic (prenatal femoral fractures)	PMID:28176803, PMID:29175271
p.Arg597Ile	c.1790G>T	16	Family of 3, mandibular reconstruction	PMID:30641283

Mutational clustering. Cuvelier et al. summarize: "GDD is caused by variants localized in a few exons, particularly in regions that encode the cytoplasmic or extracellular domains," with cysteines 356 and 360 as hotspots (PMID:38922934). Jin et al. locate them structurally: "all GDD mutations known so far locate in an extracellular domain following the first transmembrane domain or in the 4th putative transmembrane domain" (PMID:28176803).

Variant classification and population frequency

ACMG classification: GDD variants are consistently classified pathogenic or likely pathogenic (class 4/5). The fetal-case variants were "probably pathogenic (class 4)" (PMID:38922934).
Allele frequency: GDD variants are absent from all population databases. "These four ANO5 (TMEM16E) variants in GDD patients were absent in dbSNP, 1000Genomes, the Exome Variant Server (~6500 exomes) and the ExAC database." (PMID:28176803). Later studies applied MAF < 0.005 filters against dbSNP138, 1000 Genomes, CG69, EVS and ESP and retained the ANO5 variant (PMID:35982081).
In silico: consistently "probably damaging" (PolyPhen-2), "damaging"/"deleterious" (SIFT, score 0), "disease-causing" (MutationTaster, score 1), CADD 28 for C356Y (PMID:28176803, PMID:37649308).
Somatic vs germline: germline in all cases. Zhou et al. sequenced both tumour tissue and peripheral blood in FGC patients and found the same heterozygous variant in both — i.e. constitutional, not a somatic second-hit tumour mechanism (PMID:37649308). This is a key contrast with fibrous dysplasia (somatic GNAS).
De novo rate: substantial. De novo variants are documented in at least six independent probands and correlate with severity: "De novo variants correlated with more severe phenotypes and earlier onset, while familial variants showed broader age ranges." (PMID:38922934)

Functional consequence — GOF vs LOF, an unresolved and consequential dispute

This is the central mechanistic controversy in GDD and must be represented as such, not collapsed into a single answer.

The GOF position (biophysics). Di Zanni et al. provided the first direct functional demonstration:

"While the activity of wild-type TMEM16E depended on elevated cytosolic Ca2+ levels, a mutant form carrying the GDD-causing T513I substitution showed PLS and large time-dependent ion currents even at low cytosolic Ca2+ concentrations... these data provide the first direct demonstration of Ca2+-dependent PLS activity for TMEM16E and suggest a gain-of-function phenotype related to a GDD mutation." (PMID:29124309, DOI 10.1007/s00018-017-2704-9)

Quantitatively: wild-type TMEM16E activation threshold was +125.2 ± 6.1 mV at zero Ca²⁺ and +88.1 ± 2.8 mV at 3 µM Ca²⁺; the T513I mutant activated at +82.3 ± 4.1 mV at zero Ca²⁺ — i.e. mutant activity at zero calcium equalled wild-type activity at 3 µM. Wild-type Ca²⁺ dependence: half-maximal 2.9 µM, Hill coefficient 1.5. The follow-up study extended this across variants: "MD mutations are associated to loss-of-function and GDD mutations to gain-of-function phenotypes, confirming conjectures made on the basis of inheritance modes." (PMID:32112655)

The LOF position (protein abundance and cell biology). Jin et al. found "In vitro studies overexpressing GDD mutations (p.Cys356Tyr and p.Cys360Tyr) showed significantly reduced ANO5 protein" (PMID:28176803). Li et al. documented a frameshift-insertion GDD family with reduced TMEM16E protein in PBMCs and argued: "our results suggest that ANO5 is dosage-sensitive and that LOF of the TMEM16E protein caused by the heterozygous ANO5 mutation in one allele is partly compensated by another normally functional allele." (PMID:35982081)

Why both can be true. Different variant classes plausibly act differently — a folding-destabilizing cysteine substitution (C356Y/C360Y, degraded via the proteasome) is not the same lesion as a scrambling-domain-proximal substitution that renders the protein constitutively active (T513I). This maps directly onto the two bone-mass subtypes in §3d. A KB entry should curate this as competing mechanistic_hypotheses with distinct hypothesis_group_ids, not as a settled fact.

Note also that Jin et al. argue against pure haploinsufficiency on two grounds: "The lack of an obvious skeletal phenotype in Ano5 knock-out mice argue against a dose effect" and the existence of recessive truncating LGMD alleles in the same region (PMID:28176803).

Epigenetics

No DNA methylation, histone-modification, or chromatin study of GDD exists. The only epigenetic-adjacent finding is post-transcriptional: Ano5 deficiency "notably inhibited miR-34c-5p expression," de-repressing its target Klf4 (PMID:40508076) — see §6.

Chromosomal abnormalities

Not applicable. GDD is not caused by aneuploidy, translocation, inversion, or CNV. Chromosomal microarray, karyotype, and FISH have no diagnostic role.

5. Environmental Information

Environmental toxicant/occupational factors: none identified. No CTD entries link environmental chemicals to GDD.
Lifestyle factors: no established dietary, smoking, alcohol, or activity association with disease risk. Exercise is relevant only as a rhabdomyolysis trigger in the combined phenotype (PMID:34291158), and physical activity/mechanical loading as a fracture precipitant.
Infectious agents: GDD is not an infectious disease. However, secondary bacterial infection of jaw lesions is a defining complication — purulent osteomyelitis of the mandible and maxilla (PMID:28176803, PMID:29518808). Causative organisms are not systematically speciated in the literature; expect the usual odontogenic/osteomyelitis flora. Model this as a downstream complication node, not an etiological factor.

6. Mechanism / Pathophysiology

6a. Normal ANO5/TMEM16E biology

Expression. ANO5 is highly expressed in skeletal and cardiac muscle, and — critical for GDD — in growth-plate chondrocytes and osteoblasts (PMID:17418107, PMID:34291158). Mizuta et al.: "GDD1 protein is an integral membrane glycoprotein that resides predominantly in intracellular vesicles." During early embryogenesis it is expressed in myotomal and sclerotomal somites (PMID:28176803). It is also expressed in human periodontal ligament cells (PMID:29124309).

Subcellular localization. Predominantly endoplasmic reticulum — co-localizing with calreticulin and CellLight ER-RFP markers (PMID:15124103, PMID:28176803, PMID:29124309) — with partial plasma-membrane localization at high expression levels, which is what enabled the electrophysiological characterization (PMID:29124309). GO CC: GO:0005783 endoplasmic reticulum ✓.

Molecular function — three competing/complementary assignments: 1. Ca²⁺-activated chloride channel (CaCC) — the original inference from family membership (GO:1902476 chloride transmembrane transport ✓). This is now largely rejected. Tran et al. noted ANO5 has a threonine rather than a cysteine at position 611, one of three conserved cysteines in true CaCCs (ANO1/ANO2) (cited in PMID:28176803); halide-sensitive YFP assays found no anion transport (PMID:29124309); Ano5-deficient mice showed chloride currents indistinguishable from wild-type (PMID:36292621). 2. Ca²⁺-dependent phospholipid scramblase (PLS) — the currently favoured assignment (GO:0045332 phospholipid translocation ✓). Directly demonstrated by annexin-V binding assays with Ca²⁺-ionophore stimulation (PMID:29124309). "ANO5 functions predominantly in phospholipid scrambling (PLS), which facilitates the movement of phospholipids between the membrane bilayer during various biological processes." (PMID:36292621) 3. ER Ca²⁺ conduit / regulator of intracellular Ca²⁺ transients — "our data support the view that TMEM16E at the ER membrane of bone cells sustains Ca2+ transitions to the cytoplasm" (PMID:35982081) (GO:0070588 calcium ion transmembrane transport ✓; GO:0051209 release of sequestered calcium ion into cytosol ✓).

Note that ion transport may be biophysically real but physiologically irrelevant: Di Zanni et al. observed currents only at >+75 mV, and concluded "Considering furthermore their exclusive activation at highly depolarized membrane potentials, which are unlikely to be experienced by non-excitable cells, one may conclude that ion transport is not among the physiological functions of TMEM16E." (PMID:29124309)

Membrane repair (GO:0001778 plasma membrane repair ✓) is the best-established physiological role, though it is characterized in muscle rather than bone: ANO5 translocates to injured sarcolemma and is required for annexin recruitment to the repair cap (PMID:36292621).

