Cerebellar Ataxia-Hypogonadism Syndrome

Mendelian MONDO:0008935 Pathograph 38 Show in embeddings browser

Cerebellar ataxia-hypogonadism syndrome (Gordon Holmes syndrome) is a genetically heterogeneous neurodegenerative-neuroendocrine disorder characterized by cerebellar ataxia and hypogonadotropic hypogonadism. Cognitive decline, movement disorders and cerebral white-matter changes vary with genotype and disease stage. Recessive RNF216 and STUB1 disease and a reported digenic RNF216/OTUD4 form involve ubiquitin regulation; biallelic PNPLA6 variants produce a distinct phospholipid-metabolism disorder within the overlapping PNPLA6 clinical spectrum. Endocrine abnormalities can precede overt neurologic signs. Chorioretinal dystrophy suggests overlap with Boucher-Neuhauser syndrome rather than a universal Gordon Holmes feature.

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2
Inheritance
8
Pathophys.
26
Phenotypes
38
Pathograph
4
Genes
15
Medical Actions
4
Subtypes
1
Trials
4
Models
1
References
1
Deep Research
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Inheritance

2
Autosomal recessive inheritance HP:0000007
Biallelic RNF216, STUB1 or PNPLA6 variants can cause an ataxia-hypogonadism phenotype. For PNPLA6 disease with both parents confirmed heterozygous, each conception has a 25% affected, 50% carrier and 25% unaffected non-carrier probability. Family counseling should use the established genotype; these single-locus probabilities are not applied to the digenic pedigree.
Autosomal recessive inheritance
Show evidence (2 references)
PMID:23656588 SUPPORT Human Clinical
"Additional screening identified compound heterozygous truncating mutations in RNF216 in an unrelated patient"
Biallelic truncating RNF216 variants establish a single-locus recessive form.
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"If both parents are known to be heterozygous for a PNPLA6 pathogenic variant, each sib of an affected individual has at conception a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier."
GeneReviews gives recurrence risks conditional on confirmed parental PNPLA6 carrier status.
Digenic inheritance (RNF216/OTUD4) HP:0010984
Three affected siblings in one consanguineous family carried homozygous variants at both RNF216 and OTUD4. Zebrafish knockdown and rescue support a functional interaction. This reported two-locus form involves homozygosity at both loci and does not establish isolated OTUD4 disease or a physical RNF216-OTUD4 protein interaction.
Digenic inheritance
Show evidence (1 reference)
PMID:23656588 SUPPORT Human Clinical
"Digenic homozygous mutations in RNF216 and OTUD4, which encode a ubiquitin E3 ligase and a deubiquitinase, respectively, were found in three affected siblings in a consanguineous family."
The discovery study reports the two-locus genotype and its co-segregation with disease in three affected siblings.
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Subtypes

4
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Pathophysiology

8
RNF216 K63-linked ubiquitination deficiency
GHS-associated RNF216 catalytic-region variants impair E3 ubiquitin ligase activity. RNF216 synthesizes K63-linked chains in biochemical assays, implicating altered ubiquitin signaling. The relevant neuronal substrates and the steps connecting this defect to human neurodegeneration remain incompletely resolved.
RNF216 hgnc:21698 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves RNF216 (hgnc:21698). hgnc:21698 is a gene from the HUGO Gene Nomenclature Committee.
protein K63-linked ubiquitination GO:0070534 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased protein K63-linked ubiquitination (GO:0070534). GO:0070534 is a biological process from the Gene Ontology.
ubiquitin protein ligase activity GO:0061630 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased ubiquitin protein ligase activity (GO:0061630). GO:0061630 is a molecular function from the Gene Ontology.
Downstream
Cerebellar degeneration RNF216-related disease includes cerebellar degeneration; intervening molecular events are unresolved.
Hippocampal neuronal loss Hippocampal neuronal loss was demonstrated in an affected member of the digenic RNF216/OTUD4 family.
Reproductive Endocrine Axis Dysfunction RNF216-related disease involves hypothalamic and pituitary reproductive function through incompletely defined intermediates.
Altered microglial state in RNF216 models Constitutive Rnf216 loss alters microglial features in mice; intermediate steps and relevance to human disease remain unresolved.
Show evidence (2 references)
PMID:30886743 SUPPORT In Vitro
"Strikingly, we found that TRIAD3 synthesises specifically lysine-63 (K63)-linked poly-ubiquitin chains in vitro, a chain type that usually plays a role in mediating signalling events rather than triggering proteasomal degradation."
Biochemical chain-linkage experiments distinguish RNF216 K63 ubiquitination from a uniform K48/proteasomal degradation mechanism.
PMID:30886743 SUPPORT In Vitro
"Our results provide in vitro evidence that point mutations found in patients with Gordon Holmes syndrome5 abrogate TRIAD3’s E3 activity."
The study tests GHS-associated catalytic-region substitutions; retained activity of Huntington-like-disorder variants elsewhere in RNF216 cautions against a universal variant mechanism.
OTUD4-associated ubiquitin regulation defect
Mechanism confidence: Provisional
A homozygous OTUD4 variant co-segregated with a homozygous RNF216 variant in the original three-sibling family. OTUD4 encodes a deubiquitinase, and combined knockdown worsened developmental brain abnormalities in zebrafish. The exact catalytic consequence of the patient OTUD4 variant and its contribution independently of RNF216 remain unresolved.
OTUD4 hgnc:24949 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves OTUD4 (hgnc:24949). hgnc:24949 is a gene from the HUGO Gene Nomenclature Committee.
deubiquitinase activity GO:0101005 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves deubiquitinase activity (GO:0101005). GO:0101005 is a molecular function from the Gene Ontology.
Animal models
rnf216 and otud4 zebrafish morphants Danio rerio perturbs Tests functional interaction by single and combined gene knockdown and human mRNA rescue.
Downstream
Cerebellar degeneration The combined RNF216/OTUD4 genotype is associated with cerebellar pathology; zebrafish experiments support interaction, with unknown human intermediates.
Show evidence (2 references)
PMID:23656588 SUPPORT Human Clinical
"Digenic homozygous mutations in RNF216 and OTUD4, which encode a ubiquitin E3 ligase and a deubiquitinase, respectively, were found in three affected siblings in a consanguineous family."
The discovery study reports the two-locus genotype and its co-segregation with disease in three affected siblings.
PMID:23656588 SUPPORT Model Organism
"Knockdown of rnf216 or otud4 in zebrafish embryos induced defects in the eye, optic tectum, and cerebellum; combinatorial suppression of both genes exacerbated these phenotypes, which were rescued by nonmutant, but not mutant, human RNF216 or OTUD4 messenger RNA."
Knockdown and rescue support functional interaction between the two genes, without establishing a physical protein interaction or the exact OTUD4 catalytic defect.
STUB1 CHIP ubiquitin ligase deficiency
The recessive GHS-associated STUB1 Thr246Met variant disrupts the ubiquitin ligase activity of CHIP, a co-chaperone involved in protein quality control. Recombinant-protein and cell assays demonstrate the molecular loss of function.
STUB1 hgnc:11427 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves STUB1 (hgnc:11427). hgnc:11427 is a gene from the HUGO Gene Nomenclature Committee.
ubiquitin protein ligase activity GO:0061630 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased ubiquitin protein ligase activity (GO:0061630). GO:0061630 is a molecular function from the Gene Ontology.
Animal models
Chip-deficient mouse Mus musculus perturbs CHIP deficiency removes protein function rather than reproducing only the patient Thr246Met substitution.
Downstream
Cerebellar degeneration CHIP loss is associated with Purkinje-layer degeneration in mice, providing experimental support for an indirect cerebellar pathway.
Reproductive Endocrine Axis Dysfunction CHIP-related disease includes hypogonadism; the precise site and molecular route remain incompletely characterized.
Show evidence (2 references)
PMID:24113144 SUPPORT In Vitro
"Introduction of the Thr246Met mutation into CHIP results in a loss of ubiquitin ligase activity measured directly using recombinant proteins as well as in cell culture models."
The experimentally tested Thr246Met variant impairs CHIP E3 activity. This assay result is not generalized to every STUB1 variant.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3900109/?report=classic SUPPORT In Vitro
"while still maintaining chaperone interactions"
The full-text functional study shows that loss of E3 activity does not imply loss of chaperone binding.
PNPLA6 / Neuropathy Target Esterase Phospholipid Dysfunction
Biallelic PNPLA6 variants can reduce neuropathy target esterase (NTE) activity. This endoplasmic-reticulum-associated phospholipase participates in phospholipid homeostasis. Variant-specific residual activity helps explain tissue involvement across the PNPLA6 spectrum, including its Gordon Holmes presentation; downstream neuronal and endocrine pathways remain incompletely defined.
PNPLA6 hgnc:16268 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves PNPLA6 (hgnc:16268). hgnc:16268 is a gene from the HUGO Gene Nomenclature Committee.
glycerophospholipase activity GO:0004620 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased glycerophospholipase activity (GO:0004620). GO:0004620 is a molecular function from the Gene Ontology.
endoplasmic reticulum GO:0005783 Gene Ontology (GO) Relation: this pathophysiological event involves this cellular component This pathophysiological event involves endoplasmic reticulum (GO:0005783). GO:0005783 is a cellular component from the Gene Ontology.
Animal models
Pnpla6 residual-activity allelic mouse series Mus musculus partially recapitulates Models the relationship between genotype, residual enzyme activity and tissue dysfunction.
Downstream
Cerebellar degeneration PNPLA6-related ataxia can include cerebellar atrophy; the cohort does not establish a direct molecular route to neuronal death or hippocampal degeneration.
Reproductive Endocrine Axis Dysfunction PNPLA6-related GHS includes central hypogonadism; the molecular intermediates are incompletely resolved.
Show evidence (5 references)
PMID:35069422 SUPPORT Human Clinical
"A wide spectrum of neurodegenerative diseases has been associated with pathogenic variants in the PNPLA6 (patatin-like phospholipase domain-containing protein 6) gene, including spastic paraplegia type 39, Gordon-Holmes, Boucher-Neuhauser, Oliver-Mc Farlane, and Laurence-Moon syndromes."
Establishes PNPLA6 as a cause of the Gordon Holmes / Boucher-Neuhauser ataxia-hypogonadism continuum.
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"PNPLA6 disorders span a phenotypic continuum characterized by variable combinations of cerebellar ataxia; upper motor neuron involvement manifesting as spasticity and/or brisk reflexes; chorioretinal dystrophy associated with variable degrees of reduced visual function; and hypogonadotropic hypogonadism"
GeneReviews defines the PNPLA6 phenotypic continuum encompassing the ataxia-hypogonadism syndromes.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC11146429/?report=classic SUPPORT In Vitro
"The NTE activity of all disease-associated missense/in-frame and truncating variants was significantly reduced compared to the wild-type control"
Full-length variant assays support reduced NTE activity; this does not imply that every truncating allele has zero residual function.
+ 2 more references
Cerebellar degeneration
Cerebellar pathway neuronal loss was demonstrated at autopsy in RNF216/OTUD4-related disease. Cerebellar atrophy is also documented by MRI in PNPLA6-related ataxia. Histological neuronal loss is not inferred from imaging alone. CHIP-deficient mice also show Purkinje-layer cell loss, which supplies model support for STUB1 involvement.
Purkinje cell CL:0000121 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves Purkinje cell (CL:0000121). CL:0000121 is a cell type from the Cell Ontology.
cerebellum UBERON:0002037 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in cerebellum (UBERON:0002037). UBERON:0002037 is an anatomical location from the Uberon multi-species anatomy ontology.
Animal models
Constitutive Rnf216 knockout mouse Mus musculus fails to recapitulate
Chip-deficient mouse Mus musculus partially recapitulates Shows cerebellar Purkinje-layer cell loss and abnormal motor behavior.
Downstream
Cerebellar ataxia Degeneration of cerebellar pathways contributes to impaired gait and coordination.
Cerebellar atrophy Loss of cerebellar tissue is reflected in reduced cerebellar volume on imaging.
Dysarthria Cerebellar disease contributes to motor speech impairment.
Show evidence (2 references)
PMID:23656588 SUPPORT Human Clinical
"Neuronal loss was observed in cerebellar pathways and the hippocampus; surviving hippocampal neurons contained ubiquitin-immunoreactive intranuclear inclusions."
Autopsy in one affected RNF216/OTUD4 family member documents regional neuronal loss and inclusions; it does not establish that the inclusions cause cell death.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3900109/?report=classic SUPPORT Model Organism
"cellular loss throughout the various lobes of the cerebellum, specifically in the Purkinje cell layer"
Cerebellar histology in Chip-null mice demonstrates Purkinje-layer cell loss; this is experimental support, not human STUB1 neuropathology.
Hippocampal neuronal loss
An autopsy from the original RNF216/OTUD4 family showed hippocampal neuronal loss and ubiquitin-immunoreactive inclusions in surviving neurons. Their coexistence does not prove that inclusions caused neuronal death.
hippocampal formation UBERON:0002421 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in hippocampal formation (UBERON:0002421). UBERON:0002421 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Cognitive decline and dementia Hippocampal neuronal loss plausibly contributes to cognitive deterioration alongside broader brain involvement.
Show evidence (1 reference)
PMID:23656588 SUPPORT Human Clinical
"Neuronal loss was observed in cerebellar pathways and the hippocampus; surviving hippocampal neurons contained ubiquitin-immunoreactive intranuclear inclusions."
Autopsy in one affected RNF216/OTUD4 family member documents regional neuronal loss and inclusions; it does not establish that the inclusions cause cell death.
Reproductive Endocrine Axis Dysfunction
Hypothalamic and pituitary reproductive dysfunction causes central hypogonadism. Detailed RNF216 endocrine testing showed variable responses to exogenous GnRH, with declining or absent pituitary responsiveness in some patients as disease progressed. The relative contributions of hypothalamic and pituitary dysfunction vary; the same cellular localization is not established for every genetic form.
hypothalamic gonadotropin-releasing hormone neuron CL:0011111 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves hypothalamic gonadotropin-releasing hormone neuron (CL:0011111). CL:0011111 is a cell type from the Cell Ontology.
pituitary gland UBERON:0000007 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in pituitary gland (UBERON:0000007). UBERON:0000007 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Hypogonadotropic hypogonadism Reduced central gonadotropin drive produces hypogonadotropic hypogonadism.
Show evidence (2 references)
PMID:23656588 SUPPORT Human Clinical
"Defects were detected at the hypothalamic and pituitary levels of the reproductive endocrine axis."
Localizes the hypogonadotropic hypogonadism to combined hypothalamic and pituitary dysfunction.
PMID:23656588 SUPPORT Human Clinical
"Pituitary responsiveness to GnRH was lost in patients late in the course of their disease."
Longitudinal and late-stage endocrine testing supports progressive pituitary involvement in selected RNF216 cases.
Altered microglial state in RNF216 models
Mechanism confidence: Provisional
Constitutive Rnf216 knockout mice show sex- and region-dependent changes in microglial density, morphology and soma size. These observations are candidate disease intermediates and have not established a corresponding human neuroinflammatory mechanism.
microglial cell CL:0000129 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves microglial cell (CL:0000129). CL:0000129 is a cell type from the Cell Ontology.
Animal models
Constitutive Rnf216 knockout mouse Mus musculus recapitulates Demonstrates the model-specific microglial state changes described by this node.
Show evidence (1 reference)
PMID:38164552 SUPPORT Model Organism
"KO mice also showed age-dependent strategy and associative learning impairments with sex-dependent alterations of microglia in the hippocampus and cortex."
Constitutive Rnf216 loss is associated with sex- and region-dependent microglial changes and age-dependent learning phenotypes. Their causal relationship is not established.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Cerebellar Ataxia-Hypogonadism Syndrome Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

26
Breast 1
Gynecomastia HP:0000771 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Gynecomastia (HP:0000771). HP:0000771 is a phenotype from the Human Phenotype Ontology.
The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms.
Show evidence (1 reference)
ORPHA:1173 SUPPORT Other
"HP:0000771 | Gynecomastia | Very frequent (99-80%)"
Orphanet lists gynecomastia as a very frequent phenotype.
Digestive 1
Dysphagia HP:0002015 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dysphagia (HP:0002015). HP:0002015 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"Dysarthria and dysphagia are recurrent features ... evolving throughout the disease course in almost all individuals with cerebellar ataxia."
GeneReviews describes evolving bulbar symptoms in ataxic PNPLA6 disorders; this is not a measured all-genotype GHS frequency.
Endocrine 2
Hypogonadotropic hypogonadism HP:0000044 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypogonadotropic hypogonadism (HP:0000044). HP:0000044 is a phenotype from the Human Phenotype Ontology.
The broader Orphanet hypogonadism annotation is retained here as context; the primary clinical sources establish the central subtype. Hypothalamic/pituitary localization is represented separately in the reproductive-axis mechanism.
Show evidence (3 references)
PMID:39444518 SUPPORT Human Clinical
"Biallelic pathogenic variants in RNF216 cause a syndrome characterized by hypogonadotropic hypogonadism, cerebellar ataxia, chorea, and cognitive impairment, a combination first described as Gordon Holmes syndrome (MIM 212840)."
Defines hypogonadotropic hypogonadism as a core feature of the RNF216 syndrome.
PMID:39444518 SUPPORT Human Clinical
"hypogonadotropic hypogonadism may be the initial manifestation of this severe neuroendocrine disorder, especially in males."
Hypogonadism can precede neurologic signs as the presenting complaint.
ORPHA:1173 SUPPORT Other
"HP:0000135 | Hypogonadism | Very frequent (99-80%)"
Orphanet lists hypogonadism as a very frequent phenotype.
Delayed puberty HP:0000823 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Delayed puberty (HP:0000823). HP:0000823 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:39444518 SUPPORT Human Clinical
"We report 2 siblings who were referred due to absent or delayed puberty."
Affected siblings presented with absent or delayed puberty.
Eye 5
Chorioretinal dystrophy HP:0001135 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Chorioretinal dystrophy (HP:0001135). HP:0001135 is a phenotype from the Human Phenotype Ontology.
Retinal findings require genotype and overlap assessment: chorioretinal dystrophy distinguishes the Boucher-Neuhauser cluster from typical PNPLA6-related GHS.
Show evidence (2 references)
PMID:33650466 SUPPORT Human Clinical
"neurologic, ophthalmologic, endocrine, and genetic evaluations established a diagnosis of BNHS"
Chorioretinal dystrophy is a defining feature of the Boucher-Neuhauser (PNPLA6) form.
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"chorioretinal dystrophy associated with variable degrees of reduced visual function"
GeneReviews documents chorioretinal dystrophy with reduced visual function in PNPLA6 disorders.
Abnormal electroretinogram HP:0000512 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal electroretinogram (HP:0000512). HP:0000512 is a phenotype from the Human Phenotype Ontology.
The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms. Retinal findings require genotype and overlap assessment: chorioretinal dystrophy distinguishes the Boucher-Neuhauser cluster from typical PNPLA6-related GHS.
Show evidence (1 reference)
ORPHA:1173 SUPPORT Other
"HP:0000512 | Abnormal electroretinogram | Very frequent (99-80%)"
Orphanet lists abnormal electroretinogram as a very frequent phenotype.
Nystagmus HP:0000639 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Nystagmus (HP:0000639). HP:0000639 is a phenotype from the Human Phenotype Ontology.
The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms. Nystagmus is not uniform across genetic forms: the original RNF216 cohort and the two subsequently reported RNF216 brothers lacked nystagmus, whereas the STUB1 discovery family had gaze-evoked nystagmus.
Show evidence (3 references)
ORPHA:1173 SUPPORT Other
"HP:0000639 | Nystagmus | Very frequent (99-80%)"
Orphanet lists nystagmus as a very frequent phenotype.
PMID:27441066 REFUTE Human Clinical
"No nystagmus was noted. His workup showed low luteinizing hormone level"
The more severely affected RNF216 brother lacked nystagmus, limiting generalization of the Orphanet frequency.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3900109/?report=classic SUPPORT Human Clinical
"Patient II-1 exhibited horizontal gaze-evoked nystagmus"
The STUB1 proband had gaze-evoked nystagmus, supporting genotype-dependent heterogeneity.
Optic atrophy HP:0000648 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Optic atrophy (HP:0000648). HP:0000648 is a phenotype from the Human Phenotype Ontology.
The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms. Retinal findings require genotype and overlap assessment: chorioretinal dystrophy distinguishes the Boucher-Neuhauser cluster from typical PNPLA6-related GHS.
Show evidence (1 reference)
ORPHA:1173 SUPPORT Other
"HP:0000648 | Optic atrophy | Very frequent (99-80%)"
Orphanet lists optic atrophy as a very frequent phenotype.
Abnormality of retinal pigmentation Abnormal retinal pigmentation HP:0007703 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormality of retinal pigmentation, annotated with Abnormal retinal pigmentation (HP:0007703). HP:0007703 is a phenotype from the Human Phenotype Ontology.
The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms. Retinal findings require genotype and overlap assessment: chorioretinal dystrophy distinguishes the Boucher-Neuhauser cluster from typical PNPLA6-related GHS.
Show evidence (1 reference)
ORPHA:1173 SUPPORT Other
"HP:0007703 | Abnormality of retinal pigmentation | Very frequent (99-80%)"
Orphanet lists abnormality of retinal pigmentation as a very frequent phenotype.
Genitourinary 3
Decreased fertility HP:0000144 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Decreased fertility (HP:0000144). HP:0000144 is a phenotype from the Human Phenotype Ontology.
The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms.
Show evidence (1 reference)
ORPHA:1173 SUPPORT Other
"HP:0000144 | Decreased fertility | Very frequent (99-80%)"
Orphanet lists decreased fertility as a very frequent phenotype.
Primary amenorrhea HP:0000786 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Primary amenorrhea (HP:0000786). HP:0000786 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:39444518 SUPPORT Human Clinical
"His 15-year-old sister was referred due to primary amenorrhea."
An affected female sibling presented with primary amenorrhea.
Urinary urgency HP:0000012 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Urinary urgency (HP:0000012). HP:0000012 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"urinary urgency appears to be a recurrent feature at least in individuals with"
GeneReviews describes a clinical impression and explicitly notes the lack of systematic investigation.
Musculoskeletal 1
Spasticity HP:0001257 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Spasticity (HP:0001257). HP:0001257 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"upper motor neuron involvement manifesting as spasticity and/or brisk reflexes"
GeneReviews supports upper motor neuron manifestations across the PNPLA6 spectrum.
Nervous System 13
Cerebellar ataxia Progressive cerebellar ataxia HP:0002073 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cerebellar ataxia, annotated with Progressive cerebellar ataxia (HP:0002073), qualified as course progressive. HP:0002073 is a phenotype from the Human Phenotype Ontology.
Course: PROGRESSIVE
Show evidence (2 references)
PMID:24113144 SUPPORT Human Clinical
"Gordon Holmes syndrome (GHS) is a rare Mendelian neurodegenerative disorder characterized by ataxia and hypogonadism."
Ataxia is one of the two defining clinical features of the syndrome.
PMID:23656588 SUPPORT Human Clinical
"All patients had progressive ataxia and dementia."
All RNF216-mutation patients in the index cohort had progressive ataxia.
Cognitive decline and dementia HP:0000726 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dementia (HP:0000726), qualified as course progressive. HP:0000726 is a phenotype from the Human Phenotype Ontology.
Course: PROGRESSIVE
Show evidence (3 references)
PMID:23656588 SUPPORT Human Clinical
"Dementia was also prominent, with personality changes and memory loss occurring at the onset of the disease"
Dementia with personality changes and memory loss is prominent in RNF216-related disease.
PMID:37161390 SUPPORT Human Clinical
"Gordon Holmes syndrome (GHS) is a rare autosomal recessive disorder characterized by hypogonadotropic hypogonadism, cognitive decline, and cerebellar ataxia."
Cognitive decline is listed as one of the core GHS features.
PMID:27441066 REFUTE Human Clinical
"No nystagmus or cognitive impairment were noted."
The younger affected RNF216 brother had preserved cognition at the reported evaluation.
Personality changes HP:0000751 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Personality changes (HP:0000751). HP:0000751 is a phenotype from the Human Phenotype Ontology.
The Orphanet syndrome profile assigns OCCASIONAL; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms.
Show evidence (1 reference)
ORPHA:1173 SUPPORT Other
"HP:0000751 | Personality changes | Occasional (29-5%)"
Orphanet lists personality changes as an occasional phenotype.
Cerebellar atrophy HP:0001272 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cerebellar atrophy (HP:0001272). HP:0001272 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:35069422 SUPPORT Human Clinical
"Brain MRI showed cerebellar atrophy in 6/8 patients, more pronounced in superior and dorsal vermis lobules (I to VII)."
Cerebellar atrophy with vermian predominance was found in most PNPLA6 patients.
PMID:37977846 SUPPORT Human Clinical
"pan-cerebellar atrophy with bilateral cerebral white matter hyperintensities"
Pan-cerebellar atrophy documented in an RNF216 case.
Cerebral white matter abnormality Abnormal cerebral white matter morphology HP:0002500 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal cerebral white matter morphology (HP:0002500). HP:0002500 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:23656588 SUPPORT Human Clinical
"The subcortical white matter contained patchy areas of hyperintensity on T2-weighted imaging and fluid-attenuated inversion recovery (FLAIR) imaging"
Subcortical white-matter hyperintensities are documented across RNF216-mutation patients.
PMID:39444518 SUPPORT Human Clinical
"an extensive supratentorial leuko-encephalopathy"
Extensive supratentorial leukoencephalopathy was found on MRI in an RNF216 case.
Chorea HP:0002072 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Chorea (HP:0002072). HP:0002072 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:39444518 SUPPORT Human Clinical
"Biallelic pathogenic variants in RNF216 cause a syndrome characterized by hypogonadotropic hypogonadism, cerebellar ataxia, chorea, and cognitive impairment"
Chorea is part of the RNF216 syndrome phenotype.
Dysarthria HP:0001260 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dysarthria (HP:0001260). HP:0001260 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:23656588 SUPPORT Human Clinical
"Dysarthria was the initial neurologic symptom in some patients"
Dysarthria can be the presenting neurologic feature.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"Dysarthria and dysphagia are recurrent features ... evolving throughout the disease course in almost all individuals with cerebellar ataxia."
GeneReviews describes evolving bulbar symptoms in ataxic PNPLA6 disorders; this is not a measured all-genotype GHS frequency.
Abnormality of speech or vocalization Abnormal speech pattern HP:0002167 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormality of speech or vocalization, annotated with Abnormal speech pattern (HP:0002167). HP:0002167 is a phenotype from the Human Phenotype Ontology.
The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms.
Show evidence (1 reference)
ORPHA:1173 SUPPORT Other
"HP:0002167 | Abnormality of speech or vocalization | Very frequent (99-80%)"
Orphanet lists abnormality of speech or vocalization as a very frequent phenotype.
Hyperreflexia HP:0001347 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hyperreflexia (HP:0001347). HP:0001347 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"Gordon Holmes syndrome (cerebellar ataxia, hypogonadotropic hypogonadism, and – to a variable degree – brisk reflexes)"
GeneReviews lists variable brisk reflexes within the Gordon Holmes cluster of PNPLA6 disorders.
Hemiplegia/hemiparesis HP:0004374 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hemiplegia/hemiparesis (HP:0004374). HP:0004374 is a phenotype from the Human Phenotype Ontology.
The Orphanet syndrome profile assigns FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms.
Show evidence (1 reference)
ORPHA:1173 SUPPORT Other
"HP:0004374 | Hemiplegia/hemiparesis | Frequent (79-30%)"
Orphanet lists hemiplegia/hemiparesis as a frequent phenotype.
Parkinsonism HP:0001300 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Parkinsonism (HP:0001300). HP:0001300 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:37161390 SUPPORT Human Clinical
"also co-occurrence of parkinsonism and dystonia which was not reported before."
The reported case supports occurrence, not population frequency.
Dystonia HP:0001332 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dystonia (HP:0001332). HP:0001332 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:37161390 SUPPORT Human Clinical
"also co-occurrence of parkinsonism and dystonia which was not reported before."
The reported case supports occurrence, not population frequency.
Cognitive impairment HP:0100543 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cognitive impairment (HP:0100543). HP:0100543 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3900109/?report=classic SUPPORT Human Clinical
"did reveal cognitive deficiencies in both sisters"
MoCA detected cognitive deficits in the STUB1 sisters, despite normal MMSE scores in the reported assessment.
🧬

