Human chromosomal heteromorphisms in American blacks. VI. Higher incidence of longer Y owing to non-fluorescent (nf) segment.
Sixty normal male American blacks were selected to study the length of 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: very small, small, average, large, and very large. The frequencies of Y/F indices for these groups were 0.0, 3.33, 56.67, 30.00, and 10.00%, 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 segment. A longer Y was noted in blacks owing to an increase in size of the nf segment in comparison with a normal Caucasian population. Forty percent of American blacks had large or very large Y chromosomes, while this class comprised only 18.3% of Caucasians, which is significantly different (p less than 0.05). Furthermore, the length of the Y chromosome was normally distributed among Caucasians, while among blacks the distribution was skewed to the left. The mean Y/F, f/F, and nf/F indices were 1.09 +/- 0.10, 0.42 +/- 0.09, and 0.67 +/- 0.04, respectively.
D044383:Black People; D006801:Humans; D008297:Male; D008856:Microscopy, Fluorescence; D012729:Sex Chromosome Aberrations / Q000453:epidemiology*; D012730:Sex Chromosomes; D014481:United States; D014998:Y Chromosome; D001741:Black or African American