Turner Syndrome

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Mappings

MONDO

MONDO:0019499 Turner syndrome

MONDO:0020466 monosomy X Not Yet Curated

MONDO:0020467 mosaic monosomy X Not Yet Curated

MONDO:0020472 Turner syndrome due to structural X chromosome anomalies Not Yet Curated

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Inheritance

1

Not inherited (sporadic chromosomal aneuploidy)

Turner syndrome arises from a sporadic meiotic or post-zygotic mitotic error and is not transmitted in a Mendelian pattern. It is therefore not assigned an HPO mode-of-inheritance term: the standard modes describe transmission of alleles, and there is no transmission here. Recurrence risk in siblings is not appreciably raised, and the practical genetic-counselling content concerns the affected individual's own reproductive options rather than family segregation.

Show evidence (1 reference)

PMID:31213699 SUPPORT Human Clinical

"Turner syndrome is a rare condition in women that is associated with either complete or partial loss of one X chromosome, often in mosaic karyotypes."

Supports the chromosomal (aneuploidy/mosaicism) rather than Mendelian basis of the condition.

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Mechanistic Hypotheses

4

X-Escape and Pseudoautosomal Gene Haploinsufficiency Model

escape_gene_haploinsufficiency_model CANONICAL

The syndrome is caused by reduction to a single functional dose of the genes that normally escape X-inactivation, plus the pseudoautosomal genes that normally pair with a Y homologue. Human deletion mapping supports the model directly for at least two phenotypes: SHOX in PAR1 for short stature and the mesomelic skeleton, and a <2 Mb PAR1 interval for the neurocognitive profile, the latter shown to be independent of parent of origin and of X-inactivation skewing. The model's acknowledged weakness is coverage, not principle — the gonadal, cardiovascular, renal, auditory and autoimmune arms have no assigned escape gene, and the field states plainly that SHOX does not explain most Turner anomalies.

Curated as CANONICAL because it is the framework in which the field operates and is directly evidenced for two phenotypes, not because it is complete. The gap is tracked as its own discussion (gap_unassigned_escape_genes) rather than being smoothed over here.

Jugular Lymphatic Obstruction Hemodynamic Model of Left-Heart Obstruction

lymphatic_obstruction_hemodynamic_model ALTERNATIVE

Clark's 1984 proposal that the cardiac malformation is not an independent dosage effect but a secondary consequence of the lymphatic lesion: obstructed jugular lymphatic sacs raise lymphatic pressure, distended thoracic ducts compress the ascending aorta, and the redirected intracardiac flow produces coarctation and the wider spectrum of left-heart obstruction. It is a mechanically explicit account of a robust epidemiological association — coarctation prevalence of 25% with neck web versus 3% without in a 45,X series — and it makes Turner cardiac disease an example of a teratogenic event remote from the heart.

Held as ALTERNATIVE, not CANONICAL. The association it explains is strong and has been reproduced, but the causal chain itself is inferred from anatomy and flow reasoning rather than observed, and the competing account — that lymphatic and cardiac defects are parallel consequences of the same dosage lesion — is not excluded by the data curated here. No node in this entry asserts the hemodynamic chain outside this hypothesis group.

Pathograph links

Fetal Jugular Lymphatic Sac Obstruction and Lymphatic Network Dysplasia -> Left-Sided Cardiac Outflow Tract Malformation INDIRECT KNOWN INTERMEDIATES Clark's hemodynamic hypothesis: distended thoracic ducts compress the ascending aorta and redirect intracardiac flow, producing left-heart obstructive lesions. This edge is curated as belonging to a named hypothesis rather than as established fact — the epidemiological association between neck web and coarctation is strong and reproducible, but the mechanism connecting them is inferred, not observed.

Granulosa-Cell Apelin/APJ Dysfunction Model of Ovarian Attrition

granulosa_apelin_model EMERGING

Evidence balance 1 support

A human 45,X iPSC-derived granulosa-cell study places reduced apelin/APJ signaling upstream of abnormal granulosa differentiation and cell-cycle progression, then proposes that defective somatic support during ovarian development contributes to early oocyte loss. Ligand and Akt-pathway rescue provide model-specific causal support for the signaling-to-cellular step; the relay from chromosome dosage to apelin signaling and the translation from cultured cells to follicular attrition in vivo remain unproven.

This model does not replace the established ovarian-attrition path. It supplies one candidate somatic-cell relay within an arm whose responsible X-dosage-sensitive gene or genes remain unidentified.

Pathograph links

Haploinsufficiency of Pseudoautosomal and X-Inactivation Escape Genes -> Granulosa-Cell Apelin/APJ Signaling Dysfunction INDIRECT UNKNOWN INTERMEDIATES A patient-derived iPSC study nominates impaired apelin/APJ signaling as one route by which the 45,X dosage state may disrupt granulosa-cell development. The responsible X-dosage relay is not known, so the edge is indirect and belongs to an emerging hypothesis rather than the canonical disease path.

Granulosa-Cell Apelin/APJ Signaling Dysfunction -> Granulosa-Cell Differentiation and Cell-Cycle Dysfunction INDIRECT KNOWN INTERMEDIATES Apelin ligands and downstream Akt activation partly restored cell-cycle progression and granulosa marker expression, placing impaired signaling upstream of the model's cellular defect without establishing that it is the only cause. Intermediates: APJ signaling through Akt/PKB and CTPS2 regulation

Granulosa-Cell Differentiation and Cell-Cycle Dysfunction -> Accelerated Ovarian Germ Cell Attrition and Follicular Atresia INDIRECT UNKNOWN INTERMEDIATES The study proposes that defective granulosa-cell support during ovarian development contributes to early oocyte loss. This is an emerging human-cell-model hypothesis, not proof that the in-vitro state causes follicular attrition in vivo.

Show evidence (1 reference)

PMID:39543104 SUPPORT In Vitro

"We hypothesize that during early embryonic development, failures in apelin/APJ signaling in GCs of Turner syndrome patients lead to abnormalities in ovarian development, ultimately resulting in early oocyte loss and infertility."

The authors explicitly frame the in-vivo extension as a hypothesis; PARTIAL preserves that status despite the in-vitro rescue evidence.

Cardiomyocyte ceRNA and Heart-Development Transcriptome Model

cardiomyocyte_ceRNA_model EMERGING

Evidence balance 1 support

Patient-derived 45,X cardiomyocytes show global coding and non-coding RNA dysregulation, enrichment of heart-development genes, lower beating frequency, and increased mitochondrial DNA copy number. The authors propose dosage-altered X-inactivation-escaping non-coding RNAs as regulators of autosomal cardiac genes. The study does not establish that this cultured-cell state causes bicuspid valve, coarctation, generalized arteriopathy, or dissection, so no edge to those human structural lesions is asserted.

Pathograph links

Haploinsufficiency of Pseudoautosomal and X-Inactivation Escape Genes -> Turner Cardiomyocyte Transcriptome and Contractile Dysregulation INDIRECT UNKNOWN INTERMEDIATES Patient-derived 45,X cardiomyocytes show transcriptomic and beating abnormalities downstream of the chromosome-dosage state. Which escape-gene deficits produce those changes, and whether they participate in congenital valve, arch, or aortic-wall disease in vivo, remain unresolved.

Show evidence (1 reference)

PMID:38124119 SUPPORT In Vitro

"Further ceRNA network analysis has revealed that dysregulation of genes on autosomes could be possibly mediated by altered dosages of lnc/circRNAs on the X chromosome."

The source's conditional wording supports an emerging regulatory model, not an established mechanism of congenital or aortic disease.

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Discussions and Knowledge Gaps

4

Which X-inactivation escape and pseudoautosomal genes, beyond SHOX, account for the gonadal, cardiovascular, renal, auditory and autoimmune arms of Turner syndrome?

KNOWLEDGE GAP OPEN gap_unassigned_escape_genes

Attached to

pathophysiology#Haploinsufficiency of Pseudoautosomal and X-Inactivation Escape Genes

This is the central unresolved question of the disease rather than a loose end. The canonical model attributes every arm of the syndrome to haploinsufficiency of escape genes, but only one gene-to-phenotype assignment has been made — SHOX to stature and the mesomelic skeleton — and the field states explicitly that SHOX does not explain most Turner anomalies. Consequently the edges from the escape-gene node to the ovarian and lymphatic arms in this entry are curated as INDIRECT, because naming them DIRECT would assert a gene-level mechanism nobody has identified. The gap has practical weight: without the responsible genes there is no molecular target for the non-growth arms. Every therapy curated in this entry acts downstream of the unknown dosage lesion rather than on it — growth hormone drives a partially responsive growth plate, estrogen replaces a missing hormone, antihypertensives and aortic surgery act on the consequences of a malformation whose genetic cause is unassigned, and oocyte cryopreservation bypasses the attrition rather than slowing it. There is no gene-directed therapy for any arm of the disease, and there cannot be one until this gap closes.

Proposed experiments

Systematic escape-gene dosage mapping against organ-specific Turner phenotypes

exp_ts_escape_gene_dosage_mapping

Extend the partial-Xp deletion mapping strategy that localised the neurocognitive phenotype to PAR1 across the remaining organ arms, using contemporary cohorts of individuals with structurally abnormal X chromosomes and defined breakpoints, phenotyped for gonadal reserve, cardiac malformation, renal structure and audiometry. The design's strength is that it is the same human-genetics logic already shown to work here, rather than an animal model whose fidelity to human X-dosage biology would itself need establishing.

Show evidence (2 references)

PMID:21925981 SUPPORT Human Clinical

"As the inheritance of only one copy of the SHOX gene does not explain most of TS anomalies, more studies are needed to explain them."

States the gap directly — SHOX dosage leaves most of the syndrome unexplained.

PMID:38124119 SUPPORT In Vitro

"How loss of one X chromosome drive these conditions remains largely unknown."

Independent restatement of the gap from the molecular side.

Is the left-heart obstructive lesion of Turner syndrome caused by the fetal lymphatic defect through a hemodynamic mechanism, or are the two parallel consequences of the same gene-dosage lesion?

KNOWLEDGE GAP OPEN gap_lymphatic_versus_dosage_origin_of_cardiac_defect

Attached to

pathophysiology#Fetal Jugular Lymphatic Sac Obstruction and Lymphatic Network Dysplasia pathophysiology#Left-Sided Cardiac Outflow Tract Malformation

The two accounts predict the same epidemiology — neck web and coarctation co-occur — and are therefore not separated by the association data that motivated the hemodynamic model. The distinction matters because it decides whether the cardiac phenotype is in principle preventable by anything acting on lymphatic development, or whether it is an independent dosage effect that a lymphatic intervention could never touch. This entry does not resolve it: the hemodynamic chain is confined to a named ALTERNATIVE hypothesis group, and the corresponding edge is typed INDIRECT so no node asserts it as settled mechanism.

Show evidence (1 reference)

PMID:6463900 SUPPORT Human Clinical

"The following hypothesis is proposed to explain the association."

The source's own framing — a hypothesis proposed to explain an association — which is why the mechanism is not curated as established.

Should the Turner aortopathy node conform to aortopathy_tgfbeta_dysregulation, and should the osteoporosis phenotype conform to osteoporosis_bone_resorption?

KNOWLEDGE GAP OPEN note_module_conformance_withheld

Attached to

pathophysiology#Progressive Aortic Dilation

Both conformances are superficially attractive and are deliberately withheld rather than silently omitted. Turner aortopathy is a genuine heritable thoracic aortic disease, but the module's defining claim is paradoxically increased TGF-beta signalling downstream of an ECM or contractile-apparatus lesion, and no evidence curated in this entry establishes that mechanism in Turner syndrome — the aortopathy here is documented at the level of valve morphology, calibre and dissection risk. Similarly, the osteoporosis module turns on RANKL-driven osteoclastogenesis, whereas the evidence available here establishes only that bone mineral density is low and improves with estrogen replacement, which is consistent with that mechanism but does not demonstrate it. Declaring either conformance would import mechanistic claims this entry cannot support; a curator with the relevant primary literature should revisit both.

Which genetic-background determinants make monosomy X cause profound ovarian reserve loss in some mouse strains while leaving other XO females fertile, and do those determinants illuminate variability in human Turner syndrome?

HUMAN MODEL MISMATCH OPEN mismatch_xo_mouse_ovarian_background_dependence

Attached to

pathophysiology#Accelerated Ovarian Germ Cell Attrition and Follicular Atresia

The generic statement that XO mice are fertile is true for commonly used backgrounds but incomplete. A direct strain comparison found early oocyte loss and infertility or subfertility on C57BL/6J, while mixed-background XO females remained as fertile as XX controls despite a reduced neonatal oocyte count. That makes genetic background part of the mechanism, not merely a nuisance variable. It also prevents either extreme interpretation: the mouse is not a faithful generic model of human Turner infertility, but neither is murine monosomy X intrinsically incapable of reproducing ovarian attrition.

Show evidence (2 references)

PMID:32634219 SUPPORT Model Organism

"Second, while N2.XO females were as fertile as N2.XX females, both the frequency of delivery and the total number of pups delivered by B6.XO females were significantly lower than those by B6.XX females."

Direct within-study demonstration of the strain-dependent fertility mismatch.

PMID:32634219 SUPPORT Model Organism

"We conclude that the impact of monosomy X on female mouse fertility depends on the genetic background."

States the unresolved modifier problem directly.

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Pathophysiology

16

Complete or Partial Loss of One X Chromosome

A meiotic or post-zygotic mitotic error leaves a phenotypically female individual with one intact X and either no second sex chromosome (45,X), a structurally abnormal second X (ring, isochromosome, deletion), or a mosaic mixture of cell lines. This is the only whole-chromosome haploinsufficiency compatible with postnatal life, which is itself the first mechanistic fact about the disease: survival is possible because X-inactivation has already reduced most X-linked genes to one functional copy in typical cells, so only the genes exempt from that silencing are actually rendered haploinsufficient by the loss.

Downstream

Haploinsufficiency of Pseudoautosomal and X-Inactivation Escape Genes Loss of the second sex chromosome halves the dose of exactly those genes that are normally expressed from both copies.

Show evidence (2 references)

PMID:31213699 SUPPORT Human Clinical

"Turner syndrome is a rare condition in women that is associated with either complete or partial loss of one X chromosome, often in mosaic karyotypes."

States the defining chromosomal lesion and that it is frequently mosaic.

PMID:38124119 SUPPORT In Vitro

"A 45,X monosomy (Turner syndrome, TS) is the only chromosome haploinsufficiency compatible with life."

Supports the claim that this is the uniquely survivable whole-chromosome monosomy.

Haploinsufficiency of Pseudoautosomal and X-Inactivation Escape Genes

Genes in the pseudoautosomal regions and the subset of X-linked genes that escape X-inactivation are normally transcribed from both sex chromosomes. With one sex chromosome absent or truncated they drop to a single functional dose. This node is the convergence point of the disease: every downstream arm is a tissue-specific consequence of a dosage shortfall in one or more of these genes. Only SHOX is confidently assigned to its phenotype; the identity of the escape genes responsible for the gonadal, cardiovascular, renal, auditory and immune arms is unresolved, and is curated here as an explicit knowledge gap rather than as a mechanism.

Cardiomyocyte ceRNA and Heart-Development Transcriptome Model Granulosa-Cell Apelin/APJ Dysfunction Model of Ovarian Attrition

Downstream

SHOX Haploinsufficiency SHOX lies in PAR1 and is one of the escape genes rendered haploinsufficient.

Accelerated Ovarian Germ Cell Attrition and Follicular Atresia Gonadal involution is a dosage consequence of the missing X, but the specific escape gene(s) responsible have not been identified — hence INDIRECT rather than DIRECT.

Fetal Jugular Lymphatic Sac Obstruction and Lymphatic Network Dysplasia The fetal lymphatic defect is attributed to the chromosomal loss; no individual escape gene has been assigned to it.

Granulosa-Cell Apelin/APJ Signaling Dysfunction A patient-derived iPSC study nominates impaired apelin/APJ signaling as one route by which the 45,X dosage state may disrupt granulosa-cell development. The responsible X-dosage relay is not known, so the edge is indirect and belongs to an emerging hypothesis rather than the canonical disease path.

Turner Cardiomyocyte Transcriptome and Contractile Dysregulation Patient-derived 45,X cardiomyocytes show transcriptomic and beating abnormalities downstream of the chromosome-dosage state. Which escape-gene deficits produce those changes, and whether they participate in congenital valve, arch, or aortic-wall disease in vivo, remain unresolved.

Horseshoe Kidney and Renal Malformation Renal developmental malformations are strongly karyotype-dependent, but the dosage-sensitive gene or developmental relay is not assigned. The edge therefore records a major Turner arm without inventing an intermediate renal mechanism.

High-Frequency Sensorineural Hearing Loss Progressive sensorineural loss is more severe in non-mosaic 45,X, but the responsible escape gene and cochlear mechanism remain unresolved.

PAR1 Haploinsufficiency and the Turner Neurocognitive Phenotype A <2 Mb PAR1 interval is the mapped critical region for the neurocognitive profile.

Show evidence (3 references)

PMID:10931762 SUPPORT Human Clinical

"We conclude that haploinsufficiency of PAR1 gene(s) is the basis for susceptibility to the TS neurocognitive phenotype."

Deletion mapping in 34 females localises a Turner phenotype to haploinsufficiency of pseudoautosomal genes, establishing the dosage mechanism from human genetics rather than by inference.

PMID:10931762 SUPPORT Human Clinical

"The phenotype was seen with either paternally or maternally inherited deletions and with either complete or incomplete skewing of X inactivation."

Excludes imprinting and skewed inactivation as explanations, leaving gene dosage as the operative variable.

PMID:38124119 SUPPORT In Vitro

"How loss of one X chromosome drive these conditions remains largely unknown."

States that the gene-to-phenotype assignment downstream of this node is still open — retained deliberately so the node is not read as settled.

SHOX Haploinsufficiency

A single functional copy of SHOX, the PAR1 homeobox transcription factor that escapes X-inactivation. This is the molecular lesion itself — reduced SHOX gene dose — held separately from the cellular programme it dysregulates, because the same dosage lesion arises in Léri-Weill dyschondrosteosis from PAR1 deletion in individuals with two intact sex chromosomes. It is the one arm of Turner syndrome where the responsible gene is named with confidence.

Downstream

Growth-Plate Chondrocyte Dysregulation Halved SHOX dose is transduced into a disordered chondrocyte programme at the growth plate.

Show evidence (2 references)

PMID:27194967 SUPPORT Human Clinical

"SHOX in the short arm pseudoautosomal region (PAR1) of sex chromosomes is one of the major growth genes in humans."

Places the gene in PAR1 and identifies it as a major human growth gene.

PMID:27194967 SUPPORT Human Clinical

"SHOX haploinsufficiency results in idiopathic short stature and Léri-Weill dyschondrosteosis and is associated with the short stature of patients with Turner syndrome."

Connects SHOX dosage to Turner short stature and, via Léri-Weill dyschondrosteosis, to the mesomelic skeletal phenotype.

Growth-Plate Chondrocyte Dysregulation

The growth-plate chondrocyte programme downstream of SHOX. SHOX acts on chondrocyte apoptosis through targets including BNP, FGFR3, aggrecan and CTGF, so halving its dose alters the proliferation-to-hypertrophy-to-apoptosis sequence that converts cartilage into bone at the growth plate.

growth-plate chondrocyte CL:0000138

apoptotic process GO:0006915 ↕ DYSREGULATED

Downstream

Skeletal Growth Failure and Mesomelic Dysmorphism Growth-plate dysregulation is expressed at tissue level as reduced endochondral bone growth with disproportionate forearm and lower-leg involvement.

Show evidence (1 reference)

PMID:27194967 SUPPORT Human Clinical

"The SHOX protein likely controls chondrocyte apoptosis by regulating multiple target genes including BNP,Fgfr3, Agc1, and Ctgf."

Gives the chondrocyte-level molecular programme SHOX acts through.

Skeletal Growth Failure and Mesomelic Dysmorphism

Reduced endochondral bone growth produces the near-universal short stature and the mesomelic skeletal signature — cubitus valgus, short fourth metacarpals, Madelung deformity of the wrist, and a broad chest. Because the deficit is in the growth plate rather than in growth hormone secretion, growth hormone works here pharmacologically, by driving a partially responsive plate harder, not by replacing a missing hormone.

endochondral bone growth GO:0003416 ↓ DECREASED

Downstream

Short Stature Reduced endochondral growth at the SHOX-deficient growth plate produces the characteristic short stature.

Cubitus Valgus Cubitus valgus is part of the Turner mesomelic skeletal pattern attributed to SHOX-deficient growth, but the cached source supports the skeletal class rather than naming this deformity individually.

Madelung Deformity Madelung deformity lies in the SHOX-haploinsufficiency skeletal spectrum, but the available excerpt establishes the shared Léri-Weill aetiology rather than naming the Turner manifestation directly.

Show evidence (1 reference)

PMID:31213699 SUPPORT Human Clinical

"Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."

Places short stature among the defining features of the syndrome.

Granulosa-Cell Apelin/APJ Signaling Dysfunction

Reduced apelin/APJ signaling observed in 45,X patient-derived granulosa-like cells. Ligand and downstream Akt activation partly rescue the cellular phenotype, supporting a signaling contribution in this model. The state has not yet been demonstrated in intact human Turner ovaries and its connection to a specific X-dosage-sensitive gene remains unknown.

Granulosa-Cell Apelin/APJ Dysfunction Model of Ovarian Attrition

Experimental models

45,X patient-derived iPSC granulosa-like cells IPSC DERIVED MODEL The system measures reduced pathway signaling and demonstrates partial rescue with apelin ligands or downstream Akt activation.

Downstream

Granulosa-Cell Differentiation and Cell-Cycle Dysfunction Apelin ligands and downstream Akt activation partly restored cell-cycle progression and granulosa marker expression, placing impaired signaling upstream of the model's cellular defect without establishing that it is the only cause.

Show evidence (1 reference)

PMID:39543104 SUPPORT In Vitro

"The apelin/APJ pathway exhibited differential signaling between the healthy and TS groups."

Identifies the signaling difference in the patient-derived model.

Granulosa-Cell Differentiation and Cell-Cycle Dysfunction

Turner patient-derived granulosa-like cells show reduced differentiation markers and abnormal cell-cycle progression. This provides a candidate somatic-cell contribution to the ovarian phenotype, but it is not yet a demonstrated lesion in an intact human ovary and does not exclude a germ-cell-autonomous contribution.

Granulosa-Cell Apelin/APJ Dysfunction Model of Ovarian Attrition

granulosa cell CL:0000501

cell cycle GO:0007049 ↕ DYSREGULATED

Experimental models

45,X patient-derived iPSC granulosa-like cells IPSC DERIVED MODEL The system reproduces reduced granulosa marker expression and abnormal cell-cycle progression associated with 45,X donor cells.

Downstream

Accelerated Ovarian Germ Cell Attrition and Follicular Atresia The study proposes that defective granulosa-cell support during ovarian development contributes to early oocyte loss. This is an emerging human-cell-model hypothesis, not proof that the in-vitro state causes follicular attrition in vivo.

Show evidence (2 references)

PMID:39543104 SUPPORT In Vitro

"When attempting to replicate the differentiation process of embryonic granulosa cells, we observed the downregulation of specific genes-GATA4, FOXL2, AMHR2, CYP19A1, and FSH-in Turner syndrome-derived granulosa cells (TS-GCs)."

Directly supports the reduced lineage-marker programme.

PMID:39543104 SUPPORT In Vitro

"Additionally, we identified dysregulation of the cell cycle in TS-GCs."

Directly supports the cell-cycle component of the node.

Turner Cardiomyocyte Transcriptome and Contractile Dysregulation

Patient-derived 45,X iPSC cardiomyocytes exhibit altered coding and non-coding RNA profiles, lower beating frequency, and increased mitochondrial DNA copy number. These observations nominate a cardiac-cell dosage response but do not demonstrate a cause of bicuspid valve, coarctation, generalized arteriopathy, or dissection.

cardiomyocyte CL:0000746

heart development GO:0007507 ↕ DYSREGULATED

Experimental models

45,X patient-derived iPSC cardiomyocytes IPSC DERIVED MODEL The model reproduces altered coding and non-coding RNA profiles, reduced beating frequency, and increased mitochondrial DNA copy number.

Show evidence (2 references)

PMID:38124119 SUPPORT In Vitro

"We observed lower beating frequencies and higher mitochondrial DNA copies per nucleus in TS-CMs."

Supports the functional and mitochondrial readouts in the model.

