MC4R. These variants were highly significant but had modest effects with 0.06–0.4 kg/m2 per allele change in BMI and modest obesity (BMI>30 kg/m2) odds ratios ranging 1.03–1.3. Although many loci are expected to contribute to a complex trait like BMI, the large number implied by the current result was unexpected to many (Yang et al. 2005; Maher 2008). Despite the large sample size (n >000), Willer et al. (2009) estimated 5–10% power to detect genome-wide significant variants with effect sizes of 0.06–0.1 BMI units per allele. Therefore, it is likely that many variants influencing BMI did not reach genome-wide significance in these metaanalyses.
