Ancestral heterogeneity in a biethnic stroke population

Ann Hum Genet. 2011 Jul;75(4):508-15. doi: 10.1111/j.1469-1809.2011.00657.x.


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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • European Continental Ancestry Group*
  • Female
  • Gene Frequency
  • Genetic Markers
  • Humans
  • Indians, North American
  • Ischemic Attack, Transient / ethnology*
  • Ischemic Attack, Transient / genetics*
  • Male
  • Mexican Americans / genetics*
  • Middle Aged
  • Polymorphism, Single Nucleotide
  • Risk Factors
  • Stroke / ethnology*
  • Stroke / genetics*


  • Genetic Markers