[Genetic of the 21 hydroxylase deficiency].

A dose genetic linkage exist between the HLA complex (especially HLA-B), and the 21 hydroxylase deficiency form of adrenal hyperplasia. By their polymorphisms HLA antigens can be used as "markers" to follow the segregation of 21-OH deficiency in families, to diagnose the heterozygous offspring and eventually to offer a prenatal diagnosis to couples at risk. In late onset forms of 21-OH deficiency the same genetic linkage has been demonstrated with a high frequency of HLA-B14 antigen.