6b. Causal chain — trigger to clinical manifestation

Because of the GOF/LOF split, there are two parallel proximal chains converging on a shared distal phenotype. Both are supported; neither is exclusive.

Chain A — the LOF / low-bone-mass route (best evidenced by PMID:35982081, PMID:40049314, PMID:36989132):

Heterozygous ANO5 destabilizing variant
  → reduced TMEM16E protein (proteasomal degradation)          [MOLECULAR]
  → loss of ER-mediated Ca²⁺ transients; [Ca²⁺]i oscillations
    abolished in osteoblasts, blunted in osteoclasts            [CELLULAR]
  → ┌─ osteoblast arm: ↓WNT1/β-catenin/Dvl2, ↑GSK-3β/Axin1
    │    → ↓Ocn, ↓Spp1, ↓ALP, ↓mineral nodules                  [CELLULAR]
    └─ osteoclast arm: ↓RANKL-induced NFATc1/c-Fos nuclear
         translocation → ↓Trap, ↓Ctsk, ↓Mmp9, ↓Dc-stamp,
         disrupted F-actin ring, ↑ER-stress/CHOP apoptosis      [CELLULAR]
  → coupled suppression of formation AND resorption
    ("vicious cycle" of remodeling arrest)                       [TISSUE]
  → low bone volume, osteopenia, fragility                       [ORGANISM]

Chain B — the GOF / high-bone-mass route (best evidenced by PMID:29124309, PMID:32112655, PMID:27541832, PMID:34841576):

Heterozygous ANO5 GOF variant (e.g. T513I)
  → constitutive, Ca²⁺-independent phospholipid scrambling      [MOLECULAR]
  → aberrant membrane-surface phosphatidylserine exposure;
    loss of cell adhesion, cell rounding                         [CELLULAR]
  → ↑osteoblastogenesis (↑Runx2, Osterix, Col1a1, Ocn),
    hypermineralized matrix; ↓osteoclastogenesis                 [CELLULAR]
  → high-turnover osteosclerosis, cortical thickening,
    narrowed medullary canal                                     [TISSUE]
  → paradoxical fragility despite high mass                      [ORGANISM]

The paradox that unifies them. Both routes produce fragility, whether bone mass is low or high. In the high-mass form the bone is hypermineralized and therefore brittle — Jin et al.: "ANO5 may act as a negative regulator of mineralization and that reduced protein levels due to ANO5 mutations or interactions of instable mutant ANO5 proteins may result in abnormal bone deposition or remodeling with over-mineralization, hyperostosis and brittle bones." (PMID:28176803). This is mechanistically similar to the fragility of osteopetrosis and of COL1A1 C-propeptide-cleavage-site OI (PMID:24891183).

6c. Downstream signalling pathways — a rapidly expanding 2024–2026 literature

Five independent effector pathways have been nominated in the last two years, all downstream of Ano5 disruption in mouse osteoblasts/osteoclasts. They are not mutually exclusive and several intersect at AMPK.

Pathway	Finding	Rescue agent tested	Reference
Akt–NFATc1	Ano5^Cys360Tyr down-regulates Akt phosphorylation in osteoblasts; Akt activation restored TRAP⁺ multinucleated osteoclasts and F-actin rings, and reduced excess ALP/mineralization	SC79 (Akt activator) — "an Akt activator is probable a therapeutic target for GDD"	PMID:39866532 (Bone Rep 2025)
AMPK–ATG9A–autophagy	Ano5 deficiency activates autophagy in mouse calvarial osteoblasts via ATG9A upregulation; AMPK positively regulates ATG9A	3-MA, chloroquine; 3-MA "alleviated the bone phenotype abnormalities in Ano5-/- mice" in vivo	PMID:40067389 (JCI Insight 2025)
AMPK–PGC1α/PGC1β glucose metabolism	Mutation accelerates glycolysis and PGC1α-dependent mitochondrial respiration in osteoblasts; PGC1β downregulation causes abnormal osteoclast mitochondria; AMPK phosphorylation increased	Compound C (AMPK inhibitor) "reversed the bone phenotype of GDD by restraining bone formation and restoring osteoclastogenesis"	PMID:41717545 (Front Endocrinol 2026)
miR-34c-5p–KLF4–β-catenin	Ano5 deficiency inhibits miR-34c-5p; Klf4 (a validated miR-34c-5p target, dual-luciferase) is de-repressed, activating canonical Wnt/β-catenin	AAV-miR-34c-5p in vivo rescued thickened cortical bone, improved biomechanics, lowered serum P1NP	PMID:40508076 (Int J Mol Sci 2025)
ER stress–CHOP–osteoclast apoptosis	Decreased [Ca²⁺]i and calcium transients in Ano5^−/− osteoclasts → enhanced ER stress → CHOP-mediated apoptosis	none tested	PMID:40049314 (Exp Cell Res 2025)
NF-κB	RANKL-induced early signalling suppressed in Ano5^−/− osteoclasts; partially rescued by an NF-κB activator	NF-κB activator (partial)	PMID:36989132 (Oral Dis 2024)

Metabolic changes. Metabolomics + transcriptomics of Ano5^Cys360Tyr knock-in mouse calvarial osteoblasts identified 42 differential metabolites (amino acid and pyrimidine metabolism; endocrine/other-factor-regulated calcium reabsorption) and 407 differentially expressed genes, converging on cell-cycle progression (Mki67, Ccnb1, Ccna2 up) and calcium signalling (Cacna1, Slc8a1, Cyp27b1 up), with higher calcium content in mineral nodules by SEM-EDS (PMID:36742392).

6d. Protein dysfunction

Misfolding and instability. GDD cysteine mutants "fold with low efficiency and appear to be unstable and rapidly degraded via proteasomal degradation" (cited in PMID:28176803). Western blot and immunofluorescence confirm reduced mutant protein despite higher construct copy number (PMID:28176803).
Structural modelling. AlphaFold2 modelling of C356Y showed low global deviation (RMSD 0.256) but local distortion: residues Lys847/Phe848/Leu849 form a helix in wild type and a loop in the mutant (PMID:37649308).
Cellular consequence of aberrant activity. HEK293 cells expressing GDD mutants "typically became round-shaped and displayed decreased cell adhesion," and Di Zanni et al. showed "the gradual changes in HEK293 cell morphology observed upon expression of TMEM16E/ANO5GDD mutants are a consequence of aberrant protein activity" (PMID:29124309, PMID:32112655).

6e. Immune system involvement

GDD is not an autoimmune or immunodeficiency disorder. The only immune dimension is (a) the propensity to bacterial jaw osteomyelitis (§5) and (b) the fact that osteoclasts are monocyte/macrophage-lineage cells (CL:0000235 macrophage ✓), so RANKL–NFATc1–NF-κB signalling — canonically an immune pathway — is the disease's core osteoclast axis.

6f. Tissue damage mechanisms

Not ischemia, fibrosis (in the classical sense), or oxidative stress. The dominant mechanism is dysregulated bone remodeling (GO:0046849 bone remodeling ✓) with abnormal matrix mineralization (GO:0030282 bone mineralization ✓), plus fibro-osseous replacement of normal jaw architecture: "normal cancellous bones of the jaw were structurally destroyed and poorly mineralized, occupied by a large amount of fibrous tissue and cementum, leading to fibrous cementum-like lesions" (PMID:35982081). ER stress and CHOP-mediated apoptosis are the newest addition (PMID:40049314).

