PNPLA2 and obesity due to melanocortin 4 receptor deficiency: The study showed that obesity per se was not linked directly to cholelithiasis risk, and it was highly probable that both share several pathophysiologic and genomic pathways [27]: On the one hand, hormone-sensitive lipase and adipose triglyceride lipase, discovered recently in adipose tissue, mediate the mobilization of stored triacylglycerol [28].