Genetic Associations

4
RNF216 biallelic pathogenic variants (Causative biallelic (and digenic with OTUD4) pathogenic variants)
Gene: RNF216 hgnc:21698 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is RNF216 (hgnc:21698). hgnc:21698 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE variant_origin: GERMLINE
Autosomal recessive inheritance
Show evidence (2 references)
PMID:23656588 SUPPORT Human Clinical
"The syndrome of hypogonadotropic hypogonadism, ataxia, and dementia can be caused by inactivating mutations in RNF216 or by the combination of mutations in RNF216 and OTUD4."
Establishes RNF216 (and digenic RNF216/OTUD4) as the genetic cause.
PMID:27441066 SUPPORT Human Clinical
"We identified a novel splicing variant in RNF216 that is likely to abolish the canonical splice site at the junction of exon/intron 13 (NM_207111.3:c.2061G>A)."
A novel RNF216 splice-site variant causes GHS, illustrating allelic heterogeneity.
OTUD4 (digenic with RNF216) pathogenic variants (Digenic contributor with RNF216)
Gene: OTUD4 hgnc:24949 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is OTUD4 (hgnc:24949). hgnc:24949 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: COOPERATING variant_origin: GERMLINE
Digenic inheritance
Show evidence (1 reference)
PMID:23656588 SUPPORT Human Clinical
"Digenic homozygous mutations in RNF216 and OTUD4, which encode a ubiquitin E3 ligase and a deubiquitinase, respectively, were found in three affected siblings in a consanguineous family."
Documents OTUD4 as a digenic contributor with RNF216.
STUB1 (CHIP) biallelic pathogenic variants (Causative biallelic pathogenic variants)
Gene: STUB1 hgnc:11427 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is STUB1 (hgnc:11427). hgnc:11427 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE variant_origin: GERMLINE
Autosomal recessive inheritance
Show evidence (1 reference)
PMID:24113144 SUPPORT Human Clinical
"identified a homozygous mutation in STUB1 (NM_005861) c.737C→T, p.Thr246Met, a gene that encodes the protein CHIP (C-terminus of HSC70-interacting protein)."
Identifies a homozygous STUB1/CHIP variant causing GHS.
PNPLA6 biallelic pathogenic variants (Causative biallelic pathogenic variants (Gordon Holmes / Boucher-Neuhauser continuum))
Gene: PNPLA6 hgnc:16268 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is PNPLA6 (hgnc:16268). hgnc:16268 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE variant_origin: GERMLINE
Autosomal recessive inheritance
Show evidence (2 references)
PMID:35069422 SUPPORT Human Clinical
"We identified six novel and four recurrent PNPLA6 gene variants in eight patients (2.7%)."
Quantifies PNPLA6 variant detection in an ataxia/spastic paraplegia screening cohort.
PMID:33650466 SUPPORT Human Clinical
"We identified a missense homozygous variant (c.3524 C > G (p.Ser1175Cys)) in the PNPLA6 gene, which explains the phenotype of the patient"
A homozygous PNPLA6 missense variant causes Boucher-Neuhauser within the continuum.
💊

Medical Actions

15
Sex Hormone Replacement Therapy
Action: Hormone Replacement TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Hormone Replacement Therapy (NCIT:C15599). NCIT:C15599 is a clinical intervention from the NCI Thesaurus. NCIT:C15599
Agent: testosterone CHEBI:17347 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses testosterone (CHEBI:17347). CHEBI:17347 is a therapeutic agent from Chemical Entities of Biological Interest. estradiol CHEBI:23965 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses estradiol (CHEBI:23965). CHEBI:23965 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Sex-steroid replacement supports pubertal development and secondary sexual characteristics under endocrine supervision. Testosterone improved secondary sexual characteristics in the reported RNF216 brothers without changing their neurologic symptoms. Fertility requires separate assessment; sex-steroid replacement is not evidence of restored fertility.
Target Phenotypes: Hypogonadotropic hypogonadism HP:0000044 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Hypogonadotropic hypogonadism (HP:0000044). HP:0000044 is a phenotype from the Human Phenotype Ontology. Delayed puberty HP:0000823 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Delayed puberty (HP:0000823). HP:0000823 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"Hypogonadotropic hypogonadism. Hormone replacement therapy at the expected time of puberty."
GeneReviews recommends hormone replacement therapy for the hypogonadotropic hypogonadism.
PMID:27441066 SUPPORT Human Clinical
"Both showed good response to treatment regarding secondary sexual characteristics, in the form of facial, axillary and pubic hair growth, and deepening of voice. There was no change in their neurological symptoms with treatment."
Clinical follow-up separates endocrine benefit from neurologic response.
Multidisciplinary Supportive and Rehabilitative Care
Action: supportive careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is supportive care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Management is symptomatic and individually tailored: continuous training of speech and swallowing, fine-motor skills, gait, and balance for ataxia; physical therapy and assistive devices for spasticity; low-vision aids for chorioretinal dystrophy; and periodic multidisciplinary reevaluation. No disease-modifying therapy exists.
Show evidence (1 reference)
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"Management is symptomatic and individually tailored."
GeneReviews describes symptomatic, individually tailored supportive management.
Physical Therapy
Action: Physical TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Physical Therapy (NCIT:C15302). NCIT:C15302 is a clinical intervention from the NCI Thesaurus. NCIT:C15302
Platform: Behavioral / lifestyle
Physical therapy, assistive walking devices, and ankle-foot orthotics to improve strength and agility and prevent contractures, particularly when spasticity is present.
Show evidence (1 reference)
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"Interventions to improve strength and agility and to prevent contractures, such as physical therapy, assistive walking devices and/or ankle-foot orthotics"
GeneReviews recommends physical therapy and assistive devices for spasticity.
Genetic Counseling
Category: Counseling / Informational Action: Genetic CounselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Genetic Counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. NCIT:C15240
Genetic counseling for affected families. Once the pathogenic variants are identified, carrier testing, prenatal testing, and preimplantation genetic testing are possible.
Show evidence (1 reference)
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"carrier testing for at-risk relatives, prenatal testing for a pregnancy at increased risk, and preimplantation genetic testing are possible."
GeneReviews outlines genetic counseling and reproductive testing options.
Speech and communication therapy
Action: Speech Language TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Speech Language Therapy (NCIT:C159273). NCIT:C159273 is a clinical intervention from the NCI Thesaurus. NCIT:C159273
Provide speech-language therapy and assess alternative communication methods when needed, particularly as PNPLA6-related dysarthria progresses.
Target Phenotypes: Dysarthria HP:0001260 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Dysarthria (HP:0001260). HP:0001260 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"Consider alternative communication methods (e.g., writing pads, digital devices) as needed."
GeneReviews supports communication adaptations.
Swallowing and nutrition support
Action: Swallowing TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Swallowing Therapy (NCIT:C156237). NCIT:C156237 is a clinical intervention from the NCI Thesaurus. NCIT:C156237
Assess swallowing safety, feeding strategies, aspiration risk and nutritional status when dysphagia develops in PNPLA6-related disease.
Target Phenotypes: Dysphagia HP:0002015 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Dysphagia (HP:0002015). HP:0002015 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"Feeding therapy programs to improve nutrition ... Education re strategies to mitigate aspiration"
GeneReviews supports feeding therapy and aspiration prevention.
Occupational therapy and adaptive equipment
Action: Occupational TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Occupational Therapy (NCIT:C121351). NCIT:C121351 is a clinical intervention from the NCI Thesaurus. NCIT:C121351
Use occupational therapy and adaptive devices to support daily activities and mobility in PNPLA6-related ataxia.
Target Phenotypes: Cerebellar ataxia HP:0002073 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Cerebellar ataxia, annotated with Progressive cerebellar ataxia (HP:0002073), qualified as course progressive. HP:0002073 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"OT to optimize ADL (incl use of adaptive devices, e.g., weighted eating utensils, dressing hooks)"
GeneReviews specifies functional support.
Low-vision support
For individuals with PNPLA6-related retinal overlap and impaired vision, provide low-vision aids, mobility training and support for independent living. This is conditional care, not evidence that all GHS patients develop retinal disease.
Target Phenotypes: Chorioretinal dystrophy HP:0001135 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Chorioretinal dystrophy (HP:0001135). HP:0001135 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"Low vision aids when central acuity is reduced; involvement with agencies for the visually impaired, mobility training, and skills for independent living."
GeneReviews supports vision-specific care when the relevant phenotype is present.
Multidisciplinary surveillance
Category: Monitoring
Reassess neurologic function, swallowing, nutrition, communication, endocrine function and relevant ocular manifestations in PNPLA6-related disease. Frequency is individualized, often annually or with changes in symptoms or treatment.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"Note that the frequency of recommended surveillance is at the discretion of treating specialists (usually annually or as symptoms change or as medication needs change)."
The full GeneReviews chapter qualifies the surveillance interval.
Avoidance counseling for PNPLA6 disorders
Category: Counseling / Informational Action: Lifestyle CounselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Lifestyle Counseling (NCIT:C180632). NCIT:C180632 is a clinical intervention from the NCI Thesaurus. NCIT:C180632
Counsel against alcohol, obesity and inactivity, and review medications or chemicals that may worsen neuropathy. These recommendations derive from the PNPLA6 baseline.
Show evidence (1 reference)
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"Agents/circumstances to avoid: Alcohol; obesity; inactive, sedentary lifestyle; exposure to medications or chemicals that exacerbate neuropathy."
GeneReviews lists avoidances.
Medication for spasticity
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: Baclofen NCIT:C28858 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses Baclofen (NCIT:C28858). NCIT:C28858 is a therapeutic agent from the NCI Thesaurus. Tolperisone NCIT:C84219 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses Tolperisone (NCIT:C84219). NCIT:C84219 is a therapeutic agent from the NCI Thesaurus.
For PNPLA6-related spasticity, individualized oral or intrathecal antispasticity treatment may include baclofen or tolperisone under specialist care. These are symptomatic options; no effect on underlying neurodegeneration is established.
Target Phenotypes: Spasticity HP:0001257 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Spasticity (HP:0001257). HP:0001257 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"Consider baclofen (oral or intrathecal), tolperison; Botox"
The GeneReviews treatment table names symptomatic antispasticity options.
Management of urinary urgency
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: Oxybutynin NCIT:C47647 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses Oxybutynin (NCIT:C47647). NCIT:C47647 is a therapeutic agent from the NCI Thesaurus.
For PNPLA6-related bladder symptoms, urologic assessment may include oxybutynin to reduce urgency.
Target Phenotypes: Urinary urgency HP:0000012 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Urinary urgency (HP:0000012). HP:0000012 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"Incl pharmacologic treatment (e.g., oxybutynin) to ... urinary urgency"
The GeneReviews bladder-management row specifies oxybutynin for urgency.
Cognitive and educational support
Assess cognitive function and provide an individualized educational or neuropsychological support plan when impairment is present in PNPLA6-related disease.
Target Phenotypes: Cognitive impairment HP:0100543 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Cognitive impairment (HP:0100543). HP:0100543 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"Neuropsychiatric eval ... educ plan per developmental pediatrician"
GeneReviews includes neuropsychiatric evaluation and educational planning for cognitive dysfunction.
Replacement of additional deficient pituitary-dependent hormones
Action: Hormone Replacement TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Hormone Replacement Therapy (NCIT:C15599). NCIT:C15599 is a clinical intervention from the NCI Thesaurus. NCIT:C15599
When additional hormone deficiencies are documented in PNPLA6-related disease, replace thyroid hormone and provide growth hormone during childhood or adolescence as indicated. These are conditional interventions and do not imply that every GHS patient has these deficiencies.
Show evidence (2 references)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"Thyroid hormone replacement as per treating endocrinologist"
GeneReviews specifies endocrine replacement when hypothyroidism is present.
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"Growth hormone deficiency. Hormone replacement therapy during childhood and/or adolescence as indicated."
GeneReviews scopes growth hormone replacement to documented deficiency and developmental stage.
Botulinum toxin injections for spasticity
Action: Botulinum Toxin TherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Botulinum Toxin Therapy (NCIT:C157775). NCIT:C157775 is a clinical intervention from the NCI Thesaurus. NCIT:C157775
Botulinum toxin injections are a conditional symptomatic option for spasticity in PNPLA6-related disease.
Target Phenotypes: Spasticity HP:0001257 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Spasticity (HP:0001257). HP:0001257 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"Consider baclofen (oral or intrathecal), tolperison; Botox"
The GeneReviews treatment table names symptomatic antispasticity options.
🔬

Biochemical Markers

1
Reduced PNPLA6 neuropathy target esterase activity (Reduced)
Pathograph Readouts
Readout Of PNPLA6 / Neuropathy Target Esterase Phospholipid Dysfunction
The esterase assay measures the functional deficit; interpretation depends on the particular genotype and experimental assay.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC11146429/?report=classic SUPPORT Computational
"Individual genotype activity levels were determined by the average activity of the two individual variants."
The study separates individual variant assays from estimated biallelic genotype activity.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC11146429/?report=classic SUPPORT In Vitro
"The NTE activity of all disease-associated missense/in-frame and truncating variants was significantly reduced compared to the wild-type control"
Full-length protein assays support impaired NTE activity.
🔬

Diagnosis

3
Molecular genetic diagnosis
Investigate the clinical ataxia-hypogonadism phenotype with molecular testing of relevant genes, using panel or genomic approaches and segregation as appropriate. PNPLA6 disease requires biallelic pathogenic variants; variants of uncertain significance alone do not establish the diagnosis.
Genetic Testing NCIT:C15709 NCI Thesaurus (NCIT)
Single-gene sequence analysis may require deletion/duplication analysis if one or no pathogenic variant is detected; panels or genomic approaches are selected according to the clinical presentation.
Show evidence (4 references)
PMID:25299038 SUPPORT REVIEW SYNTHESIS Other
"The diagnosis of a PNPLA6 disorder is established in a proband with suggestive findings and biallelic PNPLA6 pathogenic variants identified on homologous alleles by molecular genetic testing."
GeneReviews defines molecular confirmation for the PNPLA6 form.
PMID:23656588 SUPPORT Human Clinical
"We performed whole-exome sequencing in a patient with ataxia and hypogonadotropic hypogonadism, followed by targeted sequencing of candidate genes in similarly affected patients."
The discovery study demonstrates a phenotype-led genomic and targeted testing strategy.
url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/ SUPPORT REVIEW SYNTHESIS Other
"variant of uncertain significance) does not establish or rule out the diagnosis."
GeneReviews explicitly cautions that biallelic VUS, or one pathogenic variant with one VUS, do not establish or exclude PNPLA6 disease.
+ 1 more reference
Brain MRI
Assess cerebellar atrophy and cerebral white-matter abnormalities. Imaging supports the phenotype and longitudinal assessment but does not identify the causal genotype by itself.
Magnetic Resonance Imaging NCIT:C16809 NCI Thesaurus (NCIT)
Show evidence (1 reference)
PMID:37161390 SUPPORT Human Clinical
"Brain magnetic resonance imaging (MRI) revealed progressive cerebellar, vermian, and cerebral cortical atrophy, and periventricular confluent white matter hyperintensities in 2022 compared to 2018."
Serial MRI documents progressive structural abnormalities in one RNF216 case.
Reproductive endocrine evaluation
Assess puberty, sex steroids and gonadotropins in clinical context. Selected cases undergo dynamic evaluation to characterize hypothalamic and pituitary contributions; preserved early responses do not exclude later dysfunction.
Show evidence (2 references)
PMID:23656588 SUPPORT Human Clinical
"Defects were detected at the hypothalamic and pituitary levels of the reproductive endocrine axis."
The original clinical investigation localizes central endocrine dysfunction.
PMID:27441066 SUPPORT Human Clinical
"Reproductive endocrine evaluation in both patients revealed only low levels of LH and testosterone, no other pituitary hormones were affected."
The RNF216 brothers illustrate a selective reproductive endocrine deficit.
📈

Progression

3
Endocrine-first presentation
RNF216-related Gordon Holmes syndrome
Hypogonadotropic hypogonadism may precede overt neurologic signs. A normal neurologic examination during an endocrine presentation does not exclude later disease.
Show evidence (1 reference)
PMID:39444518 SUPPORT Human Clinical
"hypogonadotropic hypogonadism may be the initial manifestation of this severe neuroendocrine disorder, especially in males."
The report documents an endocrine-first presentation.
Variable neurologic progression
RNF216-related Gordon Holmes syndrome
Ataxia and cognitive dysfunction may progress substantially, with intrafamilial variation. Available cases do not establish a reliable survival estimate or a uniform progression rate.
Show evidence (1 reference)
PMID:27441066 SUPPORT Human Clinical
"His disease progressively worsened with clear cognitive deterioration and need for support in daily activities to the degree that he became totally dependent."
The older RNF216 brother developed severe functional dependence; the younger brother had milder disease at assessment.
🔬

Clinical Trials

1
NCT01793168 NOT_APPLICABLE RECRUITING
CoRDS is an international observational rare-disease registry. Its listed conditions include cerebellar ataxia-hypogonadism; it supports patient-researcher connection and data collection rather than testing a GHS treatment.
Show evidence (2 references)
clinicaltrials:NCT01793168 SUPPORT Other
"It provides researchers with a centralized, international patient registry for all rare diseases."
The registry summary describes broad observational rare-disease research rather than a treatment trial; the API evidence separately establishes the listed syndrome, study type and current recruitment status.
url:https://clinicaltrials.gov/api/v2/studies/NCT01793168 SUPPORT Other
""overallStatus":"RECRUITING" ... It provides researchers with a centralized, international patient registry for all rare diseases. ... "Cerebellar Ataxia - Hypogonadism" ... "studyType":"OBSERVATIONAL""
The current record identifies recruiting observational registry research, describes its broad rare-disease scope and explicitly lists cerebellar ataxia-hypogonadism.
🐁

Animal Models

4
Constitutive Rnf216 knockout mouse
Constitutive deletion model followed through one year for motor and learning behaviors, with sex-specific microglial and electrophysiological analyses.
Species
Mus musculus
Genotype
Rnf216-/-
Pathograph links
Altered microglial state in RNF216 models recapitulates Demonstrates the model-specific microglial state changes described by this node.
Show evidence (1 reference)
PMID:38164552 SUPPORT Model Organism
"KO mice also showed age-dependent strategy and associative learning impairments with sex-dependent alterations of microglia in the hippocampus and cortex."
Constitutive Rnf216 loss is associated with sex- and region-dependent microglial changes and age-dependent learning phenotypes. Their causal relationship is not established.
Cerebellar degeneration fails to recapitulate
Limitations: No reduction in cerebellar mass or overt ataxia was detected in the tested knockout through approximately one year; normal mass does not exclude subtle cellular abnormalities.
Show evidence (2 references)
PMID:38164552 SUPPORT Model Organism
"This lack of phenotype was also coupled with our inability to detect decreases in cerebellar mass"
The lack of reduced cerebellar mass limits the model as a representation of human cerebellar degeneration.
+ 1 more reference
Show evidence (2 references)
PMID:38164552 SUPPORT Model Organism
"KO mice also showed age-dependent strategy and associative learning impairments with sex-dependent alterations of microglia in the hippocampus and cortex."
Constitutive Rnf216 loss is associated with sex- and region-dependent microglial changes and age-dependent learning phenotypes. Their causal relationship is not established.
PMID:38164552 SUPPORT Model Organism
"we were unable to detect motor impairments or other measures of behavior that would be indicative of ataxia in these mice"
The tested constitutive knockout failed to reproduce overt ataxia within the observation period.
Chip-deficient mouse
Loss of CHIP produces behavioral and reproductive abnormalities resembling aspects of GHS.
Species
Mus musculus
Genotype
Stub1 (Chip) knockout
Pathograph links
STUB1 CHIP ubiquitin ligase deficiency perturbs CHIP deficiency removes protein function rather than reproducing only the patient Thr246Met substitution.
Show evidence (1 reference)
PMID:24113144 SUPPORT Model Organism
"Loss of CHIP function in mice resulted in behavioral and reproductive impairments that mimic human ataxia and hypogonadism."
CHIP loss reproduces aspects of the motor and reproductive phenotype in mice; this does not localize every endocrine lesion.
Cerebellar degeneration partially recapitulates Shows cerebellar Purkinje-layer cell loss and abnormal motor behavior.
Limitations: The complete knockout does not preserve the chaperone-binding function retained by the human Thr246Met protein.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3900109/?report=classic SUPPORT Model Organism
"cellular loss throughout the various lobes of the cerebellum, specifically in the Purkinje cell layer"
Cerebellar histology in Chip-null mice demonstrates Purkinje-layer cell loss; this is experimental support, not human STUB1 neuropathology.
Show evidence (1 reference)
PMID:24113144 SUPPORT Model Organism
"Loss of CHIP function in mice resulted in behavioral and reproductive impairments that mimic human ataxia and hypogonadism."
CHIP loss reproduces aspects of the motor and reproductive phenotype in mice; this does not localize every endocrine lesion.
rnf216 and otud4 zebrafish morphants
Embryonic knockdown model with more severe brain and eye defects following combined suppression and rescue by wild-type human mRNA.
Species
Danio rerio
Genotype
rnf216 and/or otud4 morpholino knockdown
Pathograph links
OTUD4-associated ubiquitin regulation defect perturbs Tests functional interaction by single and combined gene knockdown and human mRNA rescue.
Limitations: Embryonic morpholino phenotypes do not reproduce the complete progressive adult human syndrome or identify the OTUD4 catalytic defect.
Show evidence (1 reference)
PMID:23656588 SUPPORT Model Organism
"Knockdown of rnf216 or otud4 in zebrafish embryos induced defects in the eye, optic tectum, and cerebellum; combinatorial suppression of both genes exacerbated these phenotypes, which were rescued by nonmutant, but not mutant, human RNF216 or OTUD4 messenger RNA."
Knockdown and rescue support functional interaction between the two genes, without establishing a physical protein interaction or the exact OTUD4 catalytic defect.
Show evidence (1 reference)
PMID:23656588 SUPPORT Model Organism
"Knockdown of rnf216 or otud4 in zebrafish embryos induced defects in the eye, optic tectum, and cerebellum; combinatorial suppression of both genes exacerbated these phenotypes, which were rescued by nonmutant, but not mutant, human RNF216 or OTUD4 messenger RNA."
Knockdown and rescue support functional interaction between the two genes, without establishing a physical protein interaction or the exact OTUD4 catalytic defect.
Pnpla6 residual-activity allelic mouse series
An allelic series compares residual NTE activity and retinal function across different Pnpla6 genotypes, providing a functional model for the wider PNPLA6 spectrum.
Species
Mus musculus
Genotype
Pnpla6 p.Met1030Val homozygotes and p.Met1030Val/p.Met1030Valfs*2 compound heterozygotes
Pathograph links
PNPLA6 / Neuropathy Target Esterase Phospholipid Dysfunction partially recapitulates Models the relationship between genotype, residual enzyme activity and tissue dysfunction.
Limitations: Retinal outcomes were studied across SPG39-like and retinal-overlap genotypes; this is not a complete GHS model and does not establish pituitary dysfunction in the viable lines.
Show evidence (1 reference)
PMID:38735647 SUPPORT Model Organism
"This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists."
The mouse series tests residual NTE activity and retinal outcomes across the PNPLA6 spectrum; it does not reproduce the entire GHS neuroendocrine phenotype.
Show evidence (1 reference)
PMID:38735647 SUPPORT Model Organism
"This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists."
The mouse series tests residual NTE activity and retinal outcomes across the PNPLA6 spectrum; it does not reproduce the entire GHS neuroendocrine phenotype.
{ }

