In a previous exome-sequencing study of 2548 European ancestry patients with severe, early-onset obesity (mean body mass index [BMI] SD score > 3; age of onset < 10 years) (5), we reported rare heterozygous variants in the gene-encoding steroid receptor coactivator-1 (SRC-1) (6). Here, NCOA1 is linked to obesity due to melanocortin 4 receptor deficiency.