Incomplete regression of müllerian ducts in the androgen insensitivity syndrome.

The biochemical and histological features of two related patients with the complete form of the androgen insensitivity syndrome (AIS) coexisting with incomplete regression of the Müllerian ducts are described. Both patients presented unilateral Müllerian derivatives (fallopian tube) identified by microscopic examination of surgically excised internal genital tissue. Biochemical studies performed in genital skin-derived fibroblasts from one of the affected subjects showed the existence of a specific and saturable 8.2 to 8.4 S cytosolic and 3.4 S nuclear androgen receptor exhibiting a Kd of 1.32 nmol/L. These mutant cells, however, clearly presented a significantly low maximal nuclear [3H]-5 alpha-dihydrotestosterone uptake (71.0 fmol/mg of deoxyribonucleic acid [DNA]; control strain, 284 fmol/mg DNA). Thus, an impaired uptake of the androgen receptor complex at the nuclear level was probably the cause of the complete absence of phenotypic expression of androgen action in this family. The overall findings are on line with the well-demonstrated genetic and molecular heterogeneity of the AIS.