If the extremes have different genetic inheritance or are etiologically more homogenous than the full distribution, analyzing extremes or tails of the distribution by case-control design may offer superior power. To test this empirically, we conducted meta-analyses of the full distributions of BMI and height with all studies included in stage 1 and stage 2. Only two (IGFBP4 and H6PD) out of four novel loci for tails of height reached genome-wide significance (P<5×10-8) using the full height distribution (Table 2). Four (GNAT2, ZZZ3, HNF4G, and RPTOR) out of seven novel loci identified for clinical classes of obesity achieved genome-wide significance for the full BMI distribution. The remaining loci had P-values <5×10-5 in the full distribution and thus, would likely have been detected with a larger sample size.