PMID:38124119 SUPPORT In Vitro

"Moreover, we have identified a global transcriptome dysregulation of both coding and non-coding RNAs in TS-CMs."

Supports the transcriptomic component of the node.

Accelerated Ovarian Germ Cell Attrition and Follicular Atresia

Germ cells are laid down in the Turner ovary but are then lost at an accelerated rate through follicular atresia, so the process is depletion rather than failure of germ-cell formation. The distinction is what makes the fertility picture graded rather than absolute: the rate of loss varies, it is slower in mosaic karyotypes, and it is the reason ovarian tissue or oocyte cryopreservation is even discussed — there is a window before the reserve is exhausted rather than an ovary that never had one.

oocyte CL:0000023 granulosa cell CL:0000501

ovarian follicle atresia GO:0001552 ↑ INCREASED germ cell development GO:0007281 ↓ DECREASED

Animal models

39,X (XO) mouse ovarian-reserve background series Mouse partially recapitulates C57BL/6J XO females reproduce early oocyte loss and infertility or subfertility, while mixed-background XO females show a milder reserve loss without the human fertility endpoint.

Downstream

Ovarian Dysgenesis with Streak Gonad Exhaustion of the follicular reserve leaves a fibrous streak gonad incapable of steroidogenesis.

Infertility Accelerated follicular loss depletes the ovarian reserve and thereby removes the reproductive capacity, with residual fertility possible when mosaicism slows or limits that depletion.

Show evidence (2 references)

PMID:31240242 SUPPORT Human Clinical

"Due to rapid follicular atresia, the majority of women with TS suffer from primary ovarian insufficiency around puberty."

Names accelerated follicular atresia as the mechanism and places its clinical endpoint at around puberty.

PMID:31240242 SUPPORT Human Clinical

"The rate of decline in fertility is variable in girls with TS and can be more complex in cases with mosaicism."

Supports attrition rate — not presence or absence of germ cells — as the variable that karyotype modifies.

Ovarian Dysgenesis with Streak Gonad

The involuted, fibrous streak gonad that remains once the follicular reserve is exhausted. This is the tissue-level lesion, held separately from the systemic endocrine state it produces, because the two are separated in time and in what they respond to: the streak gonad is irreversible, whereas the endocrine consequence downstream of it is fully replaceable.

ovarian stromal cell CL:0002132

Downstream

Hypergonadotropic Hypogonadism and Estrogen Deficiency A gonad that makes neither estrogen nor inhibin releases the pituitary from negative feedback, so gonadotropins rise and the systemic consequences of estrogen deficiency follow.

Gonadal Dysgenesis with Streak Ovaries The tissue-level streak-gonad state is the substrate of the corresponding clinical gonadal-dysgenesis phenotype.

Show evidence (2 references)

PMID:16641863 SUPPORT Human Clinical

"gonadal dysgenesis in 85-90% of cases"

Establishes that the great majority of individuals reach frank gonadal dysgenesis.

PMID:38748847 SUPPORT Human Clinical

"Individuals with mosaic TS are more likely to have spontaneous puberty, normal gonadotropin levels, a measurable AMH, and follicles in ovarian biopsies as compared to those who have monosomy X karyotype."

Supports karyotype as a severity modifier of this node — residual follicles are demonstrable on biopsy in mosaic individuals.

Hypergonadotropic Hypogonadism and Estrogen Deficiency

The systemic endocrine state: gonadotropins are high, gonadal steroid output is absent, and puberty does not start spontaneously in most individuals. Estrogen deficiency from an age at which the skeleton, uterus and secondary sexual characteristics all depend on it is what converts a gonadal lesion into a systemic one, and it is the reason hormone replacement is continued to the age of normal menopause rather than being used only to induce puberty.

estrogen biosynthetic process GO:0006703 ↓ DECREASED

Downstream

Hypergonadotropic Hypogonadism and Delayed Puberty The systemic endocrine state is expressed clinically as elevated gonadotropins and failure or delay of spontaneous puberty.

Osteoporosis Estrogen deficiency during the period of peak bone-mass accrual and across adult life contributes to low bone density; improvement with estrogen supplementation supports this direction while not excluding SHOX, vitamin-D, or other contributors.

Show evidence (2 references)

PMID:16641863 SUPPORT Human Clinical

"Hormone replacement treatment should be initiated at a physiological age in these patients who do not enter puberty spontaneously and should be continued up to the age of normal menopause."

Establishes both that spontaneous puberty fails and that the deficiency is lifelong rather than pubertal.

PMID:16641863 SUPPORT Human Clinical

"the improvement of bone mineral density; normal uterine growth"

Names the two end-organ deficits attributable to the estrogen shortfall, each corrected by replacement.

Fetal Jugular Lymphatic Sac Obstruction and Lymphatic Network Dysplasia

The fetal jugular lymphatic sacs fail to drain properly into the venous system, raising lymphatic pressure and distending the posterior nuchal region into a cystic hygroma. Most hygromas resolve before birth; what survives is their imprint — the webbed neck, low posterior hairline and rotated ears are the healed residue of an intrauterine distension that has already gone. Peripheral lymphatic dysplasia in the same process gives the dorsal hand and foot lymphedema characteristic of the neonate.

Jugular Lymphatic Obstruction Hemodynamic Model of Left-Heart Obstruction

lymphatic endothelial cell CL:0002138

lymph vessel development GO:0001945 ↓ DECREASED

Downstream

Left-Sided Cardiac Outflow Tract Malformation Clark's hemodynamic hypothesis: distended thoracic ducts compress the ascending aorta and redirect intracardiac flow, producing left-heart obstructive lesions. This edge is curated as belonging to a named hypothesis rather than as established fact — the epidemiological association between neck web and coarctation is strong and reproducible, but the mechanism connecting them is inferred, not observed.

Webbed Neck Resolution of the fetal nuchal lymphatic distension leaves the persistent lateral neck folds recorded clinically as webbing.

Lymphedema Dysplastic peripheral lymphatic drainage produces the neonatal and relapsing limb swelling.

Show evidence (1 reference)

PMID:6463900 SUPPORT Human Clinical

"Increased lymphatic pressure associated with jugular lymphatic sac obstruction distends the thoracic ducts, which compress the ascending aorta altering intracardiac blood flow."

States the jugular lymphatic sac obstruction that defines this node. Note this snippet also carries the downstream hemodynamic claim, which is curated separately as an ALTERNATIVE hypothesis rather than as settled mechanism.

Left-Sided Cardiac Outflow Tract Malformation

Bicuspid aortic valve and coarctation of the aorta dominate the congenital cardiac phenotype. Their importance is not primarily neonatal — many are haemodynamically tolerated in childhood — but that they identify a subgroup with substantially increased adult aortic-dilation and dissection risk.

Downstream

Progressive Aortic Dilation A malformed valve and arch mark increased dilation risk through altered hemodynamics, but they are neither necessary nor sufficient: a parallel Turner arteriopathy can produce dilation even without structural heart disease.

Bicuspid Aortic Valve The malformed outflow-tract state includes the bicuspid-valve phenotype.

Coarctation of the Aorta The malformed outflow-tract state includes narrowing of the aortic arch.

Show evidence (2 references)

PMID:31240242 SUPPORT Human Clinical

"In addition to short stature and gonadal dysgenesis, it is associated with cardiac and renal anomalies."

Places cardiac malformation among the cardinal features.

PMID:23032325 SUPPORT Human Clinical

"Of those with spontaneous aortic dissections, 18 of 19 (95%) had an associated cardiac malformation that included a bicuspid aortic valve."

Establishes that the malformed left outflow tract is present in almost every dissection case.

Progressive Aortic Dilation

The chronic, silent, measurable state: an ascending aorta enlarging over years. It is held separate from the acute dissection event downstream of it because the two differ in everything that matters clinically — time course, detectability, and above all treatment join point. Dilation is what surveillance imaging measures and what antihypertensive therapy and elective surgery are aimed at; dissection is the event those measures exist to prevent. The decisive feature of the dilation is one of calibration rather than biology: it becomes dangerous at absolute diameters that are unremarkable in an average-height adult, which is why surveillance is indexed to body surface area and why an aortic size index above 2.5 cm/m2 triggers surgical consideration.

Downstream

Aortic Dissection and Rupture A dilated ascending aorta is the substrate on which dissection occurs; the dilation is progressive and the dissection is the discrete event that terminates it.

Show evidence (2 references)

PMID:23032325 SUPPORT Human Clinical

"Individuals with Turner syndrome who are >18 years of age with an ascending aortic size index >2.5 cm/m(2) should be considered for an aortic operation to prevent aortic dissection."

Gives the indexed threshold that operationalises this node clinically.

PMID:38748847 SUPPORT Human Clinical

"Dilation of the aorta, brachiocephalic and carotid arteries may be present even in the absence of structural heart disease, consistent with an underlying generalized arteriopathy."

Supports dilation as a state of the vessel wall in its own right — present even without a structural cardiac lesion — rather than purely as a downstream consequence of the malformed outflow tract.

Aortic Dissection and Rupture

The acute catastrophic event and the leading avoidable cause of sudden death in the syndrome. It occurs at a young age relative to other aortopathies and is frequently recognised late. Dissection is also reported in individuals with no cardiac malformation at all, so a structurally normal valve reduces but does not abolish the risk.

Downstream

Aortic Dissection The acute aortic-wall event is the corresponding clinical phenotype.

Show evidence (3 references)

PMID:23032325 SUPPORT Human Clinical

"Girls and women with Turner syndrome are at risk for aortic dissection and rupture."

States the endpoint this node represents.

PMID:38748847 SUPPORT Human Clinical

"The incidence of aortic dissection in TS is approximately 164 per 100 000 person–years, compared to 6 per 100 000 person–years in the general population."

Quantifies the excess risk this node carries relative to the general population.

PMID:23032325 SUPPORT Human Clinical

"In 1 individual there was no predisposing finding other than the presence of Turner syndrome."

Supports the residual risk in the absence of a cardiac malformation, preventing this node from being read as wholly downstream of the previous one.

PAR1 Haploinsufficiency and the Turner Neurocognitive Phenotype

A characteristic cognitive profile with preserved verbal ability and selectively impaired visuospatial and perceptual processing. Deletion mapping localises it to under 2 Mb of PAR1, independent of parent of origin and of X-inactivation skewing — which is what makes it a gene-dosage phenotype rather than a consequence of estrogen deficiency or of the psychosocial impact of short stature.

Downstream

Impaired Visuospatial and Perceptual Cognition The mapped PAR1 dosage state produces the characteristic cognitive phenotype.

Show evidence (2 references)

PMID:10931762 SUPPORT Human Clinical

"Turner syndrome (TS) is associated with a characteristic neurocognitive profile that includes impaired visuospatial/perceptual abilities."

Defines the phenotype this node represents.

PMID:10931762 SUPPORT Human Clinical

"Only subjects missing approximately 10 Mb of distal Xp manifested the specified neurocognitive profile."

The deletion-mapping result establishing that the phenotype tracks a specific interval rather than the whole chromosome.

⬡

Pathograph

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

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Phenotypes

20

Cardiovascular 4

Hypertension HP:0000822

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"The prevalence of hypertension is as high as 20%-40% in children"

Gives the paediatric prevalence. No single frequency band is recorded because the guideline reports markedly different figures for children and adults, so one band would misrepresent the age dependence.

PMID:38748847 SUPPORT Human Clinical

"TS is often accompanied by hypertension, which has been linked to the development of aortic dilation or dissection, both observed with strikingly increased frequency in TS."

Connects the phenotype to the aortopathy arm, which is why it is curated rather than left as a general comorbidity.

Bicuspid Aortic Valve HP:0001647

Show evidence (1 reference)

PMID:23032325 SUPPORT Human Clinical

"Of those with spontaneous aortic dissections, 18 of 19 (95%) had an associated cardiac malformation that included a bicuspid aortic valve."

Documents bicuspid aortic valve in the dissection cohort.

Coarctation of the Aorta Coarctation of aorta HP:0001680

Show evidence (1 reference)

PMID:6463900 SUPPORT Human Clinical

"The difference was most striking in coarctation of the aorta for which the prevalence was 25% with web neck and 3% with normal neck"

Quantifies coarctation prevalence stratified by neck web in a 45,X series.

Aortic Dissection HP:0002647

Show evidence (1 reference)

PMID:23032325 SUPPORT Human Clinical

"Girls and women with Turner syndrome are at risk for aortic dissection and rupture."

States the phenotype and its clinical significance.

Ear 2

Recurrent Otitis Media and Middle Ear Disease HP:0000388

Temporal: RECURRENT

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"From early childhood through adolescence, persistent middle ear fluid and recurrent acute otitis media are common (24%-48%) in TS."

States the phenotype and its childhood time course. No frequency band is recorded because the quoted 24-48% range straddles the HPO Occasional (5-29%) and Frequent (30-79%) boundaries, and choosing either would assert a precision the source does not carry.

PMID:38748847 SUPPORT Human Clinical

"Recurrent otitis media in early childhood has been shown to be a strong predictor of future middle ear pathologies, including tympanic membrane perforations and scarring, retractions, and cholesteatoma."

Supports the cumulative structural consequences that make this more than a nuisance phenotype.

High-Frequency Sensorineural Hearing Loss FREQUENT Sensorineural hearing impairment HP:0000407

Course: PROGRESSIVE

Show evidence (3 references)

PMID:17095347 SUPPORT Human Clinical

"More than 60% of patients with TS had HFQ-SNHL."

Gives the frequency directly; >60% falls within the HPO Frequent (30-79%) band.

PMID:17095347 SUPPORT Human Clinical

"The age-dependent increase in hearing thresholds in the high frequencies was more apparent in patients with TS with monosomic 45, X than in those with the mosaic type"

Supports both the progressive course and the karyotype dependence.

PMID:17095347 SUPPORT Human Clinical

"HFQ-SNHL showed little relation to the history of middle ear infection and puberty"

Supports the separation of the sensorineural loss from the conductive consequences of otitis media.

Endocrine 2

Hypergonadotropic Hypogonadism and Delayed Puberty HP:0000815

Show evidence (2 references)

PMID:31213699 SUPPORT Human Clinical

"Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."

Names both delayed puberty and hypergonadotropic hypogonadism.

PMID:16641863 SUPPORT Human Clinical

"Hormone replacement treatment should be initiated at a physiological age in these patients who do not enter puberty spontaneously and should be continued up to the age of normal menopause."

States the failure of spontaneous puberty.

Hypothyroidism HP:0000821

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"We recommend screening for hypothyroidism with measurement of TSH every 1-2 years starting at 2 years of age and continuing through adulthood, and with new symptoms."

A graded recommendation for lifelong biochemical screening, which asserts hypothyroidism as an expected recurring complication. No frequency band is recorded: the guideline gives a pooled figure for autoimmunity overall (61% lifetime) but no separate prevalence for hypothyroidism itself.

PMID:38748847 SUPPORT Human Clinical

"Early diagnosis can also improve QoL by allowing for timely screening and intervention for complications such as strabismus, hearing loss, renal and cardiac abnormalities, hypothyroidism, celiac disease and neurodevelopmental disabilities and mental health concerns."

Lists hypothyroidism among the syndrome's expected complications.

Genitourinary 3

Gonadal Dysgenesis with Streak Ovaries VERY_FREQUENT HP:0000133

Show evidence (1 reference)

PMID:16641863 SUPPORT Human Clinical

"gonadal dysgenesis in 85-90% of cases"

Directly quantifies the frequency band: 85-90% falls in the HPO Very frequent (80-99%) range.

Infertility HP:0000789

Show evidence (2 references)

PMID:31213699 SUPPORT Human Clinical

"Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."

Lists infertility among the defining features.

PMID:31240242 SUPPORT Human Clinical

"The rate of decline in fertility is variable in girls with TS and can be more complex in cases with mosaicism."

Supports the qualification that fertility loss is graded rather than uniform.

Horseshoe Kidney and Renal Malformation OCCASIONAL HP:0000085

Show evidence (4 references)

PMID:38748847 SUPPORT Human Clinical

"Horseshoe kidney and duplicated collecting system are the most common findings in TS, each occurring at a frequency of 15%-20%."

Direct quantitative support for the HPO Occasional (5-29%) band for the grounded horseshoe-kidney phenotype.

PMID:11045397 SUPPORT Human Clinical

"Of the 82 patients, 31 had different renal malformations (37.8%)."

Gives overall renal malformation frequency in a consecutive series.

PMID:11045397 SUPPORT Human Clinical

"Horse-shoe kidney was observed in 9 (29.0%) of the 31 patients"

Identifies horseshoe kidney as the leading structural lesion within that group.

+ 1 more reference

Head and Neck 1

Webbed Neck FREQUENT HP:0000465

Show evidence (1 reference)

PMID:6463900 SUPPORT Human Clinical

"Of 193 cases with documented 45 X-O karyotype, 106 (55%) had a web neck and 87 (45%) had a normal neck."

Gives an explicit count (106/193 = 55%) in a 45,X series, which maps to the HPO Frequent (30-79%) band.

Limbs 2

Cubitus Valgus HP:0002967

Show evidence (1 reference)

PMID:21925981 SUPPORT Human Clinical

"Patients with deletions of the distal segment of the short arm of X chromosome (Xp-) including haploinsufficiency of the SHOX (short stature homeobox) have, more often, short stature, skeletal abnormalities and hearing impairments."

Marked PARTIAL: the source supports skeletal abnormality as a class attributable to SHOX dosage but does not name cubitus valgus specifically.

Madelung Deformity HP:0003067

Show evidence (1 reference)

PMID:27194967 SUPPORT Human Clinical

"SHOX haploinsufficiency results in idiopathic short stature and Léri-Weill dyschondrosteosis and is associated with the short stature of patients with Turner syndrome."

Marked PARTIAL: supports the shared SHOX aetiology with Léri-Weill dyschondrosteosis, of which Madelung deformity is the defining feature, but does not name the deformity in Turner syndrome directly.

Metabolism 1

Lymphedema OCCASIONAL HP:0001004

Temporal: RECURRENT

Show evidence (3 references)

PMID:38748847 SUPPORT Human Clinical

"Clinically apparent lymphedema occurs in 12%-27% of girls and women with TS."

Direct quantitative support for the frequency band: 12-27% falls inside the HPO Occasional (5-29%) range.

PMID:38748847 SUPPORT Human Clinical

"Clinical lymphedema is often present at birth, frequently resolves or at least improves by age 2 years, and may have a relapsing and remitting course throughout life."

Supports the recurrent temporality recorded on the descriptor.

PMID:38748847 SUPPORT Human Clinical

"Lymphedema is reported more often in association with a 45,X karyotype compared to other karyotypes."

Supports karyotype as a severity modifier here, consistent with the entry's lumping rationale.

Musculoskeletal 2

Scoliosis HP:0002650

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"Idiopathic scoliosis is the most common form of scoliosis noted in individuals with TS though congenital scoliosis, thought to be due to abnormalities of vertebral bodies, also occurs."

States the phenotype and distinguishes the two forms seen in the syndrome.

PMID:38748847 SUPPORT Human Clinical

"We recommend physical examination to identify scoliosis at diagnosis and then at least annually until skeletal maturation"

A graded guideline recommendation for annual screening, which is a statement that the phenotype is expected rather than incidental.

Osteoporosis OCCASIONAL HP:0000939

Show evidence (3 references)

PMID:38748847 SUPPORT Human Clinical

"It is estimated that 23.8% of adults with TS have osteoporosis"

Direct adult prevalence support for the HPO Occasional (5-29%) band.

PMID:31213699 SUPPORT Human Clinical

"Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."

Lists osteoporosis among the syndrome's associated disorders.

PMID:16641863 SUPPORT Human Clinical

"the improvement of bone mineral density; normal uterine growth"

Supports the estrogen-dependence of the bone deficit via its correction.

Growth 1

Short Stature HP:0004322

Course: PROGRESSIVE

Show evidence (2 references)

PMID:31213699 SUPPORT Human Clinical

"Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."

Lists short stature first among the syndrome's defining features.

PMID:27194967 SUPPORT Human Clinical

"SHOX haploinsufficiency results in idiopathic short stature and Léri-Weill dyschondrosteosis and is associated with the short stature of patients with Turner syndrome."

Attributes the stature phenotype to SHOX dosage.

Other 2

Autoimmune Thyroiditis OCCASIONAL Hashimoto thyroiditis HP:0000872

Show evidence (2 references)

PMID:41243107 SUPPORT Human Clinical

"The pooled prevalence of AIT in TS patients was 21.61%"

Quantitative support for the frequency band. Pooled across 45 studies and 14,717 patients, 21.61% falls inside the HPO Occasional band (5-29%). The reported confidence interval (12.85-30.37) crosses into Frequent at its upper bound, so the point estimate is used rather than the interval.

PMID:41243107 SUPPORT Human Clinical

"These findings also suggest potential genetic associations between AIDs and the X chromosome, highlighting avenues for further investigation."

Supports the entry's position that the X-monosomy-to-autoimmunity link is a suggested association awaiting mechanism, not an established pathway.

Impaired Visuospatial and Perceptual Cognition Impaired visuospatial constructive cognition HP:0010794

Show evidence (1 reference)

PMID:10931762 SUPPORT Human Clinical

"Turner syndrome (TS) is associated with a characteristic neurocognitive profile that includes impaired visuospatial/perceptual abilities."

States the cognitive phenotype.

🧬

Genetic Associations

1

SHOX (SHOX haploinsufficiency is causative for the short-stature and mesomelic skeletal arm of Turner syndrome, but SHOX variation is neither necessary nor sufficient for Turner syndrome as a whole; the defining lesion is loss of all or part of a sex chromosome. )

Gene: SHOX hgnc:10853

Show evidence (3 references)

PMID:27194967 SUPPORT Human Clinical

"SHOX in the short arm pseudoautosomal region (PAR1) of sex chromosomes is one of the major growth genes in humans."

Locates the gene and establishes its role in human growth.

PMID:27194967 SUPPORT Human Clinical

"SHOX haploinsufficiency frequently results from deletions and duplications in PAR1 involving SHOX exons and/or the cis-acting enhancers, while exonic point mutations account for a small percentage of cases."

Supports the allele type recorded here — dosage loss through deletion rather than point mutation.

PMID:21925981 SUPPORT Human Clinical

"Patients with deletions of the distal segment of the short arm of X chromosome (Xp-) including haploinsufficiency of the SHOX (short stature homeobox) have, more often, short stature, skeletal abnormalities and hearing impairments."

Genotype-phenotype correlation from partial Xp deletions.

💊

Medical Actions

8

Recombinant Growth Hormone

Action: Pharmacotherapy NCIT:C15986

Agent: somatropin NCIT:C837

Somatropin given from childhood to increase adult height. Mechanistically it is not replacement — growth hormone secretion is not deficient in Turner syndrome — but pharmacological stimulation of a growth plate whose SHOX dosage deficit has blunted its output. The randomised evidence to adult height gives roughly +7 cm, which is the honest size of the effect. The PROTEIN_REPLACEMENT modality tag records the therapeutic platform — somatropin is a 191-amino-acid recombinant protein — and is not a claim that the treatment replaces a deficient hormone, which it does not.

Mechanism Target:

INHIBITS Skeletal Growth Failure and Mesomelic Dysmorphism — Acts on the growth-failure node, increasing attained adult height without correcting the underlying SHOX dosage deficit.

Show evidence (1 reference)

PMID:15784709 SUPPORT Human Clinical

"This is the first evidence from a randomized, controlled trial to adult height that GH supplementation with induction of puberty at a near physiological age increases the adult height of girls with Turner syndrome."

Randomised-controlled-trial evidence that the treatment acts on this node.

Show evidence (2 references)

PMID:15784709 SUPPORT Human Clinical

"the mean height gain due to GH, estimated by analysis of covariance, was +7.2 cm"

Quantifies the treatment effect from the randomised trial.

PMID:15784709 SUPPORT Human Clinical

"One hundred fifty-four girls with Turner syndrome, aged 7-13 yr, were randomly assigned to one of two groups"

Establishes the randomised design and cohort size behind the effect estimate.

Estrogen Replacement Therapy

Action: Hormone Replacement Therapy NCIT:C15599

Agent: estradiol CHEBI:16469

Estrogen to induce puberty at a physiological age, then continued replacement to the age of normal menopause. Unlike growth hormone this is true replacement — it substitutes for the hormone the streak gonad cannot make — and its end-organ targets are the skeleton and the uterus as well as secondary sexual development.

Mechanism Target:

RESTORES Hypergonadotropic Hypogonadism and Estrogen Deficiency — Substitutes the missing gonadal steroid, addressing this node directly rather than any upstream dosage lesion.

