CHI3L1 and obesity due to melanocortin 4 receptor deficiency: Chitinases, chitotriosidase (CHIT1), acidic mammalian chitinase (AMCase or CHIA), and nonenzymatic chitinase-3-like protein 1 (CHI3L1) have been implicated in various pathological conditions, such as Gaucher’s disease (CHIT1), obesity, diabetes, cardiovascular diseases, and asthma (CHIA) [17,31].