We compared the global pattern of variation at two homologous microsatellites mapping to the long arm of the X chromosome (DXYS156X) and to the short arm of the Y chromosome (DXYS156Y) in humans. A single pair of oligonucleotide primers amplifies these two nonallelic loci, each of which contains polymorphism in the number of pentanucleotide units. We observed 11 alleles in a sample of 2290 X chromosomes and 2006 Y chromosomes from 50 populations representing 6 major geographic regions. The overlapping size range of the Xand Y-chromosome alleles indicated a more complex distribution of alleles at these two loci than previously reported. Contrasting patterns of X-chromosome-linked and Y-chromosome-linked variation were reflected in statistically significant differences in genetic diversity values among geographic regions and between X and Y chromosomes. Higher levels of diversity characterized the DXYS156X locus in Africa (0.799 ± 0.004) and the DXYS156Y locus in East Asia (0.700 ± 0.006) compared with populations from other regions. These different patterns of variation can be explained by a combination of processes at both the molecular and population levels, including variable mutation rates, different effective population sizes, and genetic drift.
Karafet, Tatiana; De Knijff, Peter; Wood, Elizabeth; Ragland, Jared; Clark, Andrew; and Hammer, Michael F.
"Different Patterns of Variation at the X- and Y-Chromosome-Linked Microsatellite Loci DXYS156X and DXYS156Y in Human Populations,"
6, Article 1.
Available at: http://digitalcommons.wayne.edu/humbiol/vol70/iss6/1