Phenotypically, cluster 4 individuals with obesity also exhibited consistently higher serum insulin levels (Fig. 5e); and while not different in height, BMI or relative fat mass (fat mass index; FatMI), cluster 4 individuals with obesity showed increased relative lean mass (lean mass index; LeanMI) (Fig. 5f). Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.