[Incomplete androgen insensitivity syndrome. Difficulties of diagnosis and management].

A familial form of incomplete androgen insensitivity syndrome (AIS) is reported. The index case was first seen at 9 months of age for ambiguous genitalia. Diagnosis of AIS, suspected but first discarded on the basis of an androgen sensitivity test, was finally made at puberty on the discordance between poor virilization and elevated levels of both testosterone and LH, a florid gynecomastia, and the exclusion of any enzymatic defect in testosterone biosynthesis of 5 alpha-reductase deficiency. Androgen receptors in public skin were within the limits of normal for total number, with normal affinity. Familial occurrence included 2 first cousins born 7 and 10 years later, a maternal grand-uncle with similar ambiguous genitalia, and a maternal uncle with the gynecomastia-preserved fertility syndrome. This case report illustrates the heterogeneity of AIS in a given family and the difficulty of and early positive diagnosis in a newborn presenting with sexual ambiguity.