LEP and obesity due to melanocortin 4 receptor deficiency: Like adiponectin and visfatin,[8,9] leptin was also known as a adipokine,[10] It was earliest found to play an important role in energy metabolism[11] because it could lead to a loss of appetite and an increased energy consumption.[12] Leptin levels in obesity, in turn, were significantly elevated in the human body.[13] Due to its high serum levels in high weight individuals and the relieving joint symptoms by losing weight in OA patients,[14,15] we hypothesized that leptin has some connections with OA caused by obesity.