INS and obesity due to melanocortin 4 receptor deficiency: In the first approach, we reproduced the five subgroups reported by Ahlqvist et al.9: cluster 1 (obesity-related, 73%), cluster 2 (age-related, 10%), cluster 3 (autoimmune-related, 5%), cluster 4 (insulin-deficient, 7%), and cluster 5 (insulin-resistant, 5%).