[Genetic aspects of the 46, XX male].

The XX males represent a proportion of 1/25 of all patients suffering of the Klinefelter syndrome. From a clinical and endocrinological point of view, they exhibit a hypogonadotropic hypogonadism. Isolated cases are rare and familial forms are exceptional. The XX males may be divided in 3 subgroups: 46, XX males with the SRY gene; 46, XX males without the SRY gene and XX/XY mosaics.