Show evidence (1 reference)

PMID:16641863 SUPPORT Human Clinical

"Hormone replacement treatment should be initiated at a physiological age in these patients who do not enter puberty spontaneously and should be continued up to the age of normal menopause."

States the indication and duration, both defined by the failed gonad.

Show evidence (2 references)

PMID:16641863 SUPPORT Human Clinical

"the improvement of bone mineral density; normal uterine growth"

Names two of the measurable end-organ benefits.

PMID:16641863 SUPPORT Human Clinical

"It is crucial that these women understand that hormone replacement is a long-term treatment."

Supports the lifelong rather than pubertal framing of the treatment.

Prophylactic Aortic Surgery

Action: Surgical Procedure NCIT:C15329

Elective replacement of the ascending aorta in individuals reaching an indexed size threshold, undertaken before dissection rather than in response to it. It is the only intervention that acts on the syndrome's leading cause of avoidable sudden death.

Mechanism Target:

INHIBITS Progressive Aortic Dilation — Removes the dilated segment before it dissects; prophylactic rather than mechanism-modifying.

Show evidence (1 reference)

PMID:23032325 SUPPORT Human Clinical

"Individuals with Turner syndrome who are >18 years of age with an ascending aortic size index >2.5 cm/m(2) should be considered for an aortic operation to prevent aortic dissection."

States the preventive indication and the threshold that triggers it.

Antihypertensive Therapy

Action: Antihypertensive Therapy NCIT:C172184

Agent: beta-blocker NCIT:C29576 angiotensin receptor blocker NCIT:C66930

Annual blood-pressure assessment with treatment of confirmed hypertension, preferentially with a beta-blocker, an angiotensin receptor blocker, or both where aortic dilation is also present. The mechanistic honesty here matters: the drug-class preference is imported from other genetically triggered aortopathies, and the guideline states plainly that no study has shown antihypertensive therapy to slow or prevent aortic dilation in Turner syndrome specifically. It is curated because it is a graded recommendation acting on a node this entry models, not because the aortic benefit is established.

Mechanism Target:

INHIBITS Hypertension — Treats the hypertension itself, which is the indication the guideline states without qualification.

Show evidence (1 reference)

PMID:38748847 SUPPORT Human Clinical

"We recommend annual assessment of blood pressure, preferably using ambulatory blood pressure monitoring (ABPM), and initiation of medical therapies if hypertension is confirmed, for all individuals with TS"

Graded recommendation to treat confirmed hypertension in every individual with TS.

INHIBITS Progressive Aortic Dilation — The intended but unproven target. Beta-blockade and angiotensin receptor blockade are chosen for their effect on aortic dilation in other aortopathies; in Turner syndrome the link between blood-pressure control and aortic events is inferential.

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"Medical therapy of hypertension for individuals with TS and aortic dilation should preferably include a beta-blocker, angiotensin receptor blocker (ARB), or both, which have been shown to prevent aortic dilation and aortic dissections in individuals with other aortopathy conditions."

Marked PARTIAL deliberately: the aortic benefit quoted is established in other aortopathies, and the sentence extends it to TS by analogy.

PMID:38748847 NO_EVIDENCE Human Clinical

"While hypertension is correlated with the presence of aortic dilation in TS, no studies have demonstrated that antihypertensive therapies slow or prevent aortic dilation."

The guideline's own explicit statement that the TS-specific evidence for this edge does not exist. Retained so the link cannot be read as established mechanism.

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"We recommend treatment with a beta-blocker, an angiotensin receptor blocker, or both for individuals with TS who have hypertension and have a dilated aorta"

Names the recommended drug classes and the population in which they are indicated.

PMID:38748847 SUPPORT Human Clinical

"As hypertension is common, maintenance of normal blood pressure may reduce the risk for aortic events."

States the rationale, in the guideline's own hedged wording.

Fertility Preservation by Oocyte Cryopreservation

Action: fertility preservation Ontology label: Fertility Preservation NCIT:C71326

Controlled ovarian stimulation followed by oocyte cryopreservation, offered to post-menarcheal individuals with residual fertility potential. The treatment exists because the ovarian lesion is attrition rather than absent germ cells: there is a window before the reserve is exhausted, and the intervention is an attempt to act inside it. The guideline is explicit that it should not be offered to premenarcheal children, which is a limit on the window as much as an ethical constraint.

Mechanism Target:

BYPASSES Accelerated Ovarian Germ Cell Attrition and Follicular Atresia — Does not slow the attrition. It removes and stores gametes before the reserve is lost, so it bypasses the node rather than modifying it.

Show evidence (1 reference)

PMID:38748847 SUPPORT Human Clinical

"We recommend controlled ovarian stimulation and oocyte cryopreservation, in females with a fertility potential, as the primary fertility preservation option in post-menarche individuals of appropriate psychological maturity"

The graded recommendation, restricted to individuals who still have fertility potential — i.e. in whom this node has not yet run to completion.

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"We recommend that controlled ovarian stimulation and oocyte cryopreservation not be offered to premenarcheal children or individuals not mature enough to understand and undergo the procedure"

Records the guideline's explicit boundary on who should be offered the procedure.

PMID:38748847 SUPPORT Human Clinical

"We recommend offering AMH measurements to all individuals with TS from diagnosis. AMH should be monitored annually if fertility preservation is considered"

Ties the intervention to the AMH biochemical marker curated in this entry.

Otologic and Audiologic Management

Action: tympanostomy tube insertion Ontology label: Myringotomy with Ear Tube Placement NCIT:C70906

Tympanostomy tube insertion and hearing aids for the conductive loss of middle ear disease in childhood, and hearing aids or cochlear implantation for the progressive sensorineural loss. The two arms are separate interventions on separate lesions and are curated on one entry only because they share a care pathway.

Mechanism Target:

INHIBITS Recurrent Otitis Media and Middle Ear Disease — Ventilating the middle ear addresses the effusion that causes the conductive loss and the structural sequelae of recurrent infection.

Show evidence (1 reference)

PMID:38748847 SUPPORT Human Clinical

"We suggest placement of tympanostomy tubes at the early stages of chronic or recurrent middle ear disease in childhood (as for a high-risk population)"

Graded recommendation targeting this node, explicitly at a lower threshold than in the general population.

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"We recommend rapid intervention with tympanostomy tube insertion or hearing aids for conductive hearing loss due to middle ear disease in childhood"

Covers the conductive arm of the intervention.

PMID:38748847 SUPPORT Human Clinical

"We recommend rehabilitation with hearing aids or cochlear implantation for sensorineural hearing loss"

Covers the sensorineural arm, which is a different lesion — the progressive high-frequency loss curated as its own phenotype.

Multidisciplinary Lifelong Surveillance

Action: Supportive Care NCIT:C15747

Coordinated follow-up across endocrinology, cardiology, nephrology, audiology and psychology. This is listed as a treatment because in Turner syndrome the organ complications are mostly silent until they are severe, so scheduled surveillance — not symptom response — is what changes outcome.

Show evidence (1 reference)

PMID:38748847 SUPPORT Human Clinical

"TS affects multiple organs through all stages of life, necessitating multidisciplinary care."

States the rationale for lifelong multidisciplinary management.

Genetic Counseling

Action: Genetic Counseling NCIT:C15240

Counseling addressed to the affected individual's reproductive options and to the interpretation of a mosaic karyotype, rather than to family recurrence risk, which is not appreciably raised.

Show evidence (1 reference)

PMID:31240242 SUPPORT Human Clinical

"Ethical, clinical and psychological dilemmas should be considered, discussed and addressed before considering such a novel approach."

Supports the counseling requirement around fertility-preservation decisions specifically.

🔬

Biochemical Markers

3

Elevated follicle-stimulating hormone (FSH) (INCREASED)

Context: FSH is the operative marker of the hypergonadotropic state. Its trajectory is biphasic rather than monotonic — high in infancy, normal through mid-childhood, rising again peripubertally — which is why the guideline specifies an age window (8-9 years, then annually) rather than a single measurement, and why a normal value in mid-childhood carries no reassurance.

Pathograph Readouts

Readout Of Hypergonadotropic Hypogonadism and Estrogen Deficiency Positive Diagnostic

A rising FSH without pubertal signs is the biochemical definition of the hypergonadotropic state this node represents, and is the trigger for hormone replacement.

Show evidence (1 reference)

PMID:38748847 SUPPORT Human Clinical

"If gonadotropins (FSH in particular) in repeated samples (two or more) measured yearly from age 8-9 years are clearly elevated without any pubertal signs on physical exam, the girl with TS will need HRT."

Makes the elevated gonadotropin the operational readout of gonadal failure.

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"Circulating concentrations of both FSH and LH present a biphasic pattern in TS individuals with hypogonadism: elevated after birth, declining to values similar to girls with normal ovarian function during mid-childhood, and rising again in the peripubertal years, or at the time of loss of..."

Documents both the elevation and the biphasic trajectory that shapes when it is measured.

PMID:38748847 SUPPORT Human Clinical

"We recommend measuring luteinizing hormone (LH), follicle stimulating hormone (FSH) and anti-Müllerian hormone (AMH) at 8-9 years and yearly until 11-12 years to enable timely referral for fertility preservation if appropriate"

Gives the guideline-specified measurement schedule.

Elevated luteinizing hormone (LH) (INCREASED)

Context: LH rises with FSH as pituitary feedback is released, and is measured alongside it. FSH is the more informative of the pair in this setting, so LH is curated as a co-marker rather than as an independent trigger for treatment.

Pathograph Readouts

Readout Of Hypergonadotropic Hypogonadism and Estrogen Deficiency Positive Diagnostic

Elevated LH reports the same loss of gonadal negative feedback as FSH.

Show evidence (1 reference)

PMID:38748847 SUPPORT Human Clinical

"LH and FSH are basic markers in the assessment of ovarian function."

States the role of both gonadotropins as markers of the ovarian state.

Show evidence (1 reference)

PMID:38748847 SUPPORT Human Clinical

"Circulating concentrations of both FSH and LH present a biphasic pattern in TS individuals with hypogonadism: elevated after birth, declining to values similar to girls with normal ovarian function during mid-childhood, and rising again in the peripubertal years, or at the time of loss of..."

Documents the LH elevation and its time course.

Low anti-Müllerian hormone (AMH) (DECREASED)

Context: AMH reports the primordial follicle pool, so it measures the upstream attrition node rather than the downstream endocrine state — which is what makes it the fertility-preservation marker rather than the hormone-replacement marker. The guideline is unusually explicit about its limits: single values vary within an individual and across assays, and its predictive value in younger children is uncertain, so serial rather than isolated measurement is recommended.

Pathograph Readouts

Readout Of Accelerated Ovarian Germ Cell Attrition and Follicular Atresia Negative Prognostic

A falling AMH tracks depletion of the follicle pool, which is the process this node represents; it is used prognostically to time fertility preservation before the reserve is gone.

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"AMH reflects the primordial follicle pool and predicts the reproductive lifespan of women as a key biomarker of ovarian reserve."

Establishes AMH as a readout of the follicular reserve rather than of gonadal endocrine output.

PMID:38748847 SUPPORT Human Clinical

"In individuals with TS, AMH is associated with clinical features of ovarian reserve"

Confirms the association holds specifically in Turner syndrome rather than only in the general population.

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"Low AMH and undetectable inhibin B can also be used to predict ovarian insufficiency in TS, and we recommend measuring AMH along with FSH and LH during assessments."

States the direction of the abnormality and its predictive use.

PMID:38748847 SUPPORT Human Clinical

"Isolated AMH measurements are influenced by several factors, including age and pubertal stage, with known intra-individual variability and variation in test accuracy. The utility of AMH to predict ovarian reserve in younger age groups is uncertain"

Marked PARTIAL: the guideline qualifies its own recommendation, and the caveat is retained so the marker is not read as a settled quantitative test.

🔬

Diagnosis

11

Karyotype Analysis

Definitive diagnosis rests on demonstrating complete or partial absence of a second sex chromosome. Because mosaicism is common and can be tissue-limited, a normal peripheral-blood karyotype does not exclude the diagnosis in a clinically suspicious case — which is why the guideline specifies a minimum of 30 metaphases rather than a standard count, and why a normal blood result in a phenotypically suspicious individual is followed by analysis of a second tissue.

Karyotyping NCIT:C16768

Show evidence (4 references)

PMID:31213699 SUPPORT Human Clinical

"Turner syndrome is a rare condition in women that is associated with either complete or partial loss of one X chromosome, often in mosaic karyotypes."

Establishes what the test must demonstrate, and that mosaic karyotypes are frequent enough to shape the testing strategy.

PMID:31213699 SUPPORT Human Clinical

"Despite an often conspicuous phenotype, the diagnostic delay can be substantial and the average age at diagnosis is around 15 years of age."

Motivates the diagnostic step: the phenotype alone is repeatedly missed for a decade and a half on average.

PMID:38748847 SUPPORT Human Clinical

"When testing for TS, we recommend that a minimum of 30 metaphases be counted on a chromosome analysis as the first-line test."

Gives the metaphase minimum, which exists because low-level mosaicism is missed at conventional counts.

+ 1 more reference

Y Chromosomal Material Screening

Molecular screening for Y-chromosome material in individuals with a 45,X karyotype and signs of virilization. This is a mechanism with a surveillance consequence rather than a diagnostic refinement: retained Y material in a dysgenetic gonad carries a gonadoblastoma and dysgerminoma risk, and the finding opens an individualised discussion about gonadectomy weighed against residual gonadal function and fertility.

Karyotyping NCIT:C16768

The diagnosis_term reuses NCIT:C16768 (Karyotyping) because NCIT has no distinct clinical-action term for targeted Y-material molecular screening. The description carries the specificity the ontology term cannot.

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"We recommend screening for Y chromosomal material by PCR or other molecular method in TS individuals with a 45,X karyotype and signs of virilization"

States the screening indication and the methods used.

PMID:38748847 SUPPORT Human Clinical

"We recommend individualized decision-making about gonadectomy/salpingo-oophorectomy in girls and women with TS and Y chromosome material identified on standard karyotyping or FISH analysis."

Gives the clinical consequence of a positive result, which is what makes this screening step worth curating separately from the diagnostic karyotype.

Cardiac Magnetic Resonance Imaging

Cross-sectional imaging of the thoracic aorta and arch, recommended in addition to or instead of screening echocardiography in every newly diagnosed adolescent or adult. It is curated separately from echocardiography because it is the modality that visualises the segments echocardiography cannot, and so is the diagnostic join point for the aortopathy arm.

cardiac magnetic resonance imaging NCIT:C137915

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"CMR should be performed, in addition to or instead of initial screening echocardiography, in all adolescents and adults newly diagnosed with TS."

States the recommendation and its scope.

PMID:38748847 SUPPORT Human Clinical

"We recommend that cardiovascular imaging, ideally CMR or CT, should be performed at least once within 2 years before planned pregnancy or assisted reproductive methods"

Gives the second, pre-pregnancy indication, which is where the aortopathy and reproductive arms of the disease intersect.

Cardiovascular Imaging Surveillance

Echocardiographic and cross-sectional imaging of the valve and thoracic aorta, indexed to body surface area rather than read against absolute adult diameters. The indexing is the point — an ascending aortic size index above 2.5 cm/m2 in an adult is the threshold at which surgery is considered, a diameter that would be unremarkable if judged in centimetres alone.

Echocardiography Test NCIT:C16525

Show evidence (2 references)

PMID:23032325 SUPPORT Human Clinical

"Individuals with Turner syndrome who are >18 years of age with an ascending aortic size index >2.5 cm/m(2) should be considered for an aortic operation to prevent aortic dissection."

Gives the indexed surveillance threshold this diagnostic step exists to detect.

PMID:23032325 SUPPORT Human Clinical

"More than half (13/19, 68%) came to medical attention >24 hours after the onset of symptoms."

Supports surveillance rather than symptom-triggered presentation as the viable detection route, given the observed delay once dissection occurs.

Renal Ultrasonography at Diagnosis

Structural renal malformation is present in over a third of cases and is largely asymptomatic, so imaging is done at diagnosis rather than in response to symptoms.

renal ultrasonography NCIT:C159885

Show evidence (2 references)

PMID:11045397 SUPPORT Human Clinical

"Of the 82 patients, 31 had different renal malformations (37.8%)."

Gives the yield that justifies screening every newly diagnosed individual.

PMID:11045397 SUPPORT Human Clinical

"We conclude that all forms of TS should have routine nephrological screening on diagnosis"

States the screening recommendation directly.

Audiological Surveillance

Repeated audiometry, because the sensorineural loss is progressive with age and is not predicted by the childhood history of middle-ear infection. The guideline sets an explicit lifelong cadence — every 2-3 years through childhood and adolescence, every 5 years in adulthood — which is what distinguishes surveillance from symptom-triggered testing here.

audiometric evaluation NCIT:C38036

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"We recommend newborn hearing screening be completed, and if this is normal, age-appropriate behavioral audiometric evaluation be conducted every 2-3 years in childhood and adolescence starting as soon as developmentally able (1-2 years of age), every 5 years in adults, and any time decreased..."

Gives the surveillance cadence across the lifespan.

PMID:17095347 SUPPORT Human Clinical

"Because the increase in hearing threshold at high frequencies was shown to depend on karyotype and aging, regular otological examination is important for the determination of proper treatment."

States the recommendation and the reason it must be repeated over time.

Thyroid Function Surveillance

Measurement of TSH every 1-2 years from age two through adulthood, with additional testing when symptoms arise and thyroid antibodies checked when TSH is elevated. This monitors the treatable functional endpoint rather than screening asymptomatic individuals for antibodies that do not change care.

Show evidence (1 reference)

PMID:38748847 SUPPORT Human Clinical

"We recommend screening for hypothyroidism with measurement of TSH every 1-2 years starting at 2 years of age and continuing through adulthood, and with new symptoms."

Gives the lifelong age and interval for thyroid surveillance.

Diabetes Surveillance

Hemoglobin A1c or fasting glucose every 1-2 years beginning at age 10-12, earlier if symptoms occur. Diabetes autoantibodies are assessed after a diabetes diagnosis because both type 1 and type 2 disease occur and can be difficult to distinguish in Turner syndrome.

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"We recommend screening for diabetes with measurement of hemoglobin A1c or fasting glucose every 1-2 years starting at age 10-12 years or sooner with symptoms of diabetes"

Gives the recommended tests, starting age, and interval.

PMID:38748847 SUPPORT Human Clinical

"We recommend assessment of diabetes autoantibodies at diagnosis of diabetes in girls and women with TS to determine the type of diabetes as it is not easy to differentiate Type 1 and Type 2 diabetes in this population"

Explains the post-diagnosis typing step.

Liver Biochemistry Surveillance

Liver enzymes are measured in childhood and every 1-2 years from age ten onward. Persistent abnormalities prompt reassessment and specialist workup; they are not, by themselves, a reason to stop hormone replacement.

Show evidence (1 reference)

PMID:38748847 SUPPORT Human Clinical

"We recommend measuring liver enzymes (alanine aminotransferase (ALT) at minimum) in childhood and every 1-2 years starting at the age of 10 and continuing throughout the lifespan."

Gives the minimum assay and lifelong cadence.

Celiac Disease Serologic Surveillance

Tissue-transglutaminase IgA with total IgA from age two and every 2-5 years thereafter, with symptom-triggered testing at any age. The clinical association is strong enough to warrant screening even though the X-dosage-to-autoimmunity mechanism remains unresolved.

Show evidence (1 reference)

PMID:38748847 SUPPORT Human Clinical

"We recommend screening for celiac disease by measuring tissue transglutaminase antibodies (TTG IgA with total IgA) in asymptomatic individuals starting at age 2 years, and subsequently every 2-5 years"

Gives the recommended assay, starting age, and interval.

Bone Health Surveillance

Vitamin D testing begins at age 9-11 and repeats every 2-3 years. DXA is obtained after linear growth is complete but before age 21 and every 5-10 years in adulthood, with closer serial assessment when fractures, inadequate estrogen replacement, celiac disease, menopause, or other risks are present.

Show evidence (2 references)

PMID:38748847 SUPPORT Human Clinical

"We recommend routine screening for vitamin D deficiency using a serum 25 (OH) vitamin D level concentration between 9 and 11 years of age and every 2-3 years ongoing and treating with inactive vitamin D supplement as necessary"

Gives the age and cadence for vitamin-D surveillance.

PMID:38748847 SUPPORT Human Clinical

"We recommend obtaining a dual energy X-ray absorptiometry (DXA) scan after completion of growth but prior to 21 years of age and every 5-10 years throughout adulthood"

Gives the DXA timing and adult interval.

📊

Prevalence

2

Females (global, clinical practice guideline estimate)

Point Prevalence 50.0 per 100,000 1–9 per 10,000

The 2024 international guideline gives 50 per 100 000 females. This is a prevalence of diagnosed Turner syndrome and is therefore an undercount: the same literature puts mean age at diagnosis at about 15 years, so a substantial fraction of mosaic and mildly affected individuals are never ascertained.

Show evidence (1 reference)

PMID:38748847 SUPPORT Human Clinical

"Turner syndrome (TS) affects 50 per 100 000 females."

Gives the guideline point-prevalence estimate used for the normalised rate.

Live-born females (review estimate)

Birth Prevalence 40.0 per 100,000 1–9 per 10,000

The commonly quoted 1:2500 live female births, normalised to 40 per 100 000. Reported as a birth prevalence, so it is not directly comparable with the 50 per 100 000 point prevalence above.

Show evidence (1 reference)

PMID:21925981 SUPPORT Human Clinical

"Turner syndrome (TS) affects 1:2500 live females."

Source for the 1:2500 live-female-birth figure.

⚖️

Clinical Burden

High

Morbidity and mortality are raised across the lifespan, and the burden is distributed across organ systems rather than concentrated in one. The dominant avoidable event is aortic dissection, which in Turner syndrome occurs younger and at smaller absolute aortic diameters than in the general population — so a diameter that would not trigger intervention in an average-height adult can be the one that dissects here. Diagnostic delay is itself part of the burden: a mean age at diagnosis around 15 years means growth-promoting and cardiac-surveillance interventions are frequently started after their window of greatest benefit.

Show evidence (4 references)

PMID:31213699 SUPPORT Human Clinical

"Morbidity and mortality are increased in women with Turner syndrome compared with the general population"

States the excess morbidity and mortality.

PMID:31213699 SUPPORT Human Clinical

"the average age at diagnosis is around 15 years of age"

Quantifies the diagnostic delay that limits timely intervention.

PMID:23032325 SUPPORT Human Clinical

"Aortic dissection in Turner syndrome occurs in young individuals at smaller aortic diameters than in the general population or other forms of genetically triggered aortopathy."

Establishes that dissection occurs at younger age and smaller calibre than standard thresholds assume.

+ 1 more reference

📊

Related Datasets

2

Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome geo:GSE271780

Bulk RNA sequencing of day-14 granulosa-like cells differentiated from 45,X Turner and unaffected-control iPSCs, with adult cumulus granulosa cells used in the study as a reference population.

human BULK RNA SEQ n=10 Illumina NovaSeq 6000

granulosa cell CL:0000501

Conditions: 2 unaffected-control iPSC-derived granulosa-like cell lines 4 45,X Turner syndrome iPSC-derived granulosa-like cell subclones from 2 source donors (2 subclones per donor) 4 adult luteinized cumulus granulosa-cell reference samples

PMID:39543104

Direct disease-model dataset discovered with `just discover-datasets`; accession, organism, publication, data type, NovaSeq platform, and 10-sample three-group composition verified against NCBI GEO metadata on 2026-08-16.

Show evidence (1 reference)

PMID:39543104 SUPPORT In Vitro

"The raw data was deposited in GEO: GSE271780."

Direct accession statement from the primary publication.

The mRNA-lncRNA-circRNA network profiling of Turner syndrome patient-derived induced pluripotent stem cells and their derived cardiomyocytes geo:GSE239758

Coding and non-coding RNA microarray profiles from three 45,X Turner and three healthy-donor iPSC lines and their matched day-14 cardiomyocyte derivatives.

human MICROARRAY n=12 High-density mRNA, lncRNA, and...

cardiomyocyte CL:0000746

Conditions: 45,X Turner syndrome-derived iPSCs and cardiomyocytes 46,XX healthy-donor-derived iPSCs and cardiomyocytes

PMID:38124119

Direct disease-model dataset discovered with `just discover-datasets`; accession, organism, publication, data type, and 12-sample count verified against NCBI GEO metadata on 2026-08-16.

Show evidence (1 reference)

PMID:38124119 SUPPORT In Vitro

"The microarray data were deposited in the Gene Expression Omnibus (GEO) database under the accession no. GSE239758."

