Fluorescence study of interphase nuclei and double Y chromosomes

A study was made of 118 institutionalized mentally handicapped men with behaviour disorders in order to screen the occurrence of double Y-chromosomes. The screening was based on identifying the extra Y-chromosomes in the interphase nuclei by fluorescence. Our intention was to test the sentisivity of this method in that respect. Altogether, we found 8 cases with cells having more than one brightly fluorescing area, and two of them proved by ordinary blood karyotyping to have double Y-chromosomes. It is known that other areas than those in the Y-chromosome may fluoresce. Thus by using interphase nuclei to determine the frequency of double Y-chromosomes by fluorescence, a number of falsely positive results is given. Nevertheless, we have found the procedure extremely valuable for screening purposes.