title: Different patterns of variation at the X- and Y-chromosome-linked microsatellite loci DXYS156X and DXYS156Y in human populations.
abstract: 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 X- and 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.
authors.affiliation: Laboratory of Molecular Systematics and Evolution, University of Arizona, Tucson 85721, USA.
authors.forename: T
authors.initials: T
authors.lastname: Karafet
authors.forename: P
authors.initials: P
authors.lastname: de Knijff
authors.forename: E
authors.initials: E
authors.lastname: Wood
authors.forename: J
authors.initials: J
authors.lastname: Ragland
authors.forename: A
authors.initials: A
authors.lastname: Clark
authors.forename: M F
authors.initials: MF
authors.lastname: Hammer
mesh_terms: D000465:Algorithms; D000483:Alleles; D002874:Chromosome Mapping; D005260:Female; D005787:Gene Frequency; D005828:Genetics, Population; D006239:Haplotypes / Q000235:genetics; D006579:Heterozygote; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics*; D016133:Polymerase Chain Reaction; D044469:Racial Groups / Q000235:genetics*; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D014960:X Chromosome / Q000235:genetics*; D014998:Y Chromosome / Q000235:genetics*