A total of 152 live born children diagnosed with HS, 151 cases of controls without HS in hospital during the same period, and their parents were included in this study to investigate the risk factors for HS, the roles of CYP1A1/CYP17A1 polymorphisms, and the gene-environment interaction in the etiology of HS in Chinese population. The gene discussed is CYP17A1; the disease is histiocytic sarcoma.