6g. Cell types and processes — ontology suggestions

Cell types (all CL labels verified against local cache): - CL:0000062 osteoblast — primary effector cell; both mouse calvarial osteoblast (mCOB) and BMSC-derived - CL:0000092 osteoclast — the more severely affected lineage in LOF models - CL:0000137 osteocyte - CL:0000138 chondrocyte — growth-plate expression (PMID:17418107) - CL:0000057 fibroblast — the fibroblastic stroma of jaw lesions - CL:0000061 cementoblast — the cementum-like deposits are the disease's histological signature - CL:0000235 macrophage — BMM osteoclast precursor - CL:0000594 skeletal muscle satellite cell — relevant only to the muscle arm

Biological processes (all GO labels verified): GO:0001649 osteoblast differentiation · GO:0030316 osteoclast differentiation · GO:0001503 ossification · GO:0030282 bone mineralization · GO:0045453 bone resorption · GO:0046849 bone remodeling · GO:0045332 phospholipid translocation · GO:0070588 calcium ion transmembrane transport · GO:0051209 release of sequestered calcium ion into cytosol · GO:0071277 cellular response to calcium ion · GO:0060070 canonical Wnt signaling pathway · GO:0006914 autophagy · GO:0034976 response to endoplasmic reticulum stress · GO:0001778 plasma membrane repair · GO:1902476 chloride transmembrane transport (curate with a caveat — largely refuted)

Cellular component: GO:0005783 endoplasmic reticulum

6h. Molecular profiling status

Modality	Status
Transcriptomics	Mouse only — 407 DEGs in Ano5^KI/KI mCOBs (PMID:36742392). No human GDD transcriptome.
Proteomics	None for GDD. (Mass-spec proteomics of muscle amyloid deposits in ANO5 myopathy exists — found amyloid P and ApoE, but not ANO5; PMID:36292621.)
Metabolomics	Mouse only — 42 differential metabolites (PMID:36742392)
Lipidomics	None — a notable gap given that the leading functional hypothesis is phospholipid scrambling
Single-cell / spatial	None
Functional genomics screens (CRISPR/RNAi)	No systematic screen. Targeted shRNA knockdown in MC3T3-E1 (PMID:28176803) and siRNA/shRNA in RAW264.7 (PMID:36989132) only.
GEO/ArrayExpress	No GDD-labelled human dataset identified. Any dataset accession must be verified with `just verify-datasets` and manually triaged for relevance — searching "ANO5" will surface muscular dystrophy datasets, which is exactly the Named Entity Confusion trap.

7. Anatomical Structures Affected

Organ level

Primary: - Mandible — UBERON:0001684 mandible ✓ — the most consistently and severely affected structure - Maxilla — UBERON:0002397 maxilla ✓ - Long tubular bones, diaphyseal regions — UBERON:0004769 diaphysis ✓ — femur, tibia, fibula, radius, ulna, humerus - Bone tissue generally — UBERON:0002481 bone tissue ✓

Secondary / less consistent: vertebrae (compression fractures, osteopenia); ilium; calvarium (doughnut lesions, PMID:32902009; lacunar skull, PMID:28176803); clavicle and ribs (fetal fractures, PMID:38922934); dentition and periodontium.

Body systems: skeletal (primary); dental/stomatognathic (primary); musculoskeletal-muscular — UBERON:0001134 skeletal muscle tissue ✓ — only in the rare combined phenotype.

Explicitly NOT affected: No consistent cardiac, renal, hepatic, neurological, or endocrine involvement in GDD proper. (Cardiac involvement of 10–30% is a feature of the recessive ANO5 muscular dystrophies, not GDD — PMID:36292621. Do not transfer it.)

Tissue and cell level

Connective/skeletal tissue is the target. Jaw lesion histology: "a fibroblastic stroma with variable cellularity and a heterogeneous osseous component composed of woven bone and more cementum-like material" (PMID:35982081); "large eosinophilic masses of cementum-like material interspersed in fibrous background" (PMID:28176803); psammomatoid bodies; "abundant mineralization in the vessel wall" (PMID:37649308).

Subcellular level

Endoplasmic reticulum (GO:0005783 ✓) — principal ANO5 residence and the locus of the Ca²⁺-transient defect
Plasma membrane / sarcolemma — partial localization; site of scrambling activity
Intracellular vesicles (PMID:17418107)
Mitochondria — secondarily abnormal in Ano5^KI/KI osteoclasts via PGC1β (PMID:41717545)

Lateralization

Bilateral, though often asymmetric in extent. Fetal case: "multiple diaphyseal fractures of the long bones... affecting femurs, tibias, and bilateral upper extremity bones" (PMID:38922934). Jaw lesions are typically multi-quadrant — bilateral maxillary and mandibular — which is a key differentiator from unilateral ossifying fibroma. One patient had "bilateral relatively symmetric, expansile lesions in the maxillary bone" (PMID:28176803).

8. Temporal Development

Onset

Extremely variable — this is a defining feature. Jin et al.: "there appears to be a wide age range in the onset of fibrous lesions of the mandible and severity of fractures." (PMID:28176803)

Documented onsets, earliest to latest: - Prenatal: bilateral femur fractures at 20 weeks gestation (PMID:28176803); fetal bowing detected at 12 weeks and confirmed at 16 weeks (PMID:38922934) - Neonatal: fractures at birth (Levin et al., cited in PMID:28176803) - Infancy: maxillary/mandibular enlargement at 2 months; jaw mass at 13 months (PMID:28176803); jaw protuberance at 6 months in an FGC case (PMID:37649308) - Childhood: most fractures; impacted teeth as presenting sign at ages 7–8 (PMID:35982081) - Adolescence: classic textbook onset — "the onset of fractures appears to be more common in the second decade of life" (PMID:28176803) - Adulthood: jaw lesion first diagnosed at age 21, 43, 62, and 67 in different individuals (PMID:28176803)

HPO records HP:0003621 Juvenile onset for this disease (HPO API-sourced; verify with OAK — not in the repository's local term cache). Orphanet records age of onset as infancy, childhood, and adolescence.

Onset pattern: insidious and chronic for jaw lesions; acute/episodic for fractures.

Progression

GDD is chronic, lifelong, and progressive. There is no spontaneous remission.

The strongest evidence for progression comes from two longitudinal documents: 1. Rolvien et al.'s 3-year follow-up of the S500F patient: DXA BMD Z-score remained stable, but "cortical thickness assessed by HR-pQCT at the distal tibia further increased at one and three years follow-up, which led to values clearly above the age-adjusted reference values." The authors conclude: "These clinical data demonstrate the progressive nature and lack of viable treatment options for this disorder." (PMID:32455153) 2. The 41-year radiographic study (PMID:40861765): diaphyseal cortical widening visible at age 3 before any jaw symptoms; alveolar sclerosis at 9; dense sclerotic mass after secondary dentition at 14; continued development into the fifth decade.

Stages (informal — no consensus staging system exists): - Pre-symptomatic / radiographic-only: diaphyseal cortical widening detectable before jaw involvement (age ~3) - Fracture-predominant: childhood to adolescence - Jaw-lesion-predominant: mixed dentition onward, expansile growth - Complication phase: adult jaw osteomyelitis, tooth loss, non-union fractures, surgical morbidity

Rate: variable; the jaw lesions can grow explosively (maxilla 2.8 → 5.1 cm in 4 months, PMID:28176803) or indolently over decades.

Course pattern: progressive with episodic acute events (fractures, osteomyelitis flares, and — in the combined phenotype — rhabdomyolysis 3–5×/year lasting 5–7 days, PMID:34291158).

Duration: lifelong.

Critical periods

Mixed-dentition transition (~age 6–14) appears to be the window in which jaw lesions initiate — the single most actionable observation for surveillance timing (PMID:40861765).
First two decades — peak fracture incidence, and therefore the window in which bone-directed therapy is most likely to matter.
Any dental extraction is a discrete risk window for osteomyelitis and non-healing.
The FGC literature describes a three-phase growth pattern for jaw lesions that may transfer: "initial onset at 11–13 years of age, rapid expansion between 14 and 16 years of age, and growth suppression around 18–20 years of age" (PMID:37649308).

Remission

No spontaneous remission. Jaw lesions recur after incomplete resection — "the recurrence rate of FGC is high, and incomplete resection or conservative curettage often leads to more rapid progression of the remaining portion, which does not recur after complete resection" (PMID:37649308).

9. Inheritance and Population

Epidemiology

Prevalence: <1 / 1,000,000 (Orphanet ORPHA:53697). In dismech PrevalenceClassEnum terms this is BELOW_1_IN_1000000, with measure_type: POINT_PREVALENCE, or arguably CASES_IN_LITERATURE given how the number was derived.
Cases reported: approximately 108 clinically diagnosed individuals across 25 families, of whom 67 individuals in 21 families have molecular confirmation (PMID:38922934). This is the most defensible case count and should be preferred over vaguer statements.
Incidence: unknown; no incidence estimate exists.
MedlinePlus Genetics: "The prevalence of gnathodiaphyseal dysplasia is unknown, but it is thought to be a rare disorder."