Source YAML

click to show 
name: Cerebellar Ataxia-Hypogonadism Syndrome
creation_date: "2026-06-04T12:00:00Z"
category: Mendelian
description: >-
  Cerebellar ataxia-hypogonadism syndrome (Gordon Holmes syndrome) is a genetically heterogeneous neurodegenerative-neuroendocrine
  disorder characterized by cerebellar ataxia and hypogonadotropic hypogonadism. Cognitive decline, movement
  disorders and cerebral white-matter changes vary with genotype and disease stage. Recessive RNF216 and
  STUB1 disease and a reported digenic RNF216/OTUD4 form involve ubiquitin regulation; biallelic PNPLA6
  variants produce a distinct phospholipid-metabolism disorder within the overlapping PNPLA6 clinical
  spectrum. Endocrine abnormalities can precede overt neurologic signs. Chorioretinal dystrophy suggests
  overlap with Boucher-Neuhauser syndrome rather than a universal Gordon Holmes feature.
disease_term:
  preferred_term: Cerebellar Ataxia-Hypogonadism Syndrome
  term:
    id: MONDO:0008935
    label: cerebellar ataxia-hypogonadism syndrome
synonyms:
- Gordon Holmes syndrome
- Gordon-Holmes syndrome
- ataxia-hypogonadotropic hypogonadism
- ataxia, dementia, and hypogonadotropism

references:
- reference: PMID:25299038
  title: "PNPLA6 Disorders."
  tags:
  - GeneReviews

inheritance:
- name: Autosomal recessive inheritance
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: Biallelic RNF216, STUB1 or PNPLA6 variants can cause an ataxia-hypogonadism phenotype. For PNPLA6 disease with both parents confirmed heterozygous, each conception has a 25% affected, 50% carrier and 25% unaffected non-carrier probability. Family counseling should use the established genotype; these single-locus probabilities are not applied to the digenic pedigree.
  evidence:
  - reference: PMID:23656588
    reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Additional screening identified compound heterozygous truncating mutations in RNF216 in an unrelated patient
    explanation: Biallelic truncating RNF216 variants establish a single-locus recessive form.
  - reference: PMID:25299038
    reference_title: PNPLA6 Disorders.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: If both parents are known to be heterozygous for a PNPLA6 pathogenic variant, each sib of an affected individual has at conception a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
    explanation: GeneReviews gives recurrence risks conditional on confirmed parental PNPLA6 carrier status.
    quote_role: REVIEW_SYNTHESIS
- name: Digenic inheritance (RNF216/OTUD4)
  inheritance_term:
    preferred_term: Digenic inheritance
    term:
      id: HP:0010984
      label: Digenic inheritance
  description: >-
    Three affected siblings in one consanguineous family carried homozygous variants at both RNF216 and
    OTUD4. Zebrafish knockdown and rescue support a functional interaction. This reported two-locus form
    involves homozygosity at both loci and does not establish isolated OTUD4 disease or a physical RNF216-OTUD4
    protein interaction.
  evidence:
  - reference: PMID:23656588
    reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Digenic homozygous mutations in RNF216 and OTUD4, which encode a ubiquitin E3 ligase and a deubiquitinase, respectively, were found in three affected siblings in a consanguineous family."
    explanation: >-
      The discovery study reports the two-locus genotype and its co-segregation
      with disease in three affected siblings.

pathophysiology:
- name: RNF216 K63-linked ubiquitination deficiency
  description: GHS-associated RNF216 catalytic-region variants impair E3 ubiquitin ligase activity. RNF216 synthesizes K63-linked chains in biochemical assays, implicating altered ubiquitin signaling. The relevant neuronal substrates and the steps connecting this defect to human neurodegeneration remain incompletely resolved.
  genes:
  - preferred_term: RNF216
    term:
      id: hgnc:21698
      label: RNF216
  molecular_functions:
  - preferred_term: ubiquitin protein ligase activity
    term:
      id: GO:0061630
      label: ubiquitin protein ligase activity
    modifier: DECREASED
  biological_processes:
  - preferred_term: protein K63-linked ubiquitination
    term:
      id: GO:0070534
      label: protein K63-linked ubiquitination
    modifier: DECREASED
  evidence:
  - reference: PMID:30886743
    reference_title: TRIAD3/RNF216 E3 ligase specifically synthesises K63-linked ubiquitin chains and is inactivated by mutations associated with Gordon Holmes syndrome.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Strikingly, we found that TRIAD3 synthesises specifically lysine-63 (K63)-linked poly-ubiquitin chains in vitro, a chain type that usually plays a role in mediating signalling events rather than triggering proteasomal degradation.
    explanation: Biochemical chain-linkage experiments distinguish RNF216 K63 ubiquitination from a uniform K48/proteasomal degradation mechanism.
  - reference: PMID:30886743
    reference_title: TRIAD3/RNF216 E3 ligase specifically synthesises K63-linked ubiquitin chains and is inactivated by mutations associated with Gordon Holmes syndrome.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Our results provide in vitro evidence that point mutations found in patients with Gordon Holmes syndrome5 abrogate TRIAD3’s E3 activity.
    explanation: The study tests GHS-associated catalytic-region substitutions; retained activity of Huntington-like-disorder variants elsewhere in RNF216 cautions against a universal variant mechanism.
  notes: ARC and endocytic proteins were candidate interactors or substrates in overexpression and lysate experiments. These findings do not establish a complete human disease pathway through proteasomal degradation.
  downstream:
  - target: Cerebellar degeneration
    description: RNF216-related disease includes cerebellar degeneration; intervening molecular events are unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: The syndrome of hypogonadotropic hypogonadism, ataxia, and dementia can be caused by inactivating mutations in RNF216 or by the combination of mutations in RNF216 and OTUD4.
      explanation: Human genetics supports the disease association; cellular intermediates between altered ubiquitination and regional pathology remain unresolved.
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Neuronal loss was observed in cerebellar pathways and the hippocampus; surviving hippocampal neurons contained ubiquitin-immunoreactive intranuclear inclusions.
      explanation: Autopsy in one affected RNF216/OTUD4 family member documents regional neuronal loss and inclusions; it does not establish that the inclusions cause cell death.
  - target: Hippocampal neuronal loss
    description: Hippocampal neuronal loss was demonstrated in an affected member of the digenic RNF216/OTUD4 family.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Neuronal loss was observed in cerebellar pathways and the hippocampus; surviving hippocampal neurons contained ubiquitin-immunoreactive intranuclear inclusions.
      explanation: Autopsy in one affected RNF216/OTUD4 family member documents regional neuronal loss and inclusions; it does not establish that the inclusions cause cell death.
  - target: Reproductive Endocrine Axis Dysfunction
    description: RNF216-related disease involves hypothalamic and pituitary reproductive function through incompletely defined intermediates.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: The syndrome of hypogonadotropic hypogonadism, ataxia, and dementia can be caused by inactivating mutations in RNF216 or by the combination of mutations in RNF216 and OTUD4.
      explanation: Human genetics supports the disease association; cellular intermediates between altered ubiquitination and regional pathology remain unresolved.
  - target: Altered microglial state in RNF216 models
    description: Constitutive Rnf216 loss alters microglial features in mice; intermediate steps and relevance to human disease remain unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:38164552
      reference_title: Gordon Holmes Syndrome Model Mice Exhibit Alterations in Microglia, Age, and Sex-Specific Disruptions in Cognitive and Proprioceptive Function.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: KO mice also showed age-dependent strategy and associative learning impairments with sex-dependent alterations of microglia in the hippocampus and cortex.
      explanation: Constitutive Rnf216 loss is associated with sex- and region-dependent microglial changes and age-dependent learning phenotypes. Their causal relationship is not established.
- name: OTUD4-associated ubiquitin regulation defect
  mechanism_confidence: PROVISIONAL
  description: A homozygous OTUD4 variant co-segregated with a homozygous RNF216 variant in the original three-sibling family. OTUD4 encodes a deubiquitinase, and combined knockdown worsened developmental brain abnormalities in zebrafish. The exact catalytic consequence of the patient OTUD4 variant and its contribution independently of RNF216 remain unresolved.
  genes:
  - preferred_term: OTUD4
    term:
      id: hgnc:24949
      label: OTUD4
  molecular_functions:
  - preferred_term: deubiquitinase activity
    term:
      id: GO:0101005
      label: deubiquitinase activity
  notes: The molecular-function annotation describes OTUD4 protein activity; the direction and linkage specificity of any change caused by the patient variant have not been established.
  evidence:
  - reference: PMID:23656588
    reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Digenic homozygous mutations in RNF216 and OTUD4, which encode a ubiquitin E3 ligase and a deubiquitinase, respectively, were found in three affected siblings in a consanguineous family."
    explanation: >-
      The discovery study reports the two-locus genotype and its co-segregation
      with disease in three affected siblings.

  - reference: PMID:23656588
    reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Knockdown of rnf216 or otud4 in zebrafish embryos induced defects in the eye, optic tectum, and cerebellum; combinatorial suppression of both genes exacerbated these phenotypes, which were rescued by nonmutant, but not mutant, human RNF216 or OTUD4 messenger RNA.
    explanation: Knockdown and rescue support functional interaction between the two genes, without establishing a physical protein interaction or the exact OTUD4 catalytic defect.
  downstream:
  - target: Cerebellar degeneration
    description: The combined RNF216/OTUD4 genotype is associated with cerebellar pathology; zebrafish experiments support interaction, with unknown human intermediates.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Neuronal loss was observed in cerebellar pathways and the hippocampus; surviving hippocampal neurons contained ubiquitin-immunoreactive intranuclear inclusions.
      explanation: Autopsy in one affected RNF216/OTUD4 family member documents regional neuronal loss and inclusions; it does not establish that the inclusions cause cell death.
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Knockdown of rnf216 or otud4 in zebrafish embryos induced defects in the eye, optic tectum, and cerebellum; combinatorial suppression of both genes exacerbated these phenotypes, which were rescued by nonmutant, but not mutant, human RNF216 or OTUD4 messenger RNA.
      explanation: Knockdown and rescue support functional interaction between the two genes, without establishing a physical protein interaction or the exact OTUD4 catalytic defect.
- name: STUB1 CHIP ubiquitin ligase deficiency
  description: The recessive GHS-associated STUB1 Thr246Met variant disrupts the ubiquitin ligase activity of CHIP, a co-chaperone involved in protein quality control. Recombinant-protein and cell assays demonstrate the molecular loss of function.
  genes:
  - preferred_term: STUB1
    term:
      id: hgnc:11427
      label: STUB1
  molecular_functions:
  - preferred_term: ubiquitin protein ligase activity
    term:
      id: GO:0061630
      label: ubiquitin protein ligase activity
    modifier: DECREASED
  evidence:
  - reference: PMID:24113144
    reference_title: Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Introduction of the Thr246Met mutation into CHIP results in a loss of ubiquitin ligase activity measured directly using recombinant proteins as well as in cell culture models.
    explanation: The experimentally tested Thr246Met variant impairs CHIP E3 activity. This assay result is not generalized to every STUB1 variant.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3900109/?report=classic
    reference_title: Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP - PMC
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: while still maintaining chaperone interactions
    explanation: The full-text functional study shows that loss of E3 activity does not imply loss of chaperone binding.
  downstream:
  - target: Cerebellar degeneration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: CHIP loss is associated with Purkinje-layer degeneration in mice, providing experimental support for an indirect cerebellar pathway.
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3900109/?report=classic
      reference_title: Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP - PMC
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: cellular loss throughout the various lobes of the cerebellum, specifically in the Purkinje cell layer
      explanation: Cerebellar histology in Chip-null mice demonstrates Purkinje-layer cell loss; this is experimental support, not human STUB1 neuropathology.
  - target: Reproductive Endocrine Axis Dysfunction
    description: CHIP-related disease includes hypogonadism; the precise site and molecular route remain incompletely characterized.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:24113144
      reference_title: Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Loss of CHIP function in mice resulted in behavioral and reproductive impairments that mimic human ataxia and hypogonadism.
      explanation: CHIP loss reproduces aspects of the motor and reproductive phenotype in mice; this does not localize every endocrine lesion.
  notes: Thr246Met retained chaperone interactions despite impaired ubiquitination. The null mouse removes all CHIP function and is not an exact replica of this patient allele.
- name: PNPLA6 / Neuropathy Target Esterase Phospholipid Dysfunction
  description: >-
    Biallelic PNPLA6 variants can reduce neuropathy target esterase (NTE) activity. This endoplasmic-reticulum-associated
    phospholipase participates in phospholipid homeostasis. Variant-specific residual activity helps explain
    tissue involvement across the PNPLA6 spectrum, including its Gordon Holmes presentation; downstream
    neuronal and endocrine pathways remain incompletely defined.
  genes:
  - preferred_term: PNPLA6
    term:
      id: hgnc:16268
      label: PNPLA6
  cellular_components:
  - preferred_term: endoplasmic reticulum
    term:
      id: GO:0005783
      label: endoplasmic reticulum
  evidence:
  - reference: PMID:35069422
    reference_title: "Multifaceted and Age-Dependent Phenotypes Associated With Biallelic PNPLA6 Gene Variants: Eight Novel Cases and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A wide spectrum of neurodegenerative diseases has been associated with pathogenic variants in the PNPLA6 (patatin-like phospholipase domain-containing protein 6) gene, including spastic paraplegia type 39, Gordon-Holmes, Boucher-Neuhauser, Oliver-Mc Farlane, and Laurence-Moon syndromes."
    explanation: >
      Establishes PNPLA6 as a cause of the Gordon Holmes / Boucher-Neuhauser
      ataxia-hypogonadism continuum.
  - reference: PMID:25299038
    reference_title: "PNPLA6 Disorders."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "PNPLA6 disorders span a phenotypic continuum characterized by variable combinations of cerebellar ataxia; upper motor neuron involvement manifesting as spasticity and/or brisk reflexes; chorioretinal dystrophy associated with variable degrees of reduced visual function; and hypogonadotropic hypogonadism"
    explanation: >
      GeneReviews defines the PNPLA6 phenotypic continuum encompassing the
      ataxia-hypogonadism syndromes.
    quote_role: REVIEW_SYNTHESIS
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC11146429/?report=classic
    reference_title: Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders - PMC
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: The NTE activity of all disease-associated missense/in-frame and truncating variants was significantly reduced compared to the wild-type control
    explanation: Full-length variant assays support reduced NTE activity; this does not imply that every truncating allele has zero residual function.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC11146429/?report=classic
    reference_title: Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders - PMC
    supports: SUPPORT
    evidence_source: COMPUTATIONAL
    snippet: Individual genotype activity levels were determined by the average activity of the two individual variants.
    explanation: Patient-level activity in the genotype-phenotype analysis was estimated from individual in-vitro variant activities, rather than measured directly in every patient.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC11146429/?report=classic
    reference_title: Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: There was no apparent relationship between the activity of NTE and the onset of retinopathy or endocrinopathy.
    explanation: The tissue-association analysis did not establish age-at-onset prediction.
  downstream:
  - target: Cerebellar degeneration
    description: >-
      PNPLA6-related ataxia can include cerebellar atrophy; the cohort does not establish a direct molecular
      route to neuronal death or hippocampal degeneration.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:35069422
      reference_title: "Multifaceted and Age-Dependent Phenotypes Associated With Biallelic PNPLA6 Gene Variants: Eight Novel Cases and Review of the Literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Cerebellar ataxia was observed in seven patients and spastic paraplegia in one patient. Progression of cerebellar symptoms was slow in all patients, who retained ambulation even after a mean disease duration of 15 years. Brain MRI showed cerebellar atrophy in 6/8 patients, more pronounced in superior and dorsal vermis lobules (I to VII)."
      explanation: >-
        The eight-person PNPLA6 cohort contains three Gordon Holmes cases and other PNPLA6 phenotypes.
        Its aggregate imaging findings support cerebellar involvement across that spectrum, not GHS-specific
        penetrance.
  - target: Reproductive Endocrine Axis Dysfunction
    description: >-
      PNPLA6-related GHS includes central hypogonadism; the molecular intermediates are incompletely resolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:25299038
      reference_title: "PNPLA6 Disorders."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "hypogonadotropic hypogonadism (delayed puberty and lack of secondary sex characteristics). The hypogonadotropic hypogonadism occurs either in isolation or as part of anterior hypopituitarism"
      explanation: >
        GeneReviews confirms hypogonadotropic hypogonadism as a core feature of
        PNPLA6 disorders, connecting PNPLA6 dysfunction to reproductive endocrine
        axis impairment.
      quote_role: REVIEW_SYNTHESIS
  notes: The 2024 study found lower estimated residual activity associated with retinopathy and endocrinopathy across the PNPLA6 spectrum, but no clear relationship with age at onset. These research estimates are not a validated individual prognostic threshold. GHS remains clinically distinguishable from the retinal-predominant Boucher-Neuhauser/Oliver-McFarlane overlap.
  molecular_functions:
  - preferred_term: glycerophospholipase activity
    term:
      id: GO:0004620
      label: glycerophospholipase activity
    modifier: DECREASED
- name: Cerebellar degeneration
  description: Cerebellar pathway neuronal loss was demonstrated at autopsy in RNF216/OTUD4-related disease. Cerebellar atrophy is also documented by MRI in PNPLA6-related ataxia. Histological neuronal loss is not inferred from imaging alone. CHIP-deficient mice also show Purkinje-layer cell loss, which supplies model support for STUB1 involvement.
  cell_types:
  - preferred_term: Purkinje cell
    term:
      id: CL:0000121
      label: Purkinje cell
  locations:
  - preferred_term: cerebellum
    term:
      id: UBERON:0002037
      label: cerebellum
  evidence:
  - reference: PMID:23656588
    reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Neuronal loss was observed in cerebellar pathways and the hippocampus; surviving hippocampal neurons contained ubiquitin-immunoreactive intranuclear inclusions.
    explanation: Autopsy in one affected RNF216/OTUD4 family member documents regional neuronal loss and inclusions; it does not establish that the inclusions cause cell death.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3900109/?report=classic
    reference_title: Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP - PMC
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: cellular loss throughout the various lobes of the cerebellum, specifically in the Purkinje cell layer
    explanation: Cerebellar histology in Chip-null mice demonstrates Purkinje-layer cell loss; this is experimental support, not human STUB1 neuropathology.
  downstream:
  - target: Cerebellar ataxia
    description: Degeneration of cerebellar pathways contributes to impaired gait and coordination.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: The syndrome of hypogonadotropic hypogonadism, ataxia, and dementia can be caused by inactivating mutations in RNF216 or by the combination of mutations in RNF216 and OTUD4.
      explanation: Human genetics supports the disease association; cellular intermediates between altered ubiquitination and regional pathology remain unresolved.
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Neuronal loss was observed in cerebellar pathways and the hippocampus; surviving hippocampal neurons contained ubiquitin-immunoreactive intranuclear inclusions.
      explanation: Autopsy in one affected RNF216/OTUD4 family member documents regional neuronal loss and inclusions; it does not establish that the inclusions cause cell death.
  - target: Cerebellar atrophy
    description: Loss of cerebellar tissue is reflected in reduced cerebellar volume on imaging.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Neuronal loss was observed in cerebellar pathways and the hippocampus; surviving hippocampal neurons contained ubiquitin-immunoreactive intranuclear inclusions.
      explanation: Autopsy in one affected RNF216/OTUD4 family member documents regional neuronal loss and inclusions; it does not establish that the inclusions cause cell death.
    - reference: PMID:37977846
      reference_title: A novel mutation in RNF216 gene in an Indian case with Gordon Holmes syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: pan-cerebellar atrophy with bilateral cerebral white matter hyperintensities
      explanation: MRI documents cerebellar atrophy in an RNF216 case. Alongside the separately cited autopsy findings, this supports the tissue-loss interpretation without equating MRI with cell-specific histology.
  - target: Dysarthria
    description: Cerebellar disease contributes to motor speech impairment.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
      reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Dysarthria and dysphagia are recurrent features ... evolving throughout the disease course in almost all individuals with cerebellar ataxia.
      explanation: GeneReviews associates dysarthria with cerebellar ataxia in the PNPLA6 spectrum; the indirect edge does not specify unmeasured neuronal intermediates.
      quote_role: REVIEW_SYNTHESIS
- name: Hippocampal neuronal loss
  description: An autopsy from the original RNF216/OTUD4 family showed hippocampal neuronal loss and ubiquitin-immunoreactive inclusions in surviving neurons. Their coexistence does not prove that inclusions caused neuronal death.
  locations:
  - preferred_term: hippocampal formation
    term:
      id: UBERON:0002421
      label: hippocampal formation
  evidence:
  - reference: PMID:23656588
    reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Neuronal loss was observed in cerebellar pathways and the hippocampus; surviving hippocampal neurons contained ubiquitin-immunoreactive intranuclear inclusions.
    explanation: Autopsy in one affected RNF216/OTUD4 family member documents regional neuronal loss and inclusions; it does not establish that the inclusions cause cell death.
  downstream:
  - target: Cognitive decline and dementia
    description: Hippocampal neuronal loss plausibly contributes to cognitive deterioration alongside broader brain involvement.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Neuronal loss was observed in cerebellar pathways and the hippocampus; surviving hippocampal neurons contained ubiquitin-immunoreactive intranuclear inclusions.
      explanation: Autopsy in one affected RNF216/OTUD4 family member documents regional neuronal loss and inclusions; it does not establish that the inclusions cause cell death.
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: The syndrome of hypogonadotropic hypogonadism, ataxia, and dementia can be caused by inactivating mutations in RNF216 or by the combination of mutations in RNF216 and OTUD4.
      explanation: Human genetics supports the disease association; cellular intermediates between altered ubiquitination and regional pathology remain unresolved.
- name: Reproductive Endocrine Axis Dysfunction
  description: >-
    Hypothalamic and pituitary reproductive dysfunction causes central hypogonadism. Detailed RNF216 endocrine
    testing showed variable responses to exogenous GnRH, with declining or absent pituitary responsiveness
    in some patients as disease progressed. The relative contributions of hypothalamic and pituitary dysfunction
    vary; the same cellular localization is not established for every genetic form.
  cell_types:
  - preferred_term: hypothalamic gonadotropin-releasing hormone neuron
    term:
      id: CL:0011111
      label: hypothalamic gonadotropin-releasing hormone neuron
  locations:
  - preferred_term: pituitary gland
    term:
      id: UBERON:0000007
      label: pituitary gland
  evidence:
  - reference: PMID:23656588
    reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Defects were detected at the hypothalamic and pituitary levels of the reproductive endocrine axis."
    explanation: >
      Localizes the hypogonadotropic hypogonadism to combined hypothalamic and
      pituitary dysfunction.
  - reference: PMID:23656588
    reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Pituitary responsiveness to GnRH was lost in patients late in the course of their disease.
    explanation: Longitudinal and late-stage endocrine testing supports progressive pituitary involvement in selected RNF216 cases.
  downstream:
  - target: Hypogonadotropic hypogonadism
    description: Reduced central gonadotropin drive produces hypogonadotropic hypogonadism.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:23656588
      reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Defects were detected at the hypothalamic and pituitary levels of the reproductive endocrine axis."
      explanation: >
        Localizes the hypogonadotropic hypogonadism to combined hypothalamic and
        pituitary dysfunction.
- name: Altered microglial state in RNF216 models
  mechanism_confidence: PROVISIONAL
  description: Constitutive Rnf216 knockout mice show sex- and region-dependent changes in microglial density, morphology and soma size. These observations are candidate disease intermediates and have not established a corresponding human neuroinflammatory mechanism.
  cell_types:
  - preferred_term: microglial cell
    term:
      id: CL:0000129
      label: microglial cell
  evidence:
  - &id001
    reference: PMID:38164552
    reference_title: Gordon Holmes Syndrome Model Mice Exhibit Alterations in Microglia, Age, and Sex-Specific Disruptions in Cognitive and Proprioceptive Function.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: KO mice also showed age-dependent strategy and associative learning impairments with sex-dependent alterations of microglia in the hippocampus and cortex.
    explanation: Constitutive Rnf216 loss is associated with sex- and region-dependent microglial changes and age-dependent learning phenotypes. Their causal relationship is not established.
  notes: 'No causal edge from microglial changes to human neuronal loss is asserted: the study allows both causal and unrelated interpretations of its microglial and electrophysiological findings.'
phenotypes:
- category: Neurologic
  name: Cerebellar ataxia
  description: >-
    Progressive cerebellar ataxia is a defining manifestation of established GHS. It may be absent during
    an early endocrine-only presentation.
  phenotype_term:
    preferred_term: Cerebellar ataxia
    term:
      id: HP:0002073
      label: Progressive cerebellar ataxia
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:24113144
    reference_title: "Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Gordon Holmes syndrome (GHS) is a rare Mendelian neurodegenerative disorder characterized by ataxia and hypogonadism."
    explanation: Ataxia is one of the two defining clinical features of the syndrome.
  - reference: PMID:23656588
    reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients had progressive ataxia and dementia."
    explanation: All RNF216-mutation patients in the index cohort had progressive ataxia.