Direct accession statement from the primary publication.

🧫

Experimental Models

2

45,X patient-derived iPSC granulosa-like cells IPSC_DERIVED_MODEL

Human patient-derived system used to test granulosa differentiation, cell-cycle progression, apelin/APJ signaling, and pathway rescue. It is the first direct cellular model represented here for a candidate somatic-cell contribution to Turner ovarian attrition.

Organism

human NCBITaxon:9606

Tissue

ovary UBERON:0000992

Cell source

Fibroblast-reprogrammed iPSCs from two unrelated 45,X Turner patients and two unrelated unaffected controls, with multiple Turner subclones

Culture

Fourteen-day embryoid-body-to-intermediate-mesoderm-to-granulosa-like-cell differentiation with transcriptomic, marker, cell-cycle, and pathway-rescue assays

Publication

PMID:39543104

Pathograph links

Granulosa-Cell Apelin/APJ Signaling Dysfunction partially recapitulates fidelity: moderate The system measures reduced pathway signaling and demonstrates partial rescue with apelin ligands or downstream Akt activation.

Limitations: The comparison is non-isogenic and includes two Turner donors. Cultures were not purified by surface markers before bulk transcriptomics, so the observed difference cannot be assigned solely to a cell-autonomous pathway defect, and intact ovarian confirmation is absent.

Show evidence (1 reference)

PMID:39543104 SUPPORT In Vitro

"The apelin/APJ pathway exhibited differential signaling between the healthy and TS groups."

Supports the pathway readout in the model.

Granulosa-Cell Differentiation and Cell-Cycle Dysfunction partially recapitulates fidelity: moderate The system reproduces reduced granulosa marker expression and abnormal cell-cycle progression associated with 45,X donor cells.

Limitations: The cells are in-vitro granulosa-like derivatives rather than purified fetal ovarian granulosa cells, the donor count is small, and genetic background is not controlled isogenically. The model cannot show oocyte loss or follicular atresia directly.

Show evidence (1 reference)

PMID:39543104 SUPPORT In Vitro

"Additionally, we identified dysregulation of the cell cycle in TS-GCs."

Supports the cellular readout.

45,X patient-derived iPSC cardiomyocytes IPSC_DERIVED_MODEL

Patient-derived cardiac-cell system that measures the transcriptomic and contractile response to 45,X dosage in differentiated cardiomyocytes.

Organism

human NCBITaxon:9606

Tissue

heart UBERON:0000948

Cell source

Peripheral-blood-cell-derived iPSCs from three 45,X Turner patients and three unrelated 46,XX healthy donors

Culture

Two-dimensional cardiomyocyte differentiation with mRNA, lncRNA, and circRNA microarrays plus beating-frequency and mitochondrial-copy-number readouts

Publication

PMID:38124119

Pathograph links

Turner Cardiomyocyte Transcriptome and Contractile Dysregulation partially recapitulates fidelity: moderate The model reproduces altered coding and non-coding RNA profiles, reduced beating frequency, and increased mitochondrial DNA copy number.

Limitations: Only three Turner and three control donor lines were profiled, the design is non-isogenic, and the cardiomyocytes are immature two-dimensional cells. The system does not form an aortic valve, arch, or vessel wall, so it cannot establish a mechanism for the syndrome's structural cardiac or aortic phenotypes; proposed ceRNA circuits also lacked direct miRNA profiling.

Show evidence (2 references)

PMID:38124119 SUPPORT In Vitro

"We observed lower beating frequencies and higher mitochondrial DNA copies per nucleus in TS-CMs."

Supports the measured cellular phenotype.

+ 1 more reference

🐁

Animal Models

1

39,X (XO) mouse ovarian-reserve background series

A background-comparison series that resolves an important limitation of the generic XO mouse. Mixed-background XO females retain fewer neonatal oocytes but remain normally fertile, whereas C57BL/6J XO females have much more severe early oocyte loss and reduced fertility. The model therefore captures a background-modified ovarian-reserve phenotype, not a stable mouse analogue of human Turner infertility.

Species

Mouse

Genotype

39,X (XO) on mixed N2(C3H.B6) and inbred C57BL/6J genetic backgrounds

Background

Mixed N2(C3H.B6) compared with C57BL/6J

Publication

PMID:32634219

Pathograph links

Accelerated Ovarian Germ Cell Attrition and Follicular Atresia partially recapitulates fidelity: moderate C57BL/6J XO females reproduce early oocyte loss and infertility or subfertility, while mixed-background XO females show a milder reserve loss without the human fertility endpoint.

Limitations: Fidelity is strongly strain-dependent: mixed-background XO females retain normal fertility, and even the C57BL/6J phenotype does not reproduce the profound prenatal lethality or near-universal ovarian failure of human non-mosaic 45,X. The series can test modifiers of oocyte loss but cannot be treated as a generic model of the full Turner ovarian phenotype.

Show evidence (2 references)

PMID:32634219 SUPPORT Model Organism

"In this article, we report that XO mice on the C57BL/6J (B6) genetic background showed early oocyte loss, infertility or subfertility and high embryonic lethality, suggesting that the effect of monosomy X in the female germline may be shared between mice and humans."

Supports the recapitulated ovarian-reserve and fertility components in the B6 strain.

+ 1 more reference

Show evidence (1 reference)

PMID:18499648 SUPPORT Model Organism

"Unlike their human counterparts, XO mice are typically fertile, and their lack of a second sex chromosome can be transmitted from one generation to the next as an X-linked dominant trait with male lethality."

Records the classic translational mismatch that the background series qualifies.

{ }

Source YAML

click to show

name: Turner Syndrome
creation_date: "2026-08-10T00:00:00Z"
category: Genetic
synonyms:
- TS
- 45,X syndrome
- Monosomy X
- Ullrich-Turner syndrome
- Gonadal dysgenesis, Turner type
description: >
  Turner syndrome is the complete or partial absence of one X chromosome in a
  phenotypic female, and it is the only whole-chromosome haploinsufficiency in
  humans that is compatible with postnatal life. Its mechanistic core is a gene
  dosage problem rather than a mutation: most X-linked genes are already
  silenced on one X by X-inactivation, so losing an X is survivable, but the
  minority of genes that normally escape inactivation — and the pseudoautosomal
  genes that pair with a Y homologue — are expressed from both sex chromosomes
  in a typical karyotype and therefore fall to a single functional copy here.
  The disease is what that dosage shortfall does in each tissue that depends on
  one of those genes.

  Only one of those genes is mapped to its phenotype with confidence. SHOX, in
  the short-arm pseudoautosomal region PAR1, is a major human growth gene, and
  its haploinsufficiency accounts for the growth-plate failure that produces
  short stature and the mesomelic skeletal features. The rest of the syndrome —
  the ovarian, cardiovascular, renal, auditory and autoimmune components — is
  not explained by SHOX, and identifying the responsible escape genes is the
  central open problem of the field rather than a detail.

  Three further mechanisms operate largely independently of each other. Ovarian
  germ cells are laid down but then lost at an accelerated rate, so the gonad
  involutes to a fibrous streak and most affected individuals reach puberty
  already in primary ovarian insufficiency: the defect is attrition, not
  agenesis, which is why mosaic individuals with a slower rate of loss can
  menstruate and occasionally conceive. Fetal jugular lymphatic sacs fail to
  connect properly to the venous system, producing nuchal cystic hygroma whose
  resolution leaves the webbed neck and low posterior hairline as scars of an
  intrauterine event that has already passed. And the left side of the heart is
  often malformed — bicuspid aortic valve and coarctation — alongside a
  generalized arteriopathy that can occur even without structural heart disease.
  Those overlapping risks make aortic dissection the syndrome's leading cause
  of avoidable sudden death, at aortic diameters that would be considered
  unalarming in a person of average height.

