It has been shown that patients suffering from ANFH have obstructed blood vessels.9, 24 Reduction in shear stress due to declined blood flow could cause apoptosis of endothelial cells, which can eventually contribute to plaque erosion and thrombus formation.25 Several genes such as A2M, which contributes to coagulation and osteogenesis, could play a role in the pathogenesis of ANFH.10 The gene discussed is A2M; the disease is familial avascular necrosis of femoral head.