HTR1A and sudden infant death syndrome: In the socially disadvantaged cohort of the prospective Safe Passage Study from Cape Town, South Africa, and the Northern Plains of the United States, we tested the hypothesis that: 1) serotonin (5-HT) receptor 1A binding is reduced within the brainstem of SIDS infants compared to controls; and 2) reduced 5-HT1A binding in SIDS is associated with maternal drinking and/or smoking during pregnancy.