PHENOTYPIC DIVERSITY IN SIBLINGS WITH PARTIAL ANDROGEN INSENSITIVITY SYNDROME

The androgen insensitivity syndrome is a heterogeneous disorder with a wide spectrum of phenotypic abnormalities, ranging from complete fema le to ambiguous forms that more closely resemble males. The primary ab normality is a defective androgen receptor protein due to a mutation o f the androgen receptor gene. This prevents normal androgen action and thus leads to impaired virilisation. A point mutation of the androgen receptor gene affecting two siblings with partial androgen insensitiv ity syndrome is described. One had cliteromegaly and labial fusion and was raised as a girl, whereas the other sibling had micropenis and pe noscrotal hypospadias and was raised as a boy. Both were shown to have the arginine 840 to cysteine mutation. The phenotypic variation in th is family is thus dependent on factors other than abnormalities of the androgen receptor gene alone.