Spatial relationship of human X and Y chromosomes at somatic metaphase.

A total of 592 cells was examined from 38 normal humans who had either small or very large Y chromosomes. Chromosome identification was based on the QFQ technique. The distance between the X and Y chromosome was measured from centromere to centromere. The spatial distance between X and Y was significantly smaller when the Y was small as compared to a very large Y (p less than 0.05). The distance increased as the length of the Y chromosome increased and a significant correlation coefficient (r = 0.58) was found (p less than 0.05). It is concluded that the length of the Y chromosome appears to play a major role in the non-random distribution of X and Y at somatic metaphase. The size and XY relationship in aneuploidy resulting from paternal non-disjunction and in patients with XXY and XYY should be investigated.