IGF1 and obesity due to melanocortin 4 receptor deficiency: In a mouse obesity model, a decrease in Crem, adaptor protein 1 (Sh2b1), desert hedgehog (Dhh), insulin-like growth factor 1 (Igf1) and leptin receptor (Lepr) transcript levels was observed, resulting in impaired fertility, such as a reduced sperm motility and decreased mating rates of obese males with female mice [62].