  Clinically the syndrome is therefore not a single-organ endocrine disorder but
  a lifelong multisystem surveillance problem, and its two mechanism-matched
  interventions act on different arms: growth hormone addresses the SHOX growth
  deficit, and estrogen replacement substitutes for the failed gonad.
disease_term:
  preferred_term: Turner syndrome
  term:
    id: MONDO:0019499
    label: Turner syndrome
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0019499
      label: Turner syndrome
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
  - term:
      id: MONDO:0020466
      label: monosomy X
    mapping_predicate: skos:narrowMatch
    mapping_source: MONDO
  - term:
      id: MONDO:0020467
      label: mosaic monosomy X
    mapping_predicate: skos:narrowMatch
    mapping_source: MONDO
  - term:
      id: MONDO:0020472
      label: Turner syndrome due to structural X chromosome anomalies
    mapping_predicate: skos:narrowMatch
    mapping_source: MONDO
references:
- reference: PMID:38748847
  title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
- reference: PMID:31213699
  title: "Turner syndrome: mechanisms and management."
- reference: PMID:10931762
  title: "The Turner syndrome-associated neurocognitive phenotype maps to distal Xp."
- reference: PMID:27194967
  title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
- reference: PMID:6463900
  title: "Neck web and congenital heart defects: a pathogenic association in 45 X-O Turner syndrome?"
- reference: PMID:23032325
  title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
- reference: PMID:39543104
  title: "Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome."
- reference: PMID:18499648
  title: "Genotype, phenotype, and karyotype correlation in the XO mouse model of Turner Syndrome."
- reference: PMID:32634219
  title: "Premature ovarian insufficiency in the XO female mouse on the C57BL/6J genetic background."
parents:
- Chromosomal Disorder
- Sex chromosome disorder of sex development
- Gonadal dysgenesis
prevalence:
- population: Females (global, clinical practice guideline estimate)
  measure_type: POINT_PREVALENCE
  prevalence_class: BAND_1_5_PER_10000
  rate_per_100000: 50.0
  notes: >
    The 2024 international guideline gives 50 per 100 000 females. This is a
    prevalence of diagnosed Turner syndrome and is therefore an undercount: the
    same literature puts mean age at diagnosis at about 15 years, so a
    substantial fraction of mosaic and mildly affected individuals are never
    ascertained.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome (TS) affects 50 per 100 000 females."
    explanation: Gives the guideline point-prevalence estimate used for the normalised rate.
- population: Live-born females (review estimate)
  measure_type: BIRTH_PREVALENCE
  prevalence_class: BAND_1_5_PER_10000
  rate_per_100000: 40.0
  notes: >
    The commonly quoted 1:2500 live female births, normalised to 40 per 100 000.
    Reported as a birth prevalence, so it is not directly comparable with the
    50 per 100 000 point prevalence above.
  evidence:
  - reference: PMID:21925981
    reference_title: "The role of the SHOX gene in the pathophysiology of Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome (TS) affects 1:2500 live females."
    explanation: Source for the 1:2500 live-female-birth figure.
clinical_burden:
  burden_level: HIGH
  rationale: >
    Morbidity and mortality are raised across the lifespan, and the burden is
    distributed across organ systems rather than concentrated in one. The
    dominant avoidable event is aortic dissection, which in Turner syndrome
    occurs younger and at smaller absolute aortic diameters than in the general
    population — so a diameter that would not trigger intervention in an
    average-height adult can be the one that dissects here. Diagnostic delay is
    itself part of the burden: a mean age at diagnosis around 15 years means
    growth-promoting and cardiac-surveillance interventions are frequently
    started after their window of greatest benefit.
  evidence:
  - reference: PMID:31213699
    reference_title: "Turner syndrome: mechanisms and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Morbidity and mortality are increased in women with Turner syndrome compared with the general population"
    explanation: States the excess morbidity and mortality.
  - reference: PMID:31213699
    reference_title: "Turner syndrome: mechanisms and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the average age at diagnosis is around 15 years of age"
    explanation: Quantifies the diagnostic delay that limits timely intervention.
  - reference: PMID:23032325
    reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Aortic dissection in Turner syndrome occurs in young individuals at smaller aortic diameters than in the general population or other forms of genetically triggered aortopathy."
    explanation: Establishes that dissection occurs at younger age and smaller calibre than standard thresholds assume.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "TS affects multiple organs through all stages of life, necessitating multidisciplinary care."
    explanation: Supports the multisystem, lifelong character of the burden.
pathophysiology:
- name: Complete or Partial Loss of One X Chromosome
  role: trigger
  biological_scale: MOLECULAR
  description: >
    A meiotic or post-zygotic mitotic error leaves a phenotypically female
    individual with one intact X and either no second sex chromosome (45,X),
    a structurally abnormal second X (ring, isochromosome, deletion), or a
    mosaic mixture of cell lines. This is the only whole-chromosome
    haploinsufficiency compatible with postnatal life, which is itself the first
    mechanistic fact about the disease: survival is possible because
    X-inactivation has already reduced most X-linked genes to one functional
    copy in typical cells, so only the genes exempt from that silencing are
    actually rendered haploinsufficient by the loss.
  evidence:
  - reference: PMID:31213699
    reference_title: "Turner syndrome: mechanisms and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome is a rare condition in women that is associated with either complete or partial loss of one X chromosome, often in mosaic karyotypes."
    explanation: States the defining chromosomal lesion and that it is frequently mosaic.
  - reference: PMID:38124119
    reference_title: "Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "A 45,X monosomy (Turner syndrome, TS) is the only chromosome haploinsufficiency compatible with life."
    explanation: Supports the claim that this is the uniquely survivable whole-chromosome monosomy.
  downstream:
  - target: Haploinsufficiency of Pseudoautosomal and X-Inactivation Escape Genes
    causal_link_type: DIRECT
    description: >
      Loss of the second sex chromosome halves the dose of exactly those genes
      that are normally expressed from both copies.
    evidence:
    - reference: PMID:38124119
      reference_title: "Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Our study has revealed a genomewide ripple effect of X chromosome halpoinsufficiency at post-transcriptional level"
      explanation: Links the chromosomal loss to genome-wide dosage consequences.
- name: Haploinsufficiency of Pseudoautosomal and X-Inactivation Escape Genes
  role: central_effector
  biological_scale: MOLECULAR
  description: >
    Genes in the pseudoautosomal regions and the subset of X-linked genes that
    escape X-inactivation are normally transcribed from both sex chromosomes.
    With one sex chromosome absent or truncated they drop to a single functional
    dose. This node is the convergence point of the disease: every downstream
    arm is a tissue-specific consequence of a dosage shortfall in one or more of
    these genes. Only SHOX is confidently assigned to its phenotype; the
    identity of the escape genes responsible for the gonadal, cardiovascular,
    renal, auditory and immune arms is unresolved, and is curated here as an
    explicit knowledge gap rather than as a mechanism.
  notes: >
    No GO annotation is attached to this node deliberately. The obvious
    candidate, GO:0009048 (dosage compensation by inactivation of X
    chromosome), misdescribes 45,X: with a single X there is no second
    chromosome to inactivate, so dosage compensation is not pathologically
    decreased, it is simply not required. The lesion is half-dose of the
    pseudoautosomal and escape genes, which the node name already states
    accurately. Preferring no term to a misleading one.
  evidence:
  - reference: PMID:10931762
    reference_title: "The Turner syndrome-associated neurocognitive phenotype maps to distal Xp."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We conclude that haploinsufficiency of PAR1 gene(s) is the basis for susceptibility to the TS neurocognitive phenotype."
    explanation: >
      Deletion mapping in 34 females localises a Turner phenotype to
      haploinsufficiency of pseudoautosomal genes, establishing the dosage
      mechanism from human genetics rather than by inference.
  - reference: PMID:10931762
    reference_title: "The Turner syndrome-associated neurocognitive phenotype maps to distal Xp."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The phenotype was seen with either paternally or maternally inherited deletions and with either complete or incomplete skewing of X inactivation."
    explanation: >
      Excludes imprinting and skewed inactivation as explanations, leaving gene
      dosage as the operative variable.
  - reference: PMID:38124119
    reference_title: "Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "How loss of one X chromosome drive these conditions remains largely unknown."
    explanation: >
      States that the gene-to-phenotype assignment downstream of this node is
      still open — retained deliberately so the node is not read as settled.
  downstream:
  - target: SHOX Haploinsufficiency
    causal_link_type: DIRECT
    description: >
      SHOX lies in PAR1 and is one of the escape genes rendered haploinsufficient.
    evidence:
    - reference: PMID:27194967
      reference_title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "SHOX in the short arm pseudoautosomal region (PAR1) of sex chromosomes is one of the major growth genes in humans."
      explanation: Places SHOX in PAR1 and identifies it as a major growth gene.
  - target: Accelerated Ovarian Germ Cell Attrition and Follicular Atresia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      Gonadal involution is a dosage consequence of the missing X, but the
      specific escape gene(s) responsible have not been identified — hence
      INDIRECT rather than DIRECT.
    evidence:
    - reference: PMID:31213699
      reference_title: "Turner syndrome: mechanisms and management."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."
      explanation: Associates ovarian dysgenesis with the chromosomal lesion at disease level.
  - target: Fetal Jugular Lymphatic Sac Obstruction and Lymphatic Network Dysplasia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      The fetal lymphatic defect is attributed to the chromosomal loss; no
      individual escape gene has been assigned to it.
    evidence:
    - reference: PMID:6463900
      reference_title: "Neck web and congenital heart defects: a pathogenic association in 45 X-O Turner syndrome?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Of 193 cases with documented 45 X-O karyotype, 106 (55%) had a web neck and 87 (45%) had a normal neck."
      explanation: >
        Establishes in a 45,X series that the neck web — the residue of the
        fetal lymphatic lesion — is present in the majority of cases.
  - target: Granulosa-Cell Apelin/APJ Signaling Dysfunction
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - granulosa_apelin_model
    description: >
      A patient-derived iPSC study nominates impaired apelin/APJ signaling as
      one route by which the 45,X dosage state may disrupt granulosa-cell
      development. The responsible X-dosage relay is not known, so the edge is
      indirect and belongs to an emerging hypothesis rather than the canonical
      disease path.
    evidence:
    - reference: PMID:39543104
      reference_title: "Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "The apelin/APJ pathway exhibited differential signaling between the healthy and TS groups."
      explanation: >
        Patient-derived granulosa-like cells show the signaling difference, but
        the non-isogenic in-vitro comparison does not identify the intervening
        X-dosage mechanism or establish the state in an intact human ovary.
  - target: Turner Cardiomyocyte Transcriptome and Contractile Dysregulation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - cardiomyocyte_ceRNA_model
    description: >
      Patient-derived 45,X cardiomyocytes show transcriptomic and beating
      abnormalities downstream of the chromosome-dosage state. Which escape-gene
      deficits produce those changes, and whether they participate in congenital
      valve, arch, or aortic-wall disease in vivo, remain unresolved.
    evidence:
    - reference: PMID:38124119
      reference_title: "Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Moreover, we have identified a global transcriptome dysregulation of both coding and non-coding RNAs in TS-CMs."
      explanation: >
        Directly supports the cellular readout while leaving its upstream gene
        assignment and human structural-cardiac relevance unsettled.
  - target: Horseshoe Kidney and Renal Malformation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      Renal developmental malformations are strongly karyotype-dependent, but
      the dosage-sensitive gene or developmental relay is not assigned. The edge
      therefore records a major Turner arm without inventing an intermediate
      renal mechanism.
    evidence:
    - reference: PMID:11045397
      reference_title: "Frequency of renal malformations in Turner syndrome: analysis of 82 Turkish children."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The prevalence of renal malformations was significantly higher in group A (51.1%) than group B (21.6%)"
      explanation: >
        Supports dependence on non-mosaic 45,X versus mosaic/structural
        karyotype; PARTIAL preserves the unknown molecular relay.
  - target: High-Frequency Sensorineural Hearing Loss
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      Progressive sensorineural loss is more severe in non-mosaic 45,X, but the
      responsible escape gene and cochlear mechanism remain unresolved.
    evidence:
    - reference: PMID:17095347
      reference_title: "Hearing loss in Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The age-dependent increase in hearing thresholds in the high frequencies was more apparent in patients with TS with monosomic 45, X than in those with the mosaic type"
      explanation: >
        Karyotype dependence supports a dosage relationship; PARTIAL records
        that it does not identify the intervening gene or tissue process.
  - target: PAR1 Haploinsufficiency and the Turner Neurocognitive Phenotype
    causal_link_type: DIRECT
    description: >
      A <2 Mb PAR1 interval is the mapped critical region for the neurocognitive
      profile.
    evidence:
    - reference: PMID:10931762
      reference_title: "The Turner syndrome-associated neurocognitive phenotype maps to distal Xp."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Fine mapping of informative deletions implicated a critical region of <2 Mb within the pseudoautosomal region (PAR1)."
      explanation: Gives the mapped interval underlying this edge.
- name: SHOX Haploinsufficiency
  role: effector
  biological_scale: MOLECULAR
  description: >
    A single functional copy of SHOX, the PAR1 homeobox transcription factor
    that escapes X-inactivation. This is the molecular lesion itself — reduced
    SHOX gene dose — held separately from the cellular programme it
    dysregulates, because the same dosage lesion arises in Léri-Weill
    dyschondrosteosis from PAR1 deletion in individuals with two intact sex
    chromosomes. It is the one arm of Turner syndrome where the responsible
    gene is named with confidence.
  evidence:
  - reference: PMID:27194967
    reference_title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SHOX in the short arm pseudoautosomal region (PAR1) of sex chromosomes is one of the major growth genes in humans."
    explanation: Places the gene in PAR1 and identifies it as a major human growth gene.
  - reference: PMID:27194967
    reference_title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SHOX haploinsufficiency results in idiopathic short stature and Léri-Weill dyschondrosteosis and is associated with the short stature of patients with Turner syndrome."
    explanation: >
      Connects SHOX dosage to Turner short stature and, via Léri-Weill
      dyschondrosteosis, to the mesomelic skeletal phenotype.
  downstream:
  - target: Growth-Plate Chondrocyte Dysregulation
    causal_link_type: DIRECT
    description: >
      Halved SHOX dose is transduced into a disordered chondrocyte programme at
      the growth plate.
    evidence:
    - reference: PMID:27194967
      reference_title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The SHOX protein likely controls chondrocyte apoptosis by regulating multiple target genes including BNP,Fgfr3, Agc1, and Ctgf."
      explanation: Names the chondrocyte-level programme through which the dosage lesion acts.
- name: Growth-Plate Chondrocyte Dysregulation
  role: effector
  biological_scale: CELLULAR
  description: >
    The growth-plate chondrocyte programme downstream of SHOX. SHOX acts on
    chondrocyte apoptosis through targets including BNP, FGFR3, aggrecan and
    CTGF, so halving its dose alters the
    proliferation-to-hypertrophy-to-apoptosis sequence that converts cartilage
    into bone at the growth plate.
  cell_types:
  - preferred_term: growth-plate chondrocyte
    term:
      id: CL:0000138
      label: chondrocyte
  biological_processes:
  - preferred_term: apoptotic process
    term:
      id: GO:0006915
      label: apoptotic process
    modifier: DYSREGULATED
  evidence:
  - reference: PMID:27194967
    reference_title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The SHOX protein likely controls chondrocyte apoptosis by regulating multiple target genes including BNP,Fgfr3, Agc1, and Ctgf."
    explanation: Gives the chondrocyte-level molecular programme SHOX acts through.
  downstream:
  - target: Skeletal Growth Failure and Mesomelic Dysmorphism
    causal_link_type: DIRECT
    description: >
      Growth-plate dysregulation is expressed at tissue level as reduced
      endochondral bone growth with disproportionate forearm and lower-leg
      involvement.
    evidence:
    - reference: PMID:21925981
      reference_title: "The role of the SHOX gene in the pathophysiology of Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Patients with deletions of the distal segment of the short arm of X chromosome (Xp-) including haploinsufficiency of the SHOX (short stature homeobox) have, more often, short stature, skeletal abnormalities and hearing impairments."
      explanation: >
        Genotype-phenotype correlation from partial Xp deletions tying SHOX
        dosage specifically to stature and skeletal abnormality.
- name: Skeletal Growth Failure and Mesomelic Dysmorphism
  role: consequence
  biological_scale: TISSUE
  description: >
    Reduced endochondral bone growth produces the near-universal short stature
    and the mesomelic skeletal signature — cubitus valgus, short fourth
    metacarpals, Madelung deformity of the wrist, and a broad chest. Because
    the deficit is in the growth plate rather than in growth hormone secretion,
    growth hormone works here pharmacologically, by driving a partially
    responsive plate harder, not by replacing a missing hormone.
  biological_processes:
  - preferred_term: endochondral bone growth
    term:
      id: GO:0003416
      label: endochondral bone growth
    modifier: DECREASED
  evidence:
  - reference: PMID:31213699
    reference_title: "Turner syndrome: mechanisms and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."
    explanation: Places short stature among the defining features of the syndrome.
  downstream:
  - target: Short Stature
    causal_link_type: DIRECT
    description: >
      Reduced endochondral growth at the SHOX-deficient growth plate produces
      the characteristic short stature.
    evidence:
    - reference: PMID:27194967
      reference_title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "SHOX haploinsufficiency results in idiopathic short stature and Léri-Weill dyschondrosteosis and is associated with the short stature of patients with Turner syndrome."
      explanation: Direct human-genetic support for the phenotype endpoint.
  - target: Cubitus Valgus
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - mesomelic disturbance of endochondral growth at the elbow
    description: >
      Cubitus valgus is part of the Turner mesomelic skeletal pattern attributed
      to SHOX-deficient growth, but the cached source supports the skeletal class
      rather than naming this deformity individually.
    evidence:
    - reference: PMID:21925981
      reference_title: "The role of the SHOX gene in the pathophysiology of Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Patients with deletions of the distal segment of the short arm of X chromosome (Xp-) including haploinsufficiency of the SHOX (short stature homeobox) have, more often, short stature, skeletal abnormalities and hearing impairments."
      explanation: >
        Supports the SHOX-associated skeletal class; PARTIAL avoids claiming
        deformity-specific evidence that the source does not contain.
  - target: Madelung Deformity
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - disordered distal radial growth shared with Léri-Weill dyschondrosteosis
    description: >
      Madelung deformity lies in the SHOX-haploinsufficiency skeletal spectrum,
      but the available excerpt establishes the shared Léri-Weill aetiology
      rather than naming the Turner manifestation directly.
    evidence:
    - reference: PMID:27194967
      reference_title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "SHOX haploinsufficiency results in idiopathic short stature and Léri-Weill dyschondrosteosis and is associated with the short stature of patients with Turner syndrome."
      explanation: >
        Supports the shared SHOX mechanism but not a Turner-specific Madelung
        assertion, hence PARTIAL.
- name: Granulosa-Cell Apelin/APJ Signaling Dysfunction
  role: effector
  biological_scale: MOLECULAR
  mechanism_confidence: PROVISIONAL
  description: >
    Reduced apelin/APJ signaling observed in 45,X patient-derived
    granulosa-like cells. Ligand and downstream Akt activation partly rescue the
    cellular phenotype, supporting a signaling contribution in this model. The
    state has not yet been demonstrated in intact human Turner ovaries and its
    connection to a specific X-dosage-sensitive gene remains unknown.
  evidence:
  - reference: PMID:39543104
    reference_title: "Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The apelin/APJ pathway exhibited differential signaling between the healthy and TS groups."
    explanation: Identifies the signaling difference in the patient-derived model.
  downstream:
  - target: Granulosa-Cell Differentiation and Cell-Cycle Dysfunction
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - APJ signaling through Akt/PKB and CTPS2 regulation
    hypothesis_groups:
    - granulosa_apelin_model
    description: >
      Apelin ligands and downstream Akt activation partly restored cell-cycle
      progression and granulosa marker expression, placing impaired signaling
      upstream of the model's cellular defect without establishing that it is
      the only cause.
    evidence:
    - reference: PMID:39543104
      reference_title: "Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Supplementation with apelin ligands and activation of apelin/APJ downstream signaling via Akt/PKB restored cell cycle progression and marker gene expression."
      explanation: A pathway-rescue experiment supports the direction of this model-specific edge.
- name: Granulosa-Cell Differentiation and Cell-Cycle Dysfunction
  role: effector
  biological_scale: CELLULAR
  mechanism_confidence: PROVISIONAL
  description: >
    Turner patient-derived granulosa-like cells show reduced differentiation
    markers and abnormal cell-cycle progression. This provides a candidate
    somatic-cell contribution to the ovarian phenotype, but it is not yet a
    demonstrated lesion in an intact human ovary and does not exclude a
    germ-cell-autonomous contribution.
  cell_types:
  - preferred_term: granulosa cell
    term:
      id: CL:0000501
      label: granulosa cell
  biological_processes:
  - preferred_term: cell cycle
    term:
      id: GO:0007049
      label: cell cycle
    modifier: DYSREGULATED
  evidence:
  - reference: PMID:39543104
    reference_title: "Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "When attempting to replicate the differentiation process of embryonic granulosa cells, we observed the downregulation of specific genes-GATA4, FOXL2, AMHR2, CYP19A1, and FSH-in Turner syndrome-derived granulosa cells (TS-GCs)."
    explanation: Directly supports the reduced lineage-marker programme.
  - reference: PMID:39543104
    reference_title: "Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Additionally, we identified dysregulation of the cell cycle in TS-GCs."
    explanation: Directly supports the cell-cycle component of the node.
  downstream:
  - target: Accelerated Ovarian Germ Cell Attrition and Follicular Atresia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - granulosa_apelin_model
    description: >
      The study proposes that defective granulosa-cell support during ovarian
      development contributes to early oocyte loss. This is an emerging
      human-cell-model hypothesis, not proof that the in-vitro state causes
      follicular attrition in vivo.
    evidence:
    - reference: PMID:39543104
      reference_title: "Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "We hypothesize that during early embryonic development, failures in apelin/APJ signaling in GCs of Turner syndrome patients lead to abnormalities in ovarian development, ultimately resulting in early oocyte loss and infertility."
      explanation: >
        The authors state the proposed in-vivo relay explicitly; PARTIAL records
        that it remains a hypothesis derived from an in-vitro model.
- name: Turner Cardiomyocyte Transcriptome and Contractile Dysregulation
  role: effector
  biological_scale: CELLULAR
  mechanism_confidence: PROVISIONAL
  description: >
    Patient-derived 45,X iPSC cardiomyocytes exhibit altered coding and
    non-coding RNA profiles, lower beating frequency, and increased
    mitochondrial DNA copy number. These observations nominate a cardiac-cell
    dosage response but do not demonstrate a cause of bicuspid valve,
    coarctation, generalized arteriopathy, or dissection.
  cell_types:
  - preferred_term: cardiomyocyte
    term:
      id: CL:0000746
      label: cardiac muscle cell
  biological_processes:
  - preferred_term: heart development
    term:
      id: GO:0007507
      label: heart development
    modifier: DYSREGULATED
  evidence:
  - reference: PMID:38124119
    reference_title: "Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We observed lower beating frequencies and higher mitochondrial DNA copies per nucleus in TS-CMs."
    explanation: Supports the functional and mitochondrial readouts in the model.
  - reference: PMID:38124119
    reference_title: "Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Moreover, we have identified a global transcriptome dysregulation of both coding and non-coding RNAs in TS-CMs."
    explanation: Supports the transcriptomic component of the node.
- name: Accelerated Ovarian Germ Cell Attrition and Follicular Atresia
  role: effector
  biological_scale: CELLULAR
  description: >
    Germ cells are laid down in the Turner ovary but are then lost at an
    accelerated rate through follicular atresia, so the process is depletion
    rather than failure of germ-cell formation. The distinction is what makes
    the fertility picture graded rather than absolute: the rate of loss varies,
    it is slower in mosaic karyotypes, and it is the reason ovarian tissue or
    oocyte cryopreservation is even discussed — there is a window before the
    reserve is exhausted rather than an ovary that never had one.
  cell_types:
  - preferred_term: oocyte
    term:
      id: CL:0000023
      label: oocyte
  - preferred_term: granulosa cell
    term:
      id: CL:0000501
      label: granulosa cell
  biological_processes:
  - preferred_term: ovarian follicle atresia
    term:
      id: GO:0001552
      label: ovarian follicle atresia
    modifier: INCREASED
  - preferred_term: germ cell development
    term:
      id: GO:0007281
      label: germ cell development
    modifier: DECREASED
  evidence:
  - reference: PMID:31240242
    reference_title: "Time to consider ovarian tissue cryopreservation for girls with Turner's syndrome: an opinion paper."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Due to rapid follicular atresia, the majority of women with TS suffer from primary ovarian insufficiency around puberty."
    explanation: >
      Names accelerated follicular atresia as the mechanism and places its
      clinical endpoint at around puberty.
  - reference: PMID:31240242
    reference_title: "Time to consider ovarian tissue cryopreservation for girls with Turner's syndrome: an opinion paper."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The rate of decline in fertility is variable in girls with TS and can be more complex in cases with mosaicism."
    explanation: >
      Supports attrition rate — not presence or absence of germ cells — as the
      variable that karyotype modifies.
  downstream:
  - target: Ovarian Dysgenesis with Streak Gonad
    causal_link_type: DIRECT
    description: >
      Exhaustion of the follicular reserve leaves a fibrous streak gonad
      incapable of steroidogenesis.
    evidence:
    - reference: PMID:16641863
      reference_title: "Hormone replacement treatment in Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "gonadal dysgenesis in 85-90% of cases"
      explanation: Quantifies how often the attrition process ends in frank gonadal dysgenesis.
  - target: Infertility
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - depletion of the ovarian follicle reserve and primary ovarian insufficiency
    description: >
      Accelerated follicular loss depletes the ovarian reserve and thereby
      removes the reproductive capacity, with residual fertility possible when
      mosaicism slows or limits that depletion.
    evidence:
    - reference: PMID:31240242
      reference_title: "Time to consider ovarian tissue cryopreservation for girls with Turner's syndrome: an opinion paper."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Due to rapid follicular atresia, the majority of women with TS suffer from primary ovarian insufficiency around puberty."
      explanation: Establishes the attrition-to-ovarian-insufficiency intermediate.
    - reference: PMID:31240242
      reference_title: "Time to consider ovarian tissue cryopreservation for girls with Turner's syndrome: an opinion paper."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The rate of decline in fertility is variable in girls with TS and can be more complex in cases with mosaicism."
      explanation: Supports the fertility endpoint and its mosaic-karyotype qualification.
- name: Ovarian Dysgenesis with Streak Gonad
  role: effector
  biological_scale: TISSUE
  description: >
    The involuted, fibrous streak gonad that remains once the follicular
    reserve is exhausted. This is the tissue-level lesion, held separately from
    the systemic endocrine state it produces, because the two are separated in
    time and in what they respond to: the streak gonad is irreversible, whereas
    the endocrine consequence downstream of it is fully replaceable.
  cell_types:
  - preferred_term: ovarian stromal cell
    term:
      id: CL:0002132
      label: stromal cell of ovary
  evidence:
  - reference: PMID:16641863
    reference_title: "Hormone replacement treatment in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "gonadal dysgenesis in 85-90% of cases"
    explanation: Establishes that the great majority of individuals reach frank gonadal dysgenesis.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals with mosaic TS are more likely to have spontaneous puberty, normal gonadotropin levels, a measurable AMH, and follicles in ovarian biopsies as compared to those who have monosomy X karyotype."
    explanation: >
      Supports karyotype as a severity modifier of this node — residual follicles
      are demonstrable on biopsy in mosaic individuals.
  downstream:
  - target: Hypergonadotropic Hypogonadism and Estrogen Deficiency
    causal_link_type: DIRECT
    description: >
      A gonad that makes neither estrogen nor inhibin releases the pituitary
      from negative feedback, so gonadotropins rise and the systemic
      consequences of estrogen deficiency follow.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Circulating concentrations of both FSH and LH present a biphasic pattern in TS individuals with hypogonadism: elevated after birth, declining to values similar to girls with normal ovarian function during mid-childhood, and rising again in the peripubertal years, or at the time of loss of ovarian function."
      explanation: >
        Ties the gonadotropin rise directly to the timing of ovarian function
        loss, which is what makes this a causal rather than merely associative edge.
  - target: Gonadal Dysgenesis with Streak Ovaries
    causal_link_type: DIRECT
    description: >
      The tissue-level streak-gonad state is the substrate of the corresponding
      clinical gonadal-dysgenesis phenotype.
    evidence:
    - reference: PMID:16641863
      reference_title: "Hormone replacement treatment in Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "gonadal dysgenesis in 85-90% of cases"
      explanation: Directly identifies and quantifies the phenotype endpoint.
- name: Hypergonadotropic Hypogonadism and Estrogen Deficiency
  role: consequence
  biological_scale: ORGANISM
  description: >
    The systemic endocrine state: gonadotropins are high, gonadal steroid output
    is absent, and puberty does not start spontaneously in most individuals.
    Estrogen deficiency from an age at which the skeleton, uterus
    and secondary sexual characteristics all depend on it is what converts a
    gonadal lesion into a systemic one, and it is the reason hormone
    replacement is continued to the age of normal menopause rather than being
    used only to induce puberty.
  biological_processes:
  - preferred_term: estrogen biosynthetic process
    term:
      id: GO:0006703
      label: estrogen biosynthetic process
    modifier: DECREASED
  evidence:
  - reference: PMID:16641863
    reference_title: "Hormone replacement treatment in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hormone replacement treatment should be initiated at a physiological age in these patients who do not enter puberty spontaneously and should be continued up to the age of normal menopause."
    explanation: >
      Establishes both that spontaneous puberty fails and that the deficiency is
      lifelong rather than pubertal.
  - reference: PMID:16641863
    reference_title: "Hormone replacement treatment in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the improvement of bone mineral density; normal uterine growth"
    explanation: >
      Names the two end-organ deficits attributable to the estrogen shortfall,
      each corrected by replacement.
  downstream:
  - target: Hypergonadotropic Hypogonadism and Delayed Puberty
    causal_link_type: DIRECT
    description: >
      The systemic endocrine state is expressed clinically as elevated
      gonadotropins and failure or delay of spontaneous puberty.
    evidence:
    - reference: PMID:31213699
      reference_title: "Turner syndrome: mechanisms and management."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."
      explanation: Names both components of the phenotype endpoint.
  - target: Osteoporosis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - impaired pubertal bone accrual and chronic loss of estrogen support
    description: >
      Estrogen deficiency during the period of peak bone-mass accrual and across
      adult life contributes to low bone density; improvement with estrogen
      supplementation supports this direction while not excluding SHOX,
      vitamin-D, or other contributors.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "BMD improves with estrogen supplementation."
      explanation: >
        Treatment response supports an estrogen-dependent component; PARTIAL
        preserves the syndrome's multifactorial bone biology.
- name: Fetal Jugular Lymphatic Sac Obstruction and Lymphatic Network Dysplasia
  role: effector
  biological_scale: TISSUE
  description: >
    The fetal jugular lymphatic sacs fail to drain properly into the venous
    system, raising lymphatic pressure and distending the posterior nuchal
    region into a cystic hygroma. Most hygromas resolve before birth; what
    survives is their imprint — the webbed neck, low posterior hairline and
    rotated ears are the healed residue of an intrauterine distension that has
    already gone. Peripheral lymphatic dysplasia in the same process gives the
    dorsal hand and foot lymphedema characteristic of the neonate.
  cell_types:
  - preferred_term: lymphatic endothelial cell
    term:
      id: CL:0002138
      label: endothelial cell of lymphatic vessel
  biological_processes:
  - preferred_term: lymph vessel development
    term:
      id: GO:0001945
      label: lymph vessel development
    modifier: DECREASED
  evidence:
  - reference: PMID:6463900
    reference_title: "Neck web and congenital heart defects: a pathogenic association in 45 X-O Turner syndrome?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Increased lymphatic pressure associated with jugular lymphatic sac obstruction distends the thoracic ducts, which compress the ascending aorta altering intracardiac blood flow."
    explanation: >
      States the jugular lymphatic sac obstruction that defines this node.
      Note this snippet also carries the downstream hemodynamic claim, which is
      curated separately as an ALTERNATIVE hypothesis rather than as settled
      mechanism.
  downstream:
  - target: Left-Sided Cardiac Outflow Tract Malformation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    hypothesis_groups:
    - lymphatic_obstruction_hemodynamic_model
    description: >
      Clark's hemodynamic hypothesis: distended thoracic ducts compress the
      ascending aorta and redirect intracardiac flow, producing left-heart
      obstructive lesions. This edge is curated as belonging to a named
      hypothesis rather than as established fact — the epidemiological
      association between neck web and coarctation is strong and reproducible,
      but the mechanism connecting them is inferred, not observed.
    evidence:
    - reference: PMID:6463900
      reference_title: "Neck web and congenital heart defects: a pathogenic association in 45 X-O Turner syndrome?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The difference was most striking in coarctation of the aorta for which the prevalence was 25% with web neck and 3% with normal neck"
      explanation: >
        The quantitative association on which the hypothesis rests — an
        eight-fold difference in coarctation prevalence stratified by neck web.
    - reference: PMID:6463900
      reference_title: "Neck web and congenital heart defects: a pathogenic association in 45 X-O Turner syndrome?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The association between web neck and congenital heart disease suggests a pathogenic relationship exists between the two."
      explanation: >
        Marked PARTIAL deliberately: the source states an association and
        proposes a mechanism, and its own wording ("suggests") does not assert
        the causal chain.
  - target: Webbed Neck
    causal_link_type: DIRECT
    description: >
      Resolution of the fetal nuchal lymphatic distension leaves the persistent
      lateral neck folds recorded clinically as webbing.
    evidence:
    - reference: PMID:6463900
      reference_title: "Neck web and congenital heart defects: a pathogenic association in 45 X-O Turner syndrome?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Of 193 cases with documented 45 X-O karyotype, 106 (55%) had a web neck and 87 (45%) had a normal neck."
      explanation: Direct clinical support for the phenotype endpoint.
  - target: Lymphedema
    causal_link_type: DIRECT
    description: >
      Dysplastic peripheral lymphatic drainage produces the neonatal and
      relapsing limb swelling.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Clinical lymphedema is often present at birth, frequently resolves or at least improves by age 2 years, and may have a relapsing and remitting course throughout life."
      explanation: Supports the developmental timing and recurrent phenotype endpoint.
- name: Left-Sided Cardiac Outflow Tract Malformation
  role: effector
  biological_scale: TISSUE
  description: >
    Bicuspid aortic valve and coarctation of the aorta dominate the congenital
    cardiac phenotype. Their importance is not primarily neonatal — many are
    haemodynamically tolerated in childhood — but that they identify a subgroup
    with substantially increased adult aortic-dilation and dissection risk.
  evidence:
  - reference: PMID:31240242
    reference_title: "Time to consider ovarian tissue cryopreservation for girls with Turner's syndrome: an opinion paper."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In addition to short stature and gonadal dysgenesis, it is associated with cardiac and renal anomalies."
    explanation: Places cardiac malformation among the cardinal features.
  - reference: PMID:23032325
    reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Of those with spontaneous aortic dissections, 18 of 19 (95%) had an associated cardiac malformation that included a bicuspid aortic valve."
    explanation: >
      Establishes that the malformed left outflow tract is present in almost
      every dissection case.
  downstream:
  - target: Progressive Aortic Dilation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - abnormal valve and arch hemodynamics
    description: >
      A malformed valve and arch mark increased dilation risk through altered
      hemodynamics, but they are neither necessary nor sufficient: a parallel
      Turner arteriopathy can produce dilation even without structural heart
      disease.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "BAV is frequently associated with thoracic aortic dilation, coronary anomalies, coarctation, and other left-sided congenital lesions"
      explanation: >
        Supports the BAV-dilation association; PARTIAL avoids converting that
        association into a direct valve-to-vessel-wall causal claim.
  - target: Bicuspid Aortic Valve
    causal_link_type: DIRECT
    description: The malformed outflow-tract state includes the bicuspid-valve phenotype.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "BAV is detected in more than 25% of individuals with TS, or 50 times the rate in the general population."
      explanation: Directly establishes the phenotype endpoint in Turner syndrome.
  - target: Coarctation of the Aorta
    causal_link_type: DIRECT
    description: The malformed outflow-tract state includes narrowing of the aortic arch.
    evidence:
    - reference: PMID:6463900
      reference_title: "Neck web and congenital heart defects: a pathogenic association in 45 X-O Turner syndrome?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The difference was most striking in coarctation of the aorta for which the prevalence was 25% with web neck and 3% with normal neck"
      explanation: Directly identifies the coarctation endpoint in a 45,X series.
- name: Progressive Aortic Dilation
  role: effector
  biological_scale: TISSUE
  description: >
    The chronic, silent, measurable state: an ascending aorta enlarging over
    years. It is held separate from the acute dissection event downstream of it
    because the two differ in everything that matters clinically — time course,
    detectability, and above all treatment join point. Dilation is what
    surveillance imaging measures and what antihypertensive therapy and elective
    surgery are aimed at; dissection is the event those measures exist to
    prevent. The decisive feature of the dilation is one of calibration rather
    than biology: it becomes dangerous at absolute diameters that are
    unremarkable in an average-height adult, which is why surveillance is
    indexed to body surface area and why an aortic size index above 2.5 cm/m2
    triggers surgical consideration.
  evidence:
  - reference: PMID:23032325
    reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals with Turner syndrome who are >18 years of age with an ascending aortic size index >2.5 cm/m(2) should be considered for an aortic operation to prevent aortic dissection."
    explanation: Gives the indexed threshold that operationalises this node clinically.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dilation of the aorta, brachiocephalic and carotid arteries may be present even in the absence of structural heart disease, consistent with an underlying generalized arteriopathy."
    explanation: >
      Supports dilation as a state of the vessel wall in its own right — present
      even without a structural cardiac lesion — rather than purely as a
      downstream consequence of the malformed outflow tract.
  downstream:
  - target: Aortic Dissection and Rupture
    causal_link_type: DIRECT
    description: >
      A dilated ascending aorta is the substrate on which dissection occurs;
      the dilation is progressive and the dissection is the discrete event that
      terminates it.
    evidence:
    - reference: PMID:23032325
      reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Aortic dissection in Turner syndrome occurs in young individuals at smaller aortic diameters than in the general population or other forms of genetically triggered aortopathy."
      explanation: >
        Establishes that diameter is a risk substrate requiring Turner-specific
        calibration: dissection occurs at smaller calibres than in comparator
        aortopathies, without implying that every dissection requires marked
        antecedent dilation.
- name: Aortic Dissection and Rupture
  role: consequence
  biological_scale: TISSUE
  description: >
    The acute catastrophic event and the leading avoidable cause of sudden
    death in the syndrome. It occurs at a young age relative to other
    aortopathies and is frequently recognised late. Dissection is also reported
    in individuals with no cardiac malformation at all, so a structurally normal
    valve reduces but does not abolish the risk.
  evidence:
  - reference: PMID:23032325
    reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Girls and women with Turner syndrome are at risk for aortic dissection and rupture."
    explanation: States the endpoint this node represents.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The incidence of aortic dissection in TS is approximately 164 per 100 000 person–years, compared to 6 per 100 000 person–years in the general population."
    explanation: Quantifies the excess risk this node carries relative to the general population.
  - reference: PMID:23032325
    reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In 1 individual there was no predisposing finding other than the presence of Turner syndrome."
    explanation: >
      Supports the residual risk in the absence of a cardiac malformation,
      preventing this node from being read as wholly downstream of the previous one.
  downstream:
  - target: Aortic Dissection
    causal_link_type: DIRECT
    description: The acute aortic-wall event is the corresponding clinical phenotype.
    evidence:
    - reference: PMID:23032325
      reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Girls and women with Turner syndrome are at risk for aortic dissection and rupture."
      explanation: Directly supports the endpoint link.
- name: PAR1 Haploinsufficiency and the Turner Neurocognitive Phenotype
  role: consequence
  biological_scale: ORGANISM
  description: >
    A characteristic cognitive profile with preserved verbal ability and
    selectively impaired visuospatial and perceptual processing. Deletion
    mapping localises it to under 2 Mb of PAR1, independent of parent of origin
    and of X-inactivation skewing — which is what makes it a gene-dosage
    phenotype rather than a consequence of estrogen deficiency or of the
    psychosocial impact of short stature.
  evidence:
  - reference: PMID:10931762
    reference_title: "The Turner syndrome-associated neurocognitive phenotype maps to distal Xp."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome (TS) is associated with a characteristic neurocognitive profile that includes impaired visuospatial/perceptual abilities."
    explanation: Defines the phenotype this node represents.
  - reference: PMID:10931762
    reference_title: "The Turner syndrome-associated neurocognitive phenotype maps to distal Xp."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Only subjects missing approximately 10 Mb of distal Xp manifested the specified neurocognitive profile."
    explanation: >
      The deletion-mapping result establishing that the phenotype tracks a
      specific interval rather than the whole chromosome.
  downstream:
  - target: Impaired Visuospatial and Perceptual Cognition
    causal_link_type: DIRECT
    description: The mapped PAR1 dosage state produces the characteristic cognitive phenotype.
    evidence:
    - reference: PMID:10931762
      reference_title: "The Turner syndrome-associated neurocognitive phenotype maps to distal Xp."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Turner syndrome (TS) is associated with a characteristic neurocognitive profile that includes impaired visuospatial/perceptual abilities."
      explanation: Directly names the phenotype endpoint supported by deletion mapping.
mechanistic_hypotheses:
- hypothesis_group_id: escape_gene_haploinsufficiency_model
  hypothesis_label: X-Escape and Pseudoautosomal Gene Haploinsufficiency Model
  status: CANONICAL
  description: >
    The syndrome is caused by reduction to a single functional dose of the genes
    that normally escape X-inactivation, plus the pseudoautosomal genes that
    normally pair with a Y homologue. Human deletion mapping supports the model
    directly for at least two phenotypes: SHOX in PAR1 for short stature and the
    mesomelic skeleton, and a <2 Mb PAR1 interval for the neurocognitive
    profile, the latter shown to be independent of parent of origin and of
    X-inactivation skewing. The model's acknowledged weakness is coverage, not
    principle — the gonadal, cardiovascular, renal, auditory and autoimmune arms
    have no assigned escape gene, and the field states plainly that SHOX does
    not explain most Turner anomalies.
  notes: >
    Curated as CANONICAL because it is the framework in which the field
    operates and is directly evidenced for two phenotypes, not because it is
    complete. The gap is tracked as its own discussion
    (gap_unassigned_escape_genes) rather than being smoothed over here.
- hypothesis_group_id: lymphatic_obstruction_hemodynamic_model
  hypothesis_label: Jugular Lymphatic Obstruction Hemodynamic Model of Left-Heart Obstruction
  status: ALTERNATIVE
  description: >
    Clark's 1984 proposal that the cardiac malformation is not an independent
    dosage effect but a secondary consequence of the lymphatic lesion: obstructed
    jugular lymphatic sacs raise lymphatic pressure, distended thoracic ducts
    compress the ascending aorta, and the redirected intracardiac flow produces
    coarctation and the wider spectrum of left-heart obstruction. It is a
    mechanically explicit account of a robust epidemiological association —
    coarctation prevalence of 25% with neck web versus 3% without in a 45,X
    series — and it makes Turner cardiac disease an example of a teratogenic
    event remote from the heart.
  notes: >
    Held as ALTERNATIVE, not CANONICAL. The association it explains is strong
    and has been reproduced, but the causal chain itself is inferred from
    anatomy and flow reasoning rather than observed, and the competing account —
    that lymphatic and cardiac defects are parallel consequences of the same
    dosage lesion — is not excluded by the data curated here. No node in this
    entry asserts the hemodynamic chain outside this hypothesis group.
- hypothesis_group_id: granulosa_apelin_model
  hypothesis_label: Granulosa-Cell Apelin/APJ Dysfunction Model of Ovarian Attrition
  status: EMERGING
  description: >
    A human 45,X iPSC-derived granulosa-cell study places reduced apelin/APJ
    signaling upstream of abnormal granulosa differentiation and cell-cycle
    progression, then proposes that defective somatic support during ovarian
    development contributes to early oocyte loss. Ligand and Akt-pathway rescue
    provide model-specific causal support for the signaling-to-cellular step;
    the relay from chromosome dosage to apelin signaling and the translation
    from cultured cells to follicular attrition in vivo remain unproven.
  evidence:
  - reference: PMID:39543104
    reference_title: "Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We hypothesize that during early embryonic development, failures in apelin/APJ signaling in GCs of Turner syndrome patients lead to abnormalities in ovarian development, ultimately resulting in early oocyte loss and infertility."
    explanation: >
      The authors explicitly frame the in-vivo extension as a hypothesis;
      PARTIAL preserves that status despite the in-vitro rescue evidence.
  notes: >
    This model does not replace the established ovarian-attrition path. It
    supplies one candidate somatic-cell relay within an arm whose responsible
    X-dosage-sensitive gene or genes remain unidentified.
- hypothesis_group_id: cardiomyocyte_ceRNA_model
  hypothesis_label: Cardiomyocyte ceRNA and Heart-Development Transcriptome Model
  status: EMERGING
  description: >
    Patient-derived 45,X cardiomyocytes show global coding and non-coding RNA
    dysregulation, enrichment of heart-development genes, lower beating
    frequency, and increased mitochondrial DNA copy number. The authors propose
    dosage-altered X-inactivation-escaping non-coding RNAs as regulators of
    autosomal cardiac genes. The study does not establish that this cultured-cell
    state causes bicuspid valve, coarctation, generalized arteriopathy, or
    dissection, so no edge to those human structural lesions is asserted.
  evidence:
  - reference: PMID:38124119
    reference_title: "Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Further ceRNA network analysis has revealed that dysregulation of genes on autosomes could be possibly mediated by altered dosages of lnc/circRNAs on the X chromosome."
    explanation: >
      The source's conditional wording supports an emerging regulatory model,
      not an established mechanism of congenital or aortic disease.
phenotypes:
- category: Growth
  name: Short Stature
  description: >
    The most consistent feature of the syndrome and usually the one that prompts
    diagnosis. Attributable to SHOX haploinsufficiency acting at the growth plate.
  phenotype_term:
    preferred_term: Short stature
    term:
      id: HP:0004322
      label: Short stature
    clinical_course: PROGRESSIVE
  evidence:
  - reference: PMID:31213699
    reference_title: "Turner syndrome: mechanisms and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."
    explanation: Lists short stature first among the syndrome's defining features.
  - reference: PMID:27194967
    reference_title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SHOX haploinsufficiency results in idiopathic short stature and Léri-Weill dyschondrosteosis and is associated with the short stature of patients with Turner syndrome."
    explanation: Attributes the stature phenotype to SHOX dosage.
- category: Skeletal
  name: Cubitus Valgus
  description: >
    Increased carrying angle at the elbow, part of the mesomelic skeletal
    signature of SHOX haploinsufficiency.
  phenotype_term:
    preferred_term: Cubitus valgus
    term:
      id: HP:0002967
      label: Cubitus valgus
  evidence:
  - reference: PMID:21925981
    reference_title: "The role of the SHOX gene in the pathophysiology of Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with deletions of the distal segment of the short arm of X chromosome (Xp-) including haploinsufficiency of the SHOX (short stature homeobox) have, more often, short stature, skeletal abnormalities and hearing impairments."
    explanation: >
      Marked PARTIAL: the source supports skeletal abnormality as a class
      attributable to SHOX dosage but does not name cubitus valgus specifically.
- category: Skeletal
  name: Madelung Deformity
  description: >
    Dorsal subluxation of the distal ulna from disordered distal radial growth —
    the wrist lesion shared with Léri-Weill dyschondrosteosis, the other SHOX
    haploinsufficiency disorder.
  phenotype_term:
    preferred_term: Madelung deformity
    term:
      id: HP:0003067
      label: Madelung deformity
  evidence:
  - reference: PMID:27194967
    reference_title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SHOX haploinsufficiency results in idiopathic short stature and Léri-Weill dyschondrosteosis and is associated with the short stature of patients with Turner syndrome."
    explanation: >
      Marked PARTIAL: supports the shared SHOX aetiology with Léri-Weill
      dyschondrosteosis, of which Madelung deformity is the defining feature,
      but does not name the deformity in Turner syndrome directly.
- category: Reproductive
  name: Gonadal Dysgenesis with Streak Ovaries
  description: >
    The fibrous streak gonad left after accelerated follicular atresia exhausts
    the ovarian reserve.
  phenotype_term:
    preferred_term: Gonadal dysgenesis
    term:
      id: HP:0000133
      label: Gonadal dysgenesis
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:16641863
    reference_title: "Hormone replacement treatment in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "gonadal dysgenesis in 85-90% of cases"
    explanation: >
      Directly quantifies the frequency band: 85-90% falls in the HPO
      Very frequent (80-99%) range.
- category: Reproductive
  name: Hypergonadotropic Hypogonadism and Delayed Puberty
  description: >
    Absent gonadal steroid and inhibin output releases pituitary feedback,
    raising gonadotropins; spontaneous puberty fails in most individuals.
  phenotype_term:
    preferred_term: Hypergonadotropic hypogonadism
    term:
      id: HP:0000815
      label: Hypergonadotropic hypogonadism
  evidence:
  - reference: PMID:31213699
    reference_title: "Turner syndrome: mechanisms and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."
    explanation: Names both delayed puberty and hypergonadotropic hypogonadism.
  - reference: PMID:16641863
    reference_title: "Hormone replacement treatment in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hormone replacement treatment should be initiated at a physiological age in these patients who do not enter puberty spontaneously and should be continued up to the age of normal menopause."
    explanation: States the failure of spontaneous puberty.
- category: Reproductive
  name: Infertility
  description: >
    A consequence of exhausted ovarian reserve. Not absolute — mosaic
    individuals with slower attrition may retain fertility for a period.
  phenotype_term:
    preferred_term: Infertility
    term:
      id: HP:0000789
      label: Infertility
  evidence:
  - reference: PMID:31213699
    reference_title: "Turner syndrome: mechanisms and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."
    explanation: Lists infertility among the defining features.
  - reference: PMID:31240242
    reference_title: "Time to consider ovarian tissue cryopreservation for girls with Turner's syndrome: an opinion paper."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The rate of decline in fertility is variable in girls with TS and can be more complex in cases with mosaicism."
    explanation: Supports the qualification that fertility loss is graded rather than uniform.
- category: Lymphatic
  name: Webbed Neck
  description: >
    Residual skin fold from an intrauterine nuchal cystic hygroma; a marker of
    the fetal lymphatic lesion rather than an active abnormality.
  phenotype_term:
    preferred_term: Webbed neck
    term:
      id: HP:0000465
      label: Webbed neck
  frequency: FREQUENT
  evidence:
  - reference: PMID:6463900
    reference_title: "Neck web and congenital heart defects: a pathogenic association in 45 X-O Turner syndrome?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Of 193 cases with documented 45 X-O karyotype, 106 (55%) had a web neck and 87 (45%) had a normal neck."
    explanation: >
      Gives an explicit count (106/193 = 55%) in a 45,X series, which maps to
      the HPO Frequent (30-79%) band.
- category: Lymphatic
  name: Lymphedema
  description: >
    Peripheral lymphedema, classically of the dorsum of the hands and feet in
    the neonate, from the same lymphatic network dysplasia that produces the
    nuchal hygroma. Often present at birth and improving through infancy, but
    with a relapsing course into adult life. Lymphoscintigraphy shows abnormal
    lymphatic vessel development even in individuals with no clinically visible
    swelling, so the curated frequency band understates the underlying lesion.
  phenotype_term:
    preferred_term: Lymphedema
    term:
      id: HP:0001004
      label: Lymphedema
    temporality: RECURRENT
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinically apparent lymphedema occurs in 12%-27% of girls and women with TS."
    explanation: >
      Direct quantitative support for the frequency band: 12-27% falls inside
      the HPO Occasional (5-29%) range.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical lymphedema is often present at birth, frequently resolves or at least improves by age 2 years, and may have a relapsing and remitting course throughout life."
    explanation: Supports the recurrent temporality recorded on the descriptor.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Lymphedema is reported more often in association with a 45,X karyotype compared to other karyotypes."
    explanation: >
      Supports karyotype as a severity modifier here, consistent with the
      entry's lumping rationale.
- category: Auditory
  name: Recurrent Otitis Media and Middle Ear Disease
  description: >
    Persistent middle ear effusion and recurrent acute otitis media through
    childhood, with a conductive hearing loss that is mechanistically distinct
    from the progressive high-frequency sensorineural loss curated separately.
    Its consequences are cumulative — tympanic membrane perforation, scarring,
    retraction and cholesteatoma — which is why the guideline treats it as a
    high-risk rather than an ordinary paediatric problem.
  phenotype_term:
    preferred_term: Otitis media
    term:
      id: HP:0000388
      label: Otitis media
    temporality: RECURRENT
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "From early childhood through adolescence, persistent middle ear fluid and recurrent acute otitis media are common (24%-48%) in TS."
    explanation: >
      States the phenotype and its childhood time course. No frequency band is
      recorded because the quoted 24-48% range straddles the HPO Occasional
      (5-29%) and Frequent (30-79%) boundaries, and choosing either would assert
      a precision the source does not carry.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Recurrent otitis media in early childhood has been shown to be a strong predictor of future middle ear pathologies, including tympanic membrane perforations and scarring, retractions, and cholesteatoma."
    explanation: Supports the cumulative structural consequences that make this more than a nuisance phenotype.
- category: Cardiovascular
  name: Hypertension
  description: >
    Systemic hypertension, present in a substantial minority of children and in
    the majority of adults. It matters here beyond its general cardiovascular
    weight because it is one of the risk factors that compounds aortic dilation
    and dissection — the arm of the disease with the highest avoidable
    mortality — and it is the indication for the antihypertensive therapy
    curated in treatments.
  phenotype_term:
    preferred_term: Hypertension
    term:
      id: HP:0000822
      label: Hypertension
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The prevalence of hypertension is as high as 20%-40% in children"
    explanation: >
      Gives the paediatric prevalence. No single frequency band is recorded
      because the guideline reports markedly different figures for children and
      adults, so one band would misrepresent the age dependence.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "TS is often accompanied by hypertension, which has been linked to the development of aortic dilation or dissection, both observed with strikingly increased frequency in TS."
    explanation: Connects the phenotype to the aortopathy arm, which is why it is curated rather than left as a general comorbidity.
- category: Skeletal
  name: Scoliosis
  description: >
    Lateral curvature of the spine, most often of idiopathic type though
    congenital forms attributable to vertebral body anomalies also occur. It is
    the reason the guideline mandates annual spinal examination until skeletal
    maturity, and it is a recognised consideration during growth-hormone-driven
    linear growth.
  phenotype_term:
    preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Idiopathic scoliosis is the most common form of scoliosis noted in individuals with TS though congenital scoliosis, thought to be due to abnormalities of vertebral bodies, also occurs."
