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46,XY true hermaphroditism, SRY-related

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Description

Individuals with 46,XY complete gonadal dysgenesis are phenotypically female; however, they do not develop secondary sexual characteristics at puberty and do not menstruate. They have bilateral 'streak gonads,' which typically consist of fibrous tissue and variable amounts of wavy ovarian stroma. A uterus and fallopian tube are present and external genitalia are female (reviewed by Berkovitz et al., 1991). Genetic Heterogeneity of 46,XY Sex Reversal Male sexual determination is initiated by Y-chromosomal SRY, which activates a cascade of genes that lead the embryonic gonad to develop into a testis. Fetal testicular Sertoli cells then produce mullerian inhibitory substance (600957), which is responsible for the involution of the mullerian ducts, which would otherwise develop into the uterus, fallopian tubes, and cervix. Fetal testicular Leydig cells produce testosterone from cholesterol by the sequential action of a series of enzymes. Subsequent differentiation of male external genitalia also requires the action of dihydrotestosterone, produced from testicular testosterone. Perturbations in the enzymes in this classic pathway or in an alternative pathway of testicular androgen biosynthesis can result in genetic males with disordered sexual development and incompletely developed ('ambiguous') external genitalia (summary by Fluck et al., 2011). Disorders of male development for which a genetic cause has been found include 46,XY sex reversal-2 (SRXY2; 300018), which is caused by duplication of the NR0B1 gene (300473) on chromosome Xp21.3-p21.2; SRXY3 (612965), caused by mutation in the NR5A1 gene (184757) on chromosome 9q33; SRXY4 (154230), caused by deletion on chromosome 9p24.3; SRXY5 (613080), caused by mutation in the CBX2 gene (602770) on chromosome 17q25; SRXY6 (613762), caused by mutation in the MAP3K1 gene (600982) on chromosome 5q11.2; SRXY7 (233420), caused by mutation in the DHH gene (605423) on chromosome 12q13; SRXY8 (614279), caused by mutation in the AKR1C2 gene (600450) on chromosome 10p15, with a possible contribution from the closely linked AKR1C4 gene (600451); SRXY9 (616067), caused by mutation in the ZFPM2 gene (603693) on chromosome 8q23; and SRXY10 (616425), caused by deletion of the XYSR regulatory region -640 kb upstream of the SOX9 gene (608160) on chromosome 17q24. Wilhelm and Koopman (2006) reviewed male sexual development and the genetics of disorders of human sexual development, noting that most cases of XY sex reversal, SRY-negative XX sex reversal, and true hermaphroditism remained unexplained at the molecular level.

OMIM

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      • OMIM
      • Orphanet
      • HPO
      • Medgen

        C2748897

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