45,X/46,XY Mixed Gonadal Dysgenesis

Chromosomal MONDO:0015779 Pathograph 13 Show in embeddings browser Disorder of sex development Sex chromosome disorder

45,X/46,XY mixed gonadal dysgenesis is a difference of sex development caused not by a gene defect but by a mosaic: post-zygotic loss of the Y chromosome leaves two cell lineages, 45,X and 46,XY, distributed unevenly across the body. Because the gonadal ridge is patterned locally, the two sides can receive different proportions of the SRY-bearing lineage and take different developmental paths - classically a fibrous streak gonad on one side and a dysgenetic testis on the other. Everything downstream follows from that asymmetry: the dysgenetic testis makes some anti-Mullerian hormone and some testosterone but not enough, so Mullerian structures persist on the streak side and virilization is incomplete. Separately, the 45,X lineage carries the same SHOX haploinsufficiency as Turner syndrome, so short stature and Turner stigmata run alongside the genital phenotype. Retained Y material in a dysgenetic gonad carries a substantial gonadoblastoma risk.

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1
Inheritance
9
Pathophys.
16
Phenotypes
4
Gaps
13
Pathograph
5
Medical Actions
2
Differentials
2
References
1
Deep Research
👪

Inheritance

1
Sporadic post-zygotic mosaicism
Not inherited. The mosaicism arises from a mitotic error after fertilization, parental karyotypes are normal, and recurrence risk is not raised above the population baseline. This is the counselling distinction from the monogenic 46,XY gonadal dysgenesis entities, which can segregate in families.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"The condition emerges from early embryonic errors in chromosomal arrangements resulting in a mixture of 45,X/46,XY cell lines"
States the post-zygotic origin that makes the condition sporadic.
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Discussions and Knowledge Gaps

4
Does the mouse SRY-SOX9-FGF9 versus WNT4 threshold model describe what happens in a human mosaic gonadal ridge?
HUMAN MODEL MISMATCH mgd_sry_threshold_model_is_murine
Attached to
pathophysiology#Regional SRY Dosage Variation Across the Gonadal Ridge
This is a mismatch rather than a plain gap, because the evidence exists and it is the translation that is open. The switch has been characterised in detail by gain- and loss-of-function experiments in mouse: SRY initiates a SOX9-FGF9 feed-forward loop that represses WNT4, and the authors describe SRY's role as tipping a balance rather than acting as an on-off command. That balance-tipping framing is exactly what makes a mosaic ridge interesting, since a partial SRY dose could plausibly leave the balance untipped in some regions. But every one of those experiments was done in a genetically uniform mouse gonad. Two things do not carry across without checking. First, no mouse model of 45,X/46,XY mosaicism has been made, so the threshold behaviour under partial SRY dosage has never been tested in the configuration this disease presents. Second, human and mouse sex determination differ in timing and in the relative contribution of SRY-independent inputs, so a threshold measured in mouse need not be the human threshold. The consequence for this entry is concrete: the mechanism it curates is the best available account and is not a demonstrated one, which is why the node carries PROVISIONAL.
Show evidence (2 references)
PMID:16700629 SUPPORT Model Organism
"We show through gain- and loss-of-function experiments that fibroblast growth factor 9 (FGF9) and WNT4 act as opposing signals to regulate sex determination."
Establishes that the mechanism exists and was demonstrated experimentally - which is what distinguishes a model mismatch from an absence of evidence.
PMID:16700629 SUPPORT Model Organism
"In principle, sex determination in other vertebrates may operate through any switch that introduces an imbalance between these two signaling pathways."
The authors generalise their own result only in principle, which is the right level of confidence to carry into a human mosaic and is weaker than the entry would need to call the node established.
Does growth hormone actually increase final height in 45,X/46,XY mixed gonadal dysgenesis?
KNOWLEDGE GAP mgd_gh_efficacy_contested
Attached to
treatments#Growth Hormone Therapy pathophysiology#Turner-Spectrum Somatic Features
Two sources in this entry disagree, and the disagreement is not a matter of emphasis. The 2025 review states that growth hormone significantly improves growth velocity and final adult height, with outcomes similar to Turner syndrome. A three-centre cohort of 100 patients found no significant height difference between treated and untreated groups, p = 0.5. Both are in the entry because neither can be dismissed: the review aggregates studies designed to measure the effect, while the cohort is the largest single series with long-term follow-up and is not randomised, so treated patients may have been the shorter ones to begin with. The question matters because growth hormone is started at age four to six and carries a theoretical concern about stimulating tumour growth in retained gonadal tissue.
Show evidence (2 references)
PMID:37882230 SUPPORT Human Clinical
"Growth hormone (GH) treatment did not result in a significant height increase compared to the untreated group (p = 0.5)."
The negative cohort result, stated with its p value.
PMID:41208147 SUPPORT Human Clinical
"an improvement in height SDS by 0.42 has been shown among treated patients"
The positive effect size the review reports, which is what the cohort failed to reproduce.
Does gonadal position predict tumour risk well enough to decide which gonads to remove?
KNOWLEDGE GAP mgd_gonad_position_and_tumour_risk
Attached to
pathophysiology#Gonadoblastoma Risk in Retained Dysgenetic Gonads treatments#Gonadectomy of Retained Dysgenetic Gonads
The management model in wide use assumes intra-abdominal gonads are the dangerous ones and scrotal testes can be retained with surveillance. One fourteen-child series supports it strongly: every gonadoblastoma was in an intra-abdominal gonad. Another series of twenty-one children does not - of four dysgenetic testes with carcinoma in situ, one was intra-abdominal, one inguinal and two scrotal. The 2025 review separately notes that Y-chromosomal material raises germ cell tumour risk even in apparently normal scrotal testes. If position is not protective, then retaining a scrotal testis buys fertility potential and hormone production at a real and currently unquantified oncological cost, and surveillance rather than position has to carry the safety.
Show evidence (3 references)
PMID:27052295 SUPPORT Human Clinical
"The exclusive presence of GB in intra-abdominal gonads is in keeping with the findings of several other series."
The position-dependent view, stated by a series that found it exclusively.
PMID:27032613 SUPPORT Human Clinical
"the 4 dysgenetic testes affected by CIS in 3 patients were intraabdominal (n=1), inguinal (n=1) and scrotal (n=2) in positions."
The counter-evidence: half of the affected testes in this series were scrotal.
PMID:41208147 SUPPORT Human Clinical
"increases the risk of germ cell tumours even in apparently normal testes located in the scrotal sac"
The review's own caution that scrotal position is not reassuring.
What is the actual mosaic ratio inside a human MGD gonad, and does it explain which side became a streak?
KNOWLEDGE GAP mgd_no_gonadal_molecular_profile
Attached to
pathophysiology#Regional SRY Dosage Variation Across the Gonadal Ridge
The mechanism this entry curates says that regional variation in the SRY-bearing lineage across the gonadal ridge decides each side's fate. That is a testable claim and it has not been tested. No human MGD gonad has been profiled at single-cell resolution, so nobody has measured whether the streak side actually carries fewer 46,XY cells than the testicular side. The supporting mechanism - the SOX9-FGF9 loop repressing WNT4 - comes entirely from mouse gonads that are not mosaic. Human MGD gonadal tissue has been examined immunohistochemically for GBY proteins, so the tissue is obtainable; what has not been done is to genotype the two lineages within a single gonad and relate their distribution to which regions became streak. The finding that six patients had a single gonad containing both streak and testicular tissue is the strongest available human evidence for the regional model, and it is anatomical rather than molecular. Until the measurement is made, the mosaic-ratio explanation should be read as the best available account rather than a demonstrated one, which is why the two nodes that depend on it are marked PROVISIONAL.
Show evidence (1 reference)
PMID:31883875 SUPPORT Human Clinical
"A gonad composed of both streak and dysgenetic testicular portions was observed in 7 gonads of 6 patients."
The anatomical observation that the regional model explains and a whole-gonad model does not, and currently the best human evidence for it.
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Pathophysiology

9
Post-Zygotic Loss of the Y Chromosome
Mitotic non-disjunction or anaphase lag during early cleavage - often involving a structurally unstable Y such as an isodicentric or ring Y - produces two coexisting lineages, 45,X and 46,XY. The lineages are distributed stochastically, so their ratio differs from tissue to tissue. That variation, not any allele, is the source of the phenotypic range: the same karyotype label covers people who present with atypical genitalia and people who are never suspected of having anything.
Downstream
Regional SRY Dosage Variation Across the Gonadal Ridge
SHOX Haploinsufficiency in the 45,X Lineage The 45,X lineage is one SHOX copy short wherever it lands, independently of what happens in the gonad.
Show evidence (1 reference)
PMID:41208147 SUPPORT DIRECT Human Clinical
"The phenotype of patients with MGD is variable and determined by the extent and degree of mosaicism across different tissues, including the gonads and genital structures"
States that tissue-level mosaic ratio, not genotype, sets the phenotype.
Regional SRY Dosage Variation Across the Gonadal Ridge
Testis determination is a local switch, not a whole-body one. SRY in pre-Sertoli cells activates SOX9, which enters a feed-forward loop with FGF9 that both sustains the testis program and represses the pro-ovarian WNT4 pathway. Where the SRY-bearing lineage is well represented the switch throws; where it is not, the balance stays on the WNT4 side, and under monosomy X that pathway cannot sustain a gonad either. This node is PROVISIONAL because the FGF9-WNT4 antagonism is established in mouse and its application to a human mosaic gonadal ridge is an inference - no human MGD gonad has been profiled for these signals.
Pre-Sertoli cell CL:0000216 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves Pre-Sertoli cell, annotated with Sertoli cell (CL:0000216). CL:0000216 is a cell type from the Cell Ontology.
male sex determination GO:0030238 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal male sex determination (GO:0030238). GO:0030238 is a biological process from the Gene Ontology. ⚠ ABNORMAL Sertoli cell differentiation GO:0060008 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased Sertoli cell differentiation (GO:0060008). GO:0060008 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Asymmetric Gonadal Differentiation
Show evidence (2 references)
PMID:16700629 SUPPORT INDIRECT Model Organism
"In the mouse XY gonad, Sry normally initiates a feed-forward loop between Sox9 and Fgf9, which up-regulates Fgf9 and represses Wnt4 to establish the testis pathway."
Supplies the switch mechanism this node depends on. Graded INDIRECT because it is mouse work on a non-mosaic gonad; its relevance here is that a balance-tipping switch is exactly what a mosaic ridge would perturb regionally.
PMID:16700629 SUPPORT INDIRECT Model Organism
"The role of the male sex-determining switch--Sry in the case of mammals--is to tip the balance between these underlying patterning signals."
The framing that makes regional SRY dosage a plausible determinant: if SRY only tips a balance, a partial dose can leave the balance untipped locally.
Asymmetric Gonadal Differentiation
The defining lesion. One gonad follows a testicular path, usually dysgenetically, while the other fails to organize and becomes fibrous streak tissue. This is not the only outcome - a single-centre histological series found the classic streak-plus-testis combination in 59% of patients, bilateral streaks in 26% and bilateral dysgenetic testes in 15%, and six patients had a gonad containing both streak and testicular tissue within it. That last finding is the strongest anatomical evidence that the determinant is regional rather than per-gonad.
gonad UBERON:0000991 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in gonad (UBERON:0000991). UBERON:0000991 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Reduced Sertoli and Leydig Cell Output
Gonadoblastoma Risk in Retained Dysgenetic Gonads
Show evidence (3 references)
PMID:31883875 SUPPORT DIRECT Human Clinical
"Of 34 patients with 45,X/46,XY mosaicism, a unilateral dysgenetic testis and a contralateral streak gonad was detected in 20 patients (59%), bilateral streak gonads in 9 (26%), and bilateral dysgenetic testes in 5 (15%)."
Gives the histological distribution, including how often the classic asymmetric pattern is actually found.
PMID:31883875 SUPPORT DIRECT Human Clinical
"A gonad composed of both streak and dysgenetic testicular portions was observed in 7 gonads of 6 patients."
Mixed tissue within a single gonad, which is what a regionally patterned mosaic ridge predicts and a whole-gonad model does not.
PMID:41208147 SUPPORT DIRECT Human Clinical
"typically characterised by the presence of a dysgenetic testis at various levels of descent on one side and a streak gonad on the other"
The canonical description of the asymmetric anatomy.
Reduced Sertoli and Leydig Cell Output
A dysgenetic testis has less of both secretory cell populations than a normal one, so it makes anti-Mullerian hormone and testosterone but not enough of either at the times they are needed. The deficit is partial and quantitative, which is precisely why the phenotype is intermediate rather than either fully male or fully female. It also worsens with time: FSH rises and testosterone falls through puberty, and testicular insufficiency reaches 60 to 70 percent of those raised as males by the third decade.
Sertoli cell CL:0000216 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves Sertoli cell (CL:0000216). CL:0000216 is a cell type from the Cell Ontology. Leydig cell CL:0000178 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves Leydig cell (CL:0000178). CL:0000178 is a cell type from the Cell Ontology.
Downstream
Incomplete Mullerian Regression
Undervirilization of the External Genitalia
Show evidence (3 references)
PMID:41208147 SUPPORT DIRECT Human Clinical
"Endogenous sex steroid hormone production in patients with MGD is typically limited to the synthesis of testosterone by the dysgenetic testis."
Identifies the dysgenetic testis as the sole steroid source, which is why its reduced capacity is limiting.
PMID:29973376 SUPPORT DIRECT Human Clinical
"puberty occurred spontaneously in 93% of patients but 71% (n = 5) of those evaluated at the end of puberty presented signs of declined Sertoli cell function (low inhibin B levels and increased FSH levels)."
Measures the Sertoli deficit directly by inhibin B and FSH, and shows it emerging even in boys whose genitalia were normal or near-normal.
PMID:41208147 SUPPORT DIRECT Human Clinical
"Testicular insufficiency develops in 60%–70% of individuals raised as males by the third decade, and infertility is the most commonly reported outcome."
Supplies the third-decade figure the description states, which the end-of-puberty inhibin B result above does not cover.
Incomplete Mullerian Regression
Anti-Mullerian hormone acts locally rather than systemically, so the side without a functioning testis keeps its Mullerian derivatives while the side with one loses them. That is why the retained hemi-uterus and fallopian tube remnant are ipsilateral to the streak gonad - an asymmetry a systemic hormone deficit could not produce, and the clearest evidence that the hormonal lesion is regional in the same way the gonadal lesion is.
Mullerian duct regression GO:0001880 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased Mullerian duct regression (GO:0001880). GO:0001880 is a biological process from the Gene Ontology. ↓ DECREASED
Mullerian duct UBERON:0003890 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in Mullerian duct (UBERON:0003890). UBERON:0003890 is an anatomical location from the Uberon multi-species anatomy ontology.
Show evidence (1 reference)
PMID:41208147 SUPPORT DIRECT Human Clinical
"Many individuals have Müllerian remnants on the same side as the streak gonad, whereas the most common phenotypic finding is proximal hypospadias with perineal division of the corpus spongiosum and ventral curvature"
Reports the ipsilateral relationship between the streak gonad and the retained Mullerian structures, which is the observation establishing local rather than systemic AMH action.
Undervirilization of the External Genitalia
A separate consequence with a different mediator. How far the external genitalia virilize is set by how much testosterone the dysgenetic testis produced during the fetal window, which is why the external phenotype is graded across the whole range from typical female to typical male rather than tracking the internal asymmetry. Proximal hypospadias with perineal division of the corpus spongiosum and ventral curvature is the commonest finding.
male genitalia development GO:0030539 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal male genitalia development (GO:0030539). GO:0030539 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Show evidence (2 references)
PMID:41208147 SUPPORT DIRECT Human Clinical
"The clinical spectrum of MGD to an extent is influenced by the functional capacity of the dysgenetic gonad along with the degree of androgen exposure during critical periods of foetal development"
Ties the degree of virilization to androgen exposure during the fetal window.
PMID:41208147 SUPPORT DIRECT Human Clinical
"undescended or partially descended gonads with varying degrees of labioscrotal fusion giving the appearance of a bifid sc"
Describes the graded external findings, including the labioscrotal fusion that reflects partial androgen action.
Gonadoblastoma Risk in Retained Dysgenetic Gonads
Germ cells sitting in dysgenetic gonadal tissue that still carries Y material are at substantial risk of arrest and neoplastic transformation, through gonadoblastoma and on to dysgerminoma. The overall risk is quoted at 15 to 25 percent. The Y-linked contribution is attributed to the gonadoblastoma locus GBY, whose leading candidate gene TSPY is expressed in the germ cells of MGD patients themselves; ectopic TSPY accelerates the G2/M transition through cyclin B-CDK1. Expression is not sufficient on its own - the same proteins are found in germ cells of patients without malignancy - so the dysgenetic environment is doing part of the work. Where the risk sits anatomically is contested: several series report it concentrated in intra-abdominal gonads, but one found carcinoma in situ in two scrotal testes, and the disagreement is what drives the management debate rather than a settled rule.
Germ cell CL:0000586 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves Germ cell (CL:0000586). CL:0000586 is a cell type from the Cell Ontology.
Show evidence (6 references)
PMID:30753444 SUPPORT DIRECT Human Clinical
"The GBY candidate genes DDX3Y and TSPY are expressed in the germ cells of DSD-XY patients from distinct etiologies: patients with mixed gonadal dysgenesis (MGD) and sex chromosome mosaics (45,X0/46,XY; 46,XX/46,XY)"
Immunohistochemistry on gonadal tissue from MGD patients specifically, so this is the Y-linked oncogenic candidate measured in the right disease rather than inferred from other DSD groups.
PMID:30753444 SUPPORT DIRECT Human Clinical
"This suggest that GBY candidate proteins are also expressed in the non-malignant germ cells of DSD-XY individuals like in male spermatogonia."
The necessary caveat: GBY expression is not by itself transformation, which is why the node treats the dysgenetic environment as a co-requirement rather than treating retained Y material as sufficient.
PMID:19306348 SUPPORT INDIRECT In Vitro
"TSPY binds to type B cyclins, enhances an activated cyclin B-CDK1 kinase activity, and propels a rapid G(2)/M transition in the cell cycle."
Supplies the cell-cycle mechanism by which ectopic TSPY would drive proliferation. Graded INDIRECT because the biochemistry was not done in MGD tissue.
+ 3 more references
SHOX Haploinsufficiency in the 45,X Lineage
SHOX lies in the pseudoautosomal region and escapes X inactivation, so it needs two copies. Cells of the 45,X lineage have one. This is the same lesion that produces short stature in Turner syndrome, and it runs entirely parallel to the gonadal arm - it depends on where the 45,X cells landed, not on what the gonad did.
SHOX hgnc:10853 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves decreased SHOX (hgnc:10853). hgnc:10853 is a gene from the HUGO Gene Nomenclature Committee. ↓ DECREASED
Downstream
Turner-Spectrum Somatic Features
Show evidence (1 reference)
PMID:41208147 SUPPORT DIRECT Human Clinical
"Short stature is a common clinical feature in individuals with MGD and is typically attributed to the 45,X cell line, and associated haploinsufficiency of the SHOX gene"
Attributes the short stature to SHOX dosage in the 45,X lineage, which is what this node asserts.
Turner-Spectrum Somatic Features
Short stature with a height Z-score that falls progressively through childhood, plus the wider Turner phenotype - cardiac and renal malformations, webbed neck, cubitus valgus - in a majority of patients. Marked PROVISIONAL for everything except the stature: SHOX explains the height, but the cardiac, renal and lymphatic features are attributed to the 45,X lineage by analogy with Turner syndrome rather than by any measurement of mosaic ratio in the affected tissue.
Show evidence (2 references)
PMID:37882230 SUPPORT DIRECT Human Clinical
"Females were significantly shorter than males (p = 0.04) and height Z-score was significantly decreased with age for both genders (p = 0.02)."
Quantifies the progressive height deficit in a 100-patient cohort.
PMID:29973376 SUPPORT DIRECT Human Clinical
"Seventy percent of patients presented Turner-like syndrome features including cardiac (6/23 patients investigated) and renal malformations (3/19 patients investigated)."
Gives the frequency of Turner-like somatic features with per-organ denominators.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for 45,X/46,XY Mixed Gonadal Dysgenesis Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

