Although we excluded related individuals in our primary GWAS analyses, a small portion (5.9%) of the replication samples were relatives. Therefore, generalized estimating equations (GEE) were applied to fit the logistic regression model in the replication samples to account for the correlated data from individuals in the same family. The GEE logistic regression estimates the same model as the standard logistic regression. Unlike standard logistic regression, GEE logistic regression allows for dependence (such as related individuals) within clusters (29). The logistic regression models were adjusted by age and sex.
