Peripheral location of the Y chromosome: relationship to race and length heteromorphism.

In the present report we examined the position of the Y chromosome with respect to its size and race to determine their relationship to its peripheral location. Peripheral blood lymphocytes were cultured from 172 normal male individuals (70 Asian Indians; 49 American Blacks; and 53 Caucasians) and 2770 QFQ cells were photographed. The length of the Y chromosome was classified into four groups i.e., small, average, large and very large as described earlier (Verma et al., J. Med. Genet., 15, 227-281, 1978). The average incidence of peripheral location of all races for small, average, large and very large was 3.64, 5.84, 10.51 and 11.17 per cent respectively. For blacks and caucasians, the peripheral location was influenced by its size while the incidence remained the same for Indians for all sizes. Consequently, it is presumed that the position of the Y chromosome in somatic metaphases depends upon race as well as its size. Furthermore, we have provided a method for determining the position of the Y chromosome which should suffice for most situations.