46,XY Disorders of Sex Development (46,XY DSD) due to Androgen Receptor Defects: Androgen Insensitivity Syndrome
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Androgen insensitivity syndrome (AIS) is a rare X-linked disorder in which 46,XY subjects have complete (CAIS) or partial (PAIS) impairment of androgen action due to abnormalities of the androgen receptor (AR). We studied 25 Brazilian subjects with AIS confirmed by identification of mutations in the AR and concluded that (1) identification of mutations in the AR is essential to classify patients with 46,XY DSD as PAIS; (2) family history and gynecomastia were useful to select patients for genetic studies; (3) gynecomastia developed in CAIS due to unopposed effect of normal estrogen levels; (4) absence of axillary hair was a better indicator of CAIS than absence of pubic hair; (5) serum LH and LH × T product were elevated in all pubertal patients, while testosterone was normal or elevated and serum FSH normal in most patients; (6) phallic size and its response to high-dose testosterone therapy were usually subnormal, but variable in PAIS; (7) in patients with female social sex, vaginal dilation was useful to obtain an adequate length for sexual intercourse; (8) all PAIS raised as girls as well as those raised as boys maintained gender assigned before puberty, despite overlap in phallic size at puberty; (9) adult height was intermediate between normal males and females; and (10) low spine BMD before gonadectomy and even in estrogen-compliant CAIS may reflect androgen resistance at the bone level.
KeywordsAndrogen Receptor Adult Height Pubic Hair Androgen Receptor Gene Androgen Action