Simopoulou et al. found that leptin and its receptor mRNA and protein are expressed in osteoarthritis articular chondrocytes, and found higher mRNA expression levels in advanced osteoarthritis cartilage compared to minimal osteoarthritis; they thought it may be related to the grade of cartilage destruction, indicating that leptin can indeed affect cartilage metabolism directly 19. This evidence concerns the gene LEP and osteoarthritis.