Inheritance

Autosomal dominant — HP:0000006 (HPO API-sourced). Established by four-generation pedigree linkage (PMID:12619924) and repeatedly confirmed by segregation (PMID:28176803, PMID:34291158, PMID:35758145).
Penetrance: appears high, possibly complete for the radiographic phenotype, but is not formally quantified in any study. In the Shaibani kindred two female carriers reported no muscle symptoms though bone findings were present, and the authors noted "the possibility remains that these 2 female patients have asymptomatic muscle involvement" (PMID:34291158). Record penetrance as not established.
Expressivity: highly variable, both interfamilial and intrafamilial. Jin et al.: "our findings strongly indicate the association of ANO5 mutations with GDD, and we show that there is considerable clinical variability in patients, even within one family. These differences in expressivity can currently not be explained due to the limited number of patients available for phenotypic/genetic studies." (PMID:28176803) The clearest example: in the Chinese C360Y family, the 73-year-old father had severe jaw disease with no fractures, while his 43-year-old son was much more mildly affected.
Genetic anticipation: none reported and none expected — GDD is not a repeat-expansion disorder.
De novo variants: common, and associated with more severe, earlier-onset disease (PMID:38922934). Documented in at least six probands (G518E, S500F, L370_A371ins, A492V, Q_I512insMet, and others).
Germline mosaicism: raised as a formal possibility but not demonstrated — "The mutation in sporadic patient 1 is either a de novo mutation or due to germline mosaicism." (PMID:28176803)
Founder effects: none for GDD. (Contrast the recessive ANO5 myopathies, where c.191dupA (p.Asn64LysfsTer15) is a well-established northern European founder allele with 45–75% homozygosity in England, Germany, and Denmark — PMID:36292621. This allele has nothing to do with GDD and must not be transferred into a GDD entry.)
Consanguinity: not a factor — GDD is dominant.
Carrier frequency: not applicable to a dominant disorder; heterozygotes are affected.

Population demographics

Affected populations: no ethnic predilection. Reported in Japanese (original family), African American, Caucasian/American, Chinese/Han, Italian, Russian, Iranian, Asian Indian, and French individuals (PMID:15124103, PMID:28176803, PMID:23047743, PMID:20005074, PMID:35758145, PMID:32902009, PMID:38922934).
Geographic distribution: worldwide; no endemic clustering.
Variant geography: C356 substitutions dominate across populations; C360Y in Chinese, C360R in Iranian, T513I in Italian and American kindreds, R597I in a French family. This reflects reporting history rather than any established population structure.
Sex ratio: no sex bias reported for GDD. Male and female patients appear in comparable numbers across pedigrees. (The 2:1–4:1 male predominance in the literature applies to ANO5 muscular dystrophies, not GDD — PMID:36292621.)
Age distribution: all ages, with diagnostic peak in childhood/adolescence.

10. Diagnostics

Clinical / laboratory tests

Serum alkaline phosphatase — often elevated; the most consistently reported biochemical abnormality (PMID:30712070, PMID:34841576, PMID:37649308)
Bone turnover panel — P1NP, N-MID osteocalcin, β-CTx. Direction is subtype-dependent (elevated in high-turnover S500F disease, PMID:27541832; reduced in low-bone-mass frameshift disease, PMID:35982081)
25-OH vitamin D, calcium (PMID:35982081)
Creatine kinase — only if muscle symptoms are present; can reach 25,000–40,000 IU/L in rhabdomyolysis episodes (PMID:34291158)

Imaging

Panoramic dental radiography — first-line for jaw lesions; shows "multiple lobular or amorphous radiopacities in the tooth-bearing segments" and "cotton-wool-like pattern in the alveolar regions" (PMID:28176803). This is often how asymptomatic family members are ascertained.
CT / 3D maxillofacial CT — lesion extent, surgical planning (PMID:35982081)
Skeletal survey / plain radiography — diaphyseal cortical thickening, narrowed medullary canals, bowing (PMID:34291158)
DXA — lumbar spine L1–L4 and femoral neck BMD, with age-adjusted Z-scores (paediatric software required in children) (PMID:27541832, PMID:35982081)
HR-pQCT at the distal tibia — the most sensitive modality for detecting progressive cortical thickening; detected progression over 3 years when DXA was static (PMID:32455153). This is a practically important point: DXA can be falsely reassuring.
Prenatal: ultrasound (bowing, shortened femurs, growth restriction) and fetal osseous CT to characterize severity and distinguish from differentials (PMID:38922934)

Histopathology

Diagnostic but not pathognomonic. Findings: cemento-ossifying fibroma pattern; fibroblastic stroma with variable cellularity; woven bone plus cementum-like material; psammomatoid bodies; abundant vessel-wall mineralization (PMID:11547842, PMID:28176803, PMID:37649308).

Caution: psammomatoid bodies are not required — the severe G518E case had "benign fibro-osseous lesions resembling cemento-ossifying fibromas of the jaw without psammomatoid bodies" (PMID:29175271).

Genetic testing — the diagnostic gold standard

Recommended approach (per PMID:38922934): 1. Targeted ANO5 sequencing where clinical suspicion is high — prioritize exons 7, 11, 15, 16, with 11 (Cys356/Cys360) highest yield 2. Skeletal dysplasia / osteogenesis imperfecta gene panel where the presentation is ambiguous 3. Trio exome sequencing (ES) — especially valuable prenatally and for apparently sporadic cases, where de novo status must be established 4. Whole genome sequencing (WGS) — has successfully identified GDD variants where panels failed (PMID:30554457)

Sanger confirmation and family segregation analysis are standard.

Not useful: chromosomal microarray, karyotype, FISH, mitochondrial DNA testing, repeat-expansion testing. None has a role in GDD.

Omics-based diagnostics: none validated. No RNA-seq, proteomic, metabolomic, epigenomic, or liquid-biopsy test exists for GDD.

Clinical criteria

There are no formal, published, consensus diagnostic criteria for GDD. Diagnosis is made by the combination of (a) fibro-osseous jaw lesions, (b) bone fragility/fractures, (c) diaphyseal cortical thickening/bowing, plus (d) a pathogenic ANO5 variant. Li et al. describe the pragmatic composite: "When hereditary, histologic and laboratory features were taken into consideration with clinical and radiographic features, GDD was the most appropriate diagnosis." (PMID:35982081)

Differential diagnosis — and a diagnostic-error rate worth curating

GDD is systematically misdiagnosed. "A review of the literature showed that 67% of GDD cases confirmed by molecular testing were initially misdiagnosed." (PMID:30554457) The 2025 surgical report adds: "clinicians are still largely unaware of this entity and continue to label and treat it as a variation of Osteogenesis Imperfecta." (PMID:41193275)

Differential	Distinguishing features
Osteogenesis imperfecta	OI lacks cemento-osseous jaw lesions and diaphyseal cortical thickening (OI cortices are thin). COL1A1/COL1A2 rather than ANO5. Exception: a COL1A1 C-propeptide cleavage-site mutation causes high bone mass, fragility, and jaw lesions and was proposed as "a new cause of gnathodiaphyseal dysplasia" (PMID:24891183) — a genuine phenocopy.
Fibrous dysplasia / McCune-Albright	Somatic activating GNAS mutations; café-au-lait macules; endocrinopathy. GDD variants are germline and GNAS is wild-type. GDD has been reported presenting as polyostotic fibrous dysplasia (PMID:25866257), and one GDD carrier's mother "was diagnosed with polyostotic fibrous dysplasia" before molecular testing corrected it (PMID:28176803).
Cherubism	SH3BP2. One large family was diagnosed as cherubism until SH3BP2 sequencing was negative and WGS found ANO5 p.C356F (PMID:30554457).
Florid cemento-osseous dysplasia (FCOD) / familial FCOD	Overlapping; *familial FCOD carries an ANO5* p.C356W mutation**, suggesting the same spectrum (Lv et al., cited in PMID:37649308)
Familial gigantiform cementoma (FGC)	All three FGC patients in the definitive genetic study carried ANO5 p.C356Y. "FGC may be an atypical variant of GDD" (PMID:37649308). Independently: "the GC and GDD likely represent the same type of bone pathology" (PMID:27216912).
Juvenile/psammomatoid ossifying fibroma	SATB2 rearrangements; ANO5 wild-type in 8 tested cases (PMID:37649308, PMID:42361776)
Camurati-Engelmann disease	TGFB1; diaphyseal hyperostosis without jaw cemento-osseous lesions (PMID:28176803)
Osteopetrosis	Generalized sclerosis without fibro-osseous jaw lesions
Stuve-Wiedemann syndrome	Prenatal bowing differential (PMID:38922934)

The 2026 WHO-aligned review consolidates the molecular picture: "familial florid cemento-osseous dysplasia, familial gigantiform cementoma and gnathodiaphyseal dysplasia sharing ANO5 mutations" (PMID:42361776). A dismech entry should decide deliberately whether FGC and familial FCOD are has_subtypes of GDD or separate entries with a Grouping — the literature now favours a shared entity.

