title: Ancestral heterogeneity in a biethnic stroke population.
abstract: To test for and characterize heterogeneity in ancestral contributions to individuals among a population of Mexican American (MA) and non-Hispanic white (NHW) stroke/transient ischemic attack (TIA) cases, data from a community-based stroke surveillance study in south Texas were used. Strokes/TIA cases were identified (2004-2006) with a random sample asked to provide blood. Race-ethnicity was self-reported. Thirty-three ancestry informative markers were genotyped and individual genetic admixture estimated using maximum likelihood methods. Three hypotheses were tested for each MA using likelihood ratio tests: (1) H(0) : μi = 0 (100% Native American), (2) H(0) : μi = 1.00 (100% European), (3) H(0) : μi = 0.59 (average European). Among 154 self-identified MAs, estimated European ancestry varied from 0.26 to 0.98, with an average of 0.59 (SE = 0.014). We rejected hypothesis 1 for every MA and rejected hypothesis 2 for all but two MAs. We rejected hypothesis 3 for 40 MAs (20 < 59%, 20 > 59%). Among 84 self-identified NHWs, the estimated fraction of European ancestry ranged from 0.83 to 1.0, with an average of 0.97 (SE = 0.014). Self-identified MAs, and to a lesser extent NHWs, from an established bi-ethnic community were heterogeneous with respect to genetic admixture. Researchers should not use simple race-ethnic categories as proxies for homogeneous genetic populations when conducting gene mapping and disease association studies in multi-ethnic populations.
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA. llisabet@umich.edu
authors.forename: Lynda D
authors.initials: LD
authors.lastname: Lisabeth
authors.forename: Lewis B
authors.initials: LB
authors.lastname: Morgenstern
authors.forename: David T
authors.initials: DT
authors.lastname: Burke
authors.forename: Yan V
authors.initials: YV
authors.lastname: Sun
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Long
mesh_terms: D000368:Aged; D005260:Female; D005787:Gene Frequency; D005819:Genetic Markers; D006801:Humans; D007198:Indians, North American; D002546:Ischemic Attack, Transient / Q000208:ethnology* / Q000235:genetics*; D008297:Male; D017058:Mexican Americans / Q000235:genetics*; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors; D020521:Stroke / Q000208:ethnology* / Q000235:genetics*; D044465:White People
chemical_list: D005819:Genetic Markers