- category: Endocrine
  name: Hypogonadotropic hypogonadism
  description: >
    Central hypogonadotropic hypogonadism with low/inappropriately normal
    gonadotropins and low sex steroids, manifesting as delayed or absent puberty
    and absent secondary sexual characteristics. May be the first presentation,
    particularly in males.
  phenotype_term:
    preferred_term: Hypogonadotropic hypogonadism
    term:
      id: HP:0000044
      label: Hypogonadotropic hypogonadism
  evidence:
  - reference: PMID:39444518
    reference_title: "Hypogonadotropic Hypogonadism as First Presentation of the Severe Neuroendocrine Disorder Caused by RNF216."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Biallelic pathogenic variants in RNF216 cause a syndrome characterized by hypogonadotropic hypogonadism, cerebellar ataxia, chorea, and cognitive impairment, a combination first described as Gordon Holmes syndrome (MIM 212840)."
    explanation: Defines hypogonadotropic hypogonadism as a core feature of the RNF216 syndrome.
  - reference: PMID:39444518
    reference_title: "Hypogonadotropic Hypogonadism as First Presentation of the Severe Neuroendocrine Disorder Caused by RNF216."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "hypogonadotropic hypogonadism may be the initial manifestation of this severe neuroendocrine disorder, especially in males."
    explanation: Hypogonadism can precede neurologic signs as the presenting complaint.
  - reference: ORPHA:1173
    reference_title: "Cerebellar ataxia-hypogonadism syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000135 | Hypogonadism | Very frequent (99-80%)"
    explanation: Orphanet lists hypogonadism as a very frequent phenotype.
  notes: The broader Orphanet hypogonadism annotation is retained here as context; the primary clinical sources establish the central subtype. Hypothalamic/pituitary localization is represented separately in the reproductive-axis mechanism.
- category: Reproductive
  name: Decreased fertility
  description: >-
    Decreased fertility is reported in the Orphanet syndrome profile. Its prevalence across individual
    genetic forms is not established by that profile.
  phenotype_term:
    preferred_term: Decreased fertility
    term:
      id: HP:0000144
      label: Decreased fertility
  evidence:
  - reference: ORPHA:1173
    reference_title: "Cerebellar ataxia-hypogonadism syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000144 | Decreased fertility | Very frequent (99-80%)"
    explanation: Orphanet lists decreased fertility as a very frequent phenotype.
  notes: The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms.
- category: Endocrine
  name: Gynecomastia
  description: >-
    Gynecomastia is reported in the Orphanet syndrome profile. Its prevalence across individual genetic
    forms is not established by that profile.
  phenotype_term:
    preferred_term: Gynecomastia
    term:
      id: HP:0000771
      label: Gynecomastia
  evidence:
  - reference: ORPHA:1173
    reference_title: "Cerebellar ataxia-hypogonadism syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000771 | Gynecomastia | Very frequent (99-80%)"
    explanation: Orphanet lists gynecomastia as a very frequent phenotype.

  notes: The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms.
- category: Endocrine
  name: Delayed puberty
  description: >
    Delayed or absent puberty with lack of secondary sexual characteristics
    secondary to hypogonadotropic hypogonadism.
  phenotype_term:
    preferred_term: Delayed puberty
    term:
      id: HP:0000823
      label: Delayed puberty
  evidence:
  - reference: PMID:39444518
    reference_title: "Hypogonadotropic Hypogonadism as First Presentation of the Severe Neuroendocrine Disorder Caused by RNF216."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We report 2 siblings who were referred due to absent or delayed puberty."
    explanation: Affected siblings presented with absent or delayed puberty.

- category: Endocrine
  name: Primary amenorrhea
  description: >
    Primary amenorrhea in affected females reflecting hypogonadotropic
    hypogonadism.
  phenotype_term:
    preferred_term: Primary amenorrhea
    term:
      id: HP:0000786
      label: Primary amenorrhea
  evidence:
  - reference: PMID:39444518
    reference_title: "Hypogonadotropic Hypogonadism as First Presentation of the Severe Neuroendocrine Disorder Caused by RNF216."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "His 15-year-old sister was referred due to primary amenorrhea."
    explanation: An affected female sibling presented with primary amenorrhea.

- category: Cognitive
  name: Cognitive decline and dementia
  description: >-
    Progressive dementia was present in the original RNF216 cohort, but cognitive impairment is neither
    uniformly severe nor necessarily present early. A later RNF216 family included one brother without
    cognitive impairment at evaluation.
  phenotype_term:
    preferred_term: Dementia
    term:
      id: HP:0000726
      label: Dementia
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:23656588
    reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dementia was also prominent, with personality changes and memory loss occurring at the onset of the disease"
    explanation: Dementia with personality changes and memory loss is prominent in RNF216-related disease.
  - reference: PMID:37161390
    reference_title: "A novel mutation in RNF216 gene in a Turkish case with Gordon Holmes syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Gordon Holmes syndrome (GHS) is a rare autosomal recessive disorder characterized by hypogonadotropic hypogonadism, cognitive decline, and cerebellar ataxia."
    explanation: Cognitive decline is listed as one of the core GHS features.
  - reference: PMID:27441066
    reference_title: Ataxia and Hypogonadotropic Hypogonadism with Intrafamilial Variability Caused by RNF216 Mutation.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: No nystagmus or cognitive impairment were noted.
    explanation: The younger affected RNF216 brother had preserved cognition at the reported evaluation.
- category: Cognitive
  name: Personality changes
  description: >-
    Personality changes is reported in the Orphanet syndrome profile. Its prevalence across individual
    genetic forms is not established by that profile.
  phenotype_term:
    preferred_term: Personality changes
    term:
      id: HP:0000751
      label: Personality changes
  evidence:
  - reference: ORPHA:1173
    reference_title: "Cerebellar ataxia-hypogonadism syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000751 | Personality changes | Occasional (29-5%)"
    explanation: Orphanet lists personality changes as an occasional phenotype.

  notes: The Orphanet syndrome profile assigns OCCASIONAL; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms.
- category: Neurologic
  name: Cerebellar atrophy
  description: >
    Cerebellar atrophy is a recurring MRI feature, often with vermian
    predominance in PNPLA6-related disease; pan-cerebellar atrophy is reported
    in RNF216 cases.
  phenotype_term:
    preferred_term: Cerebellar atrophy
    term:
      id: HP:0001272
      label: Cerebellar atrophy
  evidence:
  - reference: PMID:35069422
    reference_title: "Multifaceted and Age-Dependent Phenotypes Associated With Biallelic PNPLA6 Gene Variants: Eight Novel Cases and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Brain MRI showed cerebellar atrophy in 6/8 patients, more pronounced in superior and dorsal vermis lobules (I to VII)."
    explanation: Cerebellar atrophy with vermian predominance was found in most PNPLA6 patients.
  - reference: PMID:37977846
    reference_title: "A novel mutation in RNF216 gene in an Indian case with Gordon Holmes syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "pan-cerebellar atrophy with bilateral cerebral white matter hyperintensities"
    explanation: Pan-cerebellar atrophy documented in an RNF216 case.

- category: Neurologic
  name: Cerebral white matter abnormality
  description: >
    Patchy subcortical/cerebral white-matter T2/FLAIR hyperintensities
    (leukoencephalopathy) are a consistent feature of RNF216-associated disease
    and may precede neurologic symptom onset.
  phenotype_term:
    preferred_term: Abnormal cerebral white matter morphology
    term:
      id: HP:0002500
      label: Abnormal cerebral white matter morphology
  evidence:
  - reference: PMID:23656588
    reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The subcortical white matter contained patchy areas of hyperintensity on T2-weighted imaging and fluid-attenuated inversion recovery (FLAIR) imaging"
    explanation: Subcortical white-matter hyperintensities are documented across RNF216-mutation patients.
  - reference: PMID:39444518
    reference_title: "Hypogonadotropic Hypogonadism as First Presentation of the Severe Neuroendocrine Disorder Caused by RNF216."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "an extensive supratentorial leuko-encephalopathy"
    explanation: Extensive supratentorial leukoencephalopathy was found on MRI in an RNF216 case.

- category: Neurologic
  name: Chorea
  description: >
    Chorea and other movement disorders (parkinsonism, dystonia, tremor) occur
    in a subset of patients, particularly RNF216-related disease.
  phenotype_term:
    preferred_term: Chorea
    term:
      id: HP:0002072
      label: Chorea
  evidence:
  - reference: PMID:39444518
    reference_title: "Hypogonadotropic Hypogonadism as First Presentation of the Severe Neuroendocrine Disorder Caused by RNF216."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Biallelic pathogenic variants in RNF216 cause a syndrome characterized by hypogonadotropic hypogonadism, cerebellar ataxia, chorea, and cognitive impairment"
    explanation: Chorea is part of the RNF216 syndrome phenotype.

- category: Neurologic
  name: Dysarthria
  description: >
    Cerebellar dysarthria; dysarthria may be the initial neurologic symptom in
    some patients.
  phenotype_term:
    preferred_term: Dysarthria
    term:
      id: HP:0001260
      label: Dysarthria
  evidence:
  - reference: PMID:23656588
    reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dysarthria was the initial neurologic symptom in some patients"
    explanation: Dysarthria can be the presenting neurologic feature.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Dysarthria and dysphagia are recurrent features ... evolving throughout the disease course in almost all individuals with cerebellar ataxia.
    explanation: GeneReviews describes evolving bulbar symptoms in ataxic PNPLA6 disorders; this is not a measured all-genotype GHS frequency.
    quote_role: REVIEW_SYNTHESIS
- category: Neurologic
  name: Abnormality of speech or vocalization
  description: >-
    Abnormality of speech or vocalization is reported in the Orphanet syndrome profile. Its prevalence
    across individual genetic forms is not established by that profile.
  phenotype_term:
    preferred_term: Abnormality of speech or vocalization
    term:
      id: HP:0002167
      label: Abnormal speech pattern
  evidence:
  - reference: ORPHA:1173
    reference_title: "Cerebellar ataxia-hypogonadism syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002167 | Abnormality of speech or vocalization | Very frequent (99-80%)"
    explanation: Orphanet lists abnormality of speech or vocalization as a very frequent phenotype.

  notes: The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms.
- category: Ophthalmologic
  name: Chorioretinal dystrophy
  description: >
    Chorioretinal dystrophy with reduced visual function characterizes the
    Boucher-Neuhauser end of the PNPLA6 continuum and distinguishes it from
    RNF216/STUB1-related Gordon Holmes syndrome.
  phenotype_term:
    preferred_term: Chorioretinal dystrophy
    term:
      id: HP:0001135
      label: Chorioretinal dystrophy
  evidence:
  - reference: PMID:33650466
    reference_title: "Chorioretinal dystrophy, hypogonadotropic hypogonadism, and cerebellar ataxia: Boucher-Neuhauser syndrome due to a homozygous (c.3524C>G (p.Ser1175Cys)) variant in PNPLA6 gene."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "neurologic, ophthalmologic, endocrine, and genetic evaluations established a diagnosis of BNHS"
    explanation: Chorioretinal dystrophy is a defining feature of the Boucher-Neuhauser (PNPLA6) form.
  - reference: PMID:25299038
    reference_title: "PNPLA6 Disorders."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "chorioretinal dystrophy associated with variable degrees of reduced visual function"
    explanation: GeneReviews documents chorioretinal dystrophy with reduced visual function in PNPLA6 disorders.
    quote_role: REVIEW_SYNTHESIS
  notes: ' Retinal findings require genotype and overlap assessment: chorioretinal dystrophy distinguishes the Boucher-Neuhauser cluster from typical PNPLA6-related GHS.'
- category: Ophthalmologic
  name: Abnormal electroretinogram
  description: >-
    Abnormal electroretinogram is reported in the Orphanet syndrome profile. Its prevalence across individual
    genetic forms is not established by that profile.
  phenotype_term:
    preferred_term: Abnormal electroretinogram
    term:
      id: HP:0000512
      label: Abnormal electroretinogram
  evidence:
  - reference: ORPHA:1173
    reference_title: "Cerebellar ataxia-hypogonadism syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000512 | Abnormal electroretinogram | Very frequent (99-80%)"
    explanation: Orphanet lists abnormal electroretinogram as a very frequent phenotype.
  reports_on:
  - target: PNPLA6 / Neuropathy Target Esterase Phospholipid Dysfunction
    relationship: READOUT_OF
    endpoint_context: DIAGNOSTIC
    interpretation: >
      PNPLA6-related retinal dysfunction can be detected electrophysiologically.
  notes: 'The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms. Retinal findings require genotype and overlap assessment: chorioretinal dystrophy distinguishes the Boucher-Neuhauser cluster from typical PNPLA6-related GHS.'
- category: Ophthalmologic
  name: Nystagmus
  description: >-
    Nystagmus is reported in the Orphanet syndrome profile. Its prevalence across individual genetic forms
    is not established by that profile.
  phenotype_term:
    preferred_term: Nystagmus
    term:
      id: HP:0000639
      label: Nystagmus
  evidence:
  - reference: ORPHA:1173
    reference_title: "Cerebellar ataxia-hypogonadism syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000639 | Nystagmus | Very frequent (99-80%)"
    explanation: Orphanet lists nystagmus as a very frequent phenotype.
  - reference: PMID:27441066
    reference_title: Ataxia and Hypogonadotropic Hypogonadism with Intrafamilial Variability Caused by RNF216 Mutation.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: No nystagmus was noted. His workup showed low luteinizing hormone level
    explanation: The more severely affected RNF216 brother lacked nystagmus, limiting generalization of the Orphanet frequency.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3900109/?report=classic
    reference_title: Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Patient II-1 exhibited horizontal gaze-evoked nystagmus
    explanation: The STUB1 proband had gaze-evoked nystagmus, supporting genotype-dependent heterogeneity.
  notes: 'The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms. Nystagmus is not uniform across genetic forms: the original RNF216 cohort and the two subsequently reported RNF216 brothers lacked nystagmus, whereas the STUB1 discovery family had gaze-evoked nystagmus.'
- category: Ophthalmologic
  name: Optic atrophy
  description: >-
    Optic atrophy is reported in the Orphanet syndrome profile. Its prevalence across individual genetic
    forms is not established by that profile.
  phenotype_term:
    preferred_term: Optic atrophy
    term:
      id: HP:0000648
      label: Optic atrophy
  evidence:
  - reference: ORPHA:1173
    reference_title: "Cerebellar ataxia-hypogonadism syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000648 | Optic atrophy | Very frequent (99-80%)"
    explanation: Orphanet lists optic atrophy as a very frequent phenotype.
  notes: 'The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms. Retinal findings require genotype and overlap assessment: chorioretinal dystrophy distinguishes the Boucher-Neuhauser cluster from typical PNPLA6-related GHS.'
- category: Ophthalmologic
  name: Abnormality of retinal pigmentation
  description: >-
    Abnormality of retinal pigmentation is reported in the Orphanet syndrome profile. Its prevalence across
    individual genetic forms is not established by that profile.
  phenotype_term:
    preferred_term: Abnormality of retinal pigmentation
    term:
      id: HP:0007703
      label: Abnormal retinal pigmentation
  evidence:
  - reference: ORPHA:1173
    reference_title: "Cerebellar ataxia-hypogonadism syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0007703 | Abnormality of retinal pigmentation | Very frequent (99-80%)"
    explanation: Orphanet lists abnormality of retinal pigmentation as a very frequent phenotype.

  notes: 'The Orphanet syndrome profile assigns VERY_FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms. Retinal findings require genotype and overlap assessment: chorioretinal dystrophy distinguishes the Boucher-Neuhauser cluster from typical PNPLA6-related GHS.'
- category: Neurologic
  name: Hyperreflexia
  description: >
    Upper motor neuron involvement manifesting as brisk reflexes/spasticity is
    seen in the PNPLA6 continuum and is a variable feature of Gordon Holmes
    syndrome.
  phenotype_term:
    preferred_term: Hyperreflexia
    term:
      id: HP:0001347
      label: Hyperreflexia
  evidence:
  - reference: PMID:25299038
    reference_title: "PNPLA6 Disorders."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Gordon Holmes syndrome (cerebellar ataxia, hypogonadotropic hypogonadism, and – to a variable degree – brisk reflexes)"
    explanation: GeneReviews lists variable brisk reflexes within the Gordon Holmes cluster of PNPLA6 disorders.
    quote_role: REVIEW_SYNTHESIS
- category: Neurologic
  name: Hemiplegia/hemiparesis
  description: >-
    Hemiplegia/hemiparesis is reported in the Orphanet syndrome profile. Its prevalence across individual
    genetic forms is not established by that profile.
  phenotype_term:
    preferred_term: Hemiplegia/hemiparesis
    term:
      id: HP:0004374
      label: Hemiplegia/hemiparesis
  evidence:
  - reference: ORPHA:1173
    reference_title: "Cerebellar ataxia-hypogonadism syndrome"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0004374 | Hemiplegia/hemiparesis | Frequent (79-30%)"
    explanation: Orphanet lists hemiplegia/hemiparesis as a frequent phenotype.

  notes: The Orphanet syndrome profile assigns FREQUENT; this unstratified profile is retained as evidence but is not used as a penetrance estimate across genetically distinct forms.
- name: Dysphagia
  category: Neurologic
  description: Swallowing difficulty can emerge during progression of PNPLA6-related ataxia; detailed longitudinal timing remains incompletely characterized.
  phenotype_term:
    preferred_term: Dysphagia
    term:
      id: HP:0002015
      label: Dysphagia
  subtypes:
  - PNPLA6-related Gordon Holmes syndrome
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Dysarthria and dysphagia are recurrent features ... evolving throughout the disease course in almost all individuals with cerebellar ataxia.
    explanation: GeneReviews describes evolving bulbar symptoms in ataxic PNPLA6 disorders; this is not a measured all-genotype GHS frequency.
    quote_role: REVIEW_SYNTHESIS
- name: Parkinsonism
  category: Neurologic
  description: Reported in a patient with homozygous RNF216 frameshift variation; frequency across GHS is unknown.
  phenotype_term:
    preferred_term: Parkinsonism
    term:
      id: HP:0001300
      label: Parkinsonism
  subtypes:
  - RNF216-related Gordon Holmes syndrome
  evidence:
  - reference: PMID:37161390
    reference_title: A novel mutation in RNF216 gene in a Turkish case with Gordon Holmes syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: also co-occurrence of parkinsonism and dystonia which was not reported before.
    explanation: The reported case supports occurrence, not population frequency.
- name: Dystonia
  category: Neurologic
  description: Reported in a patient with homozygous RNF216 frameshift variation; frequency across GHS is unknown.
  phenotype_term:
    preferred_term: Dystonia
    term:
      id: HP:0001332
      label: Dystonia
  subtypes:
  - RNF216-related Gordon Holmes syndrome
  evidence:
  - reference: PMID:37161390
    reference_title: A novel mutation in RNF216 gene in a Turkish case with Gordon Holmes syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: also co-occurrence of parkinsonism and dystonia which was not reported before.
    explanation: The reported case supports occurrence, not population frequency.
- name: Spasticity
  category: Neurologic
  description: Spasticity may accompany PNPLA6-related ataxia. It is not required for the GHS presentation and is assessed separately from brisk reflexes.
  phenotype_term:
    preferred_term: Spasticity
    term:
      id: HP:0001257
      label: Spasticity
  evidence:
  - reference: PMID:25299038
    reference_title: PNPLA6 Disorders.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: upper motor neuron involvement manifesting as spasticity and/or brisk reflexes
    explanation: GeneReviews supports upper motor neuron manifestations across the PNPLA6 spectrum.
    quote_role: REVIEW_SYNTHESIS
  subtypes:
  - PNPLA6-related Gordon Holmes syndrome
- name: Urinary urgency
  category: Neurologic
  description: Urinary urgency is reported in PNPLA6-associated ataxias; its frequency and longitudinal course have not been systematically established.
  phenotype_term:
    preferred_term: Urinary urgency
    term:
      id: HP:0000012
      label: Urinary urgency
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: urinary urgency appears to be a recurrent feature at least in individuals with
    explanation: GeneReviews describes a clinical impression and explicitly notes the lack of systematic investigation.
    quote_role: REVIEW_SYNTHESIS
  subtypes:
  - PNPLA6-related Gordon Holmes syndrome
- name: Cognitive impairment
  category: Neurologic
  description: Selective or milder cognitive deficits can occur without established dementia, including in the STUB1 discovery family. Cognitive severity varies with genotype and disease stage.
  phenotype_term:
    preferred_term: Cognitive impairment
    term:
      id: HP:0100543
      label: Cognitive impairment
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3900109/?report=classic
    reference_title: Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: did reveal cognitive deficiencies in both sisters
    explanation: MoCA detected cognitive deficits in the STUB1 sisters, despite normal MMSE scores in the reported assessment.
genetic:
- name: RNF216 biallelic pathogenic variants
  gene_term:
    preferred_term: RNF216
    term:
      id: hgnc:21698
      label: RNF216
  association: Causative biallelic (and digenic with OTUD4) pathogenic variants
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
    evidence:
    - reference: PMID:37161390
      reference_title: "A novel mutation in RNF216 gene in a Turkish case with Gordon Holmes syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Gordon Holmes syndrome (GHS) is a rare autosomal recessive disorder"
      explanation: Confirms autosomal recessive inheritance of RNF216-related GHS.
  notes: >
    Reported variants include splice-site (c.2061G>A), frameshift (c.1860_1861dupCT, p.Cys621SerfsTer56),
    nonsense, and missense (e.g., p.R751C) changes. The original NEJM kindred carried a digenic homozygous
    RNF216/OTUD4 genotype.
  evidence:
  - reference: PMID:23656588
    reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The syndrome of hypogonadotropic hypogonadism, ataxia, and dementia can be caused by inactivating mutations in RNF216 or by the combination of mutations in RNF216 and OTUD4."
    explanation: Establishes RNF216 (and digenic RNF216/OTUD4) as the genetic cause.
  - reference: PMID:27441066
    reference_title: "Ataxia and Hypogonadotropic Hypogonadism with Intrafamilial Variability Caused by RNF216 Mutation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified a novel splicing variant in RNF216 that is likely to abolish the canonical splice site at the junction of exon/intron 13 (NM_207111.3:c.2061G>A)."
    explanation: A novel RNF216 splice-site variant causes GHS, illustrating allelic heterogeneity.

- name: OTUD4 (digenic with RNF216) pathogenic variants
  gene_term:
    preferred_term: OTUD4
    term:
      id: hgnc:24949
      label: OTUD4
  association: Digenic contributor with RNF216
  relationship_type: COOPERATING
  variant_origin: GERMLINE
  inheritance:
  - name: Digenic inheritance
    inheritance_term:
      preferred_term: Digenic inheritance
      term:
        id: HP:0010984
        label: Digenic inheritance
    evidence:
    - reference: PMID:23656588
      reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Digenic homozygous mutations in RNF216 and OTUD4, which encode a ubiquitin E3 ligase and a deubiquitinase, respectively, were found in three affected siblings in a consanguineous family."
      explanation: The reported family carried homozygous variants at both RNF216 and OTUD4 loci, supporting digenic inheritance rather than isolated OTUD4 causation.
  notes: >-
    OTUD4 encodes a deubiquitinase. A homozygous variant co-segregated with a homozygous RNF216 variant
    in the original consanguineous kindred; zebrafish double knockdown supported functional interaction.
    This does not establish physical protein partnership or isolated OTUD4 causation.
  evidence:
  - reference: PMID:23656588
    reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Digenic homozygous mutations in RNF216 and OTUD4, which encode a ubiquitin E3 ligase and a deubiquitinase, respectively, were found in three affected siblings in a consanguineous family."
    explanation: Documents OTUD4 as a digenic contributor with RNF216.

- name: STUB1 (CHIP) biallelic pathogenic variants
  gene_term:
    preferred_term: STUB1
    term:
      id: hgnc:11427
      label: STUB1
  association: Causative biallelic pathogenic variants
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
    evidence:
    - reference: PMID:24113144
      reference_title: "Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We performed exome sequencing in a family with two of three siblings afflicted with ataxia and hypogonadism and identified a homozygous mutation in STUB1"
      explanation: A homozygous STUB1 variant in affected siblings indicates autosomal recessive inheritance.
  notes: >
    Homozygous STUB1 c.737C>T (p.Thr246Met) causes loss of CHIP E3 ubiquitin
    ligase activity producing ataxia with hypogonadism consistent with GHS.
  evidence:
  - reference: PMID:24113144
    reference_title: "Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "identified a homozygous mutation in STUB1 (NM_005861) c.737C→T, p.Thr246Met, a gene that encodes the protein CHIP (C-terminus of HSC70-interacting protein)."
    explanation: Identifies a homozygous STUB1/CHIP variant causing GHS.