    explanation: States the phenotype and distinguishes the two forms seen in the syndrome.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend physical examination to identify scoliosis at diagnosis and then at least annually until skeletal maturation"
    explanation: >
      A graded guideline recommendation for annual screening, which is a
      statement that the phenotype is expected rather than incidental.
- category: Endocrine
  name: Hypothyroidism
  description: >
    Thyroid failure, in most cases the functional endpoint of the autoimmune
    thyroiditis curated separately. It is curated as its own phenotype because
    it is the treatable state that surveillance is aimed at, and because the
    guideline screens for it biochemically from age two through adult life
    rather than screening for the antibodies that precede it.
  phenotype_term:
    preferred_term: Hypothyroidism
    term:
      id: HP:0000821
      label: Hypothyroidism
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend screening for hypothyroidism with measurement of TSH every 1-2 years starting at 2 years of age and continuing through adulthood, and with new symptoms."
    explanation: >
      A graded recommendation for lifelong biochemical screening, which asserts
      hypothyroidism as an expected recurring complication. No frequency band is
      recorded: the guideline gives a pooled figure for autoimmunity overall
      (61% lifetime) but no separate prevalence for hypothyroidism itself.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Early diagnosis can also improve QoL by allowing for timely screening and intervention for complications such as strabismus, hearing loss, renal and cardiac abnormalities, hypothyroidism, celiac disease and neurodevelopmental disabilities and mental health concerns."
    explanation: Lists hypothyroidism among the syndrome's expected complications.
- category: Cardiovascular
  name: Bicuspid Aortic Valve
  description: >
    The commonest congenital cardiac lesion in the syndrome and the principal
    marker of aortic dissection risk.
  phenotype_term:
    preferred_term: Bicuspid aortic valve
    term:
      id: HP:0001647
      label: Bicuspid aortic valve
  evidence:
  - reference: PMID:23032325
    reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Of those with spontaneous aortic dissections, 18 of 19 (95%) had an associated cardiac malformation that included a bicuspid aortic valve."
    explanation: Documents bicuspid aortic valve in the dissection cohort.
- category: Cardiovascular
  name: Coarctation of the Aorta
  description: >
    Left-heart obstructive lesion, strongly co-associated with the neck web.
  phenotype_term:
    preferred_term: Coarctation of aorta
    term:
      id: HP:0001680
      label: Coarctation of aorta
  evidence:
  - reference: PMID:6463900
    reference_title: "Neck web and congenital heart defects: a pathogenic association in 45 X-O Turner syndrome?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The difference was most striking in coarctation of the aorta for which the prevalence was 25% with web neck and 3% with normal neck"
    explanation: Quantifies coarctation prevalence stratified by neck web in a 45,X series.
- category: Cardiovascular
  name: Aortic Dissection
  description: >
    The leading avoidable cause of sudden death, occurring at younger ages and
    smaller aortic diameters than in the general population.
  phenotype_term:
    preferred_term: Aortic dissection
    term:
      id: HP:0002647
      label: Aortic dissection
  evidence:
  - reference: PMID:23032325
    reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Girls and women with Turner syndrome are at risk for aortic dissection and rupture."
    explanation: States the phenotype and its clinical significance.
- category: Renal
  name: Horseshoe Kidney and Renal Malformation
  description: >
    Structural renal malformations, of which horseshoe kidney is the most
    characteristic, are markedly more frequent in non-mosaic 45,X than in
    mosaic or structurally abnormal karyotypes.
  phenotype_term:
    preferred_term: Horseshoe kidney
    term:
      id: HP:0000085
      label: Horseshoe kidney
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Horseshoe kidney and duplicated collecting system are the most common findings in TS, each occurring at a frequency of 15%-20%."
    explanation: >
      Direct quantitative support for the HPO Occasional (5-29%) band for the
      grounded horseshoe-kidney phenotype.
  - reference: PMID:11045397
    reference_title: "Frequency of renal malformations in Turner syndrome: analysis of 82 Turkish children."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Of the 82 patients, 31 had different renal malformations (37.8%)."
    explanation: Gives overall renal malformation frequency in a consecutive series.
  - reference: PMID:11045397
    reference_title: "Frequency of renal malformations in Turner syndrome: analysis of 82 Turkish children."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Horse-shoe kidney was observed in 9 (29.0%) of the 31 patients"
    explanation: Identifies horseshoe kidney as the leading structural lesion within that group.
  - reference: PMID:11045397
    reference_title: "Frequency of renal malformations in Turner syndrome: analysis of 82 Turkish children."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The prevalence of renal malformations was significantly higher in group A (51.1%) than group B (21.6%)"
    explanation: Supports the karyotype dependence (non-mosaic 45,X versus mosaic/structural).
- category: Auditory
  name: High-Frequency Sensorineural Hearing Loss
  description: >
    Progressive high-frequency sensorineural loss that worsens with age and is
    more severe in non-mosaic 45,X. Distinct from, and not explained by, the
    conductive loss of recurrent childhood otitis media.
  phenotype_term:
    preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
    clinical_course: PROGRESSIVE
  frequency: FREQUENT
  evidence:
  - reference: PMID:17095347
    reference_title: "Hearing loss in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "More than 60% of patients with TS had HFQ-SNHL."
    explanation: >
      Gives the frequency directly; >60% falls within the HPO Frequent
      (30-79%) band.
  - reference: PMID:17095347
    reference_title: "Hearing loss in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The age-dependent increase in hearing thresholds in the high frequencies was more apparent in patients with TS with monosomic 45, X than in those with the mosaic type"
    explanation: Supports both the progressive course and the karyotype dependence.
  - reference: PMID:17095347
    reference_title: "Hearing loss in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "HFQ-SNHL showed little relation to the history of middle ear infection and puberty"
    explanation: >
      Supports the separation of the sensorineural loss from the conductive
      consequences of otitis media.
- category: Endocrine
  name: Autoimmune Thyroiditis
  description: >
    Hashimoto thyroiditis is the commonest autoimmune comorbidity, affecting
    roughly one in five. The mechanism linking X monosomy to autoimmunity is
    not established.
  phenotype_term:
    preferred_term: Hashimoto thyroiditis
    term:
      id: HP:0000872
      label: Hashimoto thyroiditis
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:41243107
    reference_title: "Global prevalence of autoimmune diseases in turner syndrome: a systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The pooled prevalence of AIT in TS patients was 21.61%"
    explanation: >
      Quantitative support for the frequency band. Pooled across 45 studies and
      14,717 patients, 21.61% falls inside the HPO Occasional band (5-29%). The
      reported confidence interval (12.85-30.37) crosses into Frequent at its
      upper bound, so the point estimate is used rather than the interval.
  - reference: PMID:41243107
    reference_title: "Global prevalence of autoimmune diseases in turner syndrome: a systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These findings also suggest potential genetic associations between AIDs and the X chromosome, highlighting avenues for further investigation."
    explanation: >
      Supports the entry's position that the X-monosomy-to-autoimmunity link is
      a suggested association awaiting mechanism, not an established pathway.
- category: Neurologic
  name: Impaired Visuospatial and Perceptual Cognition
  description: >
    Selective impairment of visuospatial and perceptual processing with
    preserved verbal ability, mapped to PAR1 haploinsufficiency.
  phenotype_term:
    preferred_term: Impaired visuospatial constructive cognition
    term:
      id: HP:0010794
      label: Impaired visuospatial constructive cognition
  evidence:
  - reference: PMID:10931762
    reference_title: "The Turner syndrome-associated neurocognitive phenotype maps to distal Xp."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome (TS) is associated with a characteristic neurocognitive profile that includes impaired visuospatial/perceptual abilities."
    explanation: States the cognitive phenotype.
- category: Skeletal
  name: Osteoporosis
  description: >
    Reduced bone mineral density, driven substantially by estrogen deficiency
    from the age at which peak bone mass would normally accrue — hence its
    responsiveness to timely hormone replacement.
  phenotype_term:
    preferred_term: Osteoporosis
    term:
      id: HP:0000939
      label: Osteoporosis
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is estimated that 23.8% of adults with TS have osteoporosis"
    explanation: >
      Direct adult prevalence support for the HPO Occasional (5-29%) band.
  - reference: PMID:31213699
    reference_title: "Turner syndrome: mechanisms and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome is associated with short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders such as type 1 and type 2 diabetes mellitus, osteoporosis and autoimmune disorders."
    explanation: Lists osteoporosis among the syndrome's associated disorders.
  - reference: PMID:16641863
    reference_title: "Hormone replacement treatment in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the improvement of bone mineral density; normal uterine growth"
    explanation: Supports the estrogen-dependence of the bone deficit via its correction.
biochemical:
- name: Elevated follicle-stimulating hormone (FSH)
  presence: INCREASED
  context: >
    FSH is the operative marker of the hypergonadotropic state. Its trajectory
    is biphasic rather than monotonic — high in infancy, normal through
    mid-childhood, rising again peripubertally — which is why the guideline
    specifies an age window (8-9 years, then annually) rather than a single
    measurement, and why a normal value in mid-childhood carries no
    reassurance.
  biomarker_term:
    preferred_term: follicle-stimulating hormone
    term:
      id: NCIT:C181076
      label: Follicle-Stimulating Hormone
  readouts:
  - target: Hypergonadotropic Hypogonadism and Estrogen Deficiency
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: >
      A rising FSH without pubertal signs is the biochemical definition of the
      hypergonadotropic state this node represents, and is the trigger for
      hormone replacement.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "If gonadotropins (FSH in particular) in repeated samples (two or more) measured yearly from age 8-9 years are clearly elevated without any pubertal signs on physical exam, the girl with TS will need HRT."
      explanation: Makes the elevated gonadotropin the operational readout of gonadal failure.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Circulating concentrations of both FSH and LH present a biphasic pattern in TS individuals with hypogonadism: elevated after birth, declining to values similar to girls with normal ovarian function during mid-childhood, and rising again in the peripubertal years, or at the time of loss of ovarian function."
    explanation: Documents both the elevation and the biphasic trajectory that shapes when it is measured.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend measuring luteinizing hormone (LH), follicle stimulating hormone (FSH) and anti-Müllerian hormone (AMH) at 8-9 years and yearly until 11-12 years to enable timely referral for fertility preservation if appropriate"
    explanation: Gives the guideline-specified measurement schedule.
- name: Elevated luteinizing hormone (LH)
  presence: INCREASED
  context: >
    LH rises with FSH as pituitary feedback is released, and is measured
    alongside it. FSH is the more informative of the pair in this setting, so LH
    is curated as a co-marker rather than as an independent trigger for
    treatment.
  biomarker_term:
    preferred_term: luteinizing hormone
    term:
      id: NCIT:C190789
      label: Luteinizing Hormone
  readouts:
  - target: Hypergonadotropic Hypogonadism and Estrogen Deficiency
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: >
      Elevated LH reports the same loss of gonadal negative feedback as FSH.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "LH and FSH are basic markers in the assessment of ovarian function."
      explanation: States the role of both gonadotropins as markers of the ovarian state.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Circulating concentrations of both FSH and LH present a biphasic pattern in TS individuals with hypogonadism: elevated after birth, declining to values similar to girls with normal ovarian function during mid-childhood, and rising again in the peripubertal years, or at the time of loss of ovarian function."
    explanation: Documents the LH elevation and its time course.
- name: Low anti-Müllerian hormone (AMH)
  presence: DECREASED
  context: >
    AMH reports the primordial follicle pool, so it measures the upstream
    attrition node rather than the downstream endocrine state — which is what
    makes it the fertility-preservation marker rather than the
    hormone-replacement marker. The guideline is unusually explicit about its
    limits: single values vary within an individual and across assays, and its
    predictive value in younger children is uncertain, so serial rather than
    isolated measurement is recommended.
  biomarker_term:
    preferred_term: anti-Müllerian hormone
    term:
      id: NCIT:C101737
      label: Muellerian-Inhibiting Factor
  readouts:
  - target: Accelerated Ovarian Germ Cell Attrition and Follicular Atresia
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: PROGNOSTIC
    interpretation: >
      A falling AMH tracks depletion of the follicle pool, which is the process
      this node represents; it is used prognostically to time fertility
      preservation before the reserve is gone.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "AMH reflects the primordial follicle pool and predicts the reproductive lifespan of women as a key biomarker of ovarian reserve."
      explanation: Establishes AMH as a readout of the follicular reserve rather than of gonadal endocrine output.
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In individuals with TS, AMH is associated with clinical features of ovarian reserve"
      explanation: Confirms the association holds specifically in Turner syndrome rather than only in the general population.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Low AMH and undetectable inhibin B can also be used to predict ovarian insufficiency in TS, and we recommend measuring AMH along with FSH and LH during assessments."
    explanation: States the direction of the abnormality and its predictive use.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Isolated AMH measurements are influenced by several factors, including age and pubertal stage, with known intra-individual variability and variation in test accuracy. The utility of AMH to predict ovarian reserve in younger age groups is uncertain"
    explanation: >
      Marked PARTIAL: the guideline qualifies its own recommendation, and the
      caveat is retained so the marker is not read as a settled quantitative test.
  notes: >
    A measurable AMH is one of the features that distinguishes mosaic from
    non-mosaic karyotypes, consistent with the entry's treatment of karyotype as
    a severity modifier of the ovarian arm.
diagnosis:
- name: Karyotype Analysis
  description: >
    Definitive diagnosis rests on demonstrating complete or partial absence of a
    second sex chromosome. Because mosaicism is common and can be
    tissue-limited, a normal peripheral-blood karyotype does not exclude the
    diagnosis in a clinically suspicious case — which is why the guideline
    specifies a minimum of 30 metaphases rather than a standard count, and why a
    normal blood result in a phenotypically suspicious individual is followed by
    analysis of a second tissue.
  diagnosis_term:
    preferred_term: Karyotyping
    term:
      id: NCIT:C16768
      label: Karyotyping
  evidence:
  - reference: PMID:31213699
    reference_title: "Turner syndrome: mechanisms and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome is a rare condition in women that is associated with either complete or partial loss of one X chromosome, often in mosaic karyotypes."
    explanation: >
      Establishes what the test must demonstrate, and that mosaic karyotypes are
      frequent enough to shape the testing strategy.
  - reference: PMID:31213699
    reference_title: "Turner syndrome: mechanisms and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Despite an often conspicuous phenotype, the diagnostic delay can be substantial and the average age at diagnosis is around 15 years of age."
    explanation: >
      Motivates the diagnostic step: the phenotype alone is repeatedly missed
      for a decade and a half on average.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "When testing for TS, we recommend that a minimum of 30 metaphases be counted on a chromosome analysis as the first-line test."
    explanation: >
      Gives the metaphase minimum, which exists because low-level mosaicism is
      missed at conventional counts.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "if blood karyotype reveals 46,XX, but there is a high clinical suspicion of TS based on the phenotype, karyotyping or FISH analysis of a second tissue (eg, skin, buccal epithelium, urine) is indicated."
    explanation: States the second-tissue strategy that follows from tissue-limited mosaicism.
- name: Y Chromosomal Material Screening
  description: >
    Molecular screening for Y-chromosome material in individuals with a 45,X
    karyotype and signs of virilization. This is a mechanism with a surveillance
    consequence rather than a diagnostic refinement: retained Y material in a
    dysgenetic gonad carries a gonadoblastoma and dysgerminoma risk, and the
    finding opens an individualised discussion about gonadectomy weighed against
    residual gonadal function and fertility.
  diagnosis_term:
    preferred_term: Karyotyping
    term:
      id: NCIT:C16768
      label: Karyotyping
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend screening for Y chromosomal material by PCR or other molecular method in TS individuals with a 45,X karyotype and signs of virilization"
    explanation: States the screening indication and the methods used.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend individualized decision-making about gonadectomy/salpingo-oophorectomy in girls and women with TS and Y chromosome material identified on standard karyotyping or FISH analysis."
    explanation: >
      Gives the clinical consequence of a positive result, which is what makes
      this screening step worth curating separately from the diagnostic karyotype.
  notes: >
    The diagnosis_term reuses NCIT:C16768 (Karyotyping) because NCIT has no
    distinct clinical-action term for targeted Y-material molecular screening.
    The description carries the specificity the ontology term cannot.
- name: Cardiac Magnetic Resonance Imaging
  description: >
    Cross-sectional imaging of the thoracic aorta and arch, recommended in
    addition to or instead of screening echocardiography in every newly
    diagnosed adolescent or adult. It is curated separately from
    echocardiography because it is the modality that visualises the segments
    echocardiography cannot, and so is the diagnostic join point for the
    aortopathy arm.
  diagnosis_term:
    preferred_term: cardiac magnetic resonance imaging
    term:
      id: NCIT:C137915
      label: Magnetic Resonance Imaging of the Heart
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "CMR should be performed, in addition to or instead of initial screening echocardiography, in all adolescents and adults newly diagnosed with TS."
    explanation: States the recommendation and its scope.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend that cardiovascular imaging, ideally CMR or CT, should be performed at least once within 2 years before planned pregnancy or assisted reproductive methods"
    explanation: >
      Gives the second, pre-pregnancy indication, which is where the aortopathy
      and reproductive arms of the disease intersect.
- name: Cardiovascular Imaging Surveillance
  description: >
    Echocardiographic and cross-sectional imaging of the valve and thoracic
    aorta, indexed to body surface area rather than read against absolute adult
    diameters. The indexing is the point — an ascending aortic size index above
    2.5 cm/m2 in an adult is the threshold at which surgery is considered,
    a diameter that would be unremarkable if judged in centimetres alone.
  diagnosis_term:
    preferred_term: Echocardiography Test
    term:
      id: NCIT:C16525
      label: Echocardiography Test
  evidence:
  - reference: PMID:23032325
    reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals with Turner syndrome who are >18 years of age with an ascending aortic size index >2.5 cm/m(2) should be considered for an aortic operation to prevent aortic dissection."
    explanation: Gives the indexed surveillance threshold this diagnostic step exists to detect.
  - reference: PMID:23032325
    reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "More than half (13/19, 68%) came to medical attention >24 hours after the onset of symptoms."
    explanation: >
      Supports surveillance rather than symptom-triggered presentation as the
      viable detection route, given the observed delay once dissection occurs.
- name: Renal Ultrasonography at Diagnosis
  description: >
    Structural renal malformation is present in over a third of cases and is
    largely asymptomatic, so imaging is done at diagnosis rather than in
    response to symptoms.
  diagnosis_term:
    preferred_term: renal ultrasonography
    term:
      id: NCIT:C159885
      label: Renal Ultrasound
  evidence:
  - reference: PMID:11045397
    reference_title: "Frequency of renal malformations in Turner syndrome: analysis of 82 Turkish children."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Of the 82 patients, 31 had different renal malformations (37.8%)."
    explanation: Gives the yield that justifies screening every newly diagnosed individual.
  - reference: PMID:11045397
    reference_title: "Frequency of renal malformations in Turner syndrome: analysis of 82 Turkish children."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We conclude that all forms of TS should have routine nephrological screening on diagnosis"
    explanation: States the screening recommendation directly.
- name: Audiological Surveillance
  description: >
    Repeated audiometry, because the sensorineural loss is progressive with age
    and is not predicted by the childhood history of middle-ear infection. The
    guideline sets an explicit lifelong cadence — every 2-3 years through
    childhood and adolescence, every 5 years in adulthood — which is what
    distinguishes surveillance from symptom-triggered testing here.
  diagnosis_term:
    preferred_term: audiometric evaluation
    term:
      id: NCIT:C38036
      label: Audiometric Test
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend newborn hearing screening be completed, and if this is normal, age-appropriate behavioral audiometric evaluation be conducted every 2-3 years in childhood and adolescence starting as soon as developmentally able (1-2 years of age), every 5 years in adults, and any time decreased hearing is suspected"
    explanation: Gives the surveillance cadence across the lifespan.
  - reference: PMID:17095347
    reference_title: "Hearing loss in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Because the increase in hearing threshold at high frequencies was shown to depend on karyotype and aging, regular otological examination is important for the determination of proper treatment."
    explanation: States the recommendation and the reason it must be repeated over time.
- name: Thyroid Function Surveillance
  description: >
    Measurement of TSH every 1-2 years from age two through adulthood, with
    additional testing when symptoms arise and thyroid antibodies checked when
    TSH is elevated. This monitors the treatable functional endpoint rather than
    screening asymptomatic individuals for antibodies that do not change care.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend screening for hypothyroidism with measurement of TSH every 1-2 years starting at 2 years of age and continuing through adulthood, and with new symptoms."
    explanation: Gives the lifelong age and interval for thyroid surveillance.
- name: Diabetes Surveillance
  description: >
    Hemoglobin A1c or fasting glucose every 1-2 years beginning at age 10-12,
    earlier if symptoms occur. Diabetes autoantibodies are assessed after a
    diabetes diagnosis because both type 1 and type 2 disease occur and can be
    difficult to distinguish in Turner syndrome.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend screening for diabetes with measurement of hemoglobin A1c or fasting glucose every 1-2 years starting at age 10-12 years or sooner with symptoms of diabetes"
    explanation: Gives the recommended tests, starting age, and interval.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend assessment of diabetes autoantibodies at diagnosis of diabetes in girls and women with TS to determine the type of diabetes as it is not easy to differentiate Type 1 and Type 2 diabetes in this population"
    explanation: Explains the post-diagnosis typing step.
- name: Liver Biochemistry Surveillance
  description: >
    Liver enzymes are measured in childhood and every 1-2 years from age ten
    onward. Persistent abnormalities prompt reassessment and specialist workup;
    they are not, by themselves, a reason to stop hormone replacement.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend measuring liver enzymes (alanine aminotransferase (ALT) at minimum) in childhood and every 1-2 years starting at the age of 10 and continuing throughout the lifespan."
    explanation: Gives the minimum assay and lifelong cadence.
- name: Celiac Disease Serologic Surveillance
  description: >
    Tissue-transglutaminase IgA with total IgA from age two and every 2-5 years
    thereafter, with symptom-triggered testing at any age. The clinical
    association is strong enough to warrant screening even though the
    X-dosage-to-autoimmunity mechanism remains unresolved.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend screening for celiac disease by measuring tissue transglutaminase antibodies (TTG IgA with total IgA) in asymptomatic individuals starting at age 2 years, and subsequently every 2-5 years"
    explanation: Gives the recommended assay, starting age, and interval.
- name: Bone Health Surveillance
  description: >
    Vitamin D testing begins at age 9-11 and repeats every 2-3 years. DXA is
    obtained after linear growth is complete but before age 21 and every 5-10
    years in adulthood, with closer serial assessment when fractures, inadequate
    estrogen replacement, celiac disease, menopause, or other risks are present.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend routine screening for vitamin D deficiency using a serum 25 (OH) vitamin D level concentration between 9 and 11 years of age and every 2-3 years ongoing and treating with inactive vitamin D supplement as necessary"
    explanation: Gives the age and cadence for vitamin-D surveillance.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend obtaining a dual energy X-ray absorptiometry (DXA) scan after completion of growth but prior to 21 years of age and every 5-10 years throughout adulthood"
    explanation: Gives the DXA timing and adult interval.
genetic:
- name: SHOX
  association: >
    SHOX haploinsufficiency is causative for the short-stature and mesomelic
    skeletal arm of Turner syndrome, but SHOX variation is neither necessary nor
    sufficient for Turner syndrome as a whole; the defining lesion is loss of
    all or part of a sex chromosome.
  gene_term:
    preferred_term: SHOX
    term:
      id: hgnc:10853
      label: SHOX
  notes: >
    The one Turner gene assigned to its phenotype with confidence. SHOX lies in
    PAR1, escapes X-inactivation, and is therefore reduced to a single dose
    whenever the second sex chromosome is absent or its short arm deleted.
    Haploinsufficiency — not mutation of the retained copy — is the mechanism,
    which is why the same phenotype arises in Léri-Weill dyschondrosteosis from
    PAR1 deletions in individuals with two intact sex chromosomes. No
    variant_origin is recorded: there is no allele here to assign an origin to.
    The de-novo event is the loss of the chromosome, which is captured on the
    trigger pathophysiology node, not a variant in the retained SHOX copy.
    `relationship_type` is intentionally omitted: the controlled CAUSATIVE value
    means that variants in the gene are sufficient to cause the disease, which
    is false for Turner syndrome even though SHOX dosage causes one phenotype
    arm. The free-text association records the narrower, supported relationship.
  evidence:
  - reference: PMID:27194967
    reference_title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SHOX in the short arm pseudoautosomal region (PAR1) of sex chromosomes is one of the major growth genes in humans."
    explanation: Locates the gene and establishes its role in human growth.
  - reference: PMID:27194967
    reference_title: "SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SHOX haploinsufficiency frequently results from deletions and duplications in PAR1 involving SHOX exons and/or the cis-acting enhancers, while exonic point mutations account for a small percentage of cases."
    explanation: >
      Supports the allele type recorded here — dosage loss through deletion
      rather than point mutation.
  - reference: PMID:21925981
    reference_title: "The role of the SHOX gene in the pathophysiology of Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with deletions of the distal segment of the short arm of X chromosome (Xp-) including haploinsufficiency of the SHOX (short stature homeobox) have, more often, short stature, skeletal abnormalities and hearing impairments."
    explanation: Genotype-phenotype correlation from partial Xp deletions.
inheritance:
- name: Not inherited (sporadic chromosomal aneuploidy)
  description: >
    Turner syndrome arises from a sporadic meiotic or post-zygotic mitotic error
    and is not transmitted in a Mendelian pattern. It is therefore not assigned
    an HPO mode-of-inheritance term: the standard modes describe transmission of
    alleles, and there is no transmission here. Recurrence risk in siblings is
    not appreciably raised, and the practical genetic-counselling content
    concerns the affected individual's own reproductive options rather than
    family segregation.
  evidence:
  - reference: PMID:31213699
    reference_title: "Turner syndrome: mechanisms and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner syndrome is a rare condition in women that is associated with either complete or partial loss of one X chromosome, often in mosaic karyotypes."
    explanation: >
      Supports the chromosomal (aneuploidy/mosaicism) rather than Mendelian
      basis of the condition.
treatments:
- name: Recombinant Growth Hormone
  description: >
    Somatropin given from childhood to increase adult height. Mechanistically it
    is not replacement — growth hormone secretion is not deficient in Turner
    syndrome — but pharmacological stimulation of a growth plate whose SHOX
    dosage deficit has blunted its output. The randomised evidence to adult
    height gives roughly +7 cm, which is the honest size of the effect.
    The PROTEIN_REPLACEMENT modality tag records the therapeutic platform —
    somatropin is a 191-amino-acid recombinant protein — and is not a claim that
    the treatment replaces a deficient hormone, which it does not.
  therapeutic_modality: PROTEIN_REPLACEMENT
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: somatropin
      term:
        id: NCIT:C837
        label: Somatropin
  target_mechanisms:
  - target: Skeletal Growth Failure and Mesomelic Dysmorphism
    treatment_effect: INHIBITS
    description: >
      Acts on the growth-failure node, increasing attained adult height without
      correcting the underlying SHOX dosage deficit.
    evidence:
    - reference: PMID:15784709
      reference_title: "Impact of growth hormone supplementation on adult height in turner syndrome: results of the Canadian randomized controlled trial."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "This is the first evidence from a randomized, controlled trial to adult height that GH supplementation with induction of puberty at a near physiological age increases the adult height of girls with Turner syndrome."
      explanation: Randomised-controlled-trial evidence that the treatment acts on this node.
  evidence:
  - reference: PMID:15784709
    reference_title: "Impact of growth hormone supplementation on adult height in turner syndrome: results of the Canadian randomized controlled trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the mean height gain due to GH, estimated by analysis of covariance, was +7.2 cm"
    explanation: Quantifies the treatment effect from the randomised trial.
  - reference: PMID:15784709
    reference_title: "Impact of growth hormone supplementation on adult height in turner syndrome: results of the Canadian randomized controlled trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "One hundred fifty-four girls with Turner syndrome, aged 7-13 yr, were randomly assigned to one of two groups"
    explanation: Establishes the randomised design and cohort size behind the effect estimate.
- name: Estrogen Replacement Therapy
  description: >
    Estrogen to induce puberty at a physiological age, then continued
    replacement to the age of normal menopause. Unlike growth hormone this is
    true replacement — it substitutes for the hormone the streak gonad cannot
    make — and its end-organ targets are the skeleton and the uterus as well as
    secondary sexual development.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Hormone Replacement Therapy
    term:
      id: NCIT:C15599
      label: Hormone Replacement Therapy
    therapeutic_agent:
    - preferred_term: estradiol
      term:
        id: CHEBI:16469
        label: 17beta-estradiol
  target_mechanisms:
  - target: Hypergonadotropic Hypogonadism and Estrogen Deficiency
    treatment_effect: RESTORES
    description: >
      Substitutes the missing gonadal steroid, addressing this node directly
      rather than any upstream dosage lesion.
    evidence:
    - reference: PMID:16641863
      reference_title: "Hormone replacement treatment in Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Hormone replacement treatment should be initiated at a physiological age in these patients who do not enter puberty spontaneously and should be continued up to the age of normal menopause."
      explanation: States the indication and duration, both defined by the failed gonad.
  evidence:
  - reference: PMID:16641863
    reference_title: "Hormone replacement treatment in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the improvement of bone mineral density; normal uterine growth"
    explanation: Names two of the measurable end-organ benefits.
  - reference: PMID:16641863
    reference_title: "Hormone replacement treatment in Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is crucial that these women understand that hormone replacement is a long-term treatment."
    explanation: Supports the lifelong rather than pubertal framing of the treatment.
- name: Prophylactic Aortic Surgery
  description: >
    Elective replacement of the ascending aorta in individuals reaching an
    indexed size threshold, undertaken before dissection rather than in
    response to it. It is the only intervention that acts on the syndrome's
    leading cause of avoidable sudden death.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: Surgical Procedure
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  target_mechanisms:
  - target: Progressive Aortic Dilation
    treatment_effect: INHIBITS
    description: >
      Removes the dilated segment before it dissects; prophylactic rather than
      mechanism-modifying.
    evidence:
    - reference: PMID:23032325
      reference_title: "Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Individuals with Turner syndrome who are >18 years of age with an ascending aortic size index >2.5 cm/m(2) should be considered for an aortic operation to prevent aortic dissection."
      explanation: States the preventive indication and the threshold that triggers it.
- name: Antihypertensive Therapy
  description: >
    Annual blood-pressure assessment with treatment of confirmed hypertension,
    preferentially with a beta-blocker, an angiotensin receptor blocker, or both
    where aortic dilation is also present. The mechanistic honesty here matters:
    the drug-class preference is imported from other genetically triggered
    aortopathies, and the guideline states plainly that no study has shown
    antihypertensive therapy to slow or prevent aortic dilation in Turner
    syndrome specifically. It is curated because it is a graded recommendation
    acting on a node this entry models, not because the aortic benefit is
    established.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Antihypertensive Therapy
    term:
      id: NCIT:C172184
      label: Antihypertensive Therapy
    therapeutic_agent:
    - preferred_term: beta-blocker
      term:
        id: NCIT:C29576
        label: Beta-Adrenergic Antagonist
    - preferred_term: angiotensin receptor blocker
      term:
        id: NCIT:C66930
        label: Angiotensin II Receptor Antagonist
  target_mechanisms:
  - target: Hypertension
    treatment_effect: INHIBITS
    description: >
      Treats the hypertension itself, which is the indication the guideline
      states without qualification.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We recommend annual assessment of blood pressure, preferably using ambulatory blood pressure monitoring (ABPM), and initiation of medical therapies if hypertension is confirmed, for all individuals with TS"
      explanation: Graded recommendation to treat confirmed hypertension in every individual with TS.
  - target: Progressive Aortic Dilation
    treatment_effect: INHIBITS
    description: >
      The intended but unproven target. Beta-blockade and angiotensin receptor
      blockade are chosen for their effect on aortic dilation in other
      aortopathies; in Turner syndrome the link between blood-pressure control
      and aortic events is inferential.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Medical therapy of hypertension for individuals with TS and aortic dilation should preferably include a beta-blocker, angiotensin receptor blocker (ARB), or both, which have been shown to prevent aortic dilation and aortic dissections in individuals with other aortopathy conditions."
      explanation: >
        Marked PARTIAL deliberately: the aortic benefit quoted is established in
        other aortopathies, and the sentence extends it to TS by analogy.
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: NO_EVIDENCE
      evidence_source: HUMAN_CLINICAL
      snippet: "While hypertension is correlated with the presence of aortic dilation in TS, no studies have demonstrated that antihypertensive therapies slow or prevent aortic dilation."
      explanation: >
        The guideline's own explicit statement that the TS-specific evidence for
        this edge does not exist. Retained so the link cannot be read as
        established mechanism.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend treatment with a beta-blocker, an angiotensin receptor blocker, or both for individuals with TS who have hypertension and have a dilated aorta"
    explanation: Names the recommended drug classes and the population in which they are indicated.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "As hypertension is common, maintenance of normal blood pressure may reduce the risk for aortic events."
    explanation: States the rationale, in the guideline's own hedged wording.
- name: Fertility Preservation by Oocyte Cryopreservation
  description: >
    Controlled ovarian stimulation followed by oocyte cryopreservation, offered
    to post-menarcheal individuals with residual fertility potential. The
    treatment exists because the ovarian lesion is attrition rather than absent
    germ cells: there is a window before the reserve is exhausted, and the
    intervention is an attempt to act inside it. The guideline is explicit that
    it should not be offered to premenarcheal children, which is a limit on the
    window as much as an ethical constraint.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: fertility preservation
    term:
      id: NCIT:C71326
      label: Fertility Preservation
  target_mechanisms:
  - target: Accelerated Ovarian Germ Cell Attrition and Follicular Atresia
    treatment_effect: BYPASSES
    description: >
      Does not slow the attrition. It removes and stores gametes before the
      reserve is lost, so it bypasses the node rather than modifying it.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We recommend controlled ovarian stimulation and oocyte cryopreservation, in females with a fertility potential, as the primary fertility preservation option in post-menarche individuals of appropriate psychological maturity"
      explanation: >
        The graded recommendation, restricted to individuals who still have
        fertility potential — i.e. in whom this node has not yet run to
        completion.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend that controlled ovarian stimulation and oocyte cryopreservation not be offered to premenarcheal children or individuals not mature enough to understand and undergo the procedure"
    explanation: Records the guideline's explicit boundary on who should be offered the procedure.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend offering AMH measurements to all individuals with TS from diagnosis. AMH should be monitored annually if fertility preservation is considered"
    explanation: Ties the intervention to the AMH biochemical marker curated in this entry.
- name: Otologic and Audiologic Management
  description: >
    Tympanostomy tube insertion and hearing aids for the conductive loss of
    middle ear disease in childhood, and hearing aids or cochlear implantation
    for the progressive sensorineural loss. The two arms are separate
    interventions on separate lesions and are curated on one entry only because
    they share a care pathway.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: tympanostomy tube insertion
    term:
      id: NCIT:C70906
      label: Myringotomy with Ear Tube Placement
  target_mechanisms:
  - target: Recurrent Otitis Media and Middle Ear Disease
    treatment_effect: INHIBITS
    description: >
      Ventilating the middle ear addresses the effusion that causes the
      conductive loss and the structural sequelae of recurrent infection.
    evidence:
    - reference: PMID:38748847
      reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We suggest placement of tympanostomy tubes at the early stages of chronic or recurrent middle ear disease in childhood (as for a high-risk population)"
      explanation: Graded recommendation targeting this node, explicitly at a lower threshold than in the general population.
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend rapid intervention with tympanostomy tube insertion or hearing aids for conductive hearing loss due to middle ear disease in childhood"
    explanation: Covers the conductive arm of the intervention.
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We recommend rehabilitation with hearing aids or cochlear implantation for sensorineural hearing loss"
    explanation: >
      Covers the sensorineural arm, which is a different lesion — the
      progressive high-frequency loss curated as its own phenotype.
- name: Multidisciplinary Lifelong Surveillance
  description: >
    Coordinated follow-up across endocrinology, cardiology, nephrology,
    audiology and psychology. This is listed as a treatment because in Turner
    syndrome the organ complications are mostly silent until they are severe,
    so scheduled surveillance — not symptom response — is what changes outcome.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:38748847
    reference_title: "Clinical practice guidelines for the care of girls and women with Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "TS affects multiple organs through all stages of life, necessitating multidisciplinary care."
    explanation: States the rationale for lifelong multidisciplinary management.
- name: Genetic Counseling
  description: >
    Counseling addressed to the affected individual's reproductive options and
    to the interpretation of a mosaic karyotype, rather than to family
    recurrence risk, which is not appreciably raised.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:31240242
    reference_title: "Time to consider ovarian tissue cryopreservation for girls with Turner's syndrome: an opinion paper."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ethical, clinical and psychological dilemmas should be considered, discussed and addressed before considering such a novel approach."
    explanation: >
      Supports the counseling requirement around fertility-preservation
      decisions specifically.
animal_models:
- name: 39,X (XO) mouse ovarian-reserve background series
  species: Mouse
  genotype: >
    39,X (XO) on mixed N2(C3H.B6) and inbred C57BL/6J genetic backgrounds
  background: Mixed N2(C3H.B6) compared with C57BL/6J
  publication: PMID:32634219
  description: >
    A background-comparison series that resolves an important limitation of the
    generic XO mouse. Mixed-background XO females retain fewer neonatal oocytes
    but remain normally fertile, whereas C57BL/6J XO females have much more
    severe early oocyte loss and reduced fertility. The model therefore captures
    a background-modified ovarian-reserve phenotype, not a stable mouse analogue
    of human Turner infertility.
  modeled_mechanisms:
  - target: Accelerated Ovarian Germ Cell Attrition and Follicular Atresia
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    description: >
      C57BL/6J XO females reproduce early oocyte loss and infertility or
      subfertility, while mixed-background XO females show a milder reserve loss
      without the human fertility endpoint.
    limitations: >
      Fidelity is strongly strain-dependent: mixed-background XO females retain
      normal fertility, and even the C57BL/6J phenotype does not reproduce the
      profound prenatal lethality or near-universal ovarian failure of human
      non-mosaic 45,X. The series can test modifiers of oocyte loss but cannot be
      treated as a generic model of the full Turner ovarian phenotype.
    evidence:
    - reference: PMID:32634219
      reference_title: "Premature ovarian insufficiency in the XO female mouse on the C57BL/6J genetic background."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "In this article, we report that XO mice on the C57BL/6J (B6) genetic background showed early oocyte loss, infertility or subfertility and high embryonic lethality, suggesting that the effect of monosomy X in the female germline may be shared between mice and humans."
      explanation: Supports the recapitulated ovarian-reserve and fertility components in the B6 strain.
    - reference: PMID:32634219
      reference_title: "Premature ovarian insufficiency in the XO female mouse on the C57BL/6J genetic background."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "We conclude that the impact of monosomy X on female mouse fertility depends on the genetic background."
      explanation: >
        Establishes the strain dependence that limits generalization and makes
        PARTIALLY_RECAPITULATES the appropriate relationship.
  evidence:
  - reference: PMID:18499648
    reference_title: "Genotype, phenotype, and karyotype correlation in the XO mouse model of Turner Syndrome."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Unlike their human counterparts, XO mice are typically fertile, and their lack of a second sex chromosome can be transmitted from one generation to the next as an X-linked dominant trait with male lethality."
    explanation: Records the classic translational mismatch that the background series qualifies.
experimental_models:
- name: 45,X patient-derived iPSC granulosa-like cells
  experimental_model_type: IPSC_DERIVED_MODEL
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  tissue_term:
    preferred_term: ovary
    term:
      id: UBERON:0000992
      label: ovary
  cell_types:
  - preferred_term: granulosa cell
    term:
      id: CL:0000501
      label: granulosa cell
  cell_source: >
    Fibroblast-reprogrammed iPSCs from two unrelated 45,X Turner patients and
    two unrelated unaffected controls, with multiple Turner subclones
  culture_system: >
    Fourteen-day embryoid-body-to-intermediate-mesoderm-to-granulosa-like-cell
    differentiation with transcriptomic, marker, cell-cycle, and pathway-rescue assays
  conditions:
  - 45,X Turner syndrome-derived granulosa-like cells
  - Unaffected control-derived granulosa-like cells
  - Apelin/APJ ligand and Akt/PKB rescue conditions
  publication: PMID:39543104
  description: >
    Human patient-derived system used to test granulosa differentiation,
    cell-cycle progression, apelin/APJ signaling, and pathway rescue. It is the
    first direct cellular model represented here for a candidate somatic-cell
    contribution to Turner ovarian attrition.
  modeled_mechanisms:
  - target: Granulosa-Cell Apelin/APJ Signaling Dysfunction
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    description: >
      The system measures reduced pathway signaling and demonstrates partial
      rescue with apelin ligands or downstream Akt activation.
    limitations: >
      The comparison is non-isogenic and includes two Turner donors. Cultures
      were not purified by surface markers before bulk transcriptomics, so the
      observed difference cannot be assigned solely to a cell-autonomous pathway
      defect, and intact ovarian confirmation is absent.
    evidence:
    - reference: PMID:39543104
      reference_title: "Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "The apelin/APJ pathway exhibited differential signaling between the healthy and TS groups."
      explanation: Supports the pathway readout in the model.
  - target: Granulosa-Cell Differentiation and Cell-Cycle Dysfunction
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    description: >
      The system reproduces reduced granulosa marker expression and abnormal
      cell-cycle progression associated with 45,X donor cells.
    limitations: >
      The cells are in-vitro granulosa-like derivatives rather than purified
      fetal ovarian granulosa cells, the donor count is small, and genetic
      background is not controlled isogenically. The model cannot show oocyte
      loss or follicular atresia directly.
    evidence:
    - reference: PMID:39543104
      reference_title: "Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Additionally, we identified dysregulation of the cell cycle in TS-GCs."
      explanation: Supports the cellular readout.
- name: 45,X patient-derived iPSC cardiomyocytes
  experimental_model_type: IPSC_DERIVED_MODEL
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  tissue_term:
    preferred_term: heart
    term:
      id: UBERON:0000948
      label: heart
  cell_types:
  - preferred_term: cardiomyocyte
    term:
      id: CL:0000746
      label: cardiac muscle cell
  cell_source: >
    Peripheral-blood-cell-derived iPSCs from three 45,X Turner patients and
    three unrelated 46,XX healthy donors
  culture_system: >
    Two-dimensional cardiomyocyte differentiation with mRNA, lncRNA, and circRNA
    microarrays plus beating-frequency and mitochondrial-copy-number readouts
  conditions:
  - 45,X Turner syndrome-derived iPSCs and cardiomyocytes
  - 46,XX healthy-donor-derived iPSCs and cardiomyocytes
  publication: PMID:38124119
  description: >
    Patient-derived cardiac-cell system that measures the transcriptomic and
    contractile response to 45,X dosage in differentiated cardiomyocytes.
  modeled_mechanisms:
  - target: Turner Cardiomyocyte Transcriptome and Contractile Dysregulation
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    description: >
      The model reproduces altered coding and non-coding RNA profiles, reduced
      beating frequency, and increased mitochondrial DNA copy number.
    limitations: >
      Only three Turner and three control donor lines were profiled, the design
      is non-isogenic, and the cardiomyocytes are immature two-dimensional cells.
      The system does not form an aortic valve, arch, or vessel wall, so it
      cannot establish a mechanism for the syndrome's structural cardiac or
      aortic phenotypes; proposed ceRNA circuits also lacked direct miRNA profiling.
    evidence:
    - reference: PMID:38124119
      reference_title: "Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "We observed lower beating frequencies and higher mitochondrial DNA copies per nucleus in TS-CMs."
      explanation: Supports the measured cellular phenotype.
    - reference: PMID:38124119
      reference_title: "Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Firstly, owing to a restricted budget, merely three TS patient-specific cell lines and three healthy donor-derived cell lines were examined by microarrays in this study."
      explanation: Directly supports the sample-size limitation and the moderate-fidelity rating.
datasets:
- accession: geo:GSE271780
  title: Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome
  description: >
    Bulk RNA sequencing of day-14 granulosa-like cells differentiated from 45,X
    Turner and unaffected-control iPSCs, with adult cumulus granulosa cells used
    in the study as a reference population.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_types:
  - preferred_term: granulosa cell
    term:
      id: CL:0000501
      label: granulosa cell
    cell_type_term:
      preferred_term: granulosa cell
      term:
        id: CL:0000501
        label: granulosa cell
  sample_count: 10
  conditions:
  - 2 unaffected-control iPSC-derived granulosa-like cell lines
  - 4 45,X Turner syndrome iPSC-derived granulosa-like cell subclones from 2 source donors (2 subclones per donor)
  - 4 adult luteinized cumulus granulosa-cell reference samples
  publication: PMID:39543104
  platform: Illumina NovaSeq 6000
  evidence:
  - reference: PMID:39543104
    reference_title: "Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The raw data was deposited in GEO: GSE271780."
    explanation: Direct accession statement from the primary publication.
  notes: >
    Direct disease-model dataset discovered with `just discover-datasets`;
    accession, organism, publication, data type, NovaSeq platform, and 10-sample
    three-group composition verified against NCBI GEO metadata on 2026-08-16.
- accession: geo:GSE239758
  title: The mRNA-lncRNA-circRNA network profiling of Turner syndrome patient-derived induced pluripotent stem cells and their derived cardiomyocytes
  description: >
    Coding and non-coding RNA microarray profiles from three 45,X Turner and
    three healthy-donor iPSC lines and their matched day-14 cardiomyocyte
    derivatives.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: MICROARRAY
  sample_types:
  - preferred_term: cardiomyocyte
    term:
      id: CL:0000746
      label: cardiac muscle cell
    cell_type_term:
      preferred_term: cardiomyocyte
      term:
        id: CL:0000746
        label: cardiac muscle cell
  sample_count: 12
  conditions:
  - 45,X Turner syndrome-derived iPSCs and cardiomyocytes
  - 46,XX healthy-donor-derived iPSCs and cardiomyocytes
  publication: PMID:38124119
  platform: High-density mRNA, lncRNA, and circRNA microarrays
  evidence:
  - reference: PMID:38124119
    reference_title: "Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "The microarray data were deposited in the Gene Expression Omnibus (GEO) database under the accession no. GSE239758."
    explanation: Direct accession statement from the primary publication.
  notes: >
    Direct disease-model dataset discovered with `just discover-datasets`;
    accession, organism, publication, data type, and 12-sample count verified
    against NCBI GEO metadata on 2026-08-16.
discussions:
- discussion_id: gap_unassigned_escape_genes
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >
    Which X-inactivation escape and pseudoautosomal genes, beyond SHOX, account
    for the gonadal, cardiovascular, renal, auditory and autoimmune arms of
    Turner syndrome?
  rationale: >
    This is the central unresolved question of the disease rather than a loose
    end. The canonical model attributes every arm of the syndrome to
    haploinsufficiency of escape genes, but only one gene-to-phenotype
    assignment has been made — SHOX to stature and the mesomelic skeleton — and
    the field states explicitly that SHOX does not explain most Turner
    anomalies. Consequently the edges from the escape-gene node to the ovarian
    and lymphatic arms in this entry are curated as INDIRECT, because naming
    them DIRECT would assert a gene-level mechanism nobody has identified. The
    gap has practical weight: without the responsible genes there is no
    molecular target for the non-growth arms. Every therapy curated in this
    entry acts downstream of the unknown dosage lesion rather than on it —
    growth hormone drives a partially responsive growth plate, estrogen replaces
    a missing hormone, antihypertensives and aortic surgery act on the
    consequences of a malformation whose genetic cause is unassigned, and oocyte
    cryopreservation bypasses the attrition rather than slowing it. There is no
    gene-directed therapy for any arm of the disease, and there cannot be one
    until this gap closes.
  attaches_to:
  - pathophysiology#Haploinsufficiency of Pseudoautosomal and X-Inactivation Escape Genes
  evidence:
  - reference: PMID:21925981
    reference_title: "The role of the SHOX gene in the pathophysiology of Turner syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "As the inheritance of only one copy of the SHOX gene does not explain most of TS anomalies, more studies are needed to explain them."
    explanation: States the gap directly — SHOX dosage leaves most of the syndrome unexplained.
  - reference: PMID:38124119
    reference_title: "Competing endogenous RNA network analysis of Turner syndrome patient-specific iPSC-derived cardiomyocytes reveals dysregulation of autosomal heart development genes by altered dosages of X-inactivation escaping non-coding RNAs."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "How loss of one X chromosome drive these conditions remains largely unknown."
    explanation: Independent restatement of the gap from the molecular side.
  proposed_experiments:
  - experiment_id: exp_ts_escape_gene_dosage_mapping
    name: Systematic escape-gene dosage mapping against organ-specific Turner phenotypes
    description: >
      Extend the partial-Xp deletion mapping strategy that localised the
      neurocognitive phenotype to PAR1 across the remaining organ arms, using
      contemporary cohorts of individuals with structurally abnormal X
      chromosomes and defined breakpoints, phenotyped for gonadal reserve,
      cardiac malformation, renal structure and audiometry. The design's
      strength is that it is the same human-genetics logic already shown to work
      here, rather than an animal model whose fidelity to human X-dosage biology
      would itself need establishing.
- discussion_id: gap_lymphatic_versus_dosage_origin_of_cardiac_defect
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >
    Is the left-heart obstructive lesion of Turner syndrome caused by the fetal
    lymphatic defect through a hemodynamic mechanism, or are the two parallel
    consequences of the same gene-dosage lesion?
  rationale: >
    The two accounts predict the same epidemiology — neck web and coarctation
    co-occur — and are therefore not separated by the association data that
    motivated the hemodynamic model. The distinction matters because it decides
    whether the cardiac phenotype is in principle preventable by anything acting
    on lymphatic development, or whether it is an independent dosage effect that
    a lymphatic intervention could never touch. This entry does not resolve it:
    the hemodynamic chain is confined to a named ALTERNATIVE hypothesis group,
    and the corresponding edge is typed INDIRECT so no node asserts it as
    settled mechanism.
  attaches_to:
  - pathophysiology#Fetal Jugular Lymphatic Sac Obstruction and Lymphatic Network Dysplasia
  - pathophysiology#Left-Sided Cardiac Outflow Tract Malformation
  evidence:
  - reference: PMID:6463900
    reference_title: "Neck web and congenital heart defects: a pathogenic association in 45 X-O Turner syndrome?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The following hypothesis is proposed to explain the association."
    explanation: >
      The source's own framing — a hypothesis proposed to explain an
      association — which is why the mechanism is not curated as established.
- discussion_id: note_module_conformance_withheld
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >
    Should the Turner aortopathy node conform to aortopathy_tgfbeta_dysregulation,
    and should the osteoporosis phenotype conform to
    osteoporosis_bone_resorption?
  rationale: >
    Both conformances are superficially attractive and are deliberately withheld
    rather than silently omitted. Turner aortopathy is a genuine heritable
    thoracic aortic disease, but the module's defining claim is paradoxically
    increased TGF-beta signalling downstream of an ECM or contractile-apparatus
    lesion, and no evidence curated in this entry establishes that mechanism in
    Turner syndrome — the aortopathy here is documented at the level of valve
    morphology, calibre and dissection risk. Similarly, the osteoporosis module
    turns on RANKL-driven osteoclastogenesis, whereas the evidence available
    here establishes only that bone mineral density is low and improves with
    estrogen replacement, which is consistent with that mechanism but does not
    demonstrate it. Declaring either conformance would import mechanistic claims
    this entry cannot support; a curator with the relevant primary literature
    should revisit both.
  attaches_to:
  - pathophysiology#Progressive Aortic Dilation
- discussion_id: mismatch_xo_mouse_ovarian_background_dependence
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: >
    Which genetic-background determinants make monosomy X cause profound ovarian
    reserve loss in some mouse strains while leaving other XO females fertile,
    and do those determinants illuminate variability in human Turner syndrome?
  attaches_to:
  - pathophysiology#Accelerated Ovarian Germ Cell Attrition and Follicular Atresia
  rationale: >
    The generic statement that XO mice are fertile is true for commonly used
    backgrounds but incomplete. A direct strain comparison found early oocyte
    loss and infertility or subfertility on C57BL/6J, while mixed-background XO
    females remained as fertile as XX controls despite a reduced neonatal oocyte
    count. That makes genetic background part of the mechanism, not merely a
    nuisance variable. It also prevents either extreme interpretation: the mouse
    is not a faithful generic model of human Turner infertility, but neither is
    murine monosomy X intrinsically incapable of reproducing ovarian attrition.
  evidence:
  - reference: PMID:32634219
    reference_title: "Premature ovarian insufficiency in the XO female mouse on the C57BL/6J genetic background."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Second, while N2.XO females were as fertile as N2.XX females, both the frequency of delivery and the total number of pups delivered by B6.XO females were significantly lower than those by B6.XX females."
    explanation: Direct within-study demonstration of the strain-dependent fertility mismatch.
  - reference: PMID:32634219
    reference_title: "Premature ovarian insufficiency in the XO female mouse on the C57BL/6J genetic background."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We conclude that the impact of monosomy X on female mouse fertility depends on the genetic background."
    explanation: States the unresolved modifier problem directly.
notes: >-
  Scoping. This entry models Turner syndrome as the union of karyotypes under
  MONDO:0019499 — non-mosaic 45,X, mosaic 45,X/46,XX, and structural X
  abnormalities — rather than splitting them into separate entries. The three
  narrower MONDO terms are carried as narrowMatch mappings so a future split
  remains possible. The lumping decision is defensible because the mechanism is
  shared (dosage loss of escape and pseudoautosomal genes) and karyotype acts as
  a severity modifier rather than a mechanism switch: renal malformation is
  markedly commoner in non-mosaic 45,X than in mosaic or structural forms, and
  the sensorineural hearing loss progresses faster in 45,X, but neither is a
  different process. Where a cited figure is karyotype-specific it is recorded
  as such rather than generalised.