Screening

Cascade family screening is the highest-yield strategy: panoramic radiography plus targeted ANO5 sequencing in first-degree relatives. Several probands were identified through a sibling's routine panoramic radiograph (PMID:28176803).
Newborn screening: not applicable and not proposed.
Prenatal: GDD should now be on the differential for fetal long-bone bowing and fractures (PMID:38922934) — this is the newest addition to diagnostic practice.

11. Outcome / Prognosis

Survival and mortality

No survival, life-expectancy, or mortality data exist. No cohort has been followed.
GDD is generally not life-limiting, but is not uniformly benign: at least one death is recorded — "The patient died from complications related to GDD." (PMID:28176803, describing the R215G sporadic patient originally reported by Riminucci). Cuvelier et al. counsel that "symptoms can be very severe, even fatal" (PMID:38922934).
Patients survive into at least the eighth decade (a 73-year-old proband, PMID:28176803).

Morbidity and disability

Substantial and predominantly surgical, dental, and orthopaedic: - Repeated jaw debulking/resection, sometimes ≥3 operations in a young child (PMID:28176803) - Mandibular reconstruction with free vascularized fibular graft, titanium plating (PMID:35982081, PMID:30641283) - Below-knee amputation after fracture non-union complicated by osteomyelitis and skin necrosis (PMID:28176803) - Tooth loss and lifelong prosthodontic dependence (PMID:29518808) - Facial disfigurement - Compartment syndrome requiring multiple fasciotomies, with residual peroneal nerve injury (combined phenotype; PMID:34291158)

Quality-of-life instruments: never applied. No EQ-5D, SF-36, or PROMIS data exist for GDD.

Complications

Jaw osteomyelitis with purulent discharge; fracture non-union; post-traumatic limb-length discrepancy; recurrence of jaw lesions after incomplete resection; airway/feeding/speech compromise from jaw expansion; orbital and sinus involvement from maxillary expansion (in one patient the left eyeball was "compressed and anterior and laterally shifted," PMID:35982081).

Recovery potential

None — there is no recovery. Surgical resection can be curative for a given lesion if complete ("does not recur after complete resection," PMID:37649308), but the underlying skeletal disorder is permanent and progressive. Notably, surgical healing itself can be normal: "All of the fibular and mandibular osteotomies were found to be well healed" (PMID:28176803), and internal fixation of an adult tibial shaft fracture achieved "successful callus formation" (PMID:33826556).

Prognostic factors

Only one is established, and it is qualitative: De novo variant status predicts more severe disease and earlier onset, whereas familial variants show broader age ranges (PMID:38922934).

Suggestive but unvalidated: - Very early onset (prenatal/infantile jaw expansion) predicts severe course (PMID:29175271, PMID:28176803) - Variant position may predict bone-mass subtype (§3d) - Two families (p.C356F, p.L370_A371ins) had jaw lesions without fractures — a milder, jaw-restricted presentation (PMID:38922934)

No validated prognostic biomarker exists. ALP and bone turnover markers are diagnostic/monitoring aids, not validated predictors.

12. Treatment

Framing statement to carry into any KB entry: "Currently, there is no cure for GDD, and management of the disorder is focused on symptom relief and prevention of complications." (PMID:38922934). And: "Currently, the clinical treatment of GDD is limited to surgical resection." (PMID:40049314)

Pharmacotherapy

Agent	Rationale / evidence	Suggested NCIT annotation
Bisphosphonates (pamidronate)	The only antiresorptive with human GDD data — a 5-year-old received "a total of 7 pamidronate infusions commencing at age 15 months" for severe osteopenia; the report does not establish efficacy and the authors call for further evaluation (PMID:29175271, PMID:28176803). Cuvelier et al. recommend fractures be "treated similarly to Osteogenesis Imperfecta," incorporating bisphosphonate therapy where appropriate (PMID:38922934).	`treatment_term`: `NCIT:C15986` Pharmacotherapy; `therapeutic_agent`: pamidronate (CHEBI — verify with OAK); `therapeutic_modality: SMALL_MOLECULE`
Parathyroid hormone (teriparatide / PTH 1-34)	Mouse only. "Osteoanabolic treatment of parathyroid hormone was effective in enhancing bone strength in Ano5 KO mice." PTH increased cortical BMD, MAR, osteocalcin⁺ osteoblasts and TRAP⁺ osteoclasts. Critically, the authors caution: "the absence of Ano5 might partially hinder PTH-driven bone anabolism" — PTH worked less well in KO than WT mice (PMID:35982081). Proposed specifically for the low-bone-mass subtype.	`NCIT:C15986`; `therapeutic_modality: PEPTIDE`; `evidence_source: MODEL_ORGANISM`
Denosumab / antiresorptives	Proposed only, no data. "For GDD with high bone mass and a high bone turnover phenotype, we can choose antiresorptive treatments, such as bisphosphonates and denosumab" (PMID:35982081)	`therapeutic_modality: MONOCLONAL_ANTIBODY`
Calcium and vitamin D supplementation	Adjunctive; "Additional calcium supplementation can also be used to prevent bone loss" (PMID:35982081); recommended in affected pregnant patients (PMID:38922934)	`NCIT:C15433` Nutritional Support — note the CLAUDE.md caveat: do not auto-tag this `BEHAVIORAL`; these are chemical supplements
Antibiotics	Standard of care for jaw osteomyelitis; no GDD-specific regimen published	—

A treatment-strategy warning that belongs in the entry. Li et al. make the subtype-dependence explicit and it cuts the wrong way if ignored: "There are no established guidelines for the management of fracture risk in these patients. Physicians should assess the patient's skeletal status more accurately, understand the mechanisms of drugs, and formulate a treatment plan under consideration of individual differences in patients." (PMID:35982081) Giving an antiresorptive to a low-turnover, low-bone-mass GDD patient, or an osteoanabolic to a high-turnover osteosclerotic one, is mechanistically wrong. Any curated treatment must be scoped to the correct subtype.

Preclinical / experimental therapeutic targets (all mouse or in vitro only — none has entered human trials)

Target	Agent	Effect	Reference
Akt	SC79 (activator)	"obviously rescue abnormal increased osteogenesis and decreased osteoclastogenesis in Ano5 KI/KI mouse model"	PMID:39866532
Autophagy / ATG9A	3-methyladenine, chloroquine	3-MA "alleviated the bone phenotype abnormalities in Ano5-/- mice" in vivo	PMID:40067389
AMPK	Compound C (inhibitor)	"AMPK inhibitor reversed the bone phenotype of GDD by restraining bone formation and restoring osteoclastogenesis"	PMID:41717545
miR-34c-5p / KLF4	AAV-miR-34c-5p	In vivo rescue of thickened cortical bone, improved biomechanics, reduced serum P1NP	PMID:40508076
NF-κB	NF-κB activator	Partial attenuation of impaired osteoclastogenesis	PMID:36989132

Surgical and interventional

Jaw surgery (NCIT:C16186 Orthopedic Surgical Procedure / NCIT:C15329 Surgical Procedure; therapeutic_modality: SURGERY): - Debulking — the workhorse, but recurrence is the rule with incomplete removal - Segmental mandibulectomy / total mandibulectomy / subtotal or bilateral partial maxillectomy (PMID:28176803, PMID:35982081) - Microsurgical reconstruction — free vascularized fibular graft, titanium reconstruction plate. Marechal et al. flag the specific difficulty: "the challenges of craniofacial reconstruction in GDD due to the diffuse bone anomalies affecting potential flap donor zones and a specific risk for jawbone osteomyelitis" (PMID:30641283) — the donor bone is itself diseased. - Orthognathic surgery — newly demonstrated as feasible: LeFort I advancement plus bilateral sagittal split osteotomy with setback in a 21-year-old, "No complications were seen and 2-year follow-up showed stable dental occlusion. This is the first report describing orthognathic surgery safely performed on a patient with GDD1." (PMID:41193275)

Conservatism principle: Cuvelier et al. recommend surgical debulking "only for a functional problem or aesthetics" given recurrence risk (PMID:38922934).

Fracture surgery: - Intramedullary devices are recommended first-line for paediatric femoral shaft fractures in GDD (PMID:30797234) - Intramedullary nail fixation for bilateral diaphyseal femur fractures (PMID:32455153) - Internal fixation with successful callus formation in the first reported adult case (PMID:33826556)

Supportive and rehabilitative

Prosthodontic rehabilitation — a 30-year follow-up showed that "despite severe alveolar bone resorption, prosthetic treatment improved patient satisfaction and functional ability, requiring regular adjustments and monitoring" (PMID:29518808). NCIT:C15302 Physical Therapy is not the right term here; look for a dental prosthesis term with OAK.
Dental care and pain management (PMID:38922934)
Physical/occupational therapy post-fracture and post-amputation

Pharmacogenomics, gene therapy, cell therapy, RNA therapy, immunotherapy

None exist for GDD. No pharmacogenomic markers; no gene therapy, gene editing, cell therapy, or approved RNA therapeutic. The AAV-miR-34c-5p work (PMID:40508076) is the closest thing to a nucleic-acid therapeutic concept and is preclinical mouse data only.

