[1] Penn State Univ, Dept Anthropol, University Pk, PA 16802 USA
[2] London Sch Hyg & Trop Med, Dept Epidemiol & Populat Hlth, London, England
[3] Univ Pittsburgh, Dept Human Genet, Pittsburgh, PA USA
[4] Univ Mississippi, Med Ctr, Dept Med, Jackson, MS 39216 USA
[5] Univ Texas, Ctr Human Genet, Houston, TX USA
[6] Univ Texas, Inst Mol Med, Houston, TX USA