[Rare structural rearrangement of the Y chromosome (Yq-,S) in the family of a boy with a sex differentiation disorder].

In an 8-year old boy with bilateral cryptorchism the heterochromatin region deletion of Y-chromosome and the satellites in its long arm were found (karyotype 46, XYq-S). The same Y-chromosome was found in proband's father. Moreover, the proband had large brilliant satellites in the chromosome 22 and a very large segment of centromeric heterochromatin in the chromosome 1; both were inherited from his mother. The abnormal Y-chromosome is, probably, due to an exchange with heterochromatin regions between an acrocentric chromosome and Y-chromosome. The combination of above peculiarities of proband's chromosome set is supposed to promote the sex differentiation disorders in embryogenesis which led to an incomplete masculinization.