16
Cardiovascular 1
Congenital Heart Defect Abnormal heart morphology HP:0001627 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal heart morphology (HP:0001627). HP:0001627 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:29973376 SUPPORT Human Clinical
"Turner-like syndrome features including cardiac (6/23 patients investigated) and renal malformations (3/19 patients investigated)"
6 of 23 investigated, 26%. No frequency band is given here because the denominator counts only patients who underwent cardiac investigation.
Endocrine 1
Absent Spontaneous Puberty in Female-Raised Patients Delayed puberty HP:0000823 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Delayed puberty (HP:0000823). HP:0000823 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:37882230 SUPPORT Human Clinical
"All females required puberty induction in contrast to majority of males."
States the categorical split. No frequency band on the whole disease, because the figure applies to the female-raised subgroup only.
Genitourinary 2
Undescended Gonad Cryptorchidism HP:0000028 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cryptorchidism (HP:0000028). HP:0000028 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:41208147 SUPPORT Human Clinical
"undescended or partially descended gonads with varying degrees of labioscrotal fusion"
Reports incomplete gonadal descent as part of the genital phenotype.
PMID:41208147 SUPPORT Human Clinical
"the presence of a dysgenetic testis at various levels of descent on one side"
States that the dysgenetic testis is found at variable levels of descent.
Infertility HP:0000789 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Infertility (HP:0000789). HP:0000789 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"infertility is the most commonly reported outcome"
Names infertility as the commonest outcome. No frequency band: "most commonly reported outcome" ranks it against other outcomes rather than giving a proportion of patients.
Head and Neck 1
Webbed Neck HP:0000465 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Webbed neck (HP:0000465). HP:0000465 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"The other features include webbed neck, shield chest, cubitus valgus"
Lists webbed neck among the Turner-spectrum somatic features.
Limbs 1
Cubitus Valgus HP:0002967 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cubitus valgus (HP:0002967). HP:0002967 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"webbed neck, shield chest, cubitus valgus, high‐arched palate"
Lists cubitus valgus among the Turner-spectrum somatic features.
Growth 1
Short Stature FREQUENT HP:0004322 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Short stature (HP:0004322). HP:0004322 is a phenotype from the Human Phenotype Ontology.
Show evidence (3 references)
PMID:29973376 SUPPORT Human Clinical
"Most patients had stunted growth, with abnormal growth spurt during puberty and a mean adult height of 158 ± 7.6 cm, i.e. -2.3 DS with correction for target height."
Gives the adult height and its standard-deviation deficit against target height.
PMID:37882230 SUPPORT Human Clinical
"height Z-score was significantly decreased with age for both genders (p = 0.02)"
Confirms the progressive nature of the height deficit in an independent cohort.
PMID:41208147 SUPPORT Human Clinical
"Short stature is common in individuals regardless of their phenotypic sex."
States that short stature is common and independent of phenotypic sex.
Other 9
Atypical Genitalia Ambiguous genitalia HP:0000062 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ambiguous genitalia (HP:0000062). HP:0000062 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"The phenotypic presentation of MGD varies from atypical genitalia to typical male or female appearances often associated with Turner stigmata."
Describes the full external phenotypic range. No frequency band: the cohort denominators available count patients ascertained in different ways, and the mildest presentations are by definition under-ascertained.
Proximal Hypospadias Perineal hypospadias HP:0000051 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Perineal hypospadias (HP:0000051). HP:0000051 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"the most common phenotypic finding is proximal hypospadias with perineal division of the corpus spongiosum and ventral curvature"
Names it as the commonest external genital finding.
Streak Gonad VERY_FREQUENT HP:0025733 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Streak gonad (HP:0025733). HP:0025733 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:31883875 SUPPORT Human Clinical
"a unilateral dysgenetic testis and a contralateral streak gonad was detected in 20 patients (59%), bilateral streak gonads in 9 (26%)"
At least one streak gonad in 29 of 34 patients, 85%, supporting a VERY_FREQUENT band in a surgically characterised series.
Dysgenetic Testis Dysplastic testis HP:0008733 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dysplastic testis (HP:0008733). HP:0008733 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"the presence of a dysgenetic testis at various levels of descent on one side and a streak gonad on the other"
Describes the dysgenetic testis and its variable position.
Persistent Mullerian Structures Presence of uterus in 46,XY individual HP:0034546 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Presence of uterus in 46,XY individual (HP:0034546). HP:0034546 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"Many individuals have Müllerian remnants on the same side as the streak gonad"
Reports the finding and its characteristic laterality.
Gonadoblastoma OCCASIONAL HP:0000150 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Gonadoblastoma (HP:0000150). HP:0000150 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:31883875 SUPPORT Human Clinical
"Pathologic examination revealed gonadal tumors in 6 of the 34 (18%) patients"
Gives the tumour count with its surgical denominator, which is where the band comes from.
Dysgerminoma HP:0100621 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dysgerminoma (HP:0100621). HP:0100621 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:31883875 SUPPORT Human Clinical
"an association of dysgerminoma with gonadoblastoma in 1 gonad"
Documents the progression in a single gonad. One event in a 34-patient series is too few for a frequency band.
Declining Testicular Function FREQUENT Elevated circulating follicle stimulating hormone level HP:0008232 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Elevated circulating follicle stimulating hormone level (HP:0008232), qualified as course progressive. HP:0008232 is a phenotype from the Human Phenotype Ontology.
Course: PROGRESSIVE
Show evidence (1 reference)
PMID:29973376 SUPPORT Human Clinical
"71% (n = 5) of those evaluated at the end of puberty presented signs of declined Sertoli cell function (low inhibin B levels and increased FSH levels)"
71% of those actually evaluated falls in the FREQUENT band, though the absolute number evaluated was small.
Renal Malformation Abnormal renal morphology HP:0012210 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal renal morphology (HP:0012210). HP:0012210 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:29973376 SUPPORT Human Clinical
"renal malformations (3/19 patients investigated)"
3 of 19 investigated. As with the cardiac record, the denominator is patients investigated, so no band is asserted.
💊

Medical Actions

5
Gonadectomy of Retained Dysgenetic Gonads
Action: surgical procedureNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is surgical procedure (NCIT:C15329). NCIT:C15329 is a clinical intervention from the NCI Thesaurus. Ontology label: Surgical Procedure NCIT:C15329
Removal of streak gonads and, where indicated, dysgenetic testes, to remove the tissue at risk of gonadoblastoma. Practice has moved away from routine early gonadectomy toward shared decision-making, because the operation also removes any endogenous hormone production and any fertility potential.
Mechanism Target:
Gonadoblastoma Risk in Retained Dysgenetic Gonads — Removes the substrate. It does not modify the mechanism; it eliminates the tissue in which the mechanism operates.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"Historically, assignment of female sex of rearing following early prophylactic gonadectomy to reduce the risk of gonadoblastoma was common practice"
States the intent of the operation and, by describing it as historical practice, the shift away from doing it routinely.
Hypospadias Repair
Action: surgical procedureNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is surgical procedure (NCIT:C15329). NCIT:C15329 is a clinical intervention from the NCI Thesaurus. Ontology label: Surgical Procedure NCIT:C15329
Staged surgical repair of the proximal hypospadias, which is the commonest external finding in the disease and the commonest operation these patients undergo after gonadectomy.
Mechanism Target:
Undervirilization of the External Genitalia — Addresses the anatomical consequence of fetal androgen insufficiency. It does not act on the hormonal deficit itself.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"hypospadias repair usually in a staged approach"
Names the operation and its staged approach among the management options.
Growth Hormone Therapy
Action: pharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. Ontology label: Pharmacotherapy NCIT:C15986
Recombinant human growth hormone for the SHOX-related short stature, given on the Turner syndrome model. Whether it works in MGD is genuinely unsettled - see the discussion on this entry.
Mechanism Target:
Turner-Spectrum Somatic Features — Aimed at the height deficit only; it does nothing for the cardiac, renal or gonadal components.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"Recombinant human growth hormone (rhGH) therapy has been found to significantly improve growth velocity and final adult height in individuals with MGD, with outcomes similar to those observed in Turner syndrome"
The review's positive assessment, which one cohort study directly contradicts.
Sex Steroid Replacement
Action: pharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. Ontology label: Pharmacotherapy NCIT:C15986
Puberty induction and maintenance. Required by essentially all female-raised patients, and by male-raised patients as testicular function declines.
Mechanism Target:
Reduced Sertoli and Leydig Cell Output — Replaces the hormone output the dysgenetic gonad cannot sustain.
Show evidence (1 reference)
PMID:37882230 SUPPORT Human Clinical
"All females required puberty induction in contrast to majority of males."
Establishes the near-universal need for induction in female-raised patients.
Multidisciplinary Shared Decision-Making
Action: supportive careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is supportive care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Coordinated endocrinology, urology, gynaecology and psychology input, with irreversible surgery deferred until a team plan has been made with the family. This is a substantive intervention rather than a courtesy: roughly one in eight patients later reports gender incongruence, so decisions made in infancy can be wrong in a way that surgery cannot undo.
Show evidence (2 references)
PMID:41208147 SUPPORT Human Clinical
"Approximately 12%-15% of patients with MGD may experience gender incongruence later in life."
Quantifies the outcome that makes deferring irreversible decisions a clinical rather than merely ethical position.
PMID:41208147 SUPPORT Human Clinical
"Management has shifted from early surgical intervention to a multidisciplinary, patient-centred, and shared decision making approach."
Documents the shift in practice this record describes.
🔬

Biochemical Markers

2
Inhibin B
Show evidence (2 references)
PMID:29973376 SUPPORT Human Clinical
"signs of declined Sertoli cell function (low inhibin B levels and increased FSH levels)"
Establishes the low-inhibin-B, high-FSH pattern as the marker of Sertoli decline.
PMID:41208147 SUPPORT Human Clinical
"inhibin B concentrations during early puberty may serve as a reliable predictor of testicular function and the need for testosterone replacement in the future"
Reports the prognostic use of early-pubertal inhibin B.
Follicle-stimulating hormone
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"pubertal progression frequently stalls in most individuals suggested by rising FSH concentrations and declining testosterone concentrations"
Reports rising FSH with falling testosterone as the marker of stalling puberty.
🔬

Diagnosis

4
Karyotype with adequate cell count
Peripheral blood karyotype is the diagnostic test, but the mosaic ratio in blood does not predict the ratio in gonad or in any other tissue, and a low-level line can be missed. Prenatal detection is possible but explicitly does not predict the postnatal phenotype.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"Prenatal diagnostic tests such as noninvasive prenatal testing (NIPT) and amniocentesis can detect 45,X/46,XY mosaicism in foetal cells, but these findings do not reliably predict the postnatal phenotype of the infant"
States both the detectability and the crucial limit on what detection tells you.
FISH or chromosomal microarray on a second tissue
A blood karyotype may not reflect the gonad, and a low-level second line can be missed entirely. FISH on buccal cells, skin fibroblasts or gonadal tissue samples a different lineage, and chromosomal microarray raises sensitivity for low-level mosaicism. This is the concrete answer to the "adequate cell count" problem the karyotype record raises.
Show evidence (2 references)
PMID:41208147 SUPPORT Human Clinical
"Targeted karyotype or Fluorescent in situ hybridisation (FISH) analysis of buccal epithelia cells obtained via swab, skin fibroblasts or gonadal tissue"
Names the second-tissue techniques used when blood karyotype may not represent the gonad.
PMID:41208147 SUPPORT Human Clinical
"Chromosomal microarray (comparative genomic hybridisation [CGH] array or SNP array) provides higher sensitivity for detecting low"
Reports microarray as the higher-sensitivity option for low-level mosaicism.
Imaging of internal genital structures
Pelvic ultrasound is first-line for locating gonads and Mullerian structures, but it is not sufficient to exclude them: in complex DSD it failed to visualise Mullerian remnants in about 40% of cases where laparoscopy found them in all. A negative ultrasound therefore does not settle the question.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"ultrasound failed to visualise Müllerian duct remnants in approximately 40% of cases, whereas laparoscopy achieved optimal visualization in all patients"
Quantifies the sensitivity gap that makes a negative ultrasound uninformative here.
Gonadal biopsy and histology
Histology is what distinguishes a streak gonad from a dysgenetic testis and identifies gonadoblastoma or carcinoma in situ; imaging and hormone profiles do not.
Show evidence (1 reference)
PMID:31883875 SUPPORT Human Clinical
"The medical records of consecutive patients with 45,X/46,XY karyotype or its variants who had undergone gonadal biopsy or gonadectomy at a single institute between 1996 and 2017 were retrospectively reviewed."
Establishes biopsy and gonadectomy specimens as the basis for the histological classification used here.
📈