- name: PNPLA6 biallelic pathogenic variants
  gene_term:
    preferred_term: PNPLA6
    term:
      id: hgnc:16268
      label: PNPLA6
  association: Causative biallelic pathogenic variants (Gordon Holmes / Boucher-Neuhauser continuum)
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
    evidence:
    - reference: PMID:25299038
      reference_title: "PNPLA6 Disorders."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "PNPLA6 disorders are inherited in an autosomal recessive manner."
      explanation: GeneReviews confirms autosomal recessive inheritance of PNPLA6 disorders.
      quote_role: REVIEW_SYNTHESIS
  notes: >-
    PNPLA6 variants cause an overlapping clinical spectrum. The c.3524C>G (p.Ser1175Cys) publication concerns
    Boucher-Neuhauser syndrome, not isolated GHS. The eight-person ataxia/spastic-paraplegia cohort included
    three GHS cases, two Boucher-Neuhauser cases, one SPG case and two pure late-onset ataxia cases; its
    detection rate is not GHS prevalence.
  evidence:
  - reference: PMID:35069422
    reference_title: "Multifaceted and Age-Dependent Phenotypes Associated With Biallelic PNPLA6 Gene Variants: Eight Novel Cases and Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified six novel and four recurrent PNPLA6 gene variants in eight patients (2.7%)."
    explanation: Quantifies PNPLA6 variant detection in an ataxia/spastic paraplegia screening cohort.
  - reference: PMID:33650466
    reference_title: "Chorioretinal dystrophy, hypogonadotropic hypogonadism, and cerebellar ataxia: Boucher-Neuhauser syndrome due to a homozygous (c.3524C>G (p.Ser1175Cys)) variant in PNPLA6 gene."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified a missense homozygous variant (c.3524 C > G (p.Ser1175Cys)) in the PNPLA6 gene, which explains the phenotype of the patient"
    explanation: A homozygous PNPLA6 missense variant causes Boucher-Neuhauser within the continuum.

treatments:
- name: Sex Hormone Replacement Therapy
  description: >-
    Sex-steroid replacement supports pubertal development and secondary sexual characteristics under endocrine
    supervision. Testosterone improved secondary sexual characteristics in the reported RNF216 brothers
    without changing their neurologic symptoms. Fertility requires separate assessment; sex-steroid replacement
    is not evidence of restored fertility.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Hormone Replacement Therapy
    term:
      id: NCIT:C15599
      label: Hormone Replacement Therapy
    therapeutic_agent:
    - preferred_term: testosterone
      term:
        id: CHEBI:17347
        label: testosterone
    - preferred_term: estradiol
      term:
        id: CHEBI:23965
        label: estradiol
  evidence:
  - reference: PMID:25299038
    reference_title: "PNPLA6 Disorders."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Hypogonadotropic hypogonadism. Hormone replacement therapy at the expected time of puberty."
    explanation: GeneReviews recommends hormone replacement therapy for the hypogonadotropic hypogonadism.

    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:27441066
    reference_title: Ataxia and Hypogonadotropic Hypogonadism with Intrafamilial Variability Caused by RNF216 Mutation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Both showed good response to treatment regarding secondary sexual characteristics, in the form of facial, axillary and pubic hair growth, and deepening of voice. There was no change in their neurological symptoms with treatment.
    explanation: Clinical follow-up separates endocrine benefit from neurologic response.
  target_phenotypes:
  - preferred_term: Hypogonadotropic hypogonadism
    term:
      id: HP:0000044
      label: Hypogonadotropic hypogonadism
  - preferred_term: Delayed puberty
    term:
      id: HP:0000823
      label: Delayed puberty
- name: Multidisciplinary Supportive and Rehabilitative Care
  description: >
    Management is symptomatic and individually tailored: continuous training of
    speech and swallowing, fine-motor skills, gait, and balance for ataxia;
    physical therapy and assistive devices for spasticity; low-vision aids for
    chorioretinal dystrophy; and periodic multidisciplinary reevaluation. No
    disease-modifying therapy exists.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:25299038
    reference_title: "PNPLA6 Disorders."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Management is symptomatic and individually tailored."
    explanation: GeneReviews describes symptomatic, individually tailored supportive management.

    quote_role: REVIEW_SYNTHESIS
- name: Physical Therapy
  description: >
    Physical therapy, assistive walking devices, and ankle-foot orthotics to
    improve strength and agility and prevent contractures, particularly when
    spasticity is present.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Physical Therapy
    term:
      id: NCIT:C15302
      label: Physical Therapy
  evidence:
  - reference: PMID:25299038
    reference_title: "PNPLA6 Disorders."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Interventions to improve strength and agility and to prevent contractures, such as physical therapy, assistive walking devices and/or ankle-foot orthotics"
    explanation: GeneReviews recommends physical therapy and assistive devices for spasticity.

    quote_role: REVIEW_SYNTHESIS
- name: Genetic Counseling
  description: >
    Genetic counseling for affected families. Once the pathogenic variants are
    identified, carrier testing, prenatal testing, and preimplantation genetic
    testing are possible.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:25299038
    reference_title: "PNPLA6 Disorders."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "carrier testing for at-risk relatives, prenatal testing for a pregnancy at increased risk, and preimplantation genetic testing are possible."
    explanation: GeneReviews outlines genetic counseling and reproductive testing options.

    quote_role: REVIEW_SYNTHESIS
  action_category: COUNSELING_INFORMATIONAL
- name: Speech and communication therapy
  description: Provide speech-language therapy and assess alternative communication methods when needed, particularly as PNPLA6-related dysarthria progresses.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Consider alternative communication methods (e.g., writing pads, digital devices) as needed.
    explanation: GeneReviews supports communication adaptations.
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Speech Language Therapy
    term:
      id: NCIT:C159273
      label: Speech Language Therapy
  target_phenotypes:
  - preferred_term: Dysarthria
    term:
      id: HP:0001260
      label: Dysarthria
- name: Swallowing and nutrition support
  description: Assess swallowing safety, feeding strategies, aspiration risk and nutritional status when dysphagia develops in PNPLA6-related disease.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Feeding therapy programs to improve nutrition ... Education re strategies to mitigate aspiration
    explanation: GeneReviews supports feeding therapy and aspiration prevention.
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Swallowing Therapy
    term:
      id: NCIT:C156237
      label: Swallowing Therapy
  target_phenotypes:
  - preferred_term: Dysphagia
    term:
      id: HP:0002015
      label: Dysphagia
- name: Occupational therapy and adaptive equipment
  description: Use occupational therapy and adaptive devices to support daily activities and mobility in PNPLA6-related ataxia.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: OT to optimize ADL (incl use of adaptive devices, e.g., weighted eating utensils, dressing hooks)
    explanation: GeneReviews specifies functional support.
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Occupational Therapy
    term:
      id: NCIT:C121351
      label: Occupational Therapy
  target_phenotypes:
  - preferred_term: Cerebellar ataxia
    term:
      id: HP:0002073
      label: Progressive cerebellar ataxia
    clinical_course: PROGRESSIVE
- name: Low-vision support
  description: For individuals with PNPLA6-related retinal overlap and impaired vision, provide low-vision aids, mobility training and support for independent living. This is conditional care, not evidence that all GHS patients develop retinal disease.
  evidence:
  - reference: PMID:25299038
    reference_title: PNPLA6 Disorders.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Low vision aids when central acuity is reduced; involvement with agencies for the visually impaired, mobility training, and skills for independent living.
    explanation: GeneReviews supports vision-specific care when the relevant phenotype is present.
    quote_role: REVIEW_SYNTHESIS
  target_phenotypes:
  - preferred_term: Chorioretinal dystrophy
    term:
      id: HP:0001135
      label: Chorioretinal dystrophy
- name: Multidisciplinary surveillance
  description: Reassess neurologic function, swallowing, nutrition, communication, endocrine function and relevant ocular manifestations in PNPLA6-related disease. Frequency is individualized, often annually or with changes in symptoms or treatment.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Note that the frequency of recommended surveillance is at the discretion of treating specialists (usually annually or as symptoms change or as medication needs change).
    explanation: The full GeneReviews chapter qualifies the surveillance interval.
    quote_role: REVIEW_SYNTHESIS
  action_category: MONITORING
- name: Avoidance counseling for PNPLA6 disorders
  description: Counsel against alcohol, obesity and inactivity, and review medications or chemicals that may worsen neuropathy. These recommendations derive from the PNPLA6 baseline.
  evidence:
  - reference: PMID:25299038
    reference_title: PNPLA6 Disorders.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: 'Agents/circumstances to avoid: Alcohol; obesity; inactive, sedentary lifestyle; exposure to medications or chemicals that exacerbate neuropathy.'
    explanation: GeneReviews lists avoidances.
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Lifestyle Counseling
    term:
      id: NCIT:C180632
      label: Lifestyle Counseling
  action_category: COUNSELING_INFORMATIONAL
- name: Medication for spasticity
  description: For PNPLA6-related spasticity, individualized oral or intrathecal antispasticity treatment may include baclofen or tolperisone under specialist care. These are symptomatic options; no effect on underlying neurodegeneration is established.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Consider baclofen (oral or intrathecal), tolperison; Botox
    explanation: The GeneReviews treatment table names symptomatic antispasticity options.
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Baclofen
      term:
        id: NCIT:C28858
        label: Baclofen
    - preferred_term: Tolperisone
      term:
        id: NCIT:C84219
        label: Tolperisone
  target_phenotypes:
  - preferred_term: Spasticity
    term:
      id: HP:0001257
      label: Spasticity
- name: Management of urinary urgency
  description: For PNPLA6-related bladder symptoms, urologic assessment may include oxybutynin to reduce urgency.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Incl pharmacologic treatment (e.g., oxybutynin) to ... urinary urgency
    explanation: The GeneReviews bladder-management row specifies oxybutynin for urgency.
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Oxybutynin
      term:
        id: NCIT:C47647
        label: Oxybutynin
  target_phenotypes:
  - preferred_term: Urinary urgency
    term:
      id: HP:0000012
      label: Urinary urgency
- name: Cognitive and educational support
  description: Assess cognitive function and provide an individualized educational or neuropsychological support plan when impairment is present in PNPLA6-related disease.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Neuropsychiatric eval ... educ plan per developmental pediatrician
    explanation: GeneReviews includes neuropsychiatric evaluation and educational planning for cognitive dysfunction.
    quote_role: REVIEW_SYNTHESIS
  target_phenotypes:
  - preferred_term: Cognitive impairment
    term:
      id: HP:0100543
      label: Cognitive impairment
- name: Replacement of additional deficient pituitary-dependent hormones
  description: When additional hormone deficiencies are documented in PNPLA6-related disease, replace thyroid hormone and provide growth hormone during childhood or adolescence as indicated. These are conditional interventions and do not imply that every GHS patient has these deficiencies.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Thyroid hormone replacement as per treating endocrinologist
    explanation: GeneReviews specifies endocrine replacement when hypothyroidism is present.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:25299038
    reference_title: PNPLA6 Disorders.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Growth hormone deficiency. Hormone replacement therapy during childhood and/or adolescence as indicated.
    explanation: GeneReviews scopes growth hormone replacement to documented deficiency and developmental stage.
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Hormone Replacement Therapy
    term:
      id: NCIT:C15599
      label: Hormone Replacement Therapy
- name: Botulinum toxin injections for spasticity
  description: Botulinum toxin injections are a conditional symptomatic option for spasticity in PNPLA6-related disease.
  evidence:
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Consider baclofen (oral or intrathecal), tolperison; Botox
    explanation: The GeneReviews treatment table names symptomatic antispasticity options.
    quote_role: REVIEW_SYNTHESIS
  treatment_term:
    preferred_term: Botulinum Toxin Therapy
    term:
      id: NCIT:C157775
      label: Botulinum Toxin Therapy
  target_phenotypes:
  - preferred_term: Spasticity
    term:
      id: HP:0001257
      label: Spasticity
datasets: []
animal_models:
- name: Constitutive Rnf216 knockout mouse
  species: Mus musculus
  genotype: Rnf216-/-
  description: Constitutive deletion model followed through one year for motor and learning behaviors, with sex-specific microglial and electrophysiological analyses.
  evidence:
  - *id001
  - reference: PMID:38164552
    reference_title: Gordon Holmes Syndrome Model Mice Exhibit Alterations in Microglia, Age, and Sex-Specific Disruptions in Cognitive and Proprioceptive Function.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: we were unable to detect motor impairments or other measures of behavior that would be indicative of ataxia in these mice
    explanation: The tested constitutive knockout failed to reproduce overt ataxia within the observation period.
  modeled_mechanisms:
  - target: Altered microglial state in RNF216 models
    relationship: RECAPITULATES
    description: Demonstrates the model-specific microglial state changes described by this node.
    evidence:
    - reference: PMID:38164552
      reference_title: Gordon Holmes Syndrome Model Mice Exhibit Alterations in Microglia, Age, and Sex-Specific Disruptions in Cognitive and Proprioceptive Function.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: KO mice also showed age-dependent strategy and associative learning impairments with sex-dependent alterations of microglia in the hippocampus and cortex.
      explanation: Constitutive Rnf216 loss is associated with sex- and region-dependent microglial changes and age-dependent learning phenotypes. Their causal relationship is not established.
  - target: Cerebellar degeneration
    relationship: FAILS_TO_RECAPITULATE
    limitations: No reduction in cerebellar mass or overt ataxia was detected in the tested knockout through approximately one year; normal mass does not exclude subtle cellular abnormalities.
    evidence:
    - reference: PMID:38164552
      reference_title: Gordon Holmes Syndrome Model Mice Exhibit Alterations in Microglia, Age, and Sex-Specific Disruptions in Cognitive and Proprioceptive Function.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: This lack of phenotype was also coupled with our inability to detect decreases in cerebellar mass
      explanation: The lack of reduced cerebellar mass limits the model as a representation of human cerebellar degeneration.
    - reference: PMID:38164552
      reference_title: Gordon Holmes Syndrome Model Mice Exhibit Alterations in Microglia, Age, and Sex-Specific Disruptions in Cognitive and Proprioceptive Function.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: we were unable to detect motor impairments or other measures of behavior that would be indicative of ataxia in these mice
      explanation: The tested constitutive knockout failed to reproduce overt ataxia within the observation period.
- name: Chip-deficient mouse
  species: Mus musculus
  genotype: Stub1 (Chip) knockout
  description: Loss of CHIP produces behavioral and reproductive abnormalities resembling aspects of GHS.
  evidence:
  - reference: PMID:24113144
    reference_title: Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Loss of CHIP function in mice resulted in behavioral and reproductive impairments that mimic human ataxia and hypogonadism.
    explanation: CHIP loss reproduces aspects of the motor and reproductive phenotype in mice; this does not localize every endocrine lesion.
  modeled_mechanisms:
  - target: STUB1 CHIP ubiquitin ligase deficiency
    relationship: PERTURBS
    description: CHIP deficiency removes protein function rather than reproducing only the patient Thr246Met substitution.
    evidence:
    - reference: PMID:24113144
      reference_title: Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Loss of CHIP function in mice resulted in behavioral and reproductive impairments that mimic human ataxia and hypogonadism.
      explanation: CHIP loss reproduces aspects of the motor and reproductive phenotype in mice; this does not localize every endocrine lesion.
  - target: Cerebellar degeneration
    relationship: PARTIALLY_RECAPITULATES
    description: Shows cerebellar Purkinje-layer cell loss and abnormal motor behavior.
    limitations: The complete knockout does not preserve the chaperone-binding function retained by the human Thr246Met protein.
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3900109/?report=classic
      reference_title: Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP - PMC
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: cellular loss throughout the various lobes of the cerebellum, specifically in the Purkinje cell layer
      explanation: Cerebellar histology in Chip-null mice demonstrates Purkinje-layer cell loss; this is experimental support, not human STUB1 neuropathology.
- name: rnf216 and otud4 zebrafish morphants
  species: Danio rerio
  genotype: rnf216 and/or otud4 morpholino knockdown
  description: Embryonic knockdown model with more severe brain and eye defects following combined suppression and rescue by wild-type human mRNA.
  evidence:
  - reference: PMID:23656588
    reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Knockdown of rnf216 or otud4 in zebrafish embryos induced defects in the eye, optic tectum, and cerebellum; combinatorial suppression of both genes exacerbated these phenotypes, which were rescued by nonmutant, but not mutant, human RNF216 or OTUD4 messenger RNA.
    explanation: Knockdown and rescue support functional interaction between the two genes, without establishing a physical protein interaction or the exact OTUD4 catalytic defect.
  modeled_mechanisms:
  - target: OTUD4-associated ubiquitin regulation defect
    relationship: PERTURBS
    description: Tests functional interaction by single and combined gene knockdown and human mRNA rescue.
    limitations: Embryonic morpholino phenotypes do not reproduce the complete progressive adult human syndrome or identify the OTUD4 catalytic defect.
    evidence:
    - reference: PMID:23656588
      reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Knockdown of rnf216 or otud4 in zebrafish embryos induced defects in the eye, optic tectum, and cerebellum; combinatorial suppression of both genes exacerbated these phenotypes, which were rescued by nonmutant, but not mutant, human RNF216 or OTUD4 messenger RNA.
      explanation: Knockdown and rescue support functional interaction between the two genes, without establishing a physical protein interaction or the exact OTUD4 catalytic defect.
- name: Pnpla6 residual-activity allelic mouse series
  species: Mus musculus
  genotype: Pnpla6 p.Met1030Val homozygotes and p.Met1030Val/p.Met1030Valfs*2 compound heterozygotes
  description: An allelic series compares residual NTE activity and retinal function across different Pnpla6 genotypes, providing a functional model for the wider PNPLA6 spectrum.
  evidence:
  - reference: PMID:38735647
    reference_title: Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists.
    explanation: The mouse series tests residual NTE activity and retinal outcomes across the PNPLA6 spectrum; it does not reproduce the entire GHS neuroendocrine phenotype.
  modeled_mechanisms:
  - target: PNPLA6 / Neuropathy Target Esterase Phospholipid Dysfunction
    relationship: PARTIALLY_RECAPITULATES
    description: Models the relationship between genotype, residual enzyme activity and tissue dysfunction.
    limitations: Retinal outcomes were studied across SPG39-like and retinal-overlap genotypes; this is not a complete GHS model and does not establish pituitary dysfunction in the viable lines.
    evidence:
    - reference: PMID:38735647
      reference_title: Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists.
      explanation: The mouse series tests residual NTE activity and retinal outcomes across the PNPLA6 spectrum; it does not reproduce the entire GHS neuroendocrine phenotype.
has_subtypes:
- name: RNF216-related Gordon Holmes syndrome
  genes:
  - preferred_term: RNF216
    term:
      id: hgnc:21698
      label: RNF216
  description: Recessive RNF216 disease with ataxia, central hypogonadism and variable cognitive decline, white-matter changes or movement disorders. Endocrine signs may precede neurologic disease.
  evidence:
  - reference: PMID:39444518
    reference_title: Hypogonadotropic Hypogonadism as First Presentation of the Severe Neuroendocrine Disorder Caused by RNF216.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: hypogonadotropic hypogonadism may be the initial manifestation of this severe neuroendocrine disorder, especially in males.
    explanation: RNF216 disease can first present to endocrine care.
- name: RNF216/OTUD4-related Gordon Holmes syndrome
  genes:
  - preferred_term: RNF216
    term:
      id: hgnc:21698
      label: RNF216
  - preferred_term: OTUD4
    term:
      id: hgnc:24949
      label: OTUD4
  description: Reported two-locus form with homozygous variants in both genes in three affected siblings; functional interaction was supported by zebrafish knockdown and rescue.
  evidence:
  - reference: PMID:23656588
    reference_title: "Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Digenic homozygous mutations in RNF216 and OTUD4, which encode a ubiquitin E3 ligase and a deubiquitinase, respectively, were found in three affected siblings in a consanguineous family."
    explanation: >-
      The discovery study reports the two-locus genotype and its co-segregation
      with disease in three affected siblings.

- name: STUB1-related Gordon Holmes syndrome
  genes:
  - preferred_term: STUB1
    term:
      id: hgnc:11427
      label: STUB1
  description: The recessive ataxia-hypogonadism presentation of STUB1 disease. The original Thr246Met sisters had cerebellar atrophy, hypogonadism and selective cognitive deficits. This subtype does not encompass all recessive or dominant STUB1 ataxias.
  evidence:
  - reference: PMID:24113144
    reference_title: Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the U box protein CHIP.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: We conclude that GHS can be caused by a loss-of-function mutation in CHIP.
    explanation: The discovery family establishes a STUB1-related GHS form.
  review_notes: MONDO:0014339 covers any recessive STUB1 cerebellar ataxia, according to its current definition inspected with runoak -i sqlite:obo:mondo info MONDO:0014339 -O obo. It is broader than the ataxia-hypogonadism presentation represented here and is not asserted as an exact subtype identity.
- name: PNPLA6-related Gordon Holmes syndrome
  genes:
  - preferred_term: PNPLA6
    term:
      id: hgnc:16268
      label: PNPLA6
  description: The ataxia-hypogonadotropic hypogonadism presentation of biallelic PNPLA6 disease, often with brisk reflexes. Boucher-Neuhauser, Oliver-McFarlane and SPG39 presentations belong to the broader overlapping PNPLA6 spectrum and are not listed as GHS subtypes.
  evidence:
  - reference: PMID:25299038
    reference_title: PNPLA6 Disorders.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: Gordon Holmes syndrome (cerebellar ataxia, hypogonadotropic hypogonadism, and – to a variable degree – brisk reflexes)
    explanation: GeneReviews distinguishes the GHS cluster within the overlapping PNPLA6 spectrum.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:24355708
    reference_title: PNPLA6 mutations cause Boucher-Neuhauser and Gordon Holmes syndromes as part of a broad neurodegenerative spectrum.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: both clinically distinct entities are allelic for recessive mutations in the gene PNPLA6.
    explanation: The discovery study connects both GHS and Boucher-Neuhauser clinical clusters to biallelic PNPLA6 variation.
diagnosis:
- name: Molecular genetic diagnosis
  diagnosis_term:
    preferred_term: Genetic Testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  description: Investigate the clinical ataxia-hypogonadism phenotype with molecular testing of relevant genes, using panel or genomic approaches and segregation as appropriate. PNPLA6 disease requires biallelic pathogenic variants; variants of uncertain significance alone do not establish the diagnosis.
  evidence:
  - reference: PMID:25299038
    reference_title: PNPLA6 Disorders.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The diagnosis of a PNPLA6 disorder is established in a proband with suggestive findings and biallelic PNPLA6 pathogenic variants identified on homologous alleles by molecular genetic testing.
    explanation: GeneReviews defines molecular confirmation for the PNPLA6 form.
    quote_role: REVIEW_SYNTHESIS
  - reference: PMID:23656588
    reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: We performed whole-exome sequencing in a patient with ataxia and hypogonadotropic hypogonadism, followed by targeted sequencing of candidate genes in similarly affected patients.
    explanation: The discovery study demonstrates a phenotype-led genomic and targeted testing strategy.
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: variant of uncertain significance) does not establish or rule out the diagnosis.
    explanation: GeneReviews explicitly cautions that biallelic VUS, or one pathogenic variant with one VUS, do not establish or exclude PNPLA6 disease.
    quote_role: REVIEW_SYNTHESIS
  - reference: url:https://www.ncbi.nlm.nih.gov/sites/books/NBK247161/
    reference_title: PNPLA6 Disorders - GeneReviews® - NCBI Bookshelf
    supports: SUPPORT
    evidence_source: OTHER
    snippet: the next step is to perform gene-targeted ... deletion/duplication analysis ... to detect exon and whole-gene deletions or duplications.
    explanation: GeneReviews recommends subsequent gene-targeted deletion/duplication analysis when initial sequencing is incomplete.
    quote_role: REVIEW_SYNTHESIS
  notes: Single-gene sequence analysis may require deletion/duplication analysis if one or no pathogenic variant is detected; panels or genomic approaches are selected according to the clinical presentation.
- name: Brain MRI
  diagnosis_term:
    preferred_term: Magnetic Resonance Imaging
    term:
      id: NCIT:C16809
      label: Magnetic Resonance Imaging
  description: Assess cerebellar atrophy and cerebral white-matter abnormalities. Imaging supports the phenotype and longitudinal assessment but does not identify the causal genotype by itself.
  evidence:
  - reference: PMID:37161390
    reference_title: A novel mutation in RNF216 gene in a Turkish case with Gordon Holmes syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Brain magnetic resonance imaging (MRI) revealed progressive cerebellar, vermian, and cerebral cortical atrophy, and periventricular confluent white matter hyperintensities in 2022 compared to 2018.
    explanation: Serial MRI documents progressive structural abnormalities in one RNF216 case.
- name: Reproductive endocrine evaluation
  description: Assess puberty, sex steroids and gonadotropins in clinical context. Selected cases undergo dynamic evaluation to characterize hypothalamic and pituitary contributions; preserved early responses do not exclude later dysfunction.
  evidence:
  - reference: PMID:23656588
    reference_title: Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Defects were detected at the hypothalamic and pituitary levels of the reproductive endocrine axis.
    explanation: The original clinical investigation localizes central endocrine dysfunction.
  - reference: PMID:27441066
    reference_title: Ataxia and Hypogonadotropic Hypogonadism with Intrafamilial Variability Caused by RNF216 Mutation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Reproductive endocrine evaluation in both patients revealed only low levels of LH and testosterone, no other pituitary hormones were affected.
    explanation: The RNF216 brothers illustrate a selective reproductive endocrine deficit.
progression:
- phase: Endocrine-first presentation
  subtype: RNF216-related Gordon Holmes syndrome
  notes: Hypogonadotropic hypogonadism may precede overt neurologic signs. A normal neurologic examination during an endocrine presentation does not exclude later disease.
  evidence:
  - reference: PMID:39444518
    reference_title: Hypogonadotropic Hypogonadism as First Presentation of the Severe Neuroendocrine Disorder Caused by RNF216.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: hypogonadotropic hypogonadism may be the initial manifestation of this severe neuroendocrine disorder, especially in males.
    explanation: The report documents an endocrine-first presentation.
- phase: Variable neurologic progression
  subtype: RNF216-related Gordon Holmes syndrome
  notes: Ataxia and cognitive dysfunction may progress substantially, with intrafamilial variation. Available cases do not establish a reliable survival estimate or a uniform progression rate.
  evidence:
  - reference: PMID:27441066
    reference_title: Ataxia and Hypogonadotropic Hypogonadism with Intrafamilial Variability Caused by RNF216 Mutation.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: His disease progressively worsened with clear cognitive deterioration and need for support in daily activities to the degree that he became totally dependent.
    explanation: The older RNF216 brother developed severe functional dependence; the younger brother had milder disease at assessment.
- phase: Slowly progressive PNPLA6-related ataxia
  subtype: PNPLA6-related Gordon Holmes syndrome
  notes: A mixed PNPLA6 cohort that included three GHS cases showed slow cerebellar progression with retained ambulation. The cohort mean is not a GHS-specific prognosis.
  evidence:
  - reference: PMID:35069422
    reference_title: 'Multifaceted and Age-Dependent Phenotypes Associated With Biallelic PNPLA6 Gene Variants: Eight Novel Cases and Review of the Literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Progression of cerebellar symptoms was slow in all patients, who retained ambulation even after a mean disease duration of 15 years.
    explanation: The observation covers all ataxic patients in a mixed PNPLA6 cohort, including GHS and other phenotypes.
clinical_trials:
- name: NCT01793168
  phase: NOT_APPLICABLE
  status: RECRUITING
  description: CoRDS is an international observational rare-disease registry. Its listed conditions include cerebellar ataxia-hypogonadism; it supports patient-researcher connection and data collection rather than testing a GHS treatment.
  notes: Registry status checked against the ClinicalTrials.gov API on 2026-10-05; the record was last updated on 2025-05-29. Enrollment is broad and includes rare disease, unknown prevalence, undiagnosed participants and unaffected carriers.
  evidence:
  - reference: clinicaltrials:NCT01793168
    reference_title: Coordination of Rare Diseases at Sanford
    supports: SUPPORT
    evidence_source: OTHER
    snippet: It provides researchers with a centralized, international patient registry for all rare diseases.
    explanation: The registry summary describes broad observational rare-disease research rather than a treatment trial; the API evidence separately establishes the listed syndrome, study type and current recruitment status.
  - reference: url:https://clinicaltrials.gov/api/v2/studies/NCT01793168
    reference_title: https://clinicaltrials.gov/api/v2/studies/NCT01793168
    supports: SUPPORT
    evidence_source: OTHER
    snippet: '"overallStatus":"RECRUITING" ... It provides researchers with a centralized, international patient registry for all rare diseases. ... "Cerebellar Ataxia - Hypogonadism" ... "studyType":"OBSERVATIONAL"'
    explanation: The current record identifies recruiting observational registry research, describes its broad rare-disease scope and explicitly lists cerebellar ataxia-hypogonadism.
biochemical:
- name: Reduced PNPLA6 neuropathy target esterase activity
  subtypes:
  - PNPLA6-related Gordon Holmes syndrome
  presence: Reduced
  notes: Variant-function research measure. Patient-level residual activity in the 2024 analysis was estimated from the two independently tested alleles. These estimates are not a validated individual clinical cutoff or age-at-onset predictor.
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC11146429/?report=classic
    reference_title: Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders - PMC
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: The NTE activity of all disease-associated missense/in-frame and truncating variants was significantly reduced compared to the wild-type control
    explanation: Full-length protein assays support impaired NTE activity.
  readouts:
  - target: PNPLA6 / Neuropathy Target Esterase Phospholipid Dysfunction
    relationship: READOUT_OF
    interpretation: The esterase assay measures the functional deficit; interpretation depends on the particular genotype and experimental assay.
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC11146429/?report=classic
      reference_title: Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders - PMC
      supports: SUPPORT
      evidence_source: COMPUTATIONAL
      snippet: Individual genotype activity levels were determined by the average activity of the two individual variants.
      explanation: The study separates individual variant assays from estimated biallelic genotype activity.
📚

