ESR1 and obesity due to melanocortin 4 receptor deficiency: The risk factors for osteoarthritis include female sex [3], obesity [4], congenital or acquired defect in joint structure or function [5], certain systemic diseases [6], occupation, e.g., farmers, professional runners [7], and genetic factors—mutations in genes encoding collagen fibers (e.g., COL11A1), other cartilage matrix proteins (e.g., COMP), vitamin D receptor (VDR) and estrogen receptor (ESR1), as well as growth factors present in bone and cartilage (VEGF) and cytokines (IL-1B, IL-6) [8,9,10,11,12,13,14].