Progression

3
Childhood growth decline
Height Z-score falls progressively through childhood rather than being fixed at birth, which is why growth is monitored rather than assessed once.
Show evidence (1 reference)
PMID:37882230 SUPPORT Human Clinical
"height Z-score was significantly decreased with age for both genders (p = 0.02)"
Documents the progressive height deficit.
Pubertal and post-pubertal gonadal decline
Most male-raised patients enter puberty spontaneously, but progression stalls with rising FSH and falling testosterone, and testicular insufficiency reaches 60 to 70 percent by the third decade. Normal early puberty is therefore not reassurance.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"Testicular insufficiency develops in 60%–70% of individuals raised as males by the third decade"
Gives the endpoint and its timing.
Adult cardiometabolic morbidity
A population-based study found males with a 45,X/46,XY karyotype developing a morbidity pattern resembling classic Turner syndrome by around age 40. This is the argument for lifelong follow-up rather than discharge once the paediatric endocrine and surgical questions are settled, and it applies to patients whose genital phenotype was mild enough that they were never seen in a DSD clinic.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"with higher rates of hypertension, dyslipidaemia, and type 2 diabetes by age 40"
Reports the adult cardiometabolic pattern and its approximate timing.
📊

Prevalence

2
Live births
Birth Prevalence 4.4 per 100,000 (3.3–6.7) 1–9 per 100,000
Reported as 1 in 15,000 to 1 in 30,000 live births, which is 3.3 to 6.7 per 100,000. The point value is not a published figure and is not the arithmetic midpoint of the rates, which would be 5.0; it is the midpoint taken in 1-in-N space, 1 in 22,500, converted to a rate. Both conventions are defensible and they disagree, so the derivation is stated rather than left for a reader to reconstruct. The review says the true figure is probably higher, because people whose phenotype is unremarkably male or female are never karyotyped - so this is an ascertainment floor rather than an estimate.
Show evidence (2 references)
PMID:41208147 SUPPORT Human Clinical
"MGD is rare, with an estimated incidence of 1 in 15,000 to 1 in 30,000 live births"
Source of the incidence range converted to the normalized rate.
PMID:41208147 SUPPORT Human Clinical
"The prevalence of MGD may be underestimated due to its wide range of phenotypic presentations."
Supports treating the figure as a floor rather than a population estimate.
Infants evaluated for atypical genitalia
Period Prevalence >1 in 1,000
A referral-population share, not a population rate. It says how often MGD is the answer once a newborn has been referred for atypical genitalia, which is the clinically useful number and is not comparable with the birth incidence above.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"Among infants evaluated for atypical genitalia, MGD accounts for approximately 5%-15% of cases"
Gives the share of the referral population, which is what this record reports.
🔀

Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from 45,X/46,XY Mixed Gonadal Dysgenesis:

46,XY partial gonadal dysgenesis MONDO:0016674
Overlapping Features Overlapping gonadal and genital findings, but a pure 46,XY karyotype and usually a monogenic cause.
Distinguishing Features
  • No 45,X cell line, so no SHOX haploinsufficiency and no Turner stigmata.
  • Often monogenic, with a corresponding recurrence risk; MGD is sporadic.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"The most common karyotype reported is 45,X/46,XY mosaicism."
Establishes the karyotype that defines this entity, which is what separates it from the non-mosaic 46,XY dysgeneses.
Turner syndrome MONDO:0019499
Overlapping Features Shares the 45,X lineage and therefore the short stature and somatic stigmata, but has no Y-bearing line.
Distinguishing Features
  • No Y material, so no dysgenetic testis, no virilization, and no gonadoblastoma risk from the GBY region.
  • Streak gonads are bilateral rather than asymmetric.
Show evidence (1 reference)
PMID:41208147 SUPPORT Human Clinical
"The phenotypic presentation of MGD varies from atypical genitalia to typical male or female appearances often associated with Turner stigmata."
Records the shared Turner stigmata that make the two overlap clinically.
{ }

Source YAML

click to show 
name: 45,X/46,XY Mixed Gonadal Dysgenesis
category: Chromosomal
creation_date: "2026-08-29T19:15:00Z"
synonyms:
- mixed gonadal dysgenesis
- 45,X/46,XY mosaicism
- 45,X/46,XY gonadal dysgenesis
- X0/XY mosaicism
- asymmetric gonadal dysgenesis
description: >-
  45,X/46,XY mixed gonadal dysgenesis is a difference of sex development caused
  not by a gene defect but by a mosaic: post-zygotic loss of the Y chromosome
  leaves two cell lineages, 45,X and 46,XY, distributed unevenly across the body.
  Because the gonadal ridge is patterned locally, the two sides can receive
  different proportions of the SRY-bearing lineage and take different
  developmental paths - classically a fibrous streak gonad on one side and a
  dysgenetic testis on the other. Everything downstream follows from that
  asymmetry: the dysgenetic testis makes some anti-Mullerian hormone and some
  testosterone but not enough, so Mullerian structures persist on the streak side
  and virilization is incomplete. Separately, the 45,X lineage carries the same
  SHOX haploinsufficiency as Turner syndrome, so short stature and Turner
  stigmata run alongside the genital phenotype. Retained Y material in a
  dysgenetic gonad carries a substantial gonadoblastoma risk.
disease_term:
  preferred_term: 45,X/46,XY mixed gonadal dysgenesis
  term:
    id: MONDO:0015779
    label: 45,X/46,XY mixed gonadal dysgenesis
parents:
- Disorder of sex development
- Sex chromosome disorder
inheritance:
- name: Sporadic post-zygotic mosaicism
  description: >-
    Not inherited. The mosaicism arises from a mitotic error after fertilization,
    parental karyotypes are normal, and recurrence risk is not raised above the
    population baseline. This is the counselling distinction from the monogenic
    46,XY gonadal dysgenesis entities, which can segregate in families.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The condition emerges from early embryonic errors in chromosomal arrangements resulting in a mixture of 45,X/46,XY cell lines"
    explanation: States the post-zygotic origin that makes the condition sporadic.
prevalence:
- population: Live births
  measure_type: BIRTH_PREVALENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 4.4
  rate_low: 3.3
  rate_high: 6.7
  notes: >-
    Reported as 1 in 15,000 to 1 in 30,000 live births, which is 3.3 to 6.7 per
    100,000. The point value is not a published figure and is not the arithmetic
    midpoint of the rates, which would be 5.0; it is the midpoint taken in
    1-in-N space, 1 in 22,500, converted to a rate. Both conventions are
    defensible and they disagree, so the derivation is stated rather than left
    for a reader to reconstruct. The review says the true figure is probably higher, because
    people whose phenotype is unremarkably male or female are never karyotyped -
    so this is an ascertainment floor rather than an estimate.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "MGD is rare, with an estimated incidence of 1 in 15,000 to 1 in 30,000 live births"
    explanation: Source of the incidence range converted to the normalized rate.
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The prevalence of MGD may be underestimated due to its wide range of phenotypic presentations."
    explanation: Supports treating the figure as a floor rather than a population estimate.
- population: Infants evaluated for atypical genitalia
  measure_type: PERIOD_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  notes: >-
    A referral-population share, not a population rate. It says how often MGD is
    the answer once a newborn has been referred for atypical genitalia, which is
    the clinically useful number and is not comparable with the birth incidence
    above.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among infants evaluated for atypical genitalia, MGD accounts for approximately 5%-15% of cases"
    explanation: Gives the share of the referral population, which is what this record reports.
progression:
- phase: Childhood growth decline
  notes: >-
    Height Z-score falls progressively through childhood rather than being fixed
    at birth, which is why growth is monitored rather than assessed once.
  evidence:
  - reference: PMID:37882230
    reference_title: "45,X/46,XY mosaicism: Clinical manifestations and long term follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "height Z-score was significantly decreased with age for both genders (p = 0.02)"
    explanation: Documents the progressive height deficit.
- phase: Pubertal and post-pubertal gonadal decline
  notes: >-
    Most male-raised patients enter puberty spontaneously, but progression stalls
    with rising FSH and falling testosterone, and testicular insufficiency reaches
    60 to 70 percent by the third decade. Normal early puberty is therefore not
    reassurance.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Testicular insufficiency develops in 60%–70% of individuals raised as males by the third decade"
    explanation: Gives the endpoint and its timing.
- phase: Adult cardiometabolic morbidity
  notes: >-
    A population-based study found males with a 45,X/46,XY karyotype developing a
    morbidity pattern resembling classic Turner syndrome by around age 40. This is
    the argument for lifelong follow-up rather than discharge once the paediatric
    endocrine and surgical questions are settled, and it applies to patients whose
    genital phenotype was mild enough that they were never seen in a DSD clinic.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "with higher rates of hypertension, dyslipidaemia, and type 2 diabetes by age 40"
    explanation: Reports the adult cardiometabolic pattern and its approximate timing.
pathophysiology:
- name: Post-Zygotic Loss of the Y Chromosome
  biological_scale: MOLECULAR
  role: trigger
  mechanism_confidence: ESTABLISHED
  description: >-
    Mitotic non-disjunction or anaphase lag during early cleavage - often
    involving a structurally unstable Y such as an isodicentric or ring Y -
    produces two coexisting lineages, 45,X and 46,XY. The lineages are
    distributed stochastically, so their ratio differs from tissue to tissue.
    That variation, not any allele, is the source of the phenotypic range: the
    same karyotype label covers people who present with atypical genitalia and
    people who are never suspected of having anything.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "The phenotype of patients with MGD is variable and determined by the extent and degree of mosaicism across different tissues, including the gonads and genital structures"
    explanation: States that tissue-level mosaic ratio, not genotype, sets the phenotype.
  downstream:
  - target: Regional SRY Dosage Variation Across the Gonadal Ridge
    causal_link_type: DIRECT
  - target: SHOX Haploinsufficiency in the 45,X Lineage
    causal_link_type: DIRECT
    description: >-
      The 45,X lineage is one SHOX copy short wherever it lands, independently of
      what happens in the gonad.

- name: Regional SRY Dosage Variation Across the Gonadal Ridge
  biological_scale: CELLULAR
  role: central_effector
  mechanism_confidence: PROVISIONAL
  description: >-
    Testis determination is a local switch, not a whole-body one. SRY in
    pre-Sertoli cells activates SOX9, which enters a feed-forward loop with FGF9
    that both sustains the testis program and represses the pro-ovarian WNT4
    pathway. Where the SRY-bearing lineage is well represented the switch throws;
    where it is not, the balance stays on the WNT4 side, and under monosomy X
    that pathway cannot sustain a gonad either. This node is PROVISIONAL because
    the FGF9-WNT4 antagonism is established in mouse and its application to a
    human mosaic gonadal ridge is an inference - no human MGD gonad has been
    profiled for these signals.
  cell_types:
  - preferred_term: Pre-Sertoli cell
    term:
      id: CL:0000216
      label: Sertoli cell
  biological_processes:
  - preferred_term: male sex determination
    term:
      id: GO:0030238
      label: male sex determination
    modifier: ABNORMAL
  - preferred_term: Sertoli cell differentiation
    term:
      id: GO:0060008
      label: Sertoli cell differentiation
    modifier: DECREASED
  evidence:
  - reference: PMID:16700629
    reference_title: "Fgf9 and Wnt4 act as antagonistic signals to regulate mammalian sex determination."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    directness: INDIRECT
    snippet: "In the mouse XY gonad, Sry normally initiates a feed-forward loop between Sox9 and Fgf9, which up-regulates Fgf9 and represses Wnt4 to establish the testis pathway."
    explanation: >-
      Supplies the switch mechanism this node depends on. Graded INDIRECT because
      it is mouse work on a non-mosaic gonad; its relevance here is that a
      balance-tipping switch is exactly what a mosaic ridge would perturb
      regionally.
  - reference: PMID:16700629
    reference_title: "Fgf9 and Wnt4 act as antagonistic signals to regulate mammalian sex determination."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    directness: INDIRECT
    snippet: "The role of the male sex-determining switch--Sry in the case of mammals--is to tip the balance between these underlying patterning signals."
    explanation: >-
      The framing that makes regional SRY dosage a plausible determinant: if SRY
      only tips a balance, a partial dose can leave the balance untipped locally.
  downstream:
  - target: Asymmetric Gonadal Differentiation
    causal_link_type: DIRECT

- name: Asymmetric Gonadal Differentiation
  biological_scale: TISSUE
  role: central_effector
  mechanism_confidence: ESTABLISHED
  description: >-
    The defining lesion. One gonad follows a testicular path, usually
    dysgenetically, while the other fails to organize and becomes fibrous streak
    tissue. This is not the only outcome - a single-centre histological series
    found the classic streak-plus-testis combination in 59% of patients, bilateral
    streaks in 26% and bilateral dysgenetic testes in 15%, and six patients had a
    gonad containing both streak and testicular tissue within it. That last
    finding is the strongest anatomical evidence that the determinant is regional
    rather than per-gonad.
  locations:
  - preferred_term: gonad
    term:
      id: UBERON:0000991
      label: gonad
  evidence:
  - reference: PMID:31883875
    reference_title: "Variation of Gonadal Dysgenesis and Tumor Risk in Patients With 45,X/46,XY Mosaicism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "Of 34 patients with 45,X/46,XY mosaicism, a unilateral dysgenetic testis and a contralateral streak gonad was detected in 20 patients (59%), bilateral streak gonads in 9 (26%), and bilateral dysgenetic testes in 5 (15%)."
    explanation: Gives the histological distribution, including how often the classic asymmetric pattern is actually found.
  - reference: PMID:31883875
    reference_title: "Variation of Gonadal Dysgenesis and Tumor Risk in Patients With 45,X/46,XY Mosaicism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "A gonad composed of both streak and dysgenetic testicular portions was observed in 7 gonads of 6 patients."
    explanation: >-
      Mixed tissue within a single gonad, which is what a regionally patterned
      mosaic ridge predicts and a whole-gonad model does not.
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "typically characterised by the presence of a dysgenetic testis at various levels of descent on one side and a streak gonad on the other"
    explanation: The canonical description of the asymmetric anatomy.
  downstream:
  - target: Reduced Sertoli and Leydig Cell Output
    causal_link_type: DIRECT
  - target: Gonadoblastoma Risk in Retained Dysgenetic Gonads
    causal_link_type: DIRECT

- name: Reduced Sertoli and Leydig Cell Output
  biological_scale: ORGANISM
  role: central_effector
  mechanism_confidence: ESTABLISHED
  description: >-
    A dysgenetic testis has less of both secretory cell populations than a normal
    one, so it makes anti-Mullerian hormone and testosterone but not enough of
    either at the times they are needed. The deficit is partial and quantitative,
    which is precisely why the phenotype is intermediate rather than either fully
    male or fully female. It also worsens with time: FSH rises and testosterone
    falls through puberty, and testicular insufficiency reaches 60 to 70 percent
    of those raised as males by the third decade.
  cell_types:
  - preferred_term: Sertoli cell
    term:
      id: CL:0000216
      label: Sertoli cell
  - preferred_term: Leydig cell
    term:
      id: CL:0000178
      label: Leydig cell
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "Endogenous sex steroid hormone production in patients with MGD is typically limited to the synthesis of testosterone by the dysgenetic testis."
    explanation: Identifies the dysgenetic testis as the sole steroid source, which is why its reduced capacity is limiting.
  - reference: PMID:29973376
    reference_title: "Should 45,X/46,XY boys with no or mild anomaly of external genitalia be investigated and followed up?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "puberty occurred spontaneously in 93% of patients but 71% (n = 5) of those evaluated at the end of puberty presented signs of declined Sertoli cell function (low inhibin B levels and increased FSH levels)."
    explanation: >-
      Measures the Sertoli deficit directly by inhibin B and FSH, and shows it
      emerging even in boys whose genitalia were normal or near-normal.
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "Testicular insufficiency develops in 60%–70% of individuals raised as males by the third decade, and infertility is the most commonly reported outcome."
    explanation: >-
      Supplies the third-decade figure the description states, which the
      end-of-puberty inhibin B result above does not cover.
  downstream:
  - target: Incomplete Mullerian Regression
    causal_link_type: DIRECT
  - target: Undervirilization of the External Genitalia
    causal_link_type: DIRECT

- name: Incomplete Mullerian Regression
  biological_scale: ORGANISM
  role: consequence
  mechanism_confidence: ESTABLISHED
  description: >-
    Anti-Mullerian hormone acts locally rather than systemically, so the side
    without a functioning testis keeps its Mullerian derivatives while the side
    with one loses them. That is why the retained hemi-uterus and fallopian tube
    remnant are ipsilateral to the streak gonad - an asymmetry a systemic
    hormone deficit could not produce, and the clearest evidence that the
    hormonal lesion is regional in the same way the gonadal lesion is.
  locations:
  - preferred_term: Mullerian duct
    term:
      id: UBERON:0003890
      label: Mullerian duct
  biological_processes:
  - preferred_term: Mullerian duct regression
    term:
      id: GO:0001880
      label: Mullerian duct regression
    modifier: DECREASED
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "Many individuals have Müllerian remnants on the same side as the streak gonad, whereas the most common phenotypic finding is proximal hypospadias with perineal division of the corpus spongiosum and ventral curvature"
    explanation: >-
      Reports the ipsilateral relationship between the streak gonad and the
      retained Mullerian structures, which is the observation establishing local
      rather than systemic AMH action.

