INTERSEX: MALE PSEUDOHERMAPHRODITISM II HORMONAL
There are several disorders of sexual development that are accompanied by a normal karyotype (46,XY male) and are characterized by hormonal perturbations that induce sexual ambiguity. Androgen insensitivity syndrome (AIS), also referred to as androgen resistance syndrome, is a form of male disordered sex development caused by mutations of the gene encoding the androgen receptor (located on Xq11–12, X-linked recessive trait). More than 100 androgen receptor mutations causing AIS have been reported. Most forms of AIS involve variable degrees of undervirilization and/or infertility, but the degree of ambiguity varies according to the structure and sensitivity of the abnormal receptor. Reifenstein syndrome is a form of AIS with obviously ambiguous genitalia, small testes in the abdomen or scrotum, sparse to normal androgenic hair, and gynecomastia at puberty. In more subtle cases, AIS due to a mild, partial androgen receptor defect can present simply as male infertility with a low ejaculated sperm concentration.
An individual with complete androgen insensitivity syndrome (CAIS, 1:20,000 births) has an entirely female external appearance, including undescended testes, despite the normal male karyotype. They are psychosexually female, in accordance with their external appearance and genitalia. The clitoris and vagina may be underdeveloped. Bimanual palpation reveals no evidence of internal genitalia (e.g., cervix, uterus) which can be conﬁrmed laparoscopically. The testes may be found in inguinal hernias, in the canals, or intraabdominally. They appear as typical immature, undescended testes but are at higher risk for malignant degeneration (4%-9% chance) and should be removed. With AIS, medical attention is sometimes sought because of the sudden appearance of testes within the inguinal canals during pubescence, although the most common presentation is primary amenorrhea. It should be distinguished from another condition that presents with primary amenorrhea, vaginal underdevelopment, and absence of female internal genitalia in 46,XX females due to inappropriate MIS production and termed Mayer– Rokitansky–Küster–Hauser (MRKH) syndrome.