Results of Blood Chromosome Analyses in All Family Members

Chromosomal inversions appear to be common in many organisms, but their frequency in humans is not known. Routine human mitotic chromosome studies have shown few pericentric inversions, and meiotic studies, which can reveal pericentric and paracentric inversions, have been less extensively applied to human chromosomes. The evaluation of possible chromosomal inversions has also been limited by not being able to localize the few human linkage groups to specific chromosomes other than to the X chromosome. We here report studies of a Down's syndrome patient and his family in which an inherited pericentric inversion of the Y chromosome occurs.