Clinical trials

No interventional clinical trial for GDD has ever been registered or reported. A ClinicalTrials.gov search for gnathodiaphyseal dysplasia returns nothing usable. Any NCT identifier attributed to GDD should be treated as suspect and verified with just fetch-reference before curation.

Treatment outcomes

No response rates, no systematic adverse-event data. The single reported bisphosphonate course had no efficacy outcome published (PMID:29175271).

13. Prevention

Primary prevention

Disease occurrence cannot be prevented — GDD is a dominantly inherited monogenic condition. The only primary-prevention modalities are reproductive: - Genetic counselling (NCIT:C15240 Genetic Counseling) — 50% transmission risk per pregnancy, which Cuvelier et al. emphasize must be discussed (PMID:38922934) - Preimplantation genetic testing (PGT-M) and prenatal diagnosis — explicitly recommended: "prenatal/pre-implantation diagnosis and medical termination should be discussed with couples" (PMID:38922934)

Secondary prevention (early detection)

Cascade genetic testing and panoramic radiographic screening of at-risk relatives — the highest-value intervention available, since many carriers are discovered incidentally (PMID:28176803)
Prenatal ultrasound surveillance in known-affected families, targeting long-bone bowing (100% of prenatal cases) and fractures (33%) (PMID:38922934)
Timing: given the 41-year natural-history study, initiating dental radiographic surveillance around the mixed-dentition stage is the evidence-aligned choice (PMID:40861765)

Tertiary prevention (complication avoidance)

This is where most practical benefit lies: - Fracture prevention — fall/trauma avoidance, calcium and vitamin D repletion, subtype-appropriate bone-active therapy - Meticulous dental hygiene and conservative dental management — because extraction sites heal poorly and seed osteomyelitis, prophylaxis and avoidance of unnecessary extraction are rational (extrapolated from the osteomyelitis literature in PMID:28176803, PMID:29518808; not formally studied) - Complete rather than partial lesion resection where surgery is indicated, to avoid accelerated regrowth (PMID:37649308) - Obstetric planning in affected pregnant patients — vitamin D/calcium supplementation and a documented discussion of caesarean delivery based on disease severity (PMID:38922934) - In the combined muscle+bone phenotype, avoiding overexertion to prevent rhabdomyolysis and compartment syndrome (PMID:34291158, PMID:36292621)

Immunization, public health, environmental interventions

Not applicable. No vaccine strategy, no population-level public-health intervention, and no environmental risk factor to modify.

14. Other Species / Natural Disease

Taxonomy and orthologues

Ano5 is present in mouse (Mus musculus, NCBITaxon:10090), rat, rabbit (Oryctolagus cuniculus, NCBITaxon:9986), zebrafish (Danio rerio, NCBITaxon:7955), fruit fly (Drosophila melanogaster, NCBITaxon:7227), and mosquito — the Cys356 residue is "evolutionarily conserved among human, mouse, zebrafish, fruit fly, and mosquito" (PMID:15124103).
Mouse Ano5: NCBI Gene ID 233246. Human ANO5: NCBI Gene ID 203859.
Conservation caveats that matter for model design: Thr513 is not strictly conserved across vertebrate ANO5 orthologues (some carry alanine) — PMID:29124309. And Ser500 is a threonine in mouse, meaning the murine "equivalent" of p.S500F is p.T491F, a chemically different substitution. Li et al. argue this may explain that model's failure: "the amino acid sequence is not conserved between humans and mice at that mutation site... it is possible that Ano5 KI mice with p.T491F amino acid exchange did not display alterations in skeletal microarchitecture" (PMID:35982081).

Natural disease in other species

No naturally occurring GDD has been reported in any non-human species. No OMIA entry corresponds to gnathodiaphyseal dysplasia. There is no known veterinary counterpart, no breed predisposition, and therefore no VBO annotation applies.

Comparative biology

The eight extracellular-loop cysteines are conserved across humans, teleosts, and insects (PMID:28176803).
The functional divergence within the TMEM16 family is itself instructive: TMEM16A/B are Ca²⁺-activated chloride channels, TMEM16C/D/F/G/J are scramblases, and the T513-equivalent position "has divergent roles in phospholipid scrambling and chloride channel activity of TMEM16 family members" — introducing the same substitution into TMEM16B barely affected it (PMID:29124309).
The strongest comparative-biology conclusion is negative: "Ano5 is dispensable for bone homeostasis in mice, at least under unchallenged conditions, and... these animals may not present the most adequate model to study the physiological role of Anoctamin 5." (PMID:32455153)

Transmission

No zoonotic potential and no cross-species susceptibility — GDD is a germline genetic disorder, not transmissible.

15. Model Organisms

The central problem: the mouse models contradict each other

This is the single most important thing to record about GDD models, and it maps directly onto dismech's HUMAN_MODEL_MISMATCH discussion kind rather than a generic knowledge gap — evidence exists in models, and it is the translational validity that is in dispute.

Model	Genotype	Skeletal phenotype	Verdict
Ano5^−/− KO (CRISPR/Cas9, Hu lab)	Homozygous null	Replicates GDD: "massive jawbones, bowing tibia, sclerosis and cortical thickening of femoral and tibial diaphyses"; elevated serum ALP; increased osteoblastogenesis; hypermineralized matrix	`RECAPITULATES` / `PARTIALLY_RECAPITULATES` — PMID:30712070
Ano5^KI/KI p.Cys360Tyr (knock-in, Hu lab)	Homozygous KI of a human GDD variant	Replicates GDD: massive jawbones, bowing tibia, bone fragility, sclerosis, cortical thickening; elevated ALP; increased osteoblastogenesis with hypermineralized matrix; decreased osteoclastogenesis with disrupted actin rings	`RECAPITULATES` — PMID:34841576. The best available GDD model.
Ano5^+/KI and Ano5^KI/KI p.T491F (knock-in, Schinke/Yorgan lab)	Murine equivalent of human p.S500F	NO phenotype at all — no change in trabecular or cortical microarchitecture, no mandibular abnormality, no altered bone turnover, normal three-point bending, replicated in a second independent clone and in females	`FAILS_TO_RECAPITULATE` — PMID:32455153
Ano5^KO/KO (frameshift, ~40% C-terminal loss, same lab)	Near-null	Very mild: increased tissue mineral density in trabecular and cortical compartments, reduced cortical porosity; no microarchitectural change	`PARTIALLY_RECAPITULATES` — PMID:32455153
Ano5 KO (RIKEN C57BL/6-Ano5^tm1Itak, Qin lab)	Homozygous null	Opposite direction: low bone volume (femoral BV/TV −23%, Tb.Th −14%, mandibular BV/TV −34%), decreased mineral apposition rate, reduced osteoclast number and surface, abolished [Ca²⁺]i oscillations	`PARTIALLY_RECAPITULATES` (models the low-bone-mass subtype) — PMID:35982081
Ano5-deficient mouse (muscle-focused)	Homozygous null	No significant clinical myopathy or cardiomyopathy	`FAILS_TO_RECAPITULATE` (muscle) — PMID:26693275, PMID:36292621
Rabbit CRISPR indel model	Frame-disrupting exon 12/13	Dystrophic changes in gastrocnemius, tibialis anterior, tongue, diaphragm — models the muscle disease	`RECAPITULATES` (muscle only) — PMID:36292621

The authors themselves name the contradiction. Rolvien et al.: "our results are in apparent contradiction to another study, where Ano5-deficient mice recapitulated some aspects of GDD... it is quite surprising that a loss of Ano5 mimics the phenotype of GDD, especially in the light of the aforementioned study suggesting that GDD-causing mutations convey a gain-of-function... Therefore, we believe that further research is required to resolve this apparent contradiction." (PMID:32455153)

Shaibani et al. summarize the whole picture: "mouse models yielded conflicting results, including sarcolemma repair abnormalities and defective myoblast regeneration and fusion, lack of muscle phenotype, GDD phenotype in Ano5-knockout mice, as well as absence of skeletal phenotype in a knock-in model of a GDD-related mutation." (PMID:34291158)

Candidate explanations offered in the literature (none resolved): 1. Animal age — GDD onsets at 10–16 years in humans; 12–24-week mice are already adult/middle-aged and skeletal signals may be masked (PMID:35982081) 2. Residual function in one deficiency model vs complete loss in another (PMID:32455153) 3. Species-divergent residue at the mutated site (Ser vs Thr at human 500 / mouse 491) (PMID:35982081) 4. Unchallenged conditions — Ano5 may only be required under membrane damage (PMID:32455153) 5. GOF vs LOF — a knockout cannot model a gain-of-function allele

A limitation that applies to every mouse model: none reproduces the human jaw histopathology. "in mouse models, microscopic analysis revealed increased bone mineralization in the jaw lesions but not the microscopic features of fibrous-osseous lesions generally detected in patients with GDD." (PMID:37649308) Li et al. propose that large-animal models (horse, sheep, dog, pig) may be required (PMID:35982081).