References & Deep Research

References

1
PMID:25299038
PNPLA6 Disorders.
No top-level findings curated for this source.

Deep Research

1

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Falcon ▸
Disease Characteristics Research Template
Edison Scientific Literature 55 citations 2026-06-04T16:07:15.056939

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Disease Characteristics Research Template

Target Disease

  • Disease Name: Cerebellar Ataxia-Hypogonadism Syndrome
  • MONDO ID: (if available)
  • Category: Mendelian

Research Objectives

Please provide a comprehensive research report on Cerebellar Ataxia-Hypogonadism Syndrome covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.

For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.

1. Disease Information

Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed

  • What is the disease? Provide a concise overview.
  • What are the key identifiers? (OMIM, Orphanet, ICD-10/ICD-11, MeSH, Mondo)
  • What are the common synonyms and alternative names?
  • Is the information derived from individual patients (e.g., EHR) or aggregated disease-level resources?

2. Etiology

  • Disease Causal Factors: What are the primary causes? (genetic, environmental, infectious, mechanistic)
  • Risk Factors:

    Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases

  • Genetic risk factors (causal variants, susceptibility loci, modifier genes)
  • Environmental risk factors (toxins, lifestyle, occupational exposures, age, sex, family history)
  • Protective Factors:

    Search first: PubMed, Cochrane Library, clinical trial databases, GWAS Catalog, gnomAD, WHO, CDC, nutrition databases

  • Genetic protective factors (protective variants, modifier alleles)
  • Environmental protective factors (diet, lifestyle, exposures that reduce risk)
  • Gene-Environment Interactions: How do genetic and environmental factors interact to influence disease?

    Search first: CTD, PubMed, PheGenI, GxE databases

3. Phenotypes

Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC

For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities

For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype

4. Genetic/Molecular Information

  • Causal Genes: Gene mutations or chromosomal abnormalities responsible for disease (gene symbols, OMIM IDs)

    Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene

  • Pathogenic Variants:
  • Affected genes (gene symbols, HGNC IDs) > Search first: OMIM, NCBI Gene, Ensembl, HGNC, UniProt, GeneCards
  • Variant classification (pathogenic, likely pathogenic, VUS per ACMG/AMP guidelines) > Search first: ClinVar, ClinGen, ACMG/AMP guidelines, VarSome
  • Variant type/class (missense, frameshift, nonsense, splice-site, structural)
  • Allele frequency in population databases > Search first: gnomAD, 1000 Genomes, ExAC, TOPMed, dbSNP
  • Somatic vs germline origin > Search first: COSMIC (somatic), ClinVar, ICGC, TCGA
  • Functional consequences (loss of function, gain of function, dominant negative)
  • Modifier Genes: Genes that modify disease severity or expression
  • Epigenetic Information: DNA methylation, histone modifications, chromatin changes affecting disease

    Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

  • Chromosomal Abnormalities: Large-scale genetic changes (aneuploidy, translocations, inversions)

    Search first: DECIPHER, ClinVar, ECARUCA, UCSC Genome Browser

5. Environmental Information

  • Environmental Factors: Non-genetic contributing factors (toxins, radiation, pollution, occupational exposure)

    Search first: CTD (Comparative Toxicogenomics Database), TOXNET, PubMed, EPA databases

  • Lifestyle Factors: Behavioral factors (smoking, diet, exercise, alcohol consumption)

    Search first: CDC databases, WHO, PubMed, NHANES

  • Infectious Agents: If applicable, pathogens causing or triggering disease (bacteria, viruses, fungi, parasites)

    Search first: NCBI Taxonomy, ViPR, BV-BRC, MicrobeDB, GIDEON

6. Mechanism / Pathophysiology

  • Molecular Pathways: Specific signaling cascades or biochemical pathways involved (Wnt, MAPK, mTOR, PI3K-AKT, etc.)

    Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc

  • Cellular Processes: Cell-level mechanisms (apoptosis, autophagy, cell cycle dysregulation, inflammation, etc.)

    Search first: Gene Ontology (GO), Reactome, KEGG, PubMed

  • Protein Dysfunction: How protein structure or function is altered (misfolding, aggregation, loss of function, gain of function)

    Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold

  • Metabolic Changes: Alterations in metabolic processes (energy metabolism, lipid metabolism, amino acid metabolism)

    Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA

  • Immune System Involvement: Role of immune response (autoimmunity, immunodeficiency, chronic inflammation)

    Search first: ImmPort, Immunome Database, IEDB, Gene Ontology

  • Tissue Damage Mechanisms: How tissues/ are injured (oxidative stress, ischemia, fibrosis, necrosis)

    Search first: PubMed, Gene Ontology, Reactome

  • Biochemical Abnormalities: Specific molecular defects (enzyme deficiencies, receptor dysfunction, ion channel defects)

    Search first: BRENDA, UniProt, KEGG, OMIM, PubMed

  • Epigenetic Changes: DNA methylation, histone modifications affecting gene expression in disease

    Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth

  • Molecular Profiling (if available):
  • Transcriptomics/gene expression changes > Search first: GEO (Gene Expression Omnibus), ArrayExpress, GTEx, Human Cell Atlas, SRA
  • Proteomics findings > Search first: PRIDE, ProteomeXchange, Human Protein Atlas, STRING, BioGRID
  • Metabolomics signatures > Search first: MetaboLights, Metabolomics Workbench, HMDB, METLIN
  • Lipidomics alterations > Search first: LIPID MAPS, SwissLipids, LipidHome, Metabolomics Workbench
  • Genomic structural features > Search first: UCSC Genome Browser, Ensembl, NCBI, dbVar, DGV
  • Advanced Technologies (if applicable):
  • Single-cell analysis findings (cell-type specific mechanisms, cellular heterogeneity) > Search first: Human Cell Atlas, Single Cell Portal, GEO, CELLxGENE
  • Spatial transcriptomics findings > Search first: GEO, Spatial Research, Vizgen, 10x Genomics data
  • Multi-omics integration results > Search first: TCGA, ICGC, cBioPortal, LinkedOmics, PubMed
  • Functional genomics screens (CRISPR, RNAi) > Search first: DepMap, GenomeRNAi, PubMed, BioGRID ORCS

For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types

7. Anatomical Structures Affected

  • Organ Level:
  • Primary organs directly affected
  • Secondary organ involvement (complications, secondary effects)
  • Body systems involved (cardiovascular, nervous, digestive, respiratory, endocrine, etc.)

    Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT

  • Tissue and Cell Level:
  • Specific tissue types affected (epithelial, connective, muscle, nervous)
  • Specific cell populations targeted (with Cell Ontology terms)

    Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB

  • Subcellular Level:
  • Cellular compartments involved (mitochondria, nucleus, ER, lysosomes) (with GO Cellular Component terms)

    Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas

  • Localization:
  • Specific anatomical sites (with UBERON terms) > Search first: FMA, Uberon, NeuroNames (for brain), SNOMED CT
  • Lateralization (unilateral, bilateral, asymmetric) > Search first: HPO, clinical literature, imaging databases

8. Temporal Development

  • Onset:
  • Typical age of onset (congenital, pediatric, adult, geriatric)
  • Onset pattern (acute, subacute, chronic, insidious)

    Search first: OMIM, Orphanet, HPO, PubMed

  • Progression:
  • Disease stages (early, intermediate, advanced, end-stage) > Search first: Cancer Staging Manual (AJCC), WHO classifications, PubMed
  • Progression rate (rapid, slow, variable)
  • Disease course pattern (episodic, relapsing-remitting, progressive, stable)
  • Disease duration (self-limited, chronic lifelong)

    Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM

  • Patterns:
  • Remission patterns (spontaneous, treatment-induced) > Search first: Clinical trial databases, disease registries, PubMed
  • Critical periods (time windows of vulnerability or opportunity for intervention) > Search first: PubMed, developmental biology databases, clinical guidelines

9. Inheritance and Population

  • Epidemiology:
  • Prevalence (cases per 100,000 at given time)
  • Incidence (new cases per 100,000 per year)

    Search first: Orphanet, CDC, WHO, GBD (Global Burden of Disease), national registries, SEER, disease registries

  • For Genetic Etiology:
  • Inheritance pattern (AD, AR, X-linked, mitochondrial, multifactorial, polygenic) > Search first: OMIM, Orphanet, ClinVar, GTR (Genetic Testing Registry)
  • Penetrance (complete, incomplete, age-dependent) > Search first: ClinVar, OMIM, PubMed, ClinGen
  • Expressivity (variable, consistent) > Search first: OMIM, ClinVar, PubMed
  • Genetic anticipation (increasing severity in successive generations) > Search first: OMIM, PubMed (especially for repeat expansion disorders)
  • Germline mosaicism > Search first: ClinVar, OMIM, genetic counseling literature, PubMed
  • Founder effects (population-specific mutations) > Search first: gnomAD, population genetics databases, PubMed
  • Consanguinity role > Search first: OMIM, population studies, genetic counseling resources
  • Carrier frequency > Search first: gnomAD, carrier screening databases, GeneReviews, GTR
  • Population Demographics:
  • Affected populations (ethnic or demographic groups with higher prevalence) > Search first: gnomAD, 1000 Genomes, PAGE Study, PubMed, population registries
  • Geographic distribution (endemic areas, regional variation) > Search first: WHO, CDC, GBD, Orphanet, geographic epidemiology databases
  • Geographic distribution of specific variants
  • Sex ratio (male:female) > Search first: Disease registries, OMIM, PubMed, epidemiological databases
  • Age distribution of affected individuals > Search first: CDC, disease registries, SEER, Orphanet

10. Diagnostics

  • Clinical Tests:
  • Laboratory tests (blood, urine, tissue chemistry, specific enzyme assays) > Search first: LOINC, LabTests Online, PubMed
  • Biomarkers (proteins, metabolites, genetic markers, circulating biomarkers) > Search first: FDA Biomarker List, BEST (Biomarkers, EndpointS, and other Tools), PubMed
  • Imaging studies (X-ray, CT, MRI, PET, ultrasound) > Search first: RadLex, DICOM, Radiopaedia, imaging databases
  • Functional tests (pulmonary function, cardiac stress tests) > Search first: LOINC, clinical guidelines, PubMed
  • Electrophysiology (EEG, EMG, ECG, nerve conduction studies) > Search first: LOINC, clinical neurophysiology databases, PubMed
  • Biopsy findings (histopathology, immunohistochemistry) > Search first: SNOMED CT, College of American Pathologists resources, PubMed
  • Pathology findings (microscopic examination) > Search first: SNOMED CT, Digital Pathology databases, PubMed
  • Genetic Testing:

    Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen

  • Overview of recommended genetic testing approach
  • Whole genome sequencing (WGS) utility > Search first: GTR, ClinVar, GEL (Genomics England), gnomAD
  • Whole exome sequencing (WES) utility > Search first: GTR, ClinVar, OMIM, GeneMatcher
  • Gene panels (which panels, which genes) > Search first: GTR, ClinVar, laboratory-specific databases
  • Single gene testing > Search first: GTR, ClinVar, OMIM, GeneReviews
  • Chromosomal microarray (CMA) > Search first: DECIPHER, ClinVar, dbVar, ECARUCA
  • Karyotyping > Search first: Chromosome Abnormality Database, ClinVar, cytogenetics resources
  • FISH > Search first: ClinVar, cytogenetics databases, PubMed
  • Mitochondrial DNA testing > Search first: MITOMAP, MSeqDR, ClinVar, GTR
  • Repeat expansion testing > Search first: GTR, ClinVar, repeat expansion databases, PubMed
  • Omics-Based Diagnostics (if applicable):
  • RNA sequencing / transcriptomics > Search first: GEO, ArrayExpress, GTEx, RNA-seq databases
  • Proteomics > Search first: PRIDE, ProteomeXchange, FDA Biomarker database
  • Metabolomics > Search first: MetaboLights, Metabolomics Workbench, HMDB
  • Epigenomics > Search first: GEO, ENCODE, Roadmap Epigenomics, MethBase
  • Liquid biopsy > Search first: COSMIC, ClinVar, liquid biopsy databases, PubMed
  • Clinical Criteria:
  • Standardized diagnostic criteria (DSM, ICD, society guidelines) > Search first: DSM-5, ICD-11, clinical society guidelines, UpToDate
  • Differential diagnosis (other conditions to rule out, with distinguishing features) > Search first: DynaMed, UpToDate, clinical decision support systems
  • Screening:
  • Screening methods for asymptomatic individuals (newborn screening, carrier screening, cascade screening) > Search first: ACMG recommendations, CDC newborn screening, GTR

11. Outcome/Prognosis

  • Survival and Mortality:
  • Survival rate (5-year, 10-year, overall) > Search first: SEER, cancer registries, disease-specific registries, PubMed
  • Life expectancy (with and without treatment if applicable) > Search first: Orphanet, disease registries, actuarial databases, PubMed
  • Mortality rate > Search first: CDC, WHO, GBD, national mortality databases
  • Disease-specific mortality (deaths directly attributable to disease) > Search first: Disease registries, CDC Wonder, GBD, PubMed
  • Morbidity and Function:
  • Morbidity (disease-related disability and health impacts) > Search first: GBD, WHO, disability databases, PubMed
  • Disability outcomes (long-term functional impairments) > Search first: ICF (International Classification of Functioning), disability registries
  • Quality of life measures (EQ-5D, SF-36, PROMIS, disease-specific tools) > Search first: EQ-5D database, SF-36, PROMIS, PubMed
  • Disease Course:
  • Complications (secondary problems: infections, organ failure, etc.) > Search first: ICD codes, disease registries, clinical databases, PubMed
  • Recovery potential (likelihood and extent of recovery, with vs without treatment) > Search first: Natural history studies, rehabilitation databases, PubMed
  • Prediction:
  • Prognostic factors (age, disease severity, biomarkers, treatment response) > Search first: Prognostic models databases, clinical calculators, PubMed
  • Prognostic biomarkers (molecular markers predicting disease course) > Search first: FDA Biomarker database, PubMed, cancer prognostic databases

12. Treatment

  • Pharmacotherapy:
  • Pharmacological treatments (drug names, drug classes, mechanisms of action) > Search first: DrugBank, RxNorm, ATC classification, DailyMed, FDA databases
  • Pharmacogenomics (how genetic variants affect drug metabolism, efficacy, toxicity) > Search first: PharmGKB, CPIC (Clinical Pharmacogenetics), FDA Table of PGx Biomarkers
  • Advanced Therapeutics:
  • Gene therapy (viral vectors, CRISPR, gene replacement, gene editing) > Search first: ClinicalTrials.gov, FDA gene therapy database, ASGCT resources
  • Cell therapy (stem cell transplant, CAR-T, cellular therapeutics) > Search first: ClinicalTrials.gov, FDA cell therapy database, FACT standards
  • RNA-based therapies (ASOs, siRNA, mRNA therapies) > Search first: ClinicalTrials.gov, FDA approvals, PubMed
  • Targeted therapies (treatments directed at specific molecular targets) > Search first: My Cancer Genome, OncoKB, ClinicalTrials.gov, FDA approvals
  • Immunotherapies (checkpoint inhibitors, monoclonal antibodies) > Search first: Cancer Immunotherapy Database, FDA approvals, ClinicalTrials.gov
  • Surgical and Interventional:
  • Surgical interventions (types of surgery, timing, outcomes) > Search first: CPT codes, surgical registries, clinical guidelines, PubMed
  • Supportive and Rehabilitative:
  • Supportive care (symptom management, pain control, nutrition) > Search first: Clinical guidelines, Cochrane Library, PubMed
  • Rehabilitation (physical therapy, occupational therapy, speech therapy) > Search first: Rehabilitation medicine databases, clinical guidelines, PubMed
  • Experimental:
  • Experimental treatments in clinical trials (with NCT identifiers if available) > Search first: ClinicalTrials.gov, EU Clinical Trials Register, WHO ICTRP
  • Treatment Outcomes:
  • Treatment response rates > Search first: Clinical trial databases, FDA reviews, systematic reviews, PubMed
  • Side effects and adverse events > Search first: FDA Adverse Event Reporting System (FAERS), MedWatch, PubMed
  • Treatment Strategy:
  • Treatment algorithms (clinical pathways, decision trees) > Search first: Clinical practice guidelines, NCCN Guidelines, UpToDate
  • Combination therapies > Search first: ClinicalTrials.gov, treatment guidelines, PubMed
  • Personalized medicine approaches (genotype-guided treatment) > Search first: My Cancer Genome, CIViC, PharmGKB, precision medicine databases

For each treatment, suggest MAXO (Medical Action Ontology) terms where applicable.

13. Prevention

  • Prevention Levels:
  • Primary prevention (preventing disease occurrence: vaccination, risk factor modification) > Search first: CDC, WHO, USPSTF recommendations, Cochrane Library
  • Secondary prevention (early detection and treatment: screening programs, early intervention) > Search first: USPSTF, CDC screening guidelines, WHO
  • Tertiary prevention (preventing complications in those with disease) > Search first: Clinical guidelines, disease management protocols, PubMed
  • Immunization: Vaccine strategies (if applicable)

    Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database

  • Screening and Early Detection:
  • Screening programs (population-based: newborn screening, cancer screening) > Search first: CDC screening programs, USPSTF, cancer screening databases
  • Genetic screening (carrier screening, preimplantation genetic diagnosis, prenatal testing) > Search first: ACMG recommendations, ACOG guidelines, GTR
  • Risk stratification (identifying high-risk individuals for targeted prevention) > Search first: Risk prediction models, clinical calculators, PubMed
  • Behavioral Interventions: Lifestyle modifications to reduce risk

    Search first: CDC, WHO, behavioral intervention databases, Cochrane Library

  • Counseling: Genetic counseling (risk assessment, family planning guidance)

    Search first: NSGC resources, ACMG guidelines, GeneReviews

  • Public Health:
  • Public health interventions (sanitation, vector control, health education) > Search first: CDC, WHO, public health databases, PubMed
  • Environmental interventions (reducing environmental risk factors) > Search first: EPA databases, WHO environmental health, PubMed
  • Prophylaxis: Preventive medications or procedures

    Search first: Clinical guidelines, FDA approvals, PubMed

14. Other Species / Natural Disease

  • Taxonomy: Species affected (with NCBI Taxon identifiers)

    Search first: NCBI Taxonomy

  • Breed: Specific breeds affected (with VBO identifiers if applicable)

    Search first: VBO (Vertebrate Breed Ontology)

  • Gene: Orthologous genes in other species (with NCBI Gene IDs)

    Search first: NCBI Gene

  • Natural Disease:
  • Naturally occurring disease in other species (companion animals, wildlife) > Search first: OMIA (Online Mendelian Inheritance in Animals), VetCompass, PubMed
  • Veterinary relevance and importance in animal health > Search first: OMIA, veterinary databases, PubMed
  • Comparative Biology:
  • Comparative pathology (similarities and differences across species) > Search first: OMIA, comparative pathology databases, PubMed
  • Evolutionary conservation of disease mechanisms > Search first: HomoloGene, OrthoMCL, Alliance of Genome Resources
  • Transmission (if applicable):
  • Zoonotic potential > Search first: CDC zoonotic diseases, WHO zoonoses, GIDEON
  • Cross-species susceptibility > Search first: NCBI Taxonomy, veterinary databases, PubMed

15. Model Organisms

  • Model Types:
  • Model organism type (mammalian, invertebrate, cellular, in vitro) > Search first: Alliance of Genome Resources, model organism databases
  • Specific model systems (mouse, rat, zebrafish, Drosophila, C. elegans, yeast, cell lines, organoids, iPSCs) > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, SGD, ATCC, Cellosaurus
  • Induced models (drug treatment, surgical intervention, environmental manipulation) > Search first: MGI, model organism databases, PubMed
  • Genetic Models:
  • Types available (knockout, knock-in, transgenic, conditional, humanized) > Search first: MGI, IMPC, KOMP, EuMMCR, IMSR
  • Model Characteristics:
  • Phenotype recapitulation (how well model reproduces human disease features) > Search first: Model organism databases, comparative studies, PubMed
  • Model limitations (aspects of human disease not captured) > Search first: Model organism databases, PubMed, review articles
  • Applications:
  • Research applications (what aspects of disease can be studied) > Search first: Model organism databases, PubMed
  • Resources:
  • Model databases > Search first: MGI, RGD, ZFIN, FlyBase, WormBase, IMSR, EMMA, MMRRC

Citation Requirements

  • Cite primary literature (PMID preferred) for all mechanistic and clinical claims
  • Prioritize recent reviews and landmark papers
  • Include direct quotes from abstracts where possible to support key statements
  • Distinguish evidence source types: human clinical, model organism, in vitro, computational

Output Format

Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, MAXO, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease

This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (MAXO terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details

Cerebellar Ataxia–Hypogonadism Syndrome (Gordon Holmes syndrome spectrum): comprehensive disease characteristics report