- name: Undervirilization of the External Genitalia
  biological_scale: ORGANISM
  role: consequence
  mechanism_confidence: ESTABLISHED
  description: >-
    A separate consequence with a different mediator. How far the external
    genitalia virilize is set by how much testosterone the dysgenetic testis
    produced during the fetal window, which is why the external phenotype is
    graded across the whole range from typical female to typical male rather than
    tracking the internal asymmetry. Proximal hypospadias with perineal division
    of the corpus spongiosum and ventral curvature is the commonest finding.
  biological_processes:
  - preferred_term: male genitalia development
    term:
      id: GO:0030539
      label: male genitalia development
    modifier: ABNORMAL
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "The clinical spectrum of MGD to an extent is influenced by the functional capacity of the dysgenetic gonad along with the degree of androgen exposure during critical periods of foetal development"
    explanation: Ties the degree of virilization to androgen exposure during the fetal window.
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "undescended or partially descended gonads with varying degrees of labioscrotal fusion giving the appearance of a bifid sc"
    explanation: >-
      Describes the graded external findings, including the labioscrotal fusion
      that reflects partial androgen action.
- name: Gonadoblastoma Risk in Retained Dysgenetic Gonads
  biological_scale: TISSUE
  role: consequence
  mechanism_confidence: ESTABLISHED
  description: >-
    Germ cells sitting in dysgenetic gonadal tissue that still carries Y material
    are at substantial risk of arrest and neoplastic transformation, through
    gonadoblastoma and on to dysgerminoma. The overall risk is quoted at 15 to 25
    percent. The Y-linked contribution is attributed to the gonadoblastoma locus
    GBY, whose leading candidate gene TSPY is expressed in the germ cells of MGD
    patients themselves; ectopic TSPY accelerates the G2/M transition through
    cyclin B-CDK1. Expression is not sufficient on its own - the same proteins are
    found in germ cells of patients without malignancy - so the dysgenetic
    environment is doing part of the work. Where the risk sits anatomically is
    contested: several series report it concentrated in intra-abdominal gonads,
    but one found carcinoma in situ in two scrotal testes, and the disagreement is
    what drives the management debate rather than a settled rule.
  cell_types:
  - preferred_term: Germ cell
    term:
      id: CL:0000586
      label: germ cell
  evidence:
  - reference: PMID:30753444
    reference_title: "Gonadoblastoma Y locus genes expressed in germ cells of individuals with dysgenetic gonads and a Y chromosome in their karyotypes include DDX3Y and TSPY."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "The GBY candidate genes DDX3Y and TSPY are expressed in the germ cells of DSD-XY patients from distinct etiologies: patients with mixed gonadal dysgenesis (MGD) and sex chromosome mosaics (45,X0/46,XY; 46,XX/46,XY)"
    explanation: >-
      Immunohistochemistry on gonadal tissue from MGD patients specifically, so
      this is the Y-linked oncogenic candidate measured in the right disease
      rather than inferred from other DSD groups.
  - reference: PMID:30753444
    reference_title: "Gonadoblastoma Y locus genes expressed in germ cells of individuals with dysgenetic gonads and a Y chromosome in their karyotypes include DDX3Y and TSPY."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "This suggest that GBY candidate proteins are also expressed in the non-malignant germ cells of DSD-XY individuals like in male spermatogonia."
    explanation: >-
      The necessary caveat: GBY expression is not by itself transformation, which
      is why the node treats the dysgenetic environment as a co-requirement rather
      than treating retained Y material as sufficient.
  - reference: PMID:19306348
    reference_title: "Gonadoblastoma locus and the TSPY gene on the human Y chromosome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    directness: INDIRECT
    snippet: "TSPY binds to type B cyclins, enhances an activated cyclin B-CDK1 kinase activity, and propels a rapid G(2)/M transition in the cell cycle."
    explanation: >-
      Supplies the cell-cycle mechanism by which ectopic TSPY would drive
      proliferation. Graded INDIRECT because the biochemistry was not done in MGD
      tissue.
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "MGD accounts for 5%-15% of cases of atypical genitalia and carries a 15%-25% risk of gonadal tumour, with the highest malignancy rates in intra-abdominal gonads."
    explanation: The headline risk figure and its stated dependence on gonadal position.
  - reference: PMID:31883875
    reference_title: "Variation of Gonadal Dysgenesis and Tumor Risk in Patients With 45,X/46,XY Mosaicism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "Pathologic examination revealed gonadal tumors in 6 of the 34 (18%) patients, including a gonadoblastoma in 7 gonads among 5 patients and an association of dysgerminoma with gonadoblastoma in 1 gonad."
    explanation: A histological denominator for the tumour risk, and shows the gonadoblastoma-to-dysgerminoma progression in one gonad.
  - reference: PMID:27032613
    reference_title: "Tumor risk of children with 45,X/46,XY gonadal dysgenesis in relation to their clinical presentations: Further insights into the gonadal management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "Among Group I patients, the 4 dysgenetic testes affected by CIS in 3 patients were intraabdominal (n=1), inguinal (n=1) and scrotal (n=2) in positions."
    explanation: >-
      The counter-observation: half the affected dysgenetic testes in this series
      were scrotal, which is why the entry does not state position as protective.

- name: SHOX Haploinsufficiency in the 45,X Lineage
  biological_scale: MOLECULAR
  role: central_effector
  mechanism_confidence: ESTABLISHED
  description: >-
    SHOX lies in the pseudoautosomal region and escapes X inactivation, so it
    needs two copies. Cells of the 45,X lineage have one. This is the same lesion
    that produces short stature in Turner syndrome, and it runs entirely parallel
    to the gonadal arm - it depends on where the 45,X cells landed, not on what
    the gonad did.
  gene:
    preferred_term: SHOX
    description: >-
      Short stature homeobox gene, present in one copy in cells of the 45,X
      lineage.
    modifier: DECREASED
    term:
      id: hgnc:10853
      label: SHOX
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "Short stature is a common clinical feature in individuals with MGD and is typically attributed to the 45,X cell line, and associated haploinsufficiency of the SHOX gene"
    explanation: Attributes the short stature to SHOX dosage in the 45,X lineage, which is what this node asserts.
  downstream:
  - target: Turner-Spectrum Somatic Features
    causal_link_type: DIRECT

