The obesity GRSs performed similarly on the 3 predictiveness metrics (Table 2). The top panel of Table 3 addresses clinical validity. It presents the 3 metrics for the un-weighted and weighted GRSs. Among whites, weighted and un-weighted obesity GRSs explained small, but statistically significant proportions of the variance in BMI (R2), discriminated obese from non-obese participants modestly better than chance (AUC), and contributed small net improvements to the sensitivity of an obesity prediction model over and above demographic and geographic information (IDI). Among African Americans, the GRS did not contribute to the explanation of variance in BMI over and above demographic and geographic information, to the discrimination of obese from non-obese participants, or to the net sensitivity of the obesity prediction model. Use of weights derived from BMI GWAS improved the performance of the GRS among whites and African Americans, but this improvement was not statistically significant (p>0.10 for all comparisons).
