INSIG2 and obesity due to melanocortin 4 receptor deficiency: In a study of subjects ages 11 to 60 years, Herbert et al. found that the mean BMI of rs7566605 CC homozygotes under a recessive model was 0.60 kg/m2 higher than for GC or GG genotypes (p = 0.0008).1 Since then, some studies have replicated these results6–11 while other studies have not.12–20 Despite the finding in a few studies that INSIG2 is not associated with the risk for obesity, the finding of a positive association in five cohorts is unlikely a false positive finding.18–21 No study to date, however, has addressed this issue in young children.