title: Population structure of Y chromosome SNP haplogroups in the United States and forensic implications for constructing Y chromosome STR databases.
abstract: A set of 61 Y chromosome single-nucleotide-polymorphisms (Y-SNPs) is typed in a sample of 2517 individuals from 38 populations to infer the geographic origins of Y chromosomes in the United States and to test for paternal admixture among African-, European-, Hispanic-, Asian-, and Native-Americans. All of the samples were previously typed with the 11 core U.S. Y chromosome short tandem repeats (Y-STRs) recommended by SWGDAM, which revealed high levels of among ethnic group variation and low levels of among-population-within-ethnic-group variation. Admixture estimates vary greatly among populations and ethnic groups. The frequencies of non-European (3.4%) and non-Asian (4.5%) Y chromosomes are generally low in European-American and Asian-American populations, respectively. The frequencies of European Y chromosomes in Native-American populations range widely (i.e., 7-89%) and follow a West to East gradient, whereas they are relatively consistent in African-American populations (26.4+/-8.9%) from different locations. The European (77.8+/-9.3%) and Native-American (13.7+/-7.4%) components of the Hispanic paternal gene pool are also relatively constant among geographic regions; however, the African contribution is much higher in the Northeast (10.5+/-6.4%) than in the Southwest (1.5+/-0.9%) or Midwest (0%). To test for the effects of inter-ethnic admixture on the structure of Y-STR diversity in the U.S., we perform subtraction analyses in which Y chromosomes inferred to be admixed by Y-SNP analysis are removed from the database and pairwise population differentiation tests are implemented on the remaining Y-STR haplotypes. Results show that low levels of heterogeneity previously observed between pairs of Hispanic-American populations disappear when African-derived chromosomes are removed from the analysis. This is not the case for an unusual sample of European-Americans from New York City when its African-derived chromosomes are removed, or for Native-American populations when European-derived chromosomes are removed. We infer that both inter-ethnic admixture and population structure in ancestral source populations may contribute to fine scale Y-STR heterogeneity within U.S. ethnic groups.
authors.affiliation: Division of Biotechnology, University of Arizona, Tucson, AZ 85721, USA. mfh@u.arizona.edu <mfh@u.arizona.edu>
authors.forename: Michael F
authors.initials: MF
authors.lastname: Hammer
authors.forename: Veronica F
authors.initials: VF
authors.lastname: Chamberlain
authors.forename: Veronica F
authors.initials: VF
authors.lastname: Kearney
authors.forename: Daryn
authors.initials: D
authors.lastname: Stover
authors.forename: Gina
authors.initials: G
authors.lastname: Zhang
authors.forename: Tatiana
authors.initials: T
authors.lastname: Karafet
authors.forename: Bruce
authors.initials: B
authors.lastname: Walsh
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Redd
mesh_terms: D000704:Analysis of Variance; D041322:Chromosomes, Human, Y; D016172:DNA Fingerprinting; D019992:Databases as Topic; D053803:Forensic Genetics; D005828:Genetics, Population; D006239:Haplotypes; D006801:Humans; D020641:Polymorphism, Single Nucleotide; D044469:Racial Groups / Q000235:genetics*; D020080:Tandem Repeat Sequences; D014481:United States