A total of 9 of the 6,547 individuals harbored one of the 4 pathogenic MC4R variants, corresponding to a prevalence of 0.14% (95% confidence interval [CI] 0.06 to 0.26%). Subsequent unblinding of phenotype information revealed that average BMI of these 9 carriers was 32.5 kg/m2 as compared to 28.4 kg/m2 in the remainder of the population, a difference of 4.1 kg/m2 (95% CI 0.8 to 7.3; p = 0.02). However, consistent with recent observations of incomplete penetrance in an adult population (Turcot et al., 2018), only one of the 9 carriers was severely obese. An additional 3 were obese, and the remaining 5 were overweight but not obese.