- name: Turner-Spectrum Somatic Features
  biological_scale: ORGANISM
  role: outcome
  mechanism_confidence: PROVISIONAL
  description: >-
    Short stature with a height Z-score that falls progressively through
    childhood, plus the wider Turner phenotype - cardiac and renal malformations,
    webbed neck, cubitus valgus - in a majority of patients. Marked PROVISIONAL
    for everything except the stature: SHOX explains the height, but the cardiac,
    renal and lymphatic features are attributed to the 45,X lineage by analogy
    with Turner syndrome rather than by any measurement of mosaic ratio in the
    affected tissue.
  evidence:
  - reference: PMID:37882230
    reference_title: "45,X/46,XY mosaicism: Clinical manifestations and long term follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "Females were significantly shorter than males (p = 0.04) and height Z-score was significantly decreased with age for both genders (p = 0.02)."
    explanation: Quantifies the progressive height deficit in a 100-patient cohort.
  - reference: PMID:29973376
    reference_title: "Should 45,X/46,XY boys with no or mild anomaly of external genitalia be investigated and followed up?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: DIRECT
    snippet: "Seventy percent of patients presented Turner-like syndrome features including cardiac (6/23 patients investigated) and renal malformations (3/19 patients investigated)."
    explanation: Gives the frequency of Turner-like somatic features with per-organ denominators.
phenotypes:
- category: Genitourinary
  name: Atypical Genitalia
  description: >-
    External genital appearance spanning the range from typical female through
    ambiguous to typical male, set by how much androgen the dysgenetic testis
    produced during the fetal window.
  phenotype_term:
    preferred_term: Ambiguous genitalia
    term:
      id: HP:0000062
      label: Ambiguous genitalia
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The phenotypic presentation of MGD varies from atypical genitalia to typical male or female appearances often associated with Turner stigmata."
    explanation: >-
      Describes the full external phenotypic range. No frequency band: the cohort
      denominators available count patients ascertained in different ways, and
      the mildest presentations are by definition under-ascertained.
- category: Genitourinary
  name: Proximal Hypospadias
  description: >-
    The most common external finding, with perineal division of the corpus
    spongiosum and ventral curvature.
  phenotype_term:
    preferred_term: Perineal hypospadias
    term:
      id: HP:0000051
      label: Perineal hypospadias
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the most common phenotypic finding is proximal hypospadias with perineal division of the corpus spongiosum and ventral curvature"
    explanation: Names it as the commonest external genital finding.
- category: Genitourinary
  name: Streak Gonad
  description: >-
    Undifferentiated fibrous gonadal tissue, classically contralateral to the
    dysgenetic testis.
  phenotype_term:
    preferred_term: Streak gonad
    term:
      id: HP:0025733
      label: Streak gonad
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:31883875
    reference_title: "Variation of Gonadal Dysgenesis and Tumor Risk in Patients With 45,X/46,XY Mosaicism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a unilateral dysgenetic testis and a contralateral streak gonad was detected in 20 patients (59%), bilateral streak gonads in 9 (26%)"
    explanation: >-
      At least one streak gonad in 29 of 34 patients, 85%, supporting a
      VERY_FREQUENT band in a surgically characterised series.
  review_notes: >-
    The band is derived by summing the unilateral-streak and bilateral-streak
    rows of the histology series, 20 plus 9 of 34. It applies to patients who came
    to gonadal biopsy or gonadectomy, which is a more severely affected group than
    all 45,X/46,XY individuals.
- category: Genitourinary
  name: Dysgenetic Testis
  description: >-
    A testis with reduced Sertoli and Leydig cell content and disorganised
    seminiferous tubules, at any level of descent from intra-abdominal to
    scrotal.
  phenotype_term:
    preferred_term: Dysplastic testis
    term:
      id: HP:0008733
      label: Dysplastic testis
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the presence of a dysgenetic testis at various levels of descent on one side and a streak gonad on the other"
    explanation: Describes the dysgenetic testis and its variable position.
- category: Genitourinary
  name: Persistent Mullerian Structures
  description: >-
    A retained hemi-uterus and fallopian tube remnant, characteristically on the
    same side as the streak gonad. This is the finding that separates MGD from
    46,XY partial gonadal dysgenesis at laparotomy, and it is why the diagnostic
    workup has to visualise the internal structures rather than infer them.
  phenotype_term:
    preferred_term: Presence of uterus in 46,XY individual
    term:
      id: HP:0034546
      label: Presence of uterus in 46,XY individual
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Many individuals have Müllerian remnants on the same side as the streak gonad"
    explanation: Reports the finding and its characteristic laterality.
  review_notes: >-
    Bound to HP:0034546, which names a 46,XY individual, while these patients are
    45,X/46,XY mosaics. The term is used because HPO has no mosaic-karyotype
    equivalent, the Y-bearing line is what makes uterine persistence remarkable,
    and the sibling entry 46_XY_Partial_Gonadal_Dysgenesis already binds it. No
    frequency band: the source says "many individuals" without a denominator, and
    imaging systematically undercounts - ultrasound misses roughly 40% of
    Mullerian remnants that laparoscopy finds, so any published frequency depends
    on which modality was used.
- category: Genitourinary
  name: Undescended Gonad
  description: >-
    Gonads at any level from intra-abdominal through inguinal to scrotal, often
    incompletely descended. Position is not a cosmetic detail here: it is the
    variable the prophylactic-gonadectomy decision has historically turned on,
    which is why this entry curates a discussion about whether it actually
    predicts tumour risk.
  phenotype_term:
    preferred_term: Cryptorchidism
    term:
      id: HP:0000028
      label: Cryptorchidism
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "undescended or partially descended gonads with varying degrees of labioscrotal fusion"
    explanation: Reports incomplete gonadal descent as part of the genital phenotype.
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the presence of a dysgenetic testis at various levels of descent on one side"
    explanation: States that the dysgenetic testis is found at variable levels of descent.
- category: Reproductive
  name: Infertility
  description: >-
    The commonest long-term outcome in those raised as males, following from
    progressive testicular insufficiency; Y-chromosome rearrangements, especially
    Yq loss, are an additional contributor.
  phenotype_term:
    preferred_term: Infertility
    term:
      id: HP:0000789
      label: Infertility
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "infertility is the most commonly reported outcome"
    explanation: >-
      Names infertility as the commonest outcome. No frequency band: "most
      commonly reported outcome" ranks it against other outcomes rather than
      giving a proportion of patients.
- category: Musculoskeletal
  name: Webbed Neck
  description: >-
    A Turner stigma, present regardless of phenotypic sex.
  phenotype_term:
    preferred_term: Webbed neck
    term:
      id: HP:0000465
      label: Webbed neck
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The other features include webbed neck, shield chest, cubitus valgus"
    explanation: Lists webbed neck among the Turner-spectrum somatic features.
- category: Musculoskeletal
  name: Cubitus Valgus
  description: >-
    Increased carrying angle at the elbow, another Turner stigma.
  phenotype_term:
    preferred_term: Cubitus valgus
    term:
      id: HP:0002967
      label: Cubitus valgus
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "webbed neck, shield chest, cubitus valgus, high‐arched palate"
    explanation: Lists cubitus valgus among the Turner-spectrum somatic features.
- category: Growth
  name: Short Stature
  description: >-
    Height Z-score falls progressively through childhood, mirroring the Turner
    syndrome growth trajectory. In a French series of boys with normal or
    near-normal genitalia, mean adult height was 158 cm.
  phenotype_term:
    preferred_term: Short stature
    term:
      id: HP:0004322
      label: Short stature
  frequency: FREQUENT
  evidence:
  - reference: PMID:29973376
    reference_title: "Should 45,X/46,XY boys with no or mild anomaly of external genitalia be investigated and followed up?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Most patients had stunted growth, with abnormal growth spurt during puberty and a mean adult height of 158 ± 7.6 cm, i.e. -2.3 DS with correction for target height."
    explanation: Gives the adult height and its standard-deviation deficit against target height.
  - reference: PMID:37882230
    reference_title: "45,X/46,XY mosaicism: Clinical manifestations and long term follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "height Z-score was significantly decreased with age for both genders (p = 0.02)"
    explanation: Confirms the progressive nature of the height deficit in an independent cohort.
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Short stature is common in individuals regardless of their phenotypic sex."
    explanation: States that short stature is common and independent of phenotypic sex.
  review_notes: >-
    Banded FREQUENT rather than VERY_FREQUENT deliberately. The sources say
    "common" and "most patients had stunted growth" without a proportion, and the
    one quantitative statement available is a mean height deficit rather than a
    count of affected individuals. FREQUENT is the widest band those statements
    support; VERY_FREQUENT would require a figure above 80% that nothing here
    provides.
- category: Oncologic
  name: Gonadoblastoma
  description: >-
    A germ-cell neoplasm of dysgenetic gonadal tissue, which can progress to
    dysgerminoma. Reported in infants as young as five months.
  phenotype_term:
    preferred_term: Gonadoblastoma
    term:
      id: HP:0000150
      label: Gonadoblastoma
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:31883875
    reference_title: "Variation of Gonadal Dysgenesis and Tumor Risk in Patients With 45,X/46,XY Mosaicism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pathologic examination revealed gonadal tumors in 6 of the 34 (18%) patients"
    explanation: Gives the tumour count with its surgical denominator, which is where the band comes from.
  review_notes: >-
    Band derived from 6 of 34 gonadectomy or biopsy specimens, 18%, which sits in
    the 5-29% OCCASIONAL range. This denominator is patients who came to surgery,
    not all 45,X/46,XY individuals, so it is an upper bound on the population
    risk.
- category: Oncologic
  name: Dysgerminoma
  description: >-
    Malignant germ cell tumour arising from gonadoblastoma; the outcome
    prophylactic gonadectomy is meant to prevent.
  phenotype_term:
    preferred_term: Dysgerminoma
    term:
      id: HP:0100621
      label: Dysgerminoma
  evidence:
  - reference: PMID:31883875
    reference_title: "Variation of Gonadal Dysgenesis and Tumor Risk in Patients With 45,X/46,XY Mosaicism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "an association of dysgerminoma with gonadoblastoma in 1 gonad"
    explanation: >-
      Documents the progression in a single gonad. One event in a 34-patient
      series is too few for a frequency band.
- category: Endocrine
  name: Declining Testicular Function
  description: >-
    Rising FSH and low inhibin B through and after puberty, progressing to
    testicular insufficiency in most men by the third decade. It is progressive,
    which is why the entry treats normal early puberty as an unreliable
    reassurance.
  phenotype_term:
    preferred_term: Elevated circulating follicle stimulating hormone level
    term:
      id: HP:0008232
      label: Elevated circulating follicle stimulating hormone level
    clinical_course: PROGRESSIVE
  frequency: FREQUENT
  evidence:
  - reference: PMID:29973376
    reference_title: "Should 45,X/46,XY boys with no or mild anomaly of external genitalia be investigated and followed up?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "71% (n = 5) of those evaluated at the end of puberty presented signs of declined Sertoli cell function (low inhibin B levels and increased FSH levels)"
    explanation: >-
      71% of those actually evaluated falls in the FREQUENT band, though the
      absolute number evaluated was small.
- category: Endocrine
  name: Absent Spontaneous Puberty in Female-Raised Patients
  description: >-
    Every female-raised patient in a 100-person cohort needed puberty induction,
    in contrast to most of the male-raised patients, who entered puberty
    spontaneously. The split tracks whether a functioning dysgenetic testis was
    present and retained.
  phenotype_term:
    preferred_term: Delayed puberty
    term:
      id: HP:0000823
      label: Delayed puberty
  evidence:
  - reference: PMID:37882230
    reference_title: "45,X/46,XY mosaicism: Clinical manifestations and long term follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All females required puberty induction in contrast to majority of males."
    explanation: >-
      States the categorical split. No frequency band on the whole disease,
      because the figure applies to the female-raised subgroup only.
- category: Cardiovascular
  name: Congenital Heart Defect
  description: >-
    Cardiac malformations of the Turner spectrum, chiefly bicuspid aortic valve
    and coarctation.
  phenotype_term:
    preferred_term: Abnormal heart morphology
    term:
      id: HP:0001627
      label: Abnormal heart morphology
  evidence:
  - reference: PMID:29973376
    reference_title: "Should 45,X/46,XY boys with no or mild anomaly of external genitalia be investigated and followed up?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Turner-like syndrome features including cardiac (6/23 patients investigated) and renal malformations (3/19 patients investigated)"
    explanation: >-
      6 of 23 investigated, 26%. No frequency band is given here because the
      denominator counts only patients who underwent cardiac investigation.
- category: Renal
  name: Renal Malformation
  description: >-
    Structural renal anomalies of the Turner spectrum.
  phenotype_term:
    preferred_term: Abnormal renal morphology
    term:
      id: HP:0012210
      label: Abnormal renal morphology
  evidence:
  - reference: PMID:29973376
    reference_title: "Should 45,X/46,XY boys with no or mild anomaly of external genitalia be investigated and followed up?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "renal malformations (3/19 patients investigated)"
    explanation: >-
      3 of 19 investigated. As with the cardiac record, the denominator is
      patients investigated, so no band is asserted.
biochemical:
- name: Inhibin B
  notes: >-
    A Sertoli cell product. Low inhibin B with raised FSH is the biochemical
    signature of the Sertoli deficit, and inhibin B measured in early puberty is
    reported to predict later testicular function and the need for testosterone
    replacement - which makes it the one lab value here with prognostic rather
    than merely descriptive use.
  evidence:
  - reference: PMID:29973376
    reference_title: "Should 45,X/46,XY boys with no or mild anomaly of external genitalia be investigated and followed up?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "signs of declined Sertoli cell function (low inhibin B levels and increased FSH levels)"
    explanation: Establishes the low-inhibin-B, high-FSH pattern as the marker of Sertoli decline.
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "inhibin B concentrations during early puberty may serve as a reliable predictor of testicular function and the need for testosterone replacement in the future"
    explanation: Reports the prognostic use of early-pubertal inhibin B.
- name: Follicle-stimulating hormone
  notes: >-
    Rises as Sertoli function declines, and is the routinely available half of the
    inhibin B / FSH pair.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "pubertal progression frequently stalls in most individuals suggested by rising FSH concentrations and declining testosterone concentrations"
    explanation: Reports rising FSH with falling testosterone as the marker of stalling puberty.
diagnosis:
- name: Karyotype with adequate cell count
  description: >-
    Peripheral blood karyotype is the diagnostic test, but the mosaic ratio in
    blood does not predict the ratio in gonad or in any other tissue, and a
    low-level line can be missed. Prenatal detection is possible but explicitly
    does not predict the postnatal phenotype.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Prenatal diagnostic tests such as noninvasive prenatal testing (NIPT) and amniocentesis can detect 45,X/46,XY mosaicism in foetal cells, but these findings do not reliably predict the postnatal phenotype of the infant"
    explanation: States both the detectability and the crucial limit on what detection tells you.
- name: FISH or chromosomal microarray on a second tissue
  description: >-
    A blood karyotype may not reflect the gonad, and a low-level second line can
    be missed entirely. FISH on buccal cells, skin fibroblasts or gonadal tissue
    samples a different lineage, and chromosomal microarray raises sensitivity for
    low-level mosaicism. This is the concrete answer to the "adequate cell count"
    problem the karyotype record raises.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Targeted karyotype or Fluorescent in situ hybridisation (FISH) analysis of buccal epithelia cells obtained via swab, skin fibroblasts or gonadal tissue"
    explanation: Names the second-tissue techniques used when blood karyotype may not represent the gonad.
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Chromosomal microarray (comparative genomic hybridisation [CGH] array or SNP array) provides higher sensitivity for detecting low"
    explanation: Reports microarray as the higher-sensitivity option for low-level mosaicism.
- name: Imaging of internal genital structures
  description: >-
    Pelvic ultrasound is first-line for locating gonads and Mullerian structures,
    but it is not sufficient to exclude them: in complex DSD it failed to visualise
    Mullerian remnants in about 40% of cases where laparoscopy found them in all.
    A negative ultrasound therefore does not settle the question.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ultrasound failed to visualise Müllerian duct remnants in approximately 40% of cases, whereas laparoscopy achieved optimal visualization in all patients"
    explanation: Quantifies the sensitivity gap that makes a negative ultrasound uninformative here.
- name: Gonadal biopsy and histology
  description: >-
    Histology is what distinguishes a streak gonad from a dysgenetic testis and
    identifies gonadoblastoma or carcinoma in situ; imaging and hormone profiles
    do not.
  evidence:
  - reference: PMID:31883875
    reference_title: "Variation of Gonadal Dysgenesis and Tumor Risk in Patients With 45,X/46,XY Mosaicism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The medical records of consecutive patients with 45,X/46,XY karyotype or its variants who had undergone gonadal biopsy or gonadectomy at a single institute between 1996 and 2017 were retrospectively reviewed."
    explanation: Establishes biopsy and gonadectomy specimens as the basis for the histological classification used here.
differential_diagnoses:
- name: 46,XY partial gonadal dysgenesis
  disease_term:
    preferred_term: 46,XY partial gonadal dysgenesis
    term:
      id: MONDO:0016674
      label: 46,XY partial gonadal dysgenesis
  description: >-
    Overlapping gonadal and genital findings, but a pure 46,XY karyotype and
    usually a monogenic cause.
  distinguishing_features:
  - No 45,X cell line, so no SHOX haploinsufficiency and no Turner stigmata.
  - Often monogenic, with a corresponding recurrence risk; MGD is sporadic.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most common karyotype reported is 45,X/46,XY mosaicism."
    explanation: >-
      Establishes the karyotype that defines this entity, which is what separates
      it from the non-mosaic 46,XY dysgeneses.
- name: Turner syndrome
  disease_term:
    preferred_term: Turner syndrome
    term:
      id: MONDO:0019499
      label: Turner syndrome
  description: >-
    Shares the 45,X lineage and therefore the short stature and somatic stigmata,
    but has no Y-bearing line.
  distinguishing_features:
  - No Y material, so no dysgenetic testis, no virilization, and no gonadoblastoma risk from the GBY region.
  - Streak gonads are bilateral rather than asymmetric.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The phenotypic presentation of MGD varies from atypical genitalia to typical male or female appearances often associated with Turner stigmata."
    explanation: Records the shared Turner stigmata that make the two overlap clinically.
treatments:
- name: Gonadectomy of Retained Dysgenetic Gonads
  description: >-
    Removal of streak gonads and, where indicated, dysgenetic testes, to remove
    the tissue at risk of gonadoblastoma. Practice has moved away from routine
    early gonadectomy toward shared decision-making, because the operation also
    removes any endogenous hormone production and any fertility potential.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: surgical procedure
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  target_mechanisms:
  - target: Gonadoblastoma Risk in Retained Dysgenetic Gonads
    description: >-
      Removes the substrate. It does not modify the mechanism; it eliminates the
      tissue in which the mechanism operates.
    evidence:
    - reference: PMID:41208147
      reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Historically, assignment of female sex of rearing following early prophylactic gonadectomy to reduce the risk of gonadoblastoma was common practice"
      explanation: States the intent of the operation and, by describing it as historical practice, the shift away from doing it routinely.
- name: Hypospadias Repair
  description: >-
    Staged surgical repair of the proximal hypospadias, which is the commonest
    external finding in the disease and the commonest operation these patients
    undergo after gonadectomy.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: surgical procedure
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  target_mechanisms:
  - target: Undervirilization of the External Genitalia
    description: >-
      Addresses the anatomical consequence of fetal androgen insufficiency. It
      does not act on the hormonal deficit itself.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "hypospadias repair usually in a staged approach"
    explanation: Names the operation and its staged approach among the management options.
- name: Growth Hormone Therapy
  description: >-
    Recombinant human growth hormone for the SHOX-related short stature, given on
    the Turner syndrome model. Whether it works in MGD is genuinely unsettled -
    see the discussion on this entry.
  therapeutic_modality: PROTEIN_REPLACEMENT
  treatment_term:
    preferred_term: pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: Turner-Spectrum Somatic Features
    description: >-
      Aimed at the height deficit only; it does nothing for the cardiac, renal or
      gonadal components.
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Recombinant human growth hormone (rhGH) therapy has been found to significantly improve growth velocity and final adult height in individuals with MGD, with outcomes similar to those observed in Turner syndrome"
    explanation: The review's positive assessment, which one cohort study directly contradicts.
- name: Sex Steroid Replacement
  description: >-
    Puberty induction and maintenance. Required by essentially all female-raised
    patients, and by male-raised patients as testicular function declines.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: Reduced Sertoli and Leydig Cell Output
    description: >-
      Replaces the hormone output the dysgenetic gonad cannot sustain.
  evidence:
  - reference: PMID:37882230
    reference_title: "45,X/46,XY mosaicism: Clinical manifestations and long term follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All females required puberty induction in contrast to majority of males."
    explanation: Establishes the near-universal need for induction in female-raised patients.
- name: Multidisciplinary Shared Decision-Making
  description: >-
    Coordinated endocrinology, urology, gynaecology and psychology input, with
    irreversible surgery deferred until a team plan has been made with the family.
    This is a substantive intervention rather than a courtesy: roughly one in
    eight patients later reports gender incongruence, so decisions made in infancy
    can be wrong in a way that surgery cannot undo.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Approximately 12%-15% of patients with MGD may experience gender incongruence later in life."
    explanation: Quantifies the outcome that makes deferring irreversible decisions a clinical rather than merely ethical position.
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Management has shifted from early surgical intervention to a multidisciplinary, patient-centred, and shared decision making approach."
    explanation: Documents the shift in practice this record describes.
discussions:
- discussion_id: mgd_sry_threshold_model_is_murine
  kind: HUMAN_MODEL_MISMATCH
  prompt: >-
    Does the mouse SRY-SOX9-FGF9 versus WNT4 threshold model describe what happens
    in a human mosaic gonadal ridge?
  rationale: >-
    This is a mismatch rather than a plain gap, because the evidence exists and it
    is the translation that is open. The switch has been characterised in detail
    by gain- and loss-of-function experiments in mouse: SRY initiates a
    SOX9-FGF9 feed-forward loop that represses WNT4, and the authors describe
    SRY's role as tipping a balance rather than acting as an on-off command. That
    balance-tipping framing is exactly what makes a mosaic ridge interesting,
    since a partial SRY dose could plausibly leave the balance untipped in some
    regions. But every one of those experiments was done in a genetically uniform
    mouse gonad. Two things do not carry across without checking. First, no mouse
    model of 45,X/46,XY mosaicism has been made, so the threshold behaviour under
    partial SRY dosage has never been tested in the configuration this disease
    presents. Second, human and mouse sex determination differ in timing and in
    the relative contribution of SRY-independent inputs, so a threshold measured
    in mouse need not be the human threshold. The consequence for this entry is
    concrete: the mechanism it curates is the best available account and is not a
    demonstrated one, which is why the node carries PROVISIONAL.
  attaches_to:
  - pathophysiology#Regional SRY Dosage Variation Across the Gonadal Ridge
  evidence:
  - reference: PMID:16700629
    reference_title: "Fgf9 and Wnt4 act as antagonistic signals to regulate mammalian sex determination."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We show through gain- and loss-of-function experiments that fibroblast growth factor 9 (FGF9) and WNT4 act as opposing signals to regulate sex determination."
    explanation: >-
      Establishes that the mechanism exists and was demonstrated experimentally -
      which is what distinguishes a model mismatch from an absence of evidence.
  - reference: PMID:16700629
    reference_title: "Fgf9 and Wnt4 act as antagonistic signals to regulate mammalian sex determination."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "In principle, sex determination in other vertebrates may operate through any switch that introduces an imbalance between these two signaling pathways."
    explanation: >-
      The authors generalise their own result only in principle, which is the
      right level of confidence to carry into a human mosaic and is weaker than
      the entry would need to call the node established.
- discussion_id: mgd_gh_efficacy_contested
  kind: KNOWLEDGE_GAP
  prompt: >-
    Does growth hormone actually increase final height in 45,X/46,XY mixed gonadal
    dysgenesis?
  rationale: >-
    Two sources in this entry disagree, and the disagreement is not a matter of
    emphasis. The 2025 review states that growth hormone significantly improves
    growth velocity and final adult height, with outcomes similar to Turner
    syndrome. A three-centre cohort of 100 patients found no significant height
    difference between treated and untreated groups, p = 0.5. Both are in the
    entry because neither can be dismissed: the review aggregates studies designed
    to measure the effect, while the cohort is the largest single series with
    long-term follow-up and is not randomised, so treated patients may have been
    the shorter ones to begin with. The question matters because growth hormone is
    started at age four to six and carries a theoretical concern about stimulating
    tumour growth in retained gonadal tissue.
  attaches_to:
  - treatments#Growth Hormone Therapy
  - pathophysiology#Turner-Spectrum Somatic Features
  evidence:
  - reference: PMID:37882230
    reference_title: "45,X/46,XY mosaicism: Clinical manifestations and long term follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Growth hormone (GH) treatment did not result in a significant height increase compared to the untreated group (p = 0.5)."
    explanation: The negative cohort result, stated with its p value.
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "an improvement in height SDS by 0.42 has been shown among treated patients"
    explanation: The positive effect size the review reports, which is what the cohort failed to reproduce.
- discussion_id: mgd_gonad_position_and_tumour_risk
  kind: KNOWLEDGE_GAP
  prompt: >-
    Does gonadal position predict tumour risk well enough to decide which gonads
    to remove?
  rationale: >-
    The management model in wide use assumes intra-abdominal gonads are the
    dangerous ones and scrotal testes can be retained with surveillance. One
    fourteen-child series supports it strongly: every gonadoblastoma was in an
    intra-abdominal gonad. Another series of twenty-one children does not - of
    four dysgenetic testes with carcinoma in situ, one was intra-abdominal, one
    inguinal and two scrotal. The 2025 review separately notes that Y-chromosomal
    material raises germ cell tumour risk even in apparently normal scrotal
    testes. If position is not protective, then retaining a scrotal testis buys
    fertility potential and hormone production at a real and currently unquantified
    oncological cost, and surveillance rather than position has to carry the
    safety.
  attaches_to:
  - pathophysiology#Gonadoblastoma Risk in Retained Dysgenetic Gonads
  - treatments#Gonadectomy of Retained Dysgenetic Gonads
  evidence:
  - reference: PMID:27052295
    reference_title: "Gonadoblastoma in patients with 45,X/46,XY mosaicism: A 16-year experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The exclusive presence of GB in intra-abdominal gonads is in keeping with the findings of several other series."
    explanation: The position-dependent view, stated by a series that found it exclusively.
  - reference: PMID:27032613
    reference_title: "Tumor risk of children with 45,X/46,XY gonadal dysgenesis in relation to their clinical presentations: Further insights into the gonadal management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the 4 dysgenetic testes affected by CIS in 3 patients were intraabdominal (n=1), inguinal (n=1) and scrotal (n=2) in positions."
    explanation: "The counter-evidence: half of the affected testes in this series were scrotal."
  - reference: PMID:41208147
    reference_title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "increases the risk of germ cell tumours even in apparently normal testes located in the scrotal sac"
    explanation: The review's own caution that scrotal position is not reassuring.
- discussion_id: mgd_no_gonadal_molecular_profile
  kind: KNOWLEDGE_GAP
  prompt: >-
    What is the actual mosaic ratio inside a human MGD gonad, and does it explain
    which side became a streak?
  rationale: >-
    The mechanism this entry curates says that regional variation in the
    SRY-bearing lineage across the gonadal ridge decides each side's fate. That
    is a testable claim and it has not been tested. No human MGD gonad has been
    profiled at single-cell resolution, so nobody has measured whether the streak
    side actually carries fewer 46,XY cells than the testicular side. The
    supporting mechanism - the SOX9-FGF9 loop repressing WNT4 - comes entirely
    from mouse gonads that are not mosaic. Human MGD gonadal tissue has been
    examined immunohistochemically for GBY proteins, so the tissue is obtainable;
    what has not been done is to genotype the two lineages within a single gonad
    and relate their distribution to which regions became streak. The finding that
    six patients had a single gonad containing both streak and testicular tissue
    is the strongest available human evidence for the regional model, and it is
    anatomical rather than molecular. Until the measurement is made, the mosaic-ratio explanation
    should be read as the best available account rather than a demonstrated one,
    which is why the two nodes that depend on it are marked PROVISIONAL.
  attaches_to:
  - pathophysiology#Regional SRY Dosage Variation Across the Gonadal Ridge
  evidence:
  - reference: PMID:31883875
    reference_title: "Variation of Gonadal Dysgenesis and Tumor Risk in Patients With 45,X/46,XY Mosaicism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A gonad composed of both streak and dysgenetic testicular portions was observed in 7 gonads of 6 patients."
    explanation: >-
      The anatomical observation that the regional model explains and a
      whole-gonad model does not, and currently the best human evidence for it.
references:
- reference: PMID:41208147
  title: "Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches."
- reference: PMID:37882230
  title: "45,X/46,XY mosaicism: Clinical manifestations and long term follow-up."
review_notes: >-
  This PR caches more references than the entry cites. Nine are cited; the rest
  were fetched by the deep-research report's own citation-validation pass, which
  resolves every identifier the report mentions, and the report is committed
  alongside the entry. Four were fetched by hand during curation and then set
  aside rather than cited: PMID:34539919 (growth hormone dynamics in MGD, whose
  findings are already carried by the two cohort studies cited), PMID:34566299
  (clinical and reproductive characteristics, superseded by the 2025 review),
  and two included in the GBY search of which PMID:19306348 and PMID:30753444
  were subsequently cited. Nothing was cited without being read.
notes: >-
  Scope and modelling decisions.

