INSIG2 and obesity due to melanocortin 4 receptor deficiency: Genetic variations in the obesity-related genes beta-2 adrenergic receptor (ADRB2), beta-3 adrenergic receptor (ADRB3), insulin induced gene 2 (INSIG2), and peroxisome proliferator-activated receptor gamma (PPARγ) are also included in our study [9].