Racial variation of a non-fluorescent segment of the Y chromosome in East Indians.

Seventy normal male East Indians were selected to study the length of the fluorescent (f), non-fluorescent (nf), and total length of the Y chromosome by the QFQ technique. The length of the Y chromosome was classified into five groups using subjectively defined criteria, namely, very small, small, average, large, and very large. The frequencies of Y/F indices for these groups were 0.0%, 1.42%, 15.71%, 58.57%, and 24.28%, respectively. The variation in the total length of the Y chromosome was accounted for by variations in the length of the nf as well as the f segments. The mean Y/F, f/F, and nf/F indices for East Indians were 1.20, 0.47, and 0.73, respectively. A longer Y was noted in East Indians primarily owing to an increase in size of the nf segment in comparison to normal black and Caucasian populations. Furthermore, it is emphasised that the definition of 'average' or 'large' Y varies from race to race.