Cellular and in vitro models

System	Use	Reference
MC3T3-E1 subclone 14 (mouse calvarial pre-osteoblast)	shRNA Ano5 knockdown (~80% efficiency) → increased Ocn, Col1a1, Runx2, Osterix; increased alizarin-red mineral nodules	PMID:28176803
Primary mouse calvarial osteoblasts (mCOBs)	The workhorse for the 2023–2026 mechanism papers (metabolomics, autophagy, miR-34c, AMPK)	PMID:36742392, PMID:40067389, PMID:40508076, PMID:41717545
Bone marrow-derived macrophages (BMMs)	RANKL-induced osteoclastogenesis, TRAP staining, F-actin ring, Ca²⁺ oscillation imaging	PMID:35982081, PMID:39866532, PMID:36989132
RAW264.7	Ano5 knockdown osteoclast studies	PMID:36989132
HEK293 / HEK293T	Heterologous TMEM16E expression, whole-cell patch clamp, annexin-V scrambling assay	PMID:29124309, PMID:32112655, PMID:28176803
CHO cells	Ca²⁺-dependence of TMEM16E currents (0–240 µM free Ca²⁺)	PMID:29124309
COS-7	C356G/C356R localization and cell-rounding	PMID:15124103
Patient PBMCs	Western blot for TMEM16E abundance; PBMC-derived osteoclast Ca²⁺ oscillation imaging — the only human-cell functional assay in the GDD literature	PMID:35982081
Saos-2 osteosarcoma	Source of the 898-aa TMEM16E splice isoform used in electrophysiology	PMID:29124309

Notably absent: no patient-derived iPSC line, no bone organoid, no organ-on-chip, and no immortalized GDD patient osteoblast line. Riminucci's original 2001 work transplanted stromal cells grown from the jaw lesion into immunocompromised mice and achieved "a close mimicry of the native lesion" (PMID:11547842) — a xenograft model that, remarkably, has not been revisited in 25 years and represents an obvious opportunity.

Model resources

MGI (mouse Ano5), RIKEN BioResource Center (C57BL/6-Ano5^tm1Itak), and the investigator-generated lines B6-Ano5^tm1Pg/Uke, B6-Ano5^tm2Pg/Uke, B6-Ano5^tm3Pg/Uke (PolyGene AG / UKE Hamburg, PMID:32455153). No IMPC/KOMP GDD-relevant deep phenotyping has been published.

Curation notes for the dismech knowledge base

A few things that will bite whoever builds the YAML entry:

Named Entity Confusion risk is HIGH. ANO5 is far more famous for LGMDR12 / Miyoshi myopathy 3 than for GDD. A deep-research report, a dataset search, or a literature sweep keyed on "ANO5" will return predominantly muscular-dystrophy content that is coherent, correctly cited, and about the wrong disease. Run just preflight-dr <report> MONDO:0008151 before curating from any DR output. The specific facts most likely to leak across incorrectly: the c.191dupA northern European founder mutation, the 2:1–4:1 male predominance, the prevalence figures (0.27–2 per 100,000), and the 10–30% cardiac involvement — all of these belong to the recessive muscle disease and none applies to GDD.
Model the GOF/LOF dispute as competing mechanistic_hypotheses, not a single chain. Suggested groups: gain_of_function_scrambling (CANONICAL/ALTERNATIVE, per PMID:29124309, PMID:32112655) and loss_of_function_calcium_signaling (ALTERNATIVE, per PMID:35982081, PMID:28176803). Attach the two bone-mass subtypes to the respective groups.
Add a HUMAN_MODEL_MISMATCH discussion, not a generic KNOWLEDGE_GAP, for the mouse-model contradiction. Evidence exists in models; it is the translational validity that is contested. Use FAILS_TO_RECAPITULATE with mandatory limitations and evidence for the p.T491F knock-in (PMID:32455153).
Consider conforms_to targets. osteoporosis_bone_resorption#Increased Osteoclastic Bone Resorption is a poor fit — GDD osteoclastogenesis is largely decreased. A better fit may be defective_skeletal_mineralization (though GDD is over- rather than under-mineralization, so check the module's scope) and possibly loss_of_proteostasis for the misfolded-mutant-degradation arm. Do not force a conformance that the evidence does not support.
Lump/split decision on FGC and familial FCOD. Three independent lines of evidence (PMID:27216912, PMID:37649308, PMID:42361776) now place familial gigantiform cementoma and familial florid cemento-osseous dysplasia inside the ANO5 spectrum. Record the decision and reasoning explicitly.
Ontology terms flagged for OAK verification before binding: HP:0005045 (Diaphyseal cortical sclerosis), HP:0003621 (Juvenile onset), HP:0000006 (Autosomal dominant inheritance) — these came from the HPO API and are not in the repository's local cache/hp/terms.csv. An HPO term for elevated alkaline phosphatase was not found in the local cache and must be looked up. Every other HP, GO, CL, and UBERON identifier cited above was verified against the local ontology label caches.

Primary Sources

Disease definition and gene discovery - Riminucci M et al. Gnathodiaphyseal dysplasia: a syndrome of fibro-osseous lesions of jawbones, bone fragility, and long bone bowing. J Bone Miner Res 2001. PMID:11547842 - Tsutsumi S et al. Autosomal dominant gnathodiaphyseal dysplasia maps to chromosome 11p14.3-15.1. J Bone Miner Res 2003. PMID:12619924 - Tsutsumi S et al. The novel gene encoding a putative transmembrane protein is mutated in gnathodiaphyseal dysplasia (GDD). Am J Hum Genet 2004. PMID:15124103 · DOI 10.1086/421527 - Mizuta K et al. Molecular characterization of GDD1/TMEM16E. Biochem Biophys Res Commun 2007. PMID:17418107

Clinical reports and variant discovery - Marconi C et al. Eur J Hum Genet 2013 (T513I, Italian pedigree). PMID:23047743 - Rolvien T et al. J Bone Miner Res 2017 (S500F, high-turnover osteosclerosis). PMID:27541832 - Jin L et al. Sci Rep 2017 (three novel variants; osteoblast studies). PMID:28176803 · DOI 10.1038/srep40935 - Otaify GA et al. Bone 2018 (G518E, severe atypical, pamidronate). PMID:29175271 - Zeng B et al. Head Neck 2019 (C356F; 67% misdiagnosis rate). PMID:30554457 - Marechal G et al. J Stomatol Oral Maxillofac Surg 2019 (R597I; reconstruction). PMID:30641283 - Sandal S et al. Congenit Anom 2021 (calvarial doughnut lesions). PMID:32902009 - Shaibani A et al. Neurol Genet 2021 (combined myopathy + GDD). PMID:34291158 · DOI 10.1212/NXG.0000000000000612 - Iranian family, C360R. Mol Genet Genomic Med 2022. PMID:35758145 - Cuvelier V et al. Prenat Diagn 2024 (two fetal cases + 108-patient literature review). PMID:38922934 · DOI 10.1002/pd.6631 - Long-term 41-year radiographic follow-up. Cureus 2025. PMID:40861765 - Double jaw surgery case report. J Craniomaxillofac Surg 2025. PMID:41193275

Nosology / jaw-lesion spectrum - Duong HY et al. Sci Rep 2016 (WES links dental tumour to ANO5). PMID:27216912 - Zhou Z et al. Mol Genet Genomic Med 2024 (FGC with C356Y). PMID:37649308 · DOI 10.1002/mgg3.2277 - Update on molecular pathology of fibro-osseous jaw lesions. Semin Diagn Pathol 2026. PMID:42361776

