We genotyped the polymorphism of five genes associated with excessive clot formation, a disorder of clot dissolution, and a gene responsible for nitric oxide synthesis (Factor V Leiden, Prothrombin, MTHFR, tPA 25, eNOS) in 25 patients with LCPD and 100 healthy controls. The gene discussed is F2; the disease is Legg-Calve-Perthes disease.