  Chromosome and sex representation. The defining lesion is a whole- or
  partial-sex-chromosome dosage state, not a variant in a single retained gene.
  The current disease schema has no disease-level karyotype descriptor or
  phenotypic-sex slot: `SexEnum` qualifies context strata and must not be
  repurposed as the disease definition. The entry therefore preserves the
  female-phenotype and 45,X/mosaic/structural-X scope in the definition,
  narrowMatch mappings, karyotype diagnosis, and Y-material screening. For the
  same reason SHOX is no longer typed CAUSATIVE for Turner syndrome as a whole;
  its narrower causal contribution to the growth and skeletal arm is recorded
  in free text and in the pathograph.

  Evidence discipline. Every snippet in this entry is an exact quote from its
  cached source. Four judgement calls are worth flagging for a reviewer.
  First, the two skeletal dysmorphism phenotypes (cubitus valgus, Madelung
  deformity) are marked PARTIAL because the cached sources support "skeletal
  abnormality attributable to SHOX dosage" as a class and support the shared
  aetiology with Léri-Weill dyschondrosteosis, but do not name these deformities
  in Turner syndrome in the quotable text; the alternative was to drop
  well-established clinical features entirely. Second, the autoimmune
  thyroiditis frequency is set to OCCASIONAL from the pooled point estimate of
  21.61%, even though the reported confidence interval crosses into the FREQUENT
  band at 30.37%. Third, four phenotypes carry no frequency band on purpose:
  recurrent otitis media because the reported 24-48% range straddles the
  Occasional/Frequent boundary, hypertension because the guideline gives
  markedly different paediatric and adult figures, and scoliosis and
  hypothyroidism because no prevalence is stated at all in the cached sources.
  Fourth, the antihypertensive link to progressive aortic dilation carries a
  NO_EVIDENCE item quoting the guideline's own statement that no study has shown
  antihypertensive therapy to slow aortic dilation in Turner syndrome; the edge
  is curated because the recommendation exists, not because the effect is
  demonstrated.