Mechanism — biophysics - Di Zanni E et al. Cell Mol Life Sci 2018 (T513I gain of function). PMID:29124309 · DOI 10.1007/s00018-017-2704-9 - Di Zanni E et al. Hum Mutat 2020 (GDD = GOF, MD = LOF). PMID:32112655

Mechanism — bone cell biology and models - Kim JH et al. Bone 2019 (Akt-NFATc1 osteoclast). PMID:30557634 - Wang X et al. Calcif Tissue Int 2019 (Ano5 KO replicates GDD). PMID:30712070 - Rolvien T et al. Bone Rep 2020 (p.T491F KI — no phenotype). PMID:32455153 - Li H et al. J Bone Miner Res 2022 (Cys360Tyr knock-in model). PMID:34841576 - Li X et al. NPJ Genom Med 2022 (calcium signalling; LOF subtype; PTH). PMID:35982081 · DOI 10.1038/s41525-022-00312-1 - Metabolomics/transcriptomics of Ano5^Cys360Tyr. Front Endocrinol 2023. PMID:36742392 - Liu X et al. Oral Dis 2024 (impaired osteoclastogenesis, NF-κB). PMID:36989132 - Akt signalling / SC79 rescue. Bone Rep 2025. PMID:39866532 - ER stress / CHOP osteoclast apoptosis. Exp Cell Res 2025. PMID:40049314 - ATG9A-dependent autophagy. JCI Insight 2025. PMID:40067389 - miR-34c-5p/KLF4/β-catenin. Int J Mol Sci 2025. PMID:40508076 - AMPK-dependent glucose metabolism. Front Endocrinol 2026. PMID:41717545

Management - Recurrent femoral shaft fractures in a child. BMC Musculoskelet Disord 2019. PMID:30797234 - Prosthodontic treatment, 30-year follow-up. Int J Prosthodont 2018. PMID:29518808 - Adult tibial shaft fracture. JBJS Case Connect 2021. PMID:33826556

Differential / context - Soontrapa P, Liewluck T. Anoctamin 5 (ANO5) muscle disorders: a narrative review. Genes 2022. PMID:36292621 - COL1A1 C-propeptide cleavage-site mutation as a GDD phenocopy. Clin Genet 2015. PMID:24891183 - GDD presenting as polyostotic fibrous dysplasia. Am J Med Genet A 2015. PMID:25866257

Databases - OMIM #166260 · OMIM *608662 - Orphanet ORPHA:53697 - MedlinePlus Genetics — gnathodiaphyseal dysplasia - Open Targets — MONDO_0008151 - MalaCards — gnathodiaphyseal dysplasia - GARD — gnathodiaphyseal dysplasia - LOVD ANO5 variant database - PubMed — gnathodiaphyseal dysplasia (56 results)

PubMed article metadata retrieved from PubMed (NCBI/NLM); DOIs are given inline for cited articles.

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome	Count
References checked	48
Resolved	48
Unresolved (possible confabulation)	0
Unverifiable	0
Quoted claims checked	35
Quoted claims found in source	23
Quoted claims not found in source	12
References weighed for topical relevance	48
On topic	40
Off topic	0

Quotes not found in the cited source

Searched the abstract, any retrieved full text, and the title. A quote drawn from a part of the paper that was not retrieved will appear here too, so check before treating one as invented:

10 of these was searched against an abstract alone, with no full text retrieved - marked abstract only below. Where full text can be fetched, re-running with it will settle them; where the source publishes only a summary to PubMed, as GeneReviews chapters do, it will not, and the quote has to be checked by hand against the chapter itself.

PMID:11547842 (abstract only): "gnathodiaphyseal sclerosis"
Text part not found as substring: 'gnathodiaphyseal sclerosis' (note: only abstract available for PMID:11547842, full text may contain this excerpt)
PMID:12619924 (abstract only): "as a new and distinct disease entity from other systemic bone diseases"
closest text in source: "Although GDD has been considered to be a variation of osteogenesis imperfecta (MIM 166260), our results indicate that this syndrome is a new and distinct disease entity from other systemic bone diseases"
PMID:28176803: "severe facial disfigurement"
Text part not found as substring: 'severe facial disfigurement'
PMID:29175271 (abstract only): "severe facial disfigurement"
Text part not found as substring: 'severe facial disfigurement' (note: only abstract available for PMID:29175271, full text may contain this excerpt)
PMID:38922934 (abstract only): "probably pathogenic (class 4)"
Text part not found as substring: 'probably pathogenic (class 4)' (note: only abstract available for PMID:38922934, full text may contain this excerpt)
PMID:28176803: "fold with low efficiency and appear to be unstable and rapidly degraded via proteasomal degradation"
closest text in source: "Recent studies23 suggest that mutant ANO5 protein (C356G and C356R) folds with low efficiency and appears to be unstable and rapidly degraded via proteasomal degradation"
PMID:38922934 (abstract only): "multiple diaphyseal fractures of the long bones... affecting femurs, tibias, and bilateral upper extremity bones"
closest text in source: "Clinical manifestations range from recurrent dental infections with mild jaw lesions to severe bone fragility with several fractures associated with large jaw lesions requiring disfiguring surgeries"
PMID:24891183 (abstract only): "a new cause of gnathodiaphyseal dysplasia"
closest text in source: "Gnathodiaphyseal dysplasia (GDD) is a rare autosomal dominant condition characterized by bone fragility, irregular bone mineral density (BMD) and fibro-osseous lesions in the skull and jaw"
PMID:38922934 (abstract only): "symptoms can be very severe, even fatal"
closest text in source: "Clinical manifestations range from recurrent dental infections with mild jaw lesions to severe bone fragility with several fractures associated with large jaw lesions requiring disfiguring surgeries"
PMID:33826556 (abstract only): "successful callus formation"
Text part not found as substring: 'successful callus formation' (note: only abstract available for PMID:33826556, full text may contain this excerpt)
PMID:29518808 (abstract only): "despite severe alveolar bone resorption, prosthetic treatment improved patient satisfaction and functional ability, requiring regular adjustments and monitoring"
closest text in source: "Despite the severe alveolar bone resorption, prosthodontic treatment improved the patient's satisfaction and ability to perform essential functions"
PMID:38922934 (abstract only): "prenatal/pre-implantation diagnosis and medical termination should be discussed with couples"
closest text in source: "A literature review was conducted to explore GDD's clinical and paraclinical presentation, diagnosis, and management"

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Classifications

Inheritance

Mechanistic Hypotheses

Discussions and Knowledge Gaps

Pathophysiology

Histopathology

Pathograph

Phenotypes

Genetic Associations

Medical Actions

Biochemical Markers

Diagnosis

Progression

Prevalence

Differential Diagnoses

Animal Models

Source YAML

References & Deep Research

References

Deep Research

Gnathodiaphyseal Dysplasia (GDD) — Comprehensive Research Report

1. Disease Information

Overview

Key identifiers

Synonyms and alternative names

Data provenance

2. Etiology

Disease causal factors

Genetic risk factors

Environmental risk factors

Protective factors

Gene–environment interactions

3. Phenotypes

3a. Frequency data — the single best source

3b. Craniofacial / gnathic phenotypes

3c. Appendicular / axial skeletal phenotypes

3d. The bone-density paradox — two mechanistically distinct subtypes

3e. Laboratory abnormalities

3f. Muscle phenotypes — a genuinely contested boundary

3g. Quality of life

4. Genetic / Molecular Information

Causal gene

Catalogue of reported GDD-causing ANO5 variants

Variant classification and population frequency

Functional consequence — GOF vs LOF, an unresolved and consequential dispute

Epigenetics

Chromosomal abnormalities

5. Environmental Information

6. Mechanism / Pathophysiology

6a. Normal ANO5/TMEM16E biology

6b. Causal chain — trigger to clinical manifestation

6c. Downstream signalling pathways — a rapidly expanding 2024–2026 literature

6d. Protein dysfunction

6e. Immune system involvement

6f. Tissue damage mechanisms

6g. Cell types and processes — ontology suggestions

6h. Molecular profiling status

7. Anatomical Structures Affected

Organ level

Tissue and cell level

Subcellular level

Lateralization

8. Temporal Development

Onset

Progression

Critical periods

Remission

9. Inheritance and Population

Epidemiology

Inheritance

Population demographics

10. Diagnostics

Clinical / laboratory tests

Imaging

Histopathology

Genetic testing — the diagnostic gold standard

Clinical criteria

Differential diagnosis — and a diagnostic-error rate worth curating