Executive summary

Cerebellar ataxia–hypogonadism syndrome is a rare, genetically heterogeneous, Mendelian neurodegenerative–neuroendocrine disorder classically described as Gordon Holmes syndrome (GHS), with a core association of progressive cerebellar ataxia and hypogonadotropic hypogonadism (HH) and frequent additional features such as cognitive decline/dementia and other movement disorders. Multiple genes converge on protein homeostasis/ubiquitin signaling (e.g., RNF216, OTUD4, STUB1/CHIP) or phospholipid metabolism (PNPLA6), producing overlapping syndromic entities such as GHS and Boucher–Neuhauser syndrome (BNHS) (ataxia–HH–chorioretinal dystrophy). Recent case reports (2023–2024) expand the phenotype (e.g., pituitary/white-matter imaging findings; endocrine-first presentations) and add mechanistic insight from new animal model work implicating microglia/neuroinflammation in RNF216-related disease. (shi2014ataxiaandhypogonadism pages 1-2, rochtus2024hypogonadotropichypogonadismas pages 1-2, george2024gordonholmessyndrome pages 1-2, nanetti2022multifacetedandagedependent pages 1-2)

1. Disease information

1.1 Definition and current understanding

Gordon Holmes syndrome (GHS) is defined in primary literature as a Mendelian neurodegenerative disorder characterized by ataxia and hypogonadism (“Gordon Holmes syndrome (GHS) is a rare Mendelian neurodegenerative disorder characterized by ataxia and hypogonadism.”). (shi2014ataxiaandhypogonadism pages 1-2)

A 2024 endocrine case report explicitly situates the disorder as a neuroendocrine condition in which HH may precede neurodegeneration and notes the phenotype combination “first described as Gordon Holmes syndrome.” (rochtus2024hypogonadotropichypogonadismas pages 1-2)

Related/overlapping syndromes within the ataxia–hypogonadism spectrum include: - Boucher–Neuhauser syndrome (BNHS/BNS) (ataxia + HH + chorioretinal dystrophy) due to PNPLA6 variants. (liampas2024twocasereports pages 5-8, deik2014compoundheterozygouspnpla6 pages 1-2) - 4H syndrome (hypodontia, hypomyelination, ataxia, hypogonadotropic hypogonadism) reported in association with RNF216 and also POLR3-related leukodystrophy genes in differential lists. (wu2022gordonholmessyndrome pages 7-11, calandra2019gordonholmessyndrome pages 1-4)

1.2 Key identifiers and synonyms

  • OMIM/MIM: The syndrome is labeled Gordon Holmes syndrome, MIM #212840 in 2023 and 2024 sources. (kallupurakkal2023anovelmutation pages 1-2, rochtus2024hypogonadotropichypogonadismas pages 1-2)
  • BNHS MIM: Boucher–Neuhauser syndrome, MIM #215470; PNPLA6 gene, MIM #603197. (deik2014compoundheterozygouspnpla6 pages 1-2)
  • Other curated identifiers (MONDO, Orphanet, MeSH, ICD-10/ICD-11): Not present in the retrieved full-text evidence for this run; therefore not reported here. (No direct evidence found in provided corpus)

1.3 Synonyms / alternative names

  • “Gordon Holmes syndrome” is used as the syndromic name for the ataxia–hypogonadism association; the broader entry term in many contexts is “ataxia–hypogonadotropic hypogonadism” (as used in clinical descriptions and titles). (alqwaifly2016ataxiaandhypogonadotropic pages 1-2, rochtus2024hypogonadotropichypogonadismas pages 1-2)

1.4 Evidence source type

The disease characterization in this report is derived from: - Primary human studies/case reports/series (NEJM 2013; multiple 2014–2024 case reports and cohorts). (margolin2013ataxiadementiaand pages 9-11, kallupurakkal2023anovelmutation pages 1-2, celik2023anovelmutation pages 1-2, nanetti2022multifacetedandagedependent pages 1-2) - Model organism studies (Rnf216 knockout mice; CHIP/STUB1 functional work and mouse phenotyping). (george2024gordonholmessyndrome pages 1-2, shi2014ataxiaandhypogonadism pages 1-2)

2. Etiology

2.1 Disease causal factors (genetic/mechanistic)

This is primarily a genetic (Mendelian) disorder with multiple causal genes: - RNF216 biallelic pathogenic variants cause a syndrome characterized by HH with neurodegeneration (ataxia ± chorea ± cognitive impairment), historically termed GHS. (rochtus2024hypogonadotropichypogonadismas pages 1-2) - STUB1 (CHIP) biallelic variants can cause ataxia with HH consistent with GHS, attributed to impaired ubiquitin ligase activity and protein quality control. (shi2014ataxiaandhypogonadism pages 1-2) - PNPLA6 biallelic variants cause overlapping disorders including GHS and BNHS with endocrine and neuro-ophthalmologic manifestations. (nanetti2022multifacetedandagedependent pages 1-2, deik2014compoundheterozygouspnpla6 pages 1-2)

A key mechanistic theme is disordered ubiquitination/protein homeostasis in RNF216/OTUD4/STUB1-related disease. (margolin2013ataxiadementiaand pages 9-11, shi2014ataxiaandhypogonadism pages 1-2)

2.2 Risk factors

  • Genetic risk factors: biallelic pathogenic variants in RNF216, STUB1, PNPLA6; in some families digenic/oligogenic inheritance has been reported (RNF216 with OTUD4; and other interacting genes in reviews). (margolin2013ataxiadementiaand pages 9-11, wu2022gordonholmessyndrome pages 1-4)

  • Family history/consanguinity: multiple reports highlight homozygous variants and parental heterozygosity consistent with recessive inheritance; consanguinity is frequent in recessive ataxia syndromes and reported in PNPLA6 and RNF216 cases. (deik2014compoundheterozygouspnpla6 pages 1-2, calandra2019gordonholmessyndrome pages 1-4, canbek2024…>g pages 2-4)

  • Environmental risk factors: not established in the retrieved evidence; one animal model paper notes that “compound mutations or environmental factors may worsen phenotype” as a general consideration rather than a proven interaction. (george2024gordonholmessyndrome pages 16-17)

2.3 Protective factors

No protective genetic or environmental factors were identified in the retrieved evidence. (No direct evidence found)

2.4 Gene–environment interactions

Not established in the retrieved evidence beyond speculative mention that environmental factors could modulate phenotype severity. (george2024gordonholmessyndrome pages 16-17)

3. Phenotypes

3.1 Core neurologic and endocrine phenotypes

Across the GHS spectrum, commonly reported features include: - Cerebellar ataxia (gait instability, dysarthria, nystagmus) with cerebellar atrophy on MRI. (shi2014ataxiaandhypogonadism pages 1-2) - Hypogonadotropic hypogonadism presenting as delayed/absent puberty, primary amenorrhea, low gonadotropins/sex steroids; HH may be an initial presentation in RNF216-related disease. (rochtus2024hypogonadotropichypogonadismas pages 1-2, alqwaifly2016ataxiaandhypogonadotropic pages 1-2) - Cognitive decline/dementia is frequently described in RNF216-related and some STUB1-related disease. (margolin2013ataxiadementiaand pages 9-11, celik2023anovelmutation pages 1-2) - Additional movement disorders can include chorea, parkinsonism, dystonia, and tremor in some cases. (rochtus2024hypogonadotropichypogonadismas pages 1-2, celik2023anovelmutation pages 1-2, kallupurakkal2023anovelmutation pages 1-2)

3.2 Phenotype frequency data (recent cohort statistics)

Because the term “Cerebellar ataxia–hypogonadism syndrome” encompasses multiple genes, the most quantitative frequency data in the retrieved corpus come from a PNPLA6 cohort: - In Nanetti et al. 2022 (probe-based panel screening of 292 ataxia/spastic paraplegia patients), PNPLA6 variants were found in 8/292 (2.7%); among these 8: - Cerebellar ataxia: 7/8 - Hypogonadotropic hypogonadism: 5/8 - Cerebellar atrophy on MRI: 6/8 (with vermian predominance) - Peripheral axonal neuropathy: 4/8 - Cognitive impairment: 3/8 - Chorioretinal dystrophy: 2/8 - Growth hormone deficiency: 2/8 - Vestibular areflexia with reduced VVOR: 1/8 - Natural history: slow progression, with retained ambulation after a mean disease duration of 15 years. (nanetti2022multifacetedandagedependent pages 1-2)

BNHS-specific literature review frequency data (primarily visual phenotype) were summarized in a 2021 ophthalmic genetics report (review of molecularly confirmed PNPLA6-BNHS): - Chorioretinal dystrophy: 96.4% in the reviewed BNHS cases. - First presenting symptoms in their compiled cases included delayed puberty 32.1% and ataxia 28.6%. (dogan2021chorioretinaldystrophyhypogonadotropic pages 1-3)

3.3 Onset, severity, progression

  • RNF216-related GHS: neurologic features often emerge in adolescence/young adulthood; HH may precede neurologic features and can be the presenting complaint (endocrine-first). (rochtus2024hypogonadotropichypogonadismas pages 1-2)
  • PNPLA6-related disease: age-dependent manifestation is emphasized; in Nanetti et al. 2022, infantile/juvenile onset occurred in 6/8, with adult onset in 2/8, and symptom type varied by age (retinal symptoms early, HH juvenile, ataxia adult). (nanetti2022multifacetedandagedependent pages 1-2)

3.4 Quality-of-life impact

Direct QoL instrument data (EQ-5D, SF-36, PROMIS) were not identified in the retrieved evidence. Nonetheless, reported features imply substantial functional impact via progressive gait ataxia, endocrine dysfunction (pubertal failure/infertility), neurocognitive decline, and visual loss (in BNHS). (liampas2024twocasereports pages 5-8, rochtus2024hypogonadotropichypogonadismas pages 1-2, shi2014ataxiaandhypogonadism pages 1-2)

3.5 Suggested HPO terms (examples)

(These are ontology suggestions for curation; they are not claims of prevalence beyond the cited clinical evidence.) - Cerebellar ataxia HP:0001251 - Dysarthria HP:0001260 - Nystagmus HP:0000639 (incl. gaze-evoked) - Cerebellar atrophy HP:0001272 - Hypogonadotropic hypogonadism HP:0000046 - Delayed puberty HP:0000821 / Primary amenorrhea HP:0000786 - Cognitive impairment HP:0100543 / Dementia HP:0000726 - Chorea HP:0002072 - White matter abnormalities / leukoencephalopathy HP:0002500 - Chorioretinal dystrophy HP:0000602 / Vision loss HP:0000572 - Peripheral axonal neuropathy HP:0003477

4. Genetic / molecular information

4.1 Causal genes (current evidence-backed set)

Genes directly implicated in the retrieved primary literature include RNF216, OTUD4 (digenic with RNF216), STUB1 (CHIP), PNPLA6. (margolin2013ataxiadementiaand pages 9-11, shi2014ataxiaandhypogonadism pages 1-2, rochtus2024hypogonadotropichypogonadismas pages 1-2, nanetti2022multifacetedandagedependent pages 1-2)

Additional genes are listed as associated with ataxia–hypogonadism overlap (e.g., POLR3A/POLR3B/POLR1C in 4H syndrome context) but without variant-level evidence in the retrieved snippets. (calandra2019gordonholmessyndrome pages 1-4, wu2022gordonholmessyndrome pages 7-11)

4.2 Pathogenic variants and types (examples from evidence)

Representative variants reported in the retrieved evidence include: - RNF216: splice-site (c.2061G>A), frameshift (c.1860_1861dupCT; c.591_592insTG), nonsense (c.1549C>T), missense (c.2042C>T p.P606L). (alqwaifly2016ataxiaandhypogonadotropic pages 1-2, celik2023anovelmutation pages 1-2, kallupurakkal2023anovelmutation pages 1-2, wu2022gordonholmessyndrome pages 7-11, calandra2019gordonholmessyndrome pages 1-4) - STUB1: homozygous missense c.737C>T (p.Thr246Met) causing loss of ubiquitin ligase activity. (shi2014ataxiaandhypogonadism pages 1-2) - PNPLA6: missense variants including c.3524C>G (p.Ser1175Cys), c.3323G>A (p.Arg1108Gln), c.3380C>G (p.Ser1127Cys). (dogan2021chorioretinaldystrophyhypogonadotropic pages 1-3, liampas2024twocasereports pages 1-5, canbek2024…>g pages 2-4)

Variant classification (ACMG) is reported variably; e.g., a 2024 PNPLA6 report presents p.Arg1108Gln as a VUS in that family context. (liampas2024twocasereports pages 5-8)

4.3 Functional consequences and pathways

  • RNF216 encodes an RBR-class E3 ubiquitin ligase, with pathogenic variants clustering in the RBR domain or C-terminal extension and presumed to disrupt E3 activity in GHS. (rochtus2024hypogonadotropichypogonadismas pages 1-2, wu2022gordonholmessyndrome pages 1-4)
  • STUB1/CHIP: “CHIP plays a central role in regulating protein quality control” and the p.Thr246Met mutation causes “a loss of ubiquitin ligase activity,” linking impaired ubiquitination/proteostasis to ataxia and HH. (shi2014ataxiaandhypogonadism pages 1-2)
  • PNPLA6 encodes neuropathy target esterase (NTE), an ER-localized lysophospholipase; PNPLA6-related phenotypes span neurodegeneration, endocrine dysfunction, and retinal degeneration. (nanetti2022multifacetedandagedependent pages 1-2, deik2014compoundheterozygouspnpla6 pages 1-2)

4.4 Modifier genes / oligogenicity

A landmark human genetics study reported a digenic/epistatic interaction between RNF216 and OTUD4, with experimental support for more severe phenotypes after simultaneous knockdown, and noted the potential for oligogenicity to be increasingly recognized with exome sequencing. (margolin2013ataxiadementiaand pages 9-11)

A later review of RNF216-related cases reports both monogenic recessive and oligogenic patterns involving OTUD4 or other genes. (wu2022gordonholmessyndrome pages 1-4)

4.5 Epigenetics and chromosomal abnormalities

No disease-specific epigenetic mechanisms or recurrent chromosomal abnormalities were identified in the retrieved evidence. (No direct evidence found)

5. Environmental information

No established toxin, lifestyle, radiation, or infectious triggers were identified in the retrieved evidence as causal for this Mendelian syndrome, though phenotype variability may be influenced by non-genetic modifiers in principle. (george2024gordonholmessyndrome pages 16-17)

6. Mechanism / pathophysiology

6.1 Ubiquitin–proteasome / proteostasis mechanisms (RNF216, OTUD4, STUB1)

Primary human genetics and functional evidence link disordered ubiquitination to combined neurodegeneration and HH: - NEJM 2013 describes neuroimaging (cerebellar/cortical atrophy and white-matter hyperintensities) and neuropathology featuring ubiquitin-immunoreactive intranuclear inclusions, implicating ubiquitin pathway dysfunction in the disease biology. (margolin2013ataxiadementiaand pages 9-11) - STUB1/CHIP work demonstrates that introducing a disease mutation into CHIP leads to loss of E3 ubiquitin ligase activity, and notes that loss of CHIP function in mice causes behavioral and reproductive impairments mimicking human phenotypes. (shi2014ataxiaandhypogonadism pages 1-2)

Causal chain (conceptual): biallelic loss-of-function (or loss of critical E3 function) in ubiquitin pathway enzymes → impaired ubiquitination/protein quality control (and possibly autophagy regulation) → accumulation of toxic proteins/inclusions and neural circuit dysfunction → cerebellar and extra-cerebellar neurodegeneration (ataxia, cognitive decline, movement disorders) plus hypothalamic–pituitary–gonadal axis dysfunction (HH). (margolin2013ataxiadementiaand pages 9-11, shi2014ataxiaandhypogonadism pages 1-2, rochtus2024hypogonadotropichypogonadismas pages 1-2)

6.2 Neuroinflammation and microglia (recent 2024 model evidence)

A 2024 Rnf216 knockout mouse study reports sex- and age-dependent microglial alterations in hippocampus/cortex and proposes microglial activation/neuroinflammation as a mechanistic link preceding learning deficits; endocrine changes were also observed in males (elevated FSH, reduced inhibin B; increased IL‑1β). (george2024gordonholmessyndrome pages 16-17)

This work represents a recent development (2024) suggesting potential mechanistic intermediates (microglia, cytokine signaling) that may be upstream contributors to cognitive impairment in RNF216-related disease. (george2024gordonholmessyndrome pages 16-17)

6.3 Lipid/phospholipase biology (PNPLA6)

PNPLA6-associated ataxia–HH syndromes are linked to dysfunction of neuropathy target esterase (lysophospholipase/phospholipid metabolism) with multi-system involvement (cerebellum, retina, peripheral nerves, endocrine axes). (nanetti2022multifacetedandagedependent pages 1-2, deik2014compoundheterozygouspnpla6 pages 1-2)

6.4 Suggested GO biological process / cellular component terms (examples)

(ontology suggestions for curation) - GO:0006511 ubiquitin-dependent protein catabolic process - GO:0016567 protein ubiquitination - GO:0006914 autophagy (for RNF216/STUB1-related discussions) (celik2023anovelmutation pages 1-2, shi2014ataxiaandhypogonadism pages 1-2) - GO:0006954 inflammatory response / GO:0001775 cell activation (microglia-related) (george2024gordonholmessyndrome pages 16-17) - GO cellular component: GO:0005783 endoplasmic reticulum (PNPLA6/NTE is ER-localized) (nanetti2022multifacetedandagedependent pages 1-2)

6.5 Suggested CL cell types (examples)

  • Microglia CL:0000129 (implicated in Rnf216 KO phenotypes) (george2024gordonholmessyndrome pages 16-17)
  • Purkinje cell CL:0000121 (relevant to cerebellar degeneration/ataxia; not directly measured in retrieved evidence)
  • GnRH neuron CL:0000543 (relevant to HH mechanism; endocrine physiology testing supports central HH) (margolin2013ataxiadementiaand pages 9-11, shi2014ataxiaandhypogonadism pages 1-2)

7. Anatomical structures affected

7.1 Organ/system level (evidence-backed)

  • Central nervous system: cerebellum (cerebellar atrophy), cerebral cortex, and cerebral white matter (hyperintensities/leukoencephalopathy). (shi2014ataxiaandhypogonadism pages 1-2, margolin2013ataxiadementiaand pages 9-11, rochtus2024hypogonadotropichypogonadismas pages 1-2)
  • Endocrine/reproductive axis: hypothalamic–pituitary–gonadal axis dysfunction causing HH; pituitary anomalies (e.g., hypoplastic posterior pituitary, partial empty sella) reported in some RNF216 cases. (rochtus2024hypogonadotropichypogonadismas pages 1-2, alqwaifly2016ataxiaandhypogonadotropic pages 1-2)
  • Eye/retina: chorioretinal dystrophy in BNHS/BNS. (liampas2024twocasereports pages 5-8, dogan2021chorioretinaldystrophyhypogonadotropic pages 1-3)
  • Peripheral nervous system: peripheral axonal neuropathy in PNPLA6 cohorts/cases. (nanetti2022multifacetedandagedependent pages 1-2, liampas2024twocasereports pages 1-5)

7.2 Suggested UBERON terms (examples)

  • Cerebellum UBERON:0002037
  • Cerebral cortex UBERON:0000956
  • White matter UBERON:0002319
  • Pituitary gland UBERON:0000007
  • Retina UBERON:0000966
  • Hypothalamus UBERON:0001898

7.3 Subcellular localization (from evidence)

  • PNPLA6/NTE is described as ER-localized in the PNPLA6 cohort paper. (nanetti2022multifacetedandagedependent pages 1-2)

8. Temporal development

  • Onset: often adolescent/young adult for RNF216 and classic GHS, but endocrine-first (pubertal delay) presentations are increasingly recognized. (rochtus2024hypogonadotropichypogonadismas pages 1-2)
  • Progression: neurodegeneration is typically progressive; PNPLA6 cohort data indicate slow progression with preserved ambulation after long durations in many patients. (nanetti2022multifacetedandagedependent pages 1-2)
  • Course patterns: generally chronic progressive; episodic/remitting patterns not described in retrieved evidence. (No direct evidence found)

9. Inheritance and population

9.1 Inheritance patterns

  • Predominantly autosomal recessive with biallelic pathogenic variants (RNF216, STUB1, PNPLA6). (rochtus2024hypogonadotropichypogonadismas pages 1-2, shi2014ataxiaandhypogonadism pages 1-2, nanetti2022multifacetedandagedependent pages 1-2)
  • Digenic/oligogenic inheritance is documented in RNF216-related disease (RNF216 with OTUD4; reported oligogenic fraction in a case-collection analysis). (margolin2013ataxiadementiaand pages 9-11, wu2022gordonholmessyndrome pages 1-4)

9.2 Population data (epidemiology)

No prevalence/incidence estimates were identified in the retrieved evidence. The condition is consistently described as rare, and available data are largely case-based or small cohorts. (shi2014ataxiaandhypogonadism pages 1-2, kallupurakkal2023anovelmutation pages 1-2)

9.3 Sex ratio and demographics

A review of RNF216-related disorders reported male predominance in the GHS subgroup compared with Huntington-like presentations and noted sex differences in pubertal development problems. (wu2022gordonholmessyndrome pages 1-4)

10. Diagnostics

10.1 Clinical testing (endocrine and neurologic)

Common diagnostic components include: - Endocrine labs: gonadotropins (LH/FSH) and sex steroids (testosterone/estradiol); HH characterized by low/inappropriately normal LH/FSH with low sex steroids. (gonzalez‐latapi2021movementdisordersassociated pages 2-4, rochtus2024hypogonadotropichypogonadismas pages 1-2) - GnRH stimulation testing: in STUB1-related GHS sisters, GnRH stimulation demonstrated pituitary responsiveness; imaging and hormone details are summarized in Shi et al. with tabulated data. (shi2014ataxiaandhypogonadism pages 1-2, shi2014ataxiaandhypogonadism media 6ceea760)

10.2 Imaging

  • Brain MRI: cerebellar atrophy is a recurring feature (e.g., “remarkable atrophy of the cerebellum” in STUB1 sisters); white-matter hyperintensities/leukoencephalopathy and corpus callosum thinning have been reported particularly in RNF216-related disease. (shi2014ataxiaandhypogonadism pages 1-2, margolin2013ataxiadementiaand pages 9-11, calandra2019gordonholmessyndrome pages 1-4, rochtus2024hypogonadotropichypogonadismas pages 1-2)

10.3 Genetic testing approaches

  • WES / exome-based diagnosis: used across multiple reports to identify homozygous/compound heterozygous variants in RNF216, STUB1, and PNPLA6. (shi2014ataxiaandhypogonadism pages 1-2, rochtus2024hypogonadotropichypogonadismas pages 1-2, liampas2024twocasereports pages 1-5)

10.4 Differential diagnosis

A 2024 PNPLA6-BNS case report lists differential diagnoses including Gordon Holmes syndrome, Woodhouse–Sakati syndrome, and mitochondrial disorders; BNS is distinguished by chorioretinal dystrophy and often absent/mild cognitive dysfunction. (liampas2024twocasereports pages 5-8)

11. Outcome / prognosis

Robust survival estimates were not identified in the retrieved evidence. Available natural history data suggest: - PNPLA6-associated disease can show slow progression with long-term ambulation preserved in many patients (mean duration 15 years in one cohort). (nanetti2022multifacetedandagedependent pages 1-2) - RNF216 and STUB1-related presentations may include substantial cognitive decline and multisystem complications in some families, implying variable but potentially severe outcomes. (celik2023anovelmutation pages 1-2, shi2014ataxiaandhypogonadism pages 1-2)

12. Treatment and current applications (real-world implementation)

12.1 Disease-modifying therapy

No disease-modifying therapy is described in the retrieved evidence for GHS/BNHS; management is largely supportive/symptom-directed. (liampas2024twocasereports pages 5-8)

12.2 Symptomatic and supportive care

Evidence-backed management elements include: - Hormone replacement/substitution for HH to induce/maintain secondary sexual characteristics and menstruation/fertility planning (e.g., PNPLA6-related GHS case report describes hormone replacement establishing menstruation and secondary sexual features; RNF216 case series notes testosterone therapy improved secondary sexual characteristics but not neurologic signs). (canbek2024…>g pages 2-4, alqwaifly2016ataxiaandhypogonadotropic pages 1-2) - Multidisciplinary supportive care for BNS: visual aids, speech/occupational/physiotherapy, genetic and psychosocial counseling. (liampas2024twocasereports pages 5-8)

12.3 Suggested MAXO terms (examples)

(ontology suggestions) - Hormone replacement therapy MAXO:0000647 (sex steroid replacement) - Genetic counseling MAXO:0000747 - Physical therapy MAXO:0000011 - Occupational therapy MAXO:0000010 - Speech therapy MAXO:0000129 - Assistive devices for mobility/vision MAXO:0000880 (broad)

13. Prevention

Primary prevention is not applicable for an inherited Mendelian disorder in the usual sense. Preventive strategies in practice focus on: - Genetic counseling and family planning in affected families. (liampas2024twocasereports pages 5-8) - Cascade testing of at-risk relatives (implied by carrier-parent findings in recessive families). (rochtus2024hypogonadotropichypogonadismas pages 1-2, liampas2024twocasereports pages 1-5)

14. Other species / natural disease

No naturally occurring non-human disease analogs were identified in the retrieved evidence. (No direct evidence found)

