FTO and obesity due to melanocortin 4 receptor deficiency: We were struck by the observation that 122 PC1-associated loci were already present in the GWAS catalog18 or Neale Lab GWAS (http://www.nealelab.is/uk-biobank/), and of these, 83 were associated with intelligence or cognitive ability, educational attainment, or obesity-related anthropometric traits, including rs1421085 in FTO and rs429358 in APOE (Supplementary Data 4).