For cohorts 1 and 2, the associations of BMI Z-scores with SNPs were tested by linear regression under an additive model using the program QSNPGWA (www.phs.wfubmc.edu), with additional covariate adjustment for PC1. For cohorts 3–6, a variance component measured genotype method implemented in SOLAR (Almasy and Blangero 1998, http://txbiomed.org/departments/genetics/) was used for association tests in order to account for familial relationships within each cohort. Associations of BMI Z-scores with SNPs were tested under an additive model with adjustment for proportion of African ancestry. Familial correlation was accounted for using a kinship coefficient matrix, in which a correlation was calculated for each set of related pairs.