15. Model organisms

15.1 RNF216 models (2024 development)

A 2024 eNeuro study used constitutive Rnf216 knockout mice and found age- and sex-dependent abnormalities in learning strategies and microglia, providing a mechanistic foothold for RNF216-related GHS biology beyond descriptive genetics. (george2024gordonholmessyndrome pages 1-2, george2024gordonholmessyndrome pages 16-17)

15.2 STUB1/CHIP models

STUB1/CHIP functional work reports that CHIP loss of function in mice results in behavioral and reproductive impairments that mimic human ataxia and hypogonadism. (shi2014ataxiaandhypogonadism pages 1-2)

Recent developments and expert analysis (prioritizing 2023–2024)

  1. 2023 RNF216 case expansion: A 2023 BMC Medical Genomics case report reiterates core GHS features and documents expanded movement-disorder manifestations (parkinsonism, dystonia) while emphasizing limited genotype–phenotype correlation. Publication date: May 2023; URL: https://doi.org/10.1186/s12920-023-01529-4. (celik2023anovelmutation pages 1-2)
  2. 2023 BMJ Case Reports: A 2023 BMJ Case Reports paper highlights clinical utility of recognizing hypogonadism to narrow ataxia differentials and links GHS to RNF216/OTUD4 ubiquitin-proteasome biology. Publication date: Nov 2023; URL: https://doi.org/10.1136/bcr-2023-256994. (kallupurakkal2023anovelmutation pages 1-2)
  3. 2024 endocrine-first RNF216: A 2024 JCEM Case Reports article stresses that HH may be the first manifestation, particularly in males, supporting earlier genetic evaluation in delayed puberty with suggestive imaging/neuro signs. Publication date: Oct 2024; URL: https://doi.org/10.1210/jcemcr/luae195. (rochtus2024hypogonadotropichypogonadismas pages 1-2)
  4. 2024 mechanistic mouse work: A 2024 eNeuro paper provides new mechanistic data implicating microglia/neuroinflammation and sex-specific neuroendocrine differences in Rnf216 deficiency. Publication date: Dec 2024; URL: https://doi.org/10.1523/eneuro.0074-23.2023. (george2024gordonholmessyndrome pages 1-2, george2024gordonholmessyndrome pages 16-17)
  5. 2024 PNPLA6 case reports: A 2024 Molecular Biology Reports paper reiterates lack of disease-modifying treatment and provides explicit management recommendations for BNS. Publication date: Apr 2024; URL: https://doi.org/10.1007/s11033-024-09515-4. (liampas2024twocasereports pages 5-8)

Current applications and real-world implementations (registries/clinical research)

A broad rare-disease registry and natural history platform CoRDS (Coordination of Rare Diseases at Sanford; NCT01793168) is recruiting and includes rare hereditary ataxias among its condition list, providing an infrastructure for patient–researcher connection and longitudinal data collection (ClinicalTrials.gov first posted 2013-02-15; last update posted 2025-05-29). (NCT01793168 chunk 2, NCT01793168 chunk 3)

Visual evidence from primary literature

Shi et al. (Human Molecular Genetics, 2014) provides a consolidated table and MRI/hormone stimulation figure for STUB1/CHIP-related GHS: - Table with clinical scores and reproductive hormones/ultrasound findings (Table 1). (shi2014ataxiaandhypogonadism media 319d7677) - MRI evidence of cerebellar atrophy and GnRH stimulation response curves (Figure 1). (shi2014ataxiaandhypogonadism media 6ceea760) - Genetic analysis/pedigree identifying homozygous STUB1 p.Thr246Met and recessive inheritance (Figure 2). (shi2014ataxiaandhypogonadism media 8fe7f28b)

Summary tables

Gene Syndrome label(s) in sources Inheritance noted Example variants (HGVS) reported in evidence Core molecular function/pathway Key clinical features/imaging from evidence Key sources with year and DOI URL
RNF216 Gordon Holmes syndrome (GHS); RNF216-related disorder; also reported with Huntington-like disease, 4H syndrome, congenital hypogonadotropic hypogonadism Usually autosomal recessive/monogenic biallelic; oligogenic/digenic cases also reported with OTUD4 and SRA1 c.1860_1861dupCT (p.Cys621SerfsTer56); c.2061G>A (splice); c.1549C>T (p.R517X); c.591_592insTG (p.Gln198CysfsTer43); c.2042C>T (p.P606L) RBR-class E3 ubiquitin ligase; ubiquitin-proteasome/autophagy pathway; E3 activity depends on RBR domain + C-terminal extension Core phenotype: hypogonadotropic hypogonadism, cerebellar ataxia, cognitive decline/dementia, chorea/other movement disorders; MRI: cerebellar and cortical atrophy, cerebral white-matter hyperintensities/leukoencephalopathy, thin posterior corpus callosum; some pituitary anomalies (hypoplastic posterior pituitary, partial empty sella) (rochtus2024hypogonadotropichypogonadismas pages 1-2, alqwaifly2016ataxiaandhypogonadotropic pages 1-2, calandra2019gordonholmessyndrome pages 1-4, wu2022gordonholmessyndrome pages 7-11, wu2022gordonholmessyndrome pages 1-4, kallupurakkal2023anovelmutation pages 1-2, celik2023anovelmutation pages 1-2) Rochtus 2024, https://doi.org/10.1210/jcemcr/luae195; Çelik 2023, https://doi.org/10.1186/s12920-023-01529-4; Kallupurakkal 2023, https://doi.org/10.1136/bcr-2023-256994; Alqwaifly 2016, https://doi.org/10.4081/ni.2016.6444; Calandra 2019, https://doi.org/10.1002/mdc3.12721; Wu 2022, https://doi.org/10.21203/rs.3.rs-1310364/v1
OTUD4 GHS; RNF216/OTUD4 digenic form Digenic/oligogenic with RNF216 reported Not specified in provided snippets Deubiquitinase; disordered ubiquitination pathway Included in GHS spectrum with ataxia, hypogonadotropic hypogonadism, dementia/cognitive decline; more severe phenotypes reported when combined with RNF216 dysfunction in source summaries (margolin2013ataxiadementiaand pages 9-11, alqwaifly2016ataxiaandhypogonadotropic pages 1-2, calandra2019gordonholmessyndrome pages 1-4, wu2022gordonholmessyndrome pages 7-11, george2024gordonholmessyndrome pages 16-17) Margolin 2013, https://doi.org/10.1056/NEJMoa1215993; Alqwaifly 2016, https://doi.org/10.4081/ni.2016.6444; Wu 2022, https://doi.org/10.21203/rs.3.rs-1310364/v1
STUB1 (CHIP) GHS; SCAR16/STUB1-related multisystemic neurodegeneration Autosomal recessive/biallelic in reported GHS cases c.737C>T (p.Thr246Met); c.194A>G (p.Asn65Ser); c.82G>A (p.Glu28Lys); c.430A>T (p.Lys144Ter) Co-chaperone/E3 ubiquitin ligase in protein quality control/homeostasis Cerebellar ataxia with hypogonadotropic hypogonadism; dysarthria, gaze-evoked nystagmus, severe dementia/cognitive impairment in some families; MRI: remarkable cerebellar atrophy; pituitary responsive to GnRH in reported sisters; broader multisystemic features can include spastic tetraparesis, epilepsy, autonomic dysfunction (shi2014ataxiaandhypogonadism pages 1-2, shi2014ataxiaandhypogonadism media 319d7677, shi2014ataxiaandhypogonadism media 6ceea760, shi2014ataxiaandhypogonadism media 8fe7f28b) Shi 2014, https://doi.org/10.1093/hmg/ddt497; Hayer 2017, https://doi.org/10.1186/s13023-017-0580-x; Heimdal 2014, https://doi.org/10.1186/s13023-014-0146-0
PNPLA6 Gordon Holmes syndrome (GH/GDHS); Boucher-Neuhauser syndrome (BNHS/BNS); also broader PNPLA6-related spectrum (SPG39, Oliver-McFarlane, Laurence-Moon) Autosomal recessive/biallelic; often sibling cases; consanguinity common in several reports c.3524C>G (p.Ser1175Cys); c.3323G>A (p.Arg1108Gln); c.3380C>G (p.Ser1127Cys); c.3847G>A (p.V1283M); c.3929A>T (p.D1310V) Neuropathy target esterase (NTE); ER-localized lysophospholipase/phospholipase esterase GHS/BNHS spectrum with cerebellar ataxia, hypogonadotropic hypogonadism, chorioretinal dystrophy/vision loss; additional features include peripheral axonal neuropathy, spasticity, growth hormone deficiency, cognitive impairment, vestibular areflexia; MRI often shows cerebellar atrophy, especially superior/dorsal vermis; progression may be slow with retained ambulation after long disease duration in some cohorts (nanetti2022multifacetedandagedependent pages 1-2, dogan2021chorioretinaldystrophyhypogonadotropic pages 1-3, nanetti2022multifacetedandagedependent pages 3-5, liampas2024twocasereports pages 5-8, liampas2024twocasereports pages 1-5, deik2014compoundheterozygouspnpla6 pages 1-2, canbek2024…>g pages 2-4, teive2018differentcerebellarataxia pages 5-6) Nanetti 2022, https://doi.org/10.3389/fneur.2021.793547; Doğan 2021, https://doi.org/10.1080/13816810.2021.1894461; Liampas 2024, https://doi.org/10.1007/s11033-024-09515-4; Deik 2014, https://doi.org/10.1007/s00415-014-7516-3; Teive 2018, https://doi.org/10.1007/s12311-017-0909-y
POLR3A / POLR3B / POLR1C 4H syndrome listed among ataxia-hypogonadism differential/overlap disorders Not specified in provided snippets Not specified in provided snippets RNA polymerase III pathway (specific function not detailed in snippets) Mentioned as genes associated with ataxia plus hypogonadism spectrum/4H overlap; no variant-level or imaging detail provided in the retrieved evidence snippets (calandra2019gordonholmessyndrome pages 1-4, wu2022gordonholmessyndrome pages 7-11, kallupurakkal2023anovelmutation pages 1-2, celik2023anovelmutation pages 1-2) Calandra 2019, https://doi.org/10.1002/mdc3.12721; Wu 2022, https://doi.org/10.21203/rs.3.rs-1310364/v1; Kallupurakkal 2023, https://doi.org/10.1136/bcr-2023-256994

Table: This table summarizes the principal genes implicated across the cerebellar ataxia–hypogonadism / Gordon Holmes syndrome spectrum, including inheritance models, representative variants, molecular functions, and phenotype/imaging findings supported by the retrieved evidence.

Key evidence-backed abstract quotes (verbatim)

  • “Gordon Holmes syndrome (GHS) is a rare Mendelian neurodegenerative disorder characterized by ataxia and hypogonadism.” (Shi et al., 2014; https://doi.org/10.1093/hmg/ddt497) (shi2014ataxiaandhypogonadism pages 1-2)

Evidence gaps / limitations

  • Curated identifiers beyond MIM/OMIM (MONDO, Orphanet, MeSH, ICD-10/11) were not present in the retrieved evidence for this run; population prevalence/incidence and standardized diagnostic criteria were also not identified.
  • Many “Cerebellar ataxia–hypogonadism” cases are genetically heterogeneous; phenotype frequencies depend strongly on the causal gene (e.g., RNF216 vs PNPLA6), so frequency statements are reported only where explicitly quantified in the cited sources (not generalized across the entire syndrome label). (nanetti2022multifacetedandagedependent pages 1-2, rochtus2024hypogonadotropichypogonadismas pages 1-2)

References

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  3. (george2024gordonholmessyndrome pages 1-2): Arlene J. George, Wei Wei, Dhanya N. Pyaram, Morgan Gomez, Nitheyaa Shree, Jayashree Kadirvelu, Hannah Lail, Desiree Wanders, Anne Z. Murphy, and Angela M. Mabb. Gordon holmes syndrome model mice exhibit alterations in microglia, age, and sex-specific disruptions in cognitive and proprioceptive function. eNeuro, 11:ENEURO.0074-23.2023, Dec 2024. URL: https://doi.org/10.1523/eneuro.0074-23.2023, doi:10.1523/eneuro.0074-23.2023. This article has 0 citations and is from a peer-reviewed journal.

  4. (nanetti2022multifacetedandagedependent pages 1-2): Lorenzo Nanetti, Daniela Di Bella, Stefania Magri, Mario Fichera, Elisa Sarto, Anna Castaldo, Alessia Mongelli, Silvia Baratta, Silvia Fenu, Marco Moscatelli, Maria Teresa Bonati, Andrea Martinuzzi, Caterina Mariotti, and Franco Taroni. Multifaceted and age-dependent phenotypes associated with biallelic pnpla6 gene variants: eight novel cases and review of the literature. Frontiers in Neurology, Jan 2022. URL: https://doi.org/10.3389/fneur.2021.793547, doi:10.3389/fneur.2021.793547. This article has 18 citations and is from a peer-reviewed journal.

  5. (liampas2024twocasereports pages 5-8): Andreas Liampas, Paschalis Nicolaou, Christina Votsi, Anthi Georghiou, Kyproula Christodoulou, George A Tanteles, and Marios Pantzaris. Two case reports of a novel missense mutation in the pnpla6 gene in two siblings with chorioretinal dystrophy, hypogonadotropic hypogonadism, and cerebellar ataxia. Molecular biology reports, 51 1:590, Apr 2024. URL: https://doi.org/10.1007/s11033-024-09515-4, doi:10.1007/s11033-024-09515-4. This article has 0 citations and is from a peer-reviewed journal.

  6. (deik2014compoundheterozygouspnpla6 pages 1-2): A. Deik, Brooke Johannes, J. Rucker, E. Sánchez, S. Brodie, E. Deegan, K. Landy, Y. Kajiwara, S. Scelsa, R. Saunders-Pullman, R. Saunders-Pullman, and C. Paisán-Ruiz. Compound heterozygous pnpla6 mutations cause boucher–neuhäuser syndrome with late-onset ataxia. Journal of Neurology, 261:2411-2423, Sep 2014. URL: https://doi.org/10.1007/s00415-014-7516-3, doi:10.1007/s00415-014-7516-3. This article has 44 citations and is from a domain leading peer-reviewed journal.

  7. (wu2022gordonholmessyndrome pages 7-11): Chujun Wu and Zaiqiang Zhang. Gordon holmes syndrome and huntington-like disease: two types of rnf216-related disorders. ArXiv, Feb 2022. URL: https://doi.org/10.21203/rs.3.rs-1310364/v1, doi:10.21203/rs.3.rs-1310364/v1. This article has 1 citations.

  8. (calandra2019gordonholmessyndrome pages 1-4): Cristian R. Calandra, Yamile Mocarbel, Sebastian A. Vishnopolska, Vanessa Toneguzzo, Jaen Oliveri, Enrique Carlos Cazado, German Biagioli, Adrián G. Turjanksi, and Marcelo Marti. Gordon holmes syndrome caused by rnf216 novel mutation in 2 argentinean siblings. Movement Disorders Clinical Practice, 6:259-262, Mar 2019. URL: https://doi.org/10.1002/mdc3.12721, doi:10.1002/mdc3.12721. This article has 26 citations and is from a peer-reviewed journal.

  9. (kallupurakkal2023anovelmutation pages 1-2): Arjun Bal Kallupurakkal, Rajesh Verma, and Rajarshi Chakraborty. A novel mutation in rnf216 gene in an indian case with gordon holmes syndrome. BMJ Case Reports, 16:e256994, Nov 2023. URL: https://doi.org/10.1136/bcr-2023-256994, doi:10.1136/bcr-2023-256994. This article has 6 citations and is from a peer-reviewed journal.

  10. (alqwaifly2016ataxiaandhypogonadotropic pages 1-2): Mohammed Alqwaifly and Saeed Bohlega. Ataxia and hypogonadotropic hypogonadism with intrafamilial variability caused by rnf216 mutation. Neurology International, Jun 2016. URL: https://doi.org/10.4081/ni.2016.6444, doi:10.4081/ni.2016.6444. This article has 46 citations.

  11. (margolin2013ataxiadementiaand pages 9-11): David H. Margolin, Maria Kousi, Yee-Ming Chan, Elaine T. Lim, Jeremy D. Schmahmann, Marios Hadjivassiliou, Janet E. Hall, Ibrahim Adam, Andrew Dwyer, Lacey Plummer, Stephanie V. Aldrin, Julia O'Rourke, Andrew Kirby, Kasper Lage, Aubrey Milunsky, Jeff M. Milunsky, Jennifer Chan, E. Tessa Hedley-Whyte, Mark J. Daly, Nicholas Katsanis, and Stephanie B. Seminara. Ataxia, dementia, and hypogonadotropism caused by disordered ubiquitination. New England Journal of Medicine, 368:1992-2003, May 2013. URL: https://doi.org/10.1056/nejmoa1215993, doi:10.1056/nejmoa1215993. This article has 268 citations and is from a highest quality peer-reviewed journal.

  12. (celik2023anovelmutation pages 1-2): Nazlı Durmaz Çelik, Ebru Erzurumluoğlu, Serkan Özben, Uğur Toprak, Göknur Yorulmaz, Sevilhan Artan, and Serhat Özkan. A novel mutation in rnf216 gene in a turkish case with gordon holmes syndrome. BMC Medical Genomics, May 2023. URL: https://doi.org/10.1186/s12920-023-01529-4, doi:10.1186/s12920-023-01529-4. This article has 9 citations and is from a peer-reviewed journal.

  13. (wu2022gordonholmessyndrome pages 1-4): Chujun Wu and Zaiqiang Zhang. Gordon holmes syndrome and huntington-like disease: two types of rnf216-related disorders. ArXiv, Feb 2022. URL: https://doi.org/10.21203/rs.3.rs-1310364/v1, doi:10.21203/rs.3.rs-1310364/v1. This article has 1 citations.

  14. (canbek2024…>g pages 2-4): S Canbek and MG Şenol. … > g missense mutation in pnpla6 gene in a case of gordon holmes syndrome associated with hypogonadotropic hypogonadism, cerebellar ataxia, and juvenile type …. Unknown journal, 2024.

  15. (george2024gordonholmessyndrome pages 16-17): Arlene J. George, Wei Wei, Dhanya N. Pyaram, Morgan Gomez, Nitheyaa Shree, Jayashree Kadirvelu, Hannah Lail, Desiree Wanders, Anne Z. Murphy, and Angela M. Mabb. Gordon holmes syndrome model mice exhibit alterations in microglia, age, and sex-specific disruptions in cognitive and proprioceptive function. eNeuro, 11:ENEURO.0074-23.2023, Dec 2024. URL: https://doi.org/10.1523/eneuro.0074-23.2023, doi:10.1523/eneuro.0074-23.2023. This article has 0 citations and is from a peer-reviewed journal.

  16. (dogan2021chorioretinaldystrophyhypogonadotropic pages 1-3): Mustafa Doğan, Recep Eröz, and Emrah Öztürk. Chorioretinal dystrophy, hypogonadotropic hypogonadism, and cerebellar ataxia: boucher-neuhauser syndrome due to a homozygous (c.3524c>g (p.ser1175cys)) variant in pnpla6 gene. Ophthalmic Genetics, 42:276-282, Mar 2021. URL: https://doi.org/10.1080/13816810.2021.1894461, doi:10.1080/13816810.2021.1894461. This article has 12 citations and is from a peer-reviewed journal.

  17. (liampas2024twocasereports pages 1-5): Andreas Liampas, Paschalis Nicolaou, Christina Votsi, Anthi Georghiou, Kyproula Christodoulou, George A Tanteles, and Marios Pantzaris. Two case reports of a novel missense mutation in the pnpla6 gene in two siblings with chorioretinal dystrophy, hypogonadotropic hypogonadism, and cerebellar ataxia. Molecular biology reports, 51 1:590, Apr 2024. URL: https://doi.org/10.1007/s11033-024-09515-4, doi:10.1007/s11033-024-09515-4. This article has 0 citations and is from a peer-reviewed journal.

  18. (gonzalez‐latapi2021movementdisordersassociated pages 2-4): Paulina Gonzalez‐Latapi, Mario Sousa, and Anthony E. Lang. Movement disorders associated with hypogonadism. Movement Disorders Clinical Practice, 8:997-1011, Jul 2021. URL: https://doi.org/10.1002/mdc3.13308, doi:10.1002/mdc3.13308. This article has 17 citations and is from a peer-reviewed journal.

  19. (shi2014ataxiaandhypogonadism media 6ceea760): Chang-He Shi, Jonathan C. Schisler, Carrie E. Rubel, Song Tan, Bo Song, Holly McDonough, Lei Xu, Andrea L. Portbury, Cheng-Yuan Mao, Cadence True, Rui-Hao Wang, Qing-Zhi Wang, Shi-Lei Sun, Stephanie B. Seminara, Cam Patterson, and Yu-Ming Xu. Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the u box protein chip. Human molecular genetics, 23 4:1013-24, Feb 2014. URL: https://doi.org/10.1093/hmg/ddt497, doi:10.1093/hmg/ddt497. This article has 153 citations and is from a domain leading peer-reviewed journal.

  20. (NCT01793168 chunk 2): Rare Disease Patient Registry & Natural History Study - Coordination of Rare Diseases at Sanford. Sanford Health. 2010. ClinicalTrials.gov Identifier: NCT01793168

  21. (NCT01793168 chunk 3): Rare Disease Patient Registry & Natural History Study - Coordination of Rare Diseases at Sanford. Sanford Health. 2010. ClinicalTrials.gov Identifier: NCT01793168

  22. (shi2014ataxiaandhypogonadism media 319d7677): Chang-He Shi, Jonathan C. Schisler, Carrie E. Rubel, Song Tan, Bo Song, Holly McDonough, Lei Xu, Andrea L. Portbury, Cheng-Yuan Mao, Cadence True, Rui-Hao Wang, Qing-Zhi Wang, Shi-Lei Sun, Stephanie B. Seminara, Cam Patterson, and Yu-Ming Xu. Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the u box protein chip. Human molecular genetics, 23 4:1013-24, Feb 2014. URL: https://doi.org/10.1093/hmg/ddt497, doi:10.1093/hmg/ddt497. This article has 153 citations and is from a domain leading peer-reviewed journal.

  23. (shi2014ataxiaandhypogonadism media 8fe7f28b): Chang-He Shi, Jonathan C. Schisler, Carrie E. Rubel, Song Tan, Bo Song, Holly McDonough, Lei Xu, Andrea L. Portbury, Cheng-Yuan Mao, Cadence True, Rui-Hao Wang, Qing-Zhi Wang, Shi-Lei Sun, Stephanie B. Seminara, Cam Patterson, and Yu-Ming Xu. Ataxia and hypogonadism caused by the loss of ubiquitin ligase activity of the u box protein chip. Human molecular genetics, 23 4:1013-24, Feb 2014. URL: https://doi.org/10.1093/hmg/ddt497, doi:10.1093/hmg/ddt497. This article has 153 citations and is from a domain leading peer-reviewed journal.

  24. (nanetti2022multifacetedandagedependent pages 3-5): Lorenzo Nanetti, Daniela Di Bella, Stefania Magri, Mario Fichera, Elisa Sarto, Anna Castaldo, Alessia Mongelli, Silvia Baratta, Silvia Fenu, Marco Moscatelli, Maria Teresa Bonati, Andrea Martinuzzi, Caterina Mariotti, and Franco Taroni. Multifaceted and age-dependent phenotypes associated with biallelic pnpla6 gene variants: eight novel cases and review of the literature. Frontiers in Neurology, Jan 2022. URL: https://doi.org/10.3389/fneur.2021.793547, doi:10.3389/fneur.2021.793547. This article has 18 citations and is from a peer-reviewed journal.

  25. (teive2018differentcerebellarataxia pages 5-6): Hélio Afonso Ghizoni Teive, Carlos Henrique F. Camargo, Mario Teruo Sato, Naoye Shiokawa, Cesar L. Boguszewski, Salmo Raskin, Cassandra Buck, Stephanie B. Seminara, and Renato Puppi Munhoz. Different cerebellar ataxia phenotypes associated with mutations of the pnpla6 gene in brazilian patients with recessive ataxias. The Cerebellum, 17:380-385, Dec 2018. URL: https://doi.org/10.1007/s12311-017-0909-y, doi:10.1007/s12311-017-0909-y. This article has 35 citations.

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.3.0rc3.

Outcome Count
References checked 18
Resolved 18
Unresolved (possible confabulation) 0
Unverifiable 0
Quoted claims checked 0
Quoted claims found in source 0
Quoted claims not found in source 0
Quoted claims with nothing to check against 1
References weighed for topical relevance 18
On topic 8
Off topic 0

Quotes that could not be checked

There was no text to compare these against, so they are neither confirmed nor contradicted:

  • DOI:10.1093/hmg/ddt497: "Gordon Holmes syndrome (GHS) is a rare Mendelian neurodegenerative disorder characterized by ataxia and hypogonadism."
  • Reference resolved but exposes no abstract or full text to search

All extracted references resolved successfully.

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Outcome Count
Terms checked 35
Resolved 33
Unresolved (possible confabulation) 0
Obsolete 2
Unverifiable 0

Obsolete terms

These terms are real but deprecated. Citing one is not a fabrication; it does mean the report is naming something the ontology has retired:

  • CL:0000543 (obsolete sieve tube member) (1 mention) - replaced by PO:0000289
  • MAXO:0000129 (obsolete biopsy procedure) (1 mention) - replaced by OBI:0002650

33 of 35 terms resolved to a current term; the rest could not be looked up either way.