Androgen receptor (AR) gene mutations are the most frequent cause of 46,XY disorders of sex development (DSD), and are associated with a variety of phenotypes ranging from phenotypic women (Complete Androgen Insensitivity Syndrome or CAIS) to milder degrees of undervirilisation (Partial Androgen Insensitivity Syndrome or PAIS) or men with infertility only (Mild Androgen Insensitivity Syndrome or MAIS).
We have characterized two different mutations of the human androgen receptor (hAR) found in two unrelated subjects with androgen insensitivity syndrome (AIS): in one, the external genitalia were ambiguous (partial, PAIS); in the other, they were male, but small (mild, MAIS).
The activity of 5 alpha-reductase and the binding of androgen to its receptor (KD-values, Bmax, thermolability) were determined in genital skin fibroblasts from 20 patients with various degrees of defects in virilization (2 CAIS, complete AIS; 18 PAIS, partial AIS patients).