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#XX mammals

2 public questions tagged with this topic.

Sex determination-l

Which gene mutation can cause XX mammals to develop testes?

Dataset key indicates mutation causing XX mammals to develop testes listed is Rspo1, illustrating ovary-maintenance failure leading to masculinization. Classically XX sex reversal with complete testes also arises from Sox9 enhancer duplication or gain-of-function rearrangements upregulating Sox9 independent of Sry, or from FOXL2 loss. However provided options highlight Rspo1 loss which eliminates Wnt4/β-catenin reinforcement, permitting Sox9/Fgf9 male program to dominate even without Sry. Such XX individuals develop testes, male internal ducts and external masculinization despite absence of Y, recapitulating human RSPO1-related disorder of sex development.

Ref: Nature Genetics, RSPO1 loss causes XX testes; Gilbert Chapter 6: Genes causing XX sex reversal.

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sex determination-ll

XX mammals lacking Wnt4 exhibit:

Wnt4 indispensably maintains ovarian identity in XX mammals; its absence causes masculinization. Knockout XX mice display perinatal partial sex reversal with testis-like coelomic vessel development, ectopic steroidogenic cells synthesizing testosterone, persistence of Wolffian duct remnants, reduction of Müllerian ducts due to reduced Fst, and transdifferentiation of granulosa precursors. Germ cell meiosis entry fails, follicles deplete resembling polycystic phenotype. Human WNT4 mutations associate with androgen excess and absence of Müllerian structures. Phenotype reflects derepression of Sox9/Fgf9 male program when Wnt4/β-catenin antagonism removed.

Ref: NCBI, Wnt4 knockout phenotype - masculinized XX gonads; Gilbert Chapter 6 Ovarian maintenance.

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