  No genetic section. The disease has no causal gene - MONDO records none, and
  the preflight gene-identity check could not run for that reason. SHOX and SRY
  appear inside pathophysiology nodes because the mechanism runs through their
  dosage, but neither is a disease gene here and listing them under genetic would
  misrepresent a chromosomal disorder as a monogenic one.

  No animal models. Mouse gonadal-determination work is cited as evidence for the
  SRY-SOX9-FGF9-WNT4 switch, but those animals are not mosaic and so are not
  models of this disease; they are models of the pathway the mosaicism perturbs.
  Curating them as animal_models would assert a correspondence that does not
  exist.

  No environmental section. Post-zygotic chromosome loss has no established
  environmental contributor.

  No comorbidities block. Disease has no comorbidities slot - comorbidity
  records live in kb/comorbidities/ as their own files. The adult
  Turner-like cardiometabolic morbidity is real and cited, so it is recorded as a
  progression phase rather than dropped; a proper comorbidity record pairing this
  entry with hypertension, dyslipidaemia and type 2 diabetes would be a
  reasonable follow-up.

  Gonadal tissue cryopreservation and miR-371a-3p tumour surveillance are
  deliberately out of scope. Both appear in the deep-research report as emerging
  rather than established practice, and the review that supports the rest of this
  entry describes them as future directions. Adding them as treatments would put
  prospective practice beside current practice without distinguishing them.

  No has_subtypes. The phenotypic range is continuous and set by mosaic
  distribution, so any cut point - female-raised versus male-raised, Turner-like
  versus genital-predominant - would be a description of ascertainment rather than
  of biology. The variation is carried by the cohort denominators recorded on
  individual phenotypes instead.
📚

References & Deep Research

References

2
PMID:41208147
Mixed Gonadal Dysgenesis: A Comprehensive Review of Clinical Spectrum, Diagnostic Strategies, and Management Approaches.
No top-level findings curated for this source.
PMID:37882230
45,X/46,XY mosaicism: Clinical manifestations and long term follow-up.
No top-level findings curated for this source.

Deep Research

1
Claude Code ▸
45,X/46,XY Mixed Gonadal Dysgenesis: Comprehensive Research Report
claude-haiku-4-5-20251001, claude-sonnet-5 21 citations 2026-08-29T19:42:01.621445

45,X/46,XY Mixed Gonadal Dysgenesis: Comprehensive Research Report

1. Disease Information

Overview. 45,X/46,XY Mixed Gonadal Dysgenesis (MGD; also called 45,X/46,XY mosaicism) is a chromosomal disorder of sex development (DSD) caused by somatic mosaicism for a 45,X cell line and a 46,XY cell line arising from post-zygotic mitotic loss of the Y chromosome (or, more rarely, loss/structural rearrangement of the Y in a subset of cells). The defining anatomic feature is asymmetric gonadal development: classically a streak (undifferentiated fibrous) gonad on one side and a dysgenetic-to-normal testis on the other, with variably persistent Müllerian structures (hemi-uterus, fallopian tube remnant) reflecting incomplete anti-Müllerian hormone (AMH) action from the dysgenetic testis (Wikipedia; NORD; StatPearls — PMID:2294747, PMID:22605431, PMID:27064253).

Identifiers. - MONDO: MONDO:0015779 (45,X/46,XY mixed gonadal dysgenesis) — Monarch Initiative record aggregates OMIM/Orphanet/UMLS cross-references, though the live page content could not be fully retrieved in this session; verify the CURIE against the dismech term-validation pipeline before curation use. - Orphanet: A related, broader entry exists for "46,XY partial gonadal dysgenesis" (Orphanet ORPHA:251510); MGD itself (with the 45,X cell line) is generally indexed as a DSD-sex-chromosome-abnormality subtype distinct from pure 46,XY partial gonadal dysgenesis (PGD), which lacks the 45,X line (tp.amegroups.org case report; ScienceDirect "Genetics of 46,XY gonadal dysgenesis"). - MedGen: Concept ID CN279762 ("45,X/46,XY mixed gonadal dysgenesis") (NCBI MedGen). - GARD/NORD: Listed as a rare disease; GARD notes detailed symptom/cause/treatment fields are still sparse in that particular resource, underscoring reliance on primary literature (rarediseases.info.nih.gov). - ICD‑10/ICD‑11: Falls under Q99.1 (Chromosomal mosaic, sex chromosomes) / general "gonadal dysgenesis" categories in ICD-10-CM; ICD-11 codes it under disorders of sex development due to chromosome anomalies (LD2A.Y-type entries) — exact codes vary by coding system and were not independently confirmed against a primary ICD source in this pass. - Synonyms: X0/XY mosaicism; 45,X/46,XY mosaicism; mixed gonadal dysgenesis; asymmetric gonadal dysgenesis (Wikipedia; GARD).

Distinction from related entities. MGD (with a 45,X line) is distinguished from: - 46,XY partial gonadal dysgenesis (PGD): karyotype is pure 46,XY (no 45,X line), typically due to monogenic causes (SRY, NR5A1/SF1, MAP3K1 variants) rather than chromosomal mosaicism, and lacks Turner-syndrome stigmata (PMC3827999; NORD PGD page). - Complete gonadal dysgenesis (Swyer syndrome): 46,XY karyotype with bilateral streak gonads and female phenotype. - Persistent Müllerian Duct Syndrome (PMDS): normal testicular differentiation with isolated failure of AMH/AMHR2 signaling; gonadal histology is normal testis (not dysgenetic), distinguishing it from MGD on biopsy (PMC10411253).

Data provenance. Information in the literature is drawn overwhelmingly from aggregated case series and retrospective single/multi-center cohorts (e.g., 10–38 patient series) rather than large-scale EHR/registry studies, reflecting the rarity of the condition; a 2025 systematic narrative review (Giri et al., Clinical Endocrinology, PMID:41208147) synthesizes literature from 2000–2024.

2. Etiology

Disease Causal Mechanism

MGD arises from postzygotic mitotic non-disjunction or anaphase lag affecting the Y chromosome (or, less commonly, structural instability of a rearranged/dicentric Y) during early cleavage divisions, producing two (or more) cell lineages: 45,X and 46,XY, distributed in varying proportions across tissues, including the gonads themselves (Wikipedia, citing StatPearls mechanistic description; PMC11521797 case of idic(Y) mosaicism). This is fundamentally a somatic mosaicism / chromosomal instability mechanism rather than a single-gene Mendelian defect.

Molecular consequence. The presence or absence of a functional SRY-bearing Y chromosome in individual gonadal ridge cells determines whether that region differentiates toward testis (SRY⁺ Sertoli cell precursors activate SOX9, which establishes a SOX9–FGF9 positive-feedback loop while repressing the pro-ovarian WNT4/RSPO1/β-catenin pathway) or toward ovary/streak tissue (SRY-negative cells default toward WNT4-driven pre-granulosa fate) (PMC7291083; journals.biologists.com Sry critical-window study; PMC3735148). Because the two cell lines are admixed in variable ratios across and within the gonads, one gonad can differentiate predominantly along the testicular pathway (dysgenetic testis) while the contralateral gonad, dominated by the 45,X line, fails to organize (streak gonad) — the anatomic hallmark of MGD.

Y-chromosome structural abnormalities. A substantial subset of 45,X/46,XY cases actually involve a structurally abnormal Y (isodicentric Y, ring Y, Yp or Yq deletions) rather than a normal Y in the second line; such abnormal Y chromosomes are mitotically unstable and predispose to secondary loss of a normal-appearing X0 line, which is proposed as the origin mechanism for many 45,X/46,XY mosaics (PMC11521797; PMC3827999 on Y-microdeletion screening).

Genetic Risk Factors

  • SRY gene status/dosage: Presence and expression level of SRY on the retained Y chromosome is the principal driver of the degree of virilization; irregular/mosaic SRY and downstream SOX9 expression are implicated in the partial/mixed phenotype (WebSearch synthesis; PMC3055899 SOX9 regulation failure in 46,XY DSD).
  • Y-chromosome microdeletions (AZF regions): A high frequency of Y-chromosome microdeletions has been reported specifically in males with 45,X/46,XY mosaicism presenting with infertility, and in 46,XY PGD patients screened alongside 45,X/46,XY variants (PMC3827999; PMC7025455 "High frequency of Y chromosome microdeletions in male infertility patients with 45,X/46,XY mosaicism").
  • SHOX haploinsufficiency: The short-stature Turner-like phenotype is attributed to dosage loss of the SHOX gene (pseudoautosomal region) in the 45,X-predominant tissue fraction, analogous to classic Turner syndrome (Wikipedia; Giri et al. 2025 review).
  • DAX1 (NR0B1): Proposed as an X-linked "anti-testis" gene whose relative dosage in 45,X/46,XY mosaics may suppress testicular differentiation, contributing to the streak-gonad phenotype (WebSearch synthesis of NORD/Malacards content; note this remains a hypothesis rather than an established mechanism and should be treated cautiously in curation).
  • MAP3K1: Implicated in 13–18% of 46,XY gonadal dysgenesis broadly (not MGD-specific), acting via decreased SOX9 expression (StatPearls, PMC12757904 synthesis).
  • NR5A1 (SF1): A recognized monogenic cause of 46,XY PGD, occasionally invoked in the differential/overlap literature for atypical MGD-like presentations (PMC10754607 case report).

Environmental Risk Factors

No established environmental, toxin, or exposure-related risk factors were identified in the literature searched; MGD is understood as a stochastic, sporadic post-zygotic chromosomal event rather than an exposure-driven condition. Advanced parental age or other epidemiologic risk modifiers were not substantiated by the sources reviewed.

Protective Factors

No specific genetic or environmental protective factors against MGD were identified in the literature. This reflects the mosaic/stochastic mitotic origin of the condition rather than absence of research — a de novo somatic event has no established "susceptibility-lowering" allele analog.

Gene–Environment Interactions

Not applicable/not documented; no GxE data were found for this condition.

3. Phenotypes

The phenotypic spectrum of 45,X/46,XY mosaicism is exceptionally broad — from phenotypically normal males, through the full range of atypical/ambiguous genitalia, to phenotypically normal females with Turner-syndrome features (Wikipedia; PMC8418569; multiple case series PMID:3595646, PMID:10429013, PMID:25351753, PMID:26759215).

Genital/Reproductive Phenotypes

Phenotype Frequency/Notes Suggested HPO term
Ambiguous/atypical genitalia Most reported presentation in DSD referral cohorts (~5–15% of atypical genitalia cases attributable to MGD) HP:0000062 (Ambiguous genitalia)
Clitoromegaly 80% of initial presentations in one 10-patient cohort (PMC8418569) HP:0000053 (Clitoral hypertrophy)
Hypospadias (perineal/scrotal) Common in phallus-predominant presentations HP:0000047 (Hypospadias)
Bifid/labioscrotal fusion Reported in neonatal presentation spectrum HP:0000048 (Bifid scrotum)
Micropenis / ventral chordee Part of the atypical-genitalia spectrum HP:0000054 (Micropenis)
Cryptorchidism / non-palpable gonad Streak gonad classically non-palpable; dysgenetic testis variably descended HP:0000028 (Cryptorchidism)
Persistent Müllerian structures (hemi-uterus, fallopian tube) Reflects incomplete AMH action; ultrasound under-detects vs. laparoscopy (~40% miss rate by US) HP:0000130 (Uterus present in an individual with a Y chromosome) / HP:0008734
Delayed puberty / primary amenorrhea 20% of one cohort; common in undiagnosed female-reared cases presenting in adolescence HP:0000823 (Delayed puberty)
Infertility (near-universal) Testicular insufficiency in 60–70% of males by third decade; spontaneous fertility "extremely rare" HP:0000789 (Infertility)

Turner-like Somatic Phenotypes

Phenotype Notes HPO term
Short stature Universal/near-universal finding; mean height SDS ≈ −3.77 in one cohort HP:0004322 (Short stature)
Webbed neck Classic Turner stigma HP:0000465 (Webbed neck)
Shield chest / widely spaced nipples Turner-overlap feature HP:0000900 (Broad chest); HP:0006610
Cubitus valgus Reported Turner stigma HP:0002967 (Cubitus valgus)
High-arched palate Reported HP:0000218 (High palate)
Low posterior hairline Reported (Johansen 2012) HP:0002162 (Low posterior hairline)
Renal anomalies (horseshoe kidney, unilateral agenesis) 40% in one cohort (30% unilateral agenesis, 10% horseshoe kidney) HP:0000085 (Horseshoe kidney); HP:0000122
Cardiac defects (bicuspid aortic valve, coarctation of aorta) Documented in reviews, though absent in some smaller cohorts HP:0001647 (Bicuspid aortic valve); HP:0001680 (Coarctation of aorta)
Sensorineural hearing loss 10% in one cohort HP:0000407
Autoimmune thyroid disease (Hashimoto's/Graves') 40% in one cohort (autoimmune hypothyroidism + Graves') HP:0000850 / HP:0100647
Mild intellectual disability, autism, facial dysmorphism Reported in a minority (Johansen 2012 synthesis) — "Normal psychomotor development" also reported in other series, indicating this is not a core/consistent feature HP:0001256; HP:0000717

Laboratory/Endocrine Phenotypes

  • Elevated gonadotropins (LH/FSH) — hypergonadotropic state when gonads are non-functional.
  • Low or low-normal testosterone in males, with blunted hCG-stimulated testosterone response reflecting Leydig cell dysfunction.
  • Low-to-normal AMH — toward the lower end of the male reference range, reflecting Sertoli cell dysfunction in the dysgenetic testis.

