POMC and obesity due to melanocortin 4 receptor deficiency: In 3/37 cases, a heterozygous mutation/CNV was identified (in 2 patients in POMC and in 1 patient in PCSK1), which constitutes important genetic risk factors for early-onset obesity as demonstrated in association studies, [27, 39] in contrast to their autosomal recessive forms which cause a more severe clinical phenotype (S1 Appendix).