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.