Onset, Severity, Progression

  • Onset: Congenital (present from birth in genital phenotype), but diagnosis timing varies: prenatal (amniocentesis), neonatal (atypical genitalia), or later childhood/adolescence (short stature, delayed puberty) when genitalia are near-normal at birth.
  • Severity/course: Highly variable and largely determined by the tissue distribution of the two cell lines; not a progressive degenerative disease per se, though gonadal function (Leydig/germ cell) can decline with age, and short stature/height-SDS reduction is progressive without growth hormone intervention.
  • Quality of life: Long-term sex-of-rearing satisfaction reported at 80–85% in reviewed cohorts, with persistent body-image and short-stature-related dissatisfaction as leading QoL detractors; ~50% of parents report unmet psychosocial-support needs during the neonatal/diagnostic period (PMC12757904/Giri et al. 2025).

4. Genetic/Molecular Information

Karyotype/chromosomal basis: 45,X/46,XY mosaicism (most common); rarer variants include 45,X/47,XYY and 45,X/46,X,idic(Y), 45,X/46,X,der(Y) (ring or isodicentric Y), and higher-order mosaics such as 45,X/46,XY/47,XYY (multiple case reports: PMC11521797, PMC3625110). Low-level mosaicism can be missed by standard peripheral-blood karyotyping and requires chromosomal microarray, FISH, or tissue-specific (buccal/skin/gonadal) analysis to detect.

Causal/associated genes: - SRY (Yp11.2) — master testis-determining switch; irregular expression across the mosaic cell population drives partial masculinization (no HGNC/OMIM number retrieved in this pass beyond general Y-linked SRY locus). - SOX9 — downstream of SRY, essential for Sertoli cell/testis-cord formation; failure of SOX9 up-regulation is implicated in 46,XY DSD broadly (PMC3055899). - AMH / AMHR2 — anti-Müllerian hormone and its receptor; reduced Sertoli-cell AMH output in the dysgenetic testis underlies persistent Müllerian structures (differentiates MGD from isolated PMDS, where testis histology is otherwise normal) (PMC10411253). - SHOX (Xp22.33/Yp11.32, pseudoautosomal region) — haploinsufficiency from the 45,X cell fraction drives short stature. - MAP3K1 — implicated in a minority (13–18%) of 46,XY gonadal dysgenesis cases generally, via decreased SOX9 expression. - NR5A1/SF1 — monogenic cause in overlapping 46,XY PGD phenotypes; occasionally cited in atypical MGD differential work-ups. - DAX1/NR0B1 — hypothesized X-linked antagonist of testis differentiation whose relative dosage may influence the streak-gonad phenotype in 45,X/46,XY mosaics (hypothesis-level; treat cautiously). - WT1 — associated with complete gonadal dysgenesis/absence in related but distinct syndromes (Denys-Drash/Frasier spectrum), cited as part of the broader gonadal-dysgenesis gene landscape rather than MGD-specific.

Variant classification/type: The primary "variant" is chromosomal-scale mosaicism/aneuploidy rather than a discrete point variant; secondary contributory findings (Y microdeletions in AZF regions, structural Y rearrangements) are structural/copy-number in nature. No systematic ClinVar/gnomAD allele-frequency data apply, since this is not a classic single-locus Mendelian disorder.

Somatic vs. germline origin: The 45,X/46,XY mosaicism itself is somatic in origin (post-zygotic mitotic error), not inherited in a Mendelian sense — recurrence risk to future pregnancies is not elevated by parental carrier status. This is a key genetic-counseling point.

Functional consequences: Loss-of-function-like effect at the tissue level — SRY⁺ cells drive testis differentiation while SRY-negative (45,X) cells default to streak/ovarian-like tissue; net phenotype reflects the spatial/proportional mixture rather than a single gain- or loss-of-function allele.

Epigenetics: No disease-specific DNA methylation/chromatin literature was identified in this search; this remains an underexplored area for MGD specifically (in contrast to better-studied epigenetic regulation of Sox9/enhancer elements in general testis-determination biology).

Chromosomal abnormality detail: Structural Y anomalies (isodicentric Y, ring Y) are mitotically unstable and are hypothesized as a common upstream cause generating the associated 45,X cell line via secondary loss during subsequent divisions (PMC11521797).

5. Environmental Information

No environmental toxin, occupational, radiation, or infectious contributing factors were identified in the literature for 45,X/46,XY MGD — consistent with its origin as a stochastic post-zygotic mitotic chromosomal error rather than an environmentally triggered condition. No lifestyle risk-factor or infectious-agent data apply. (This is a genuine absence of evidence in the literature searched, not merely an unresearched gap — the mitotic-error mechanism does not have an established environmental trigger analogous to, e.g., maternal age in meiotic non-disjunction trisomies.)

6. Mechanism / Pathophysiology

Causal Chain (Upstream → Downstream)

  1. Initiating event (molecular/chromosomal): Post-zygotic mitotic non-disjunction or anaphase lag of the Y chromosome (often a structurally unstable Y — isodicentric/ring Y) during early cleavage divisions → generation of two coexisting cell lineages, 45,X and 46,XY, distributed stochastically across tissues including the bipotential gonadal ridge.
  2. Gonadal ridge patterning (cellular, ~E10.5–E12.5 equivalent in human development): In SRY⁺ (46,XY) somatic-cell-dominant regions of the ridge, SRY expression in pre-Sertoli cells activates SOX9, establishing a SOX9–FGF9 positive-feedback loop that (a) drives Sertoli cell and testis-cord differentiation and (b) actively represses the pro-ovarian WNT4/RSPO1/β-catenin pathway. In SRY-negative (45,X-dominant) regions, the absence of this switch allows default WNT4-driven pre-granulosa-like differentiation, which under monosomy-X conditions fails to sustain a functional ovary and instead regresses to fibrous streak gonad tissue (PMC7291083; journals.biologists.com Sry critical-window paper; PMC3735148).
  3. Asymmetric gonadal outcome (tissue level): Because the two cell lines are unevenly distributed left-to-right and within each gonadal primordium, one gonad differentiates along a (variably dysgenetic) testicular pathway while the contralateral gonad fails to organize — the defining streak gonad + dysgenetic/normal testis anatomy of MGD.
  4. Sertoli/Leydig cell dysfunction (endocrine level): The dysgenetic testis has quantitatively reduced Sertoli cell mass, yielding low-to-low-normal AMH (insufficient to fully regress Müllerian ducts, hence persistent hemi-uterus/fallopian tube) and reduced Leydig cell steroidogenic capacity, yielding low/low-normal testosterone with blunted hCG-stimulated response — the proximate cause of incomplete virilization/ambiguous genitalia.
  5. Systemic (organism level) consequences of the 45,X cell fraction: SHOX haploinsufficiency in 45,X-predominant tissue → short stature; broader Turner-like somatic phenotype (renal anomalies, cardiac defects, lymphatic-derived webbed neck, autoimmune thyroiditis) via mechanisms shared with classic Turner syndrome, though the degree of expression depends on the tissue-specific 45,X:46,XY ratio (mosaic "dilution" of the Turner phenotype).
  6. Neoplastic transformation risk (downstream, age-dependent): Retained Y-chromosome material (specifically the GBY locus, containing TSPY, on the Y short arm — implicated generally in Y-bearing dysgenetic gonad tumorigenesis, though not explicitly detailed in the sources retrieved here) in a dysgenetic gonadal microenvironment predisposes resident primordial/immature germ cells to arrest and malignant transformation, driving the well-documented gonadoblastoma → dysgerminoma progression pathway, particularly in intra-abdominal (undescended) gonads (75% premalignant-neoplasm risk vs. 16% inguinal, 9% scrotal) (PMC12757904/Giri et al. 2025; PMID:31883875; PMID:27032613).

Cell Types Involved

  • Sertoli cells (dysfunctional/reduced in dysgenetic testis) — CL:0000216
  • Leydig cells (steroidogenically impaired) — CL:0000178
  • Primordial/immature germ cells (arrested, tumor-initiating population) — CL:0000670 / CL:0000586
  • Granulosa-like/pre-granulosa cells (in streak gonad remnant tissue) — CL:0000501 (approximate)
  • Gonadal stromal/supporting cells

Biological Processes (suggested GO terms)

  • Male sex determination: GO:0030238
  • Testis development: GO:0009888 / GO:0001708 (cell fate specification)
  • Sertoli cell differentiation: GO:0060008
  • Anti-Müllerian hormone signaling / Müllerian duct regression: GO:0001880 (Müllerian duct regression)
  • Wnt signaling pathway involved in female gonad development: GO:0060065
  • Germ cell development: GO:0007281
  • Positive regulation of transcription (SOX9-driven testis program): GO:0045893

Molecular Profiling

No disease-specific transcriptomic/proteomic/single-cell atlases for MGD gonadal tissue were identified in this search (a plausible knowledge gap — human dysgenetic-gonad single-cell profiling is more developed for Turner-syndrome ovaries and general DSD cohorts than for MGD specifically). Mouse single-cell gonadal atlases (from the SRY/SOX9/WNT4 mechanistic studies cited above) are the closest available molecular-profiling proxy and would need explicit HUMAN_MODEL_MISMATCH framing if cited for MGD curation, since murine gonadal-ridge chimera/knockout models are not MGD per se but rather models of the underlying testis-vs-ovary determination pathway.

7. Anatomical Structures Affected

Organ level: - Primary: Gonads (asymmetric — one streak, one dysgenetic/normal testis), internal genital ducts (Müllerian remnants: hemi-uterus, fallopian tube, prostatic utricle; Wolffian derivatives variably present), external genitalia (variable ambiguous phenotype). - Secondary/associated: Kidneys (horseshoe kidney, unilateral agenesis), heart/great vessels (bicuspid aortic valve, coarctation of aorta), thyroid (autoimmune thyroiditis/Graves'), skeletal system (short stature via SHOX, cubitus valgus), inner ear (sensorineural hearing loss). - Systems involved: Reproductive/endocrine (primary), renal, cardiovascular, musculoskeletal, immune (autoimmune thyroid disease).

Tissue/cell level: - Gonadal ridge-derived tissue: dysgenetic seminiferous tubules with reduced Sertoli/Leydig cell content on the testicular side; fibrous streak tissue (devoid of germ cells, composed of ovarian-type stroma) on the contralateral side. - Suggested UBERON terms: gonad (UBERON:0000991), testis (UBERON:0000473), ovary (UBERON:0000992), uterus (UBERON:0000995), Müllerian duct (UBERON:0003508), Wolffian duct/mesonephric duct (UBERON:0001301), kidney (UBERON:0002113), thyroid gland (UBERON:0002046).

Subcellular level: No MGD-specific subcellular pathology (e.g., organelle-level defect) was identified; the mechanism operates at the chromosomal/cell-fate-decision level rather than a subcellular organelle dysfunction.

Localization/laterality: By definition asymmetric/unilateral discordant gonadal differentiation is the hallmark finding (streak vs. testis, left vs. right variable), though bilateral streak or bilateral dysgenetic-testis variants also occur within the phenotypic spectrum.

8. Temporal Development

  • Onset: Congenital (chromosomal mosaicism established at the post-zygotic cleavage stage; gonadal/genital phenotype is present from fetal development), but clinical recognition spans the full life course — prenatal (incidental karyotype finding at amniocentesis), neonatal (atypical genitalia), childhood (short stature, incidentally discovered), or adolescence (delayed puberty, primary amenorrhea).
  • Progression: Not a classically "progressive" degenerative disease; however, individual components evolve with age — testicular (Leydig/germ cell) function commonly declines, with testicular insufficiency reported in 60–70% of males by the third decade; height-SDS deficit worsens over childhood without growth-hormone intervention; gonadal tumor risk rises with age (though cases before age 20 are described as rare, risk is cumulative and lifelong for retained dysgenetic gonadal tissue).
  • Disease course pattern: Largely stable/static with respect to the core chromosomal mosaicism, but the endocrine and oncologic sequelae are age-dependent and require lifelong surveillance.
  • Critical periods: The "mini-puberty" window (first ~3 months of life) is clinically important for assessing baseline Leydig cell (testosterone) function; the prenatal/early postnatal period is critical for sex-of-rearing and gonadectomy decision-making; puberty (age 11–13) is a critical window for hormone-replacement initiation and for gender-identity development/disclosure counseling.

9. Inheritance and Population

Epidemiology: - Incidence estimates range from 1 in 15,000 to 1 in 30,000 live births across sources (Wikipedia/StatPearls cite ~1/15,000; PMC12757904 cites the 1/15,000–1/30,000 range). - Among infants presenting with atypical/ambiguous genitalia, MGD accounts for ~5–15% of cases (Giri et al. 2025). - 45,X/46,XY mosaic is described as the most common karyotype underlying the mixed-gonadal-dysgenesis phenotype. - True population prevalence is likely underestimated because many individuals with near-normal male or female phenotypes are never karyotyped.

Inheritance pattern: Sporadic — arises from a post-zygotic somatic mitotic error, not inherited via a Mendelian mechanism; parental karyotypes are typically normal, and recurrence risk in subsequent pregnancies is not increased above general population risk. This is an important genetic-counseling distinction from single-gene 46,XY PGD causes (e.g., NR5A1, MAP3K1), which may have autosomal patterns.

Penetrance/expressivity: Effectively 100% "penetrant" in the sense that mosaicism is present from conception, but expressivity is extremely variable — phenotype is determined by the proportion and tissue distribution of the 45,X vs. 46,XY cell lines, which cannot be reliably predicted from a peripheral-blood karyotype or amniotic-fluid cell ratio alone (explicitly noted: "amniotic fluid 45,X cell proportion cannot predict phenotypic outcomes").

Founder effects/consanguinity/carrier frequency: Not applicable, given the somatic/sporadic mechanism.

Population demographics: No specific ethnic or geographic predilection was identified in the literature reviewed; cohorts span Danish (Johansen 2012), Chinese (PMC10154695, 38 patients), Brazilian (PMID:25351753, 14 patients), and other national referral-center series, suggesting a broadly similar global distribution, though systematic multi-population prevalence comparisons were not found.

Sex ratio: Not meaningfully applicable as a simple M:F ratio, since "sex" itself is the variable clinical outcome in this condition; cohorts show a spread across female-reared, male-reared, and intersex presentations (e.g., 9 female-reared : 1 male-reared in one 10-patient cohort, though this reflects referral/rearing patterns rather than an underlying biological ratio).

10. Diagnostics

Chromosomal/genetic testing: - QF-PCR: first-line rapid screen for SRY presence. - Standard peripheral-blood karyotype: confirms 45,X/46,XY mosaicism; sensitivity limited for low-level mosaicism. - Chromosomal microarray (CGH/SNP array): detects low-level mosaicism and submicroscopic Y copy-number variation missed by standard karyotype. - FISH: rapid (within 24h) detection of monosomy X; can be applied to buccal, skin, or gonadal tissue when blood karyotype is normal but clinical suspicion persists (tissue-specific mosaicism). - Y-chromosome microdeletion (AZF) screening: recommended in males with 45,X/46,XY presenting with infertility, given high reported frequency of microdeletions in this subgroup (PMC3827999, PMC7025455).

Imaging: - Pelvic ultrasound: gonadal localization, uterus/Müllerian structure identification (though ultrasound reportedly misses Müllerian remnants in ~40% of cases vs. 100% detection by laparoscopy). - Abdominal ultrasound: renal anomaly screening. - MRI: reserved for ultrasound-inconclusive cases. - Echocardiography: cardiac anomaly screening (bicuspid aortic valve, coarctation of aorta). - Laparoscopy: considered superior for definitive anatomic delineation and enables targeted gonadal biopsy/removal.

Endocrine evaluation: - Serum electrolytes, cortisol, 17-hydroxyprogesterone: to exclude congenital adrenal hyperplasia as an alternative/co-existing cause of atypical genitalia. - Testosterone (ideally within the "mini-puberty" window, first 3 months of life): indicates Leydig cell function. - hCG stimulation test: assesses testicular testosterone reserve outside the mini-puberty window or when baseline is low. - AMH: marker of testicular (Sertoli cell) tissue presence/function. - LH/FSH: elevation indicates a hypergonadotropic state from non-functional gonadal tissue.

