PIGZ and obesity due to melanocortin 4 receptor deficiency: In all three discovery analyses, in addition to loci mapping to established BMI and obesity loci, we identified PIGZ and C3orf38, two putative novel loci in the thin vs control analysis, that reached conventional genome-wide significance (GWS) (p≤5x10-8) (S5–S7 Tables, Fig 2).