NOS3 and Legg-Calve-Perthes disease: The literature reports associations of LCPD with gene mutations such as Factor-V Leiden, prothrombin G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T, endothelial nitric oxide synthase (eNOS), and plasminogen activator inhibitor-1 4G/5G [15,16,17].