Histopathology: Gonadal biopsy remains important for distinguishing MGD (streak + dysgenetic testis) from related entities (e.g., PMDS, where testicular histology is normal) and for detecting occult germ cell neoplasia in situ/gonadoblastoma.

Differential diagnosis: 46,XY partial gonadal dysgenesis (no 45,X line), Swyer syndrome (complete gonadal dysgenesis, bilateral streaks), persistent Müllerian duct syndrome, congenital adrenal hyperplasia (as an alternative cause of atypical genitalia), NR5A1-related DSD.

Screening: No population-level newborn screening program exists for MGD specifically (unlike, e.g., metabolic newborn screening panels); detection is via prenatal incidental karyotype finding, or postnatal clinical suspicion (atypical genitalia, short stature, delayed puberty) prompting targeted karyotyping.

11. Outcome/Prognosis

  • Gonadal malignancy: Lifetime risk estimated at 15–25%, with strong risk-stratification by gonadal location: ~75% premalignant-neoplasm risk for intra-abdominal (undescended) gonads, ~16% for inguinal, ~9% for scrotal position — underscoring why gonadal position drives management urgency (PMC12757904/Giri et al. 2025). Independent series report gonadal tumors (gonadoblastoma ± dysgerminoma) in ~18% of surgically assessed patients (6/34), rising to 37.5–54.5% in subgroups with significant genital ambiguity or female phenotype (PMID:31883875-related synthesis).
  • Testicular function: Testicular insufficiency develops in an estimated 60–70% of males by the third decade of life.
  • Fertility: Spontaneous fertility is "extremely rare"; assisted reproduction (testicular sperm extraction, gonadal tissue cryopreservation in prepubertal patients) is an emerging but still largely experimental option.
  • Growth/height: Progressive height-SDS reduction with age if untreated; recombinant human growth hormone therapy improves growth velocity and final height (reported improvement of 0.42 SDS), with response paralleling that seen in classic Turner syndrome; typically initiated age 4–6 years.
  • Metabolic/cardiovascular morbidity: A population-based study cited in the 2025 review identified a Turner-like long-term morbidity pattern — hypertension, dyslipidemia, and type 2 diabetes emerging by around age 40.
  • Psychosocial/gender outcomes: Long-term satisfaction with sex of rearing reported at 80–85%; gender incongruence prevalence reported at 12–15% in MGD cohorts; persistent body-image concerns (short stature prominent) are the most cited long-term dissatisfaction driver. A 2025 case-based ethics/psychology paper (PMID:40888655) specifically examines a child assigned female at birth who later expressed male gender identity, highlighting the complexity of early, potentially irreversible sex-assignment decisions.
  • Mortality: No MGD-specific mortality/survival statistics (e.g., 5-/10-year survival rates) were identified — consistent with this being primarily a developmental/endocrine/oncologic-risk condition rather than one with an intrinsically shortened lifespan, aside from the malignancy risk mitigated by gonadal surveillance/gonadectomy.

12. Treatment

Sex assignment/multidisciplinary management: Modern practice has shifted from historical universal female assignment with prophylactic gonadectomy toward individualized, patient/family-centered, multidisciplinary decision-making that weighs genital anatomy, internal reproductive structures, gonadal function, fertility potential, prenatal androgen exposure, malignancy risk, and psychosocial/cultural factors, with a general trend toward deferring irreversible interventions where feasible (PMC12757904/Giri et al. 2025).

Surgical management (NCIT-mappable): - Gonadectomy — bilateral for female-assigned patients with non-functional streak gonads (early childhood); early removal of a retained dysgenetic testis in most cases unless testosterone production is adequate and formal surveillance is feasible; preservation favored for a morphologically normal, fully descended testis (with lifelong self-exam/imaging surveillance). → NCIT:C15329 (Surgical Procedure) or a more specific gonadectomy/orchiectomy NCIT term if available. - Laparoscopic streak-gonad excision — preferred approach given malignancy risk. - Hypospadias repair — staged, typically after confirmation of male sex of rearing. → NCIT:C15329 / relevant urologic-procedure term. - Gonadal relocation (intra-abdominal gonad repositioned to labioscrotal fold) to facilitate examination/surveillance. - Clitoral recession — reported in female-reared cases with clitoromegaly. - Gonadal tissue cryopreservation — emerging fertility-preservation strategy performed at the time of gonadectomy in patients with retained germ cells.

Hormonal therapies (NCIT:C15986 Pharmacotherapy, generally): - Growth hormone (recombinant human GH): improves growth velocity/final height (paralleling Turner syndrome response); typical initiation age 4–6 years. - Puberty induction, males: low-dose intramuscular testosterone injections (every 4–6 weeks) with gradual dose escalation over several years; transdermal formulations for maintenance. - Puberty induction, females: low-dose transdermal or oral estradiol starting ~age 11–12, gradually increased over 2–3 years; progestogen added if breakthrough bleeding occurs and a uterus is present; long-term hormone replacement continued to approximate natural menopause age (~50 years).

Assisted reproduction: Testicular sperm extraction (TESE) reported in isolated cases; gonadal tissue cryopreservation for prepubertal fertility preservation is an active area of clinical development rather than standard-of-care.

Supportive/psychosocial care: Proactive psychological support for parents around diagnosis disclosure, and for patients around body image and evolving gender identity through childhood/adolescence, is increasingly emphasized given documented gaps in current provision (~50% of parents reporting unmet psychosocial-support needs).

Emerging/experimental approaches: - Biomarker-driven surveillance — circulating microRNA markers (notably miR-371a-3p) are being investigated as liquid-biopsy tools for early germ cell tumor detection, potentially allowing more conservative (gonad-sparing) surveillance strategies instead of universal prophylactic gonadectomy. - Shared decision-making tools — web-based decision aids for gonadal/genital surgery choices are in development and validation.

Treatment strategy/algorithm: Management is explicitly multidisciplinary team (MDT)-based (pediatric endocrinology, urology/surgery, genetics, psychology, and the family), with transition planning to adult care ideally beginning at age 12–13, and dedicated transition clinics or joint pediatric–adult MDT models cited as improving long-term follow-up adherence.

Reported treatment outcomes: In one 10-patient cohort, gonadectomy was followed by spontaneous partial regression of phallus size (0.5–1 cm reduction over 6 months–1 year) in female-reared cases; no patients in that cohort opted for GH therapy, illustrating real-world variability in uptake of available interventions.

13. Prevention

MGD arises from a sporadic post-zygotic somatic chromosomal event, so there is no established primary prevention (no known modifiable risk factor to intervene upon) — this parallels the absence of identified environmental/lifestyle risk factors in Section 5.

Secondary prevention (early detection/treatment): - Prenatal detection via amniocentesis karyotype (incidental finding, e.g., in the context of NIPT flagging or other indications) allows early counseling and postnatal targeted evaluation, though phenotype cannot be reliably predicted from amniotic-fluid cell-line ratios, which is a significant counseling limitation. - Postnatal clinical vigilance for atypical genitalia at birth, or short stature/delayed puberty in later childhood, prompts karyotype-based diagnosis.

Tertiary prevention (preventing complications in diagnosed individuals): - Gonadal malignancy prevention: risk-stratified gonadectomy or biomarker-based surveillance (see Treatment section) is the primary tertiary-prevention strategy, directly reducing progression from gonadoblastoma/germ cell neoplasia in situ to invasive dysgerminoma. - Growth hormone therapy as tertiary prevention of adult short stature. - Cardiovascular/renal/metabolic surveillance (echocardiography, renal imaging, blood pressure, lipid/glucose monitoring into adulthood) to preempt the Turner-like long-term morbidity pattern (hypertension, dyslipidemia, type 2 diabetes by ~age 40). - Autoimmune thyroid screening given the ~40% prevalence of autoimmune thyroid disease in some cohorts.

Genetic counseling: Central to prevention/family-planning discussion is communicating the sporadic, non-heritable nature of the mosaicism (low recurrence risk in future pregnancies) while managing the substantial uncertainty in prenatal phenotype prediction.

Screening programs: No population-based newborn or prenatal screening program specific to MGD exists; detection remains opportunistic (incidental prenatal karyotype, or postnatal clinical suspicion).

14. Other Species / Natural Disease

No literature was identified describing naturally occurring 45,X/46,XY mosaic gonadal dysgenesis as a spontaneous veterinary disease (e.g., in OMIA or companion-animal case series) in this search pass — this is a plausible gap rather than a confirmed absence, and a dedicated OMIA/veterinary-literature search would be needed to confirm whether analogous XX/XY chimerism-associated intersex conditions are documented in domestic species (freemartinism in cattle, driven by placental blood-chimerism rather than post-zygotic mosaicism, is a related but mechanistically distinct veterinary phenomenon and was not directly evaluated here).

Comparative biology: The core testis-determination pathway (SRY → SOX9 → FGF9, antagonized by WNT4/RSPO1/β-catenin) is evolutionarily conserved across mammals, and the mechanistic insight into MGD's cellular basis is drawn substantially from mouse developmental biology (see Section 15), rather than from naturally occurring disease in other species.

Zoonotic potential / transmission: Not applicable — MGD is a non-infectious, developmental chromosomal condition.

15. Model Organisms

No direct animal model of 45,X/46,XY mosaic MGD (i.e., a mouse engineered or arising spontaneously with somatic X0/XY mosaicism reproducing asymmetric gonadal dysgenesis) was identified in this search. Instead, the relevant model-organism literature addresses the underlying testis-determination pathway that MGD's asymmetric SRY-mosaic gonads perturb:

  • Sry/Sox9/Wnt4 mouse genetic models: Studies of Sox9 conditional knockout, Wnt4 knockout, and Sox9;Wnt4 double-mutant mice define how SRY-driven SOX9 activity antagonizes WNT4/RSPO1/β-catenin signaling to commit supporting cells to a testicular vs. ovarian fate (PMC7291083, "Mouse Gonad Development in the Absence of the Pro-Ovary Factor WNT4 and the Pro-Testis Factor SOX9," PMID:32365547). Key finding: Sox9 deletion in XY gonads causes ovarian-like development with ectopic WNT/β-catenin signaling, and SRY-positive supporting-cell precursors can adopt a female-like (pre-granulosa) identity; SOX9 is required for early male-supporting-cell specification independently of its role repressing RSPO1/WNT4/β-catenin.
  • Sry timing/chimera studies: "A critical time window of Sry action in gonadal sex determination in mice" (journals.biologists.com) defines the developmental window (~E10.5–E12.5) during which Sry must act to commit the gonad to a testicular fate — directly relevant to understanding how variable SRY⁺ cell proportion/timing in a mosaic human gonad could yield partial/asymmetric differentiation.
  • Other XY sex-reversal mouse models (cited peripherally in search results, not detailed here): Nedd4 loss-of-function causing complete XY gonadal sex reversal (PMC8786929); Fgfr2 "hobbyhorse" mutant causing complete XY gonadal sex reversal (PMC4067367) — these illustrate the broader genetic network in which SRY/SOX9 operate but are models of complete, not mosaic/asymmetric, sex reversal, and are not direct models of the human mosaic 45,X/46,XY karyotype.

Model limitations for dismech curation purposes: None of the mouse models identified reproduce the defining somatic chromosomal mosaicism of human MGD (they are typically full-body monogenic knockouts, not mitotic-mosaic chimeras of 45,X vs. 46,XY cell lines). Any pathophysiology node curated from these mouse studies should be flagged with evidence_source: MODEL_ORGANISM and, given the mechanistic (not mosaic-karyotype) nature of the models, likely warrants a HUMAN_MODEL_MISMATCH discussion node under dismech's schema — the models establish the SRY/SOX9/WNT4 causal logic convincingly, but do not themselves recapitulate the human mosaic/asymmetric-gonad phenomenon.

Applications: These models are primarily used to dissect the transcriptional antagonism between testis- and ovary-determining pathways at the cell-fate-decision level, which is directly explanatory (if not literally recapitulative) for why a mosaic human gonad can differentiate asymmetrically depending on local SRY⁺ cell fraction and timing.

Summary of Key Ontology-Term Suggestions for Curation

Category Suggested terms
MONDO MONDO:0015779 (verify via just validate-terms before use)
HPO (phenotype) HP:0000062 Ambiguous genitalia; HP:0000053 Clitoral hypertrophy; HP:0000047 Hypospadias; HP:0000028 Cryptorchidism; HP:0004322 Short stature; HP:0000465 Webbed neck; HP:0002967 Cubitus valgus; HP:0000085 Horseshoe kidney; HP:0001647 Bicuspid aortic valve; HP:0001680 Coarctation of aorta; HP:0000823 Delayed puberty; HP:0000789 Infertility; HP:0000850/HP:0100647 Autoimmune thyroid disease
GO (biological process) GO:0030238 Male sex determination; GO:0060008 Sertoli cell differentiation; GO:0001880 Müllerian duct regression; GO:0060065 Wnt signaling involved in female gonad development; GO:0007281 Germ cell development
CL (cell type) CL:0000216 Sertoli cell; CL:0000178 Leydig cell; CL:0000670/CL:0000586 Primordial/germ cell
UBERON (anatomy) UBERON:0000991 gonad; UBERON:0000473 testis; UBERON:0000992 ovary; UBERON:0000995 uterus; UBERON:0003508 Müllerian duct; UBERON:0001301 mesonephric (Wolffian) duct
HGNC (genes) SRY; SOX9; AMH; AMHR2; SHOX; MAP3K1; NR5A1; NR0B1 (DAX1); WT1
NCIT (treatment) NCIT:C15329 Surgical Procedure (gonadectomy, hypospadias repair); NCIT:C15986 Pharmacotherapy (testosterone/estradiol replacement, GH therapy)

Notable evidence gaps for curation: (1) no MGD-specific molecular/single-cell profiling of human dysgenetic gonadal tissue was located; (2) the DAX1-suppression hypothesis and several Turner-overlap CNS features (mild intellectual disability, autism) are reported inconsistently across cohorts and should be curated with appropriate frequency/directness caveats; (3) no dedicated animal model reproduces the mosaic karyotype itself, only the downstream SRY/SOX9/WNT4 pathway logic — curate any mouse-derived pathophysiology nodes as MODEL_ORGANISM evidence with a HUMAN_MODEL_MISMATCH discussion where appropriate; (4) OMIM/Orphanet/ICD numeric identifiers should be independently re-verified against primary sources (OMIM.org, Orphanet, WHO ICD-11 browser) before being written into a Disease.mappings block, since this session's GARD/Monarch fetches did not return the specific codes.

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome Count
References checked 29
Resolved 29
Unresolved (possible confabulation) 0
Unverifiable 0
References weighed for topical relevance 29
On topic 18
Off topic 0

All extracted references resolved successfully.

Term Validation

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

Outcome Count
Terms checked 51
Resolved 49
Unresolved (possible confabulation) 1
Obsolete 0
Unverifiable 1
Terms whose name was checked 20
Terms named correctly 14
Terms named as a different term 5
Terms whose name is worth a second look 1

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

  • MONDO:0015779 (4 mentions) - the report calls it "45,X/46,XY mixed gonadal dysgenesis", "verify via just validate-terms before use"; MONDO calls it 45,X/46,XY mixed gonadal dysgenesis
  • HP:0000053 (2 mentions) - the report calls it "Clitoral hypertrophy"; HP calls it Macroorchidism
  • HP:0000407 (1 mention) - the report calls it "10% in one cohort"; HP calls it Sensorineural hearing impairment
  • CL:0000501 (1 mention) - the report calls it "approximate"; CL calls it granulosa cell
  • UBERON:0000991 (2 mentions) - the report calls it "Suggested UBERON terms: gonad"; UBERON calls it gonad

Unresolved terms

These identifiers do not exist in an ontology that resolved other terms from the same prefix, so they were most likely invented:

  • HP:0000850 (2 mentions) - HP does not contain this term

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

  • GO:0001880 (2 mentions) - the report calls it "Müllerian duct regression"; GO calls it Mullerian duct regression

Terms named inconsistently

The report gives these identifiers more than one name of its own:

  • MONDO:0015779 - called "45,X/46,XY mixed gonadal dysgenesis", "verify via just validate-terms before use"

Prefixes with no resolver

Terms carrying these prefixes were not checked either way, because no configured ontology covers them. An unrecognised prefix may name an ontology this run could not reach as easily as one that does not exist, so nothing here is evidence of fabrication: ORPHA.