Additionally, COL2A1 is suggested to be one of the representative causal genes, as Li et al. found a mutation in COL2A1 G1888A in a Chinese family affected by LCPD and osteonecrosis of the femoral head [12, 26], and Miyamoto et al. identified a mutation in COL2A1 G3508A in a Japanese family with LCPD. This evidence concerns the gene COL2A1 and familial avascular necrosis of femoral head.