  Model calibration. Two new human iPSC-derived systems are represented as
  PROVISIONAL mechanism nodes rather than promoted into the established human
  path. The granulosa model supplies pathway-rescue evidence for an emerging
  apelin/APJ-to-cell-cycle relay, but the cultures are non-isogenic, derived from
  two Turner donors, and were not purified before bulk transcriptomics. The
  cardiomyocyte model contains three Turner and three control donors and supports
  a cellular transcriptome/contractility state; it does not form a valve, arch,
  or vessel wall, so no edge to bicuspid valve, coarctation, or aortopathy is
  asserted. The XO mouse is likewise represented as a genetic-background series:
  C57BL/6J partially recapitulates ovarian reserve loss, whereas mixed-background
  XO females remain fertile. These limitations are structural model links and an
  open HUMAN_MODEL_MISMATCH discussion, not caveats left only in prose.

  What is deliberately absent. There is no `conforms_to` declaration anywhere in
  this entry. Two candidate module conformances were considered and rejected on
  evidence grounds, and the reasoning is recorded as an open discussion
  (note_module_conformance_withheld) rather than left to be inferred from the
  omission. Type 1 and type 2 diabetes, celiac disease and alopecia areata are
  all documented comorbidities with quantitative pooled prevalences available in
  PMID:41243107, and are not curated as phenotypes here only because the
  mechanism linking X monosomy to autoimmunity is unknown, so they would be
  association without pathway; the autoimmune arm is represented by the single
  best-evidenced member.

  Sources. The 2024 international clinical practice guideline (PMID:38748847,
  282 graded recommendations) is the principal clinical source for the
  phenotype, biochemical, diagnosis and treatment sections; the established
  mechanism sections rest on primary human genetics and clinical cohorts. No
  deep-research provider report was generated, and no dedicated Turner syndrome
  GeneReviews chapter was identified in NCBI Bookshelf or PubMed during this
  review. The entry should therefore be read as a guideline-anchored curation,
  augmented by primary human deletion mapping, clinical cohorts, two
  patient-derived cellular studies, and a mouse background-comparison study,
  rather than as an exhaustive primary-literature synthesis. The two direct GEO
  datasets (GSE271780 and GSE239758) were discovered with the repository tool and
  verified against NCBI metadata on 2026-08-16. Ovarian tissue
  cryopreservation specifically is still not curated as a treatment — the source
  available here for it is an opinion paper proposing the approach rather than
  reporting outcomes — but controlled ovarian stimulation with oocyte
  cryopreservation is, because the guideline recommends it outright.

📚

References & Deep Research

References

9

PMID:38748847

Clinical practice guidelines for the care of girls and women with Turner syndrome.

No top-level findings curated for this source.

PMID:31213699

Turner syndrome: mechanisms and management.

No top-level findings curated for this source.

PMID:10931762

The Turner syndrome-associated neurocognitive phenotype maps to distal Xp.

No top-level findings curated for this source.

PMID:27194967

SHOX Haploinsufficiency as a Cause of Syndromic and Nonsyndromic Short Stature.

No top-level findings curated for this source.

PMID:6463900

Neck web and congenital heart defects: a pathogenic association in 45 X-O Turner syndrome?

No top-level findings curated for this source.

PMID:23032325

Moderate aortic enlargement and bicuspid aortic valve are associated with aortic dissection in Turner syndrome: report of the international turner syndrome aortic dissection registry.

No top-level findings curated for this source.

PMID:39543104

Identification of apelin/APJ signaling dysregulation in a human iPSC-derived granulosa cell model of Turner syndrome.

No top-level findings curated for this source.

PMID:18499648

Genotype, phenotype, and karyotype correlation in the XO mouse model of Turner Syndrome.

No top-level findings curated for this source.

PMID:32634219

Premature ovarian insufficiency in the XO female mouse on the C57BL/6J genetic background.

No top-level findings curated for this source.

Turner Syndrome

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References