a, The estimated variance in BMI explained by SNPs selected at a range of P values using unrelated individuals from the QIMR (n = 3,924; purple) and TwinGene (n = 5,668; gold), their weighted average (cyan), inferred from within-family prediction (red; Extended Data Fig. 2), and by all HapMap phase III SNPs in 16,275 unrelated individuals from the QIMR, TwinGene and ARIC studies (orange). b, Plot of the region surrounding MC4R (ref. 36). SNP associations from the European sex-combined meta-analysis are plotted with joint conditional P values (Pj) indicated for the three conditionally significant signals. SNPs are shaded and shaped based on the index SNP with which they are in strongest LD (rs6567160 in blue, rs994545 in yellow and rs17066842 in green).