[1] Natl Res Inst Family Planning, Beijing, Peoples R China
[2] Natl Human Genet Resources Ctr, Beijing, Peoples R China
[3] Kailuan Gen Hosp, Hlth Dept Kailuan Grp, Tangshan, Peoples R China
[4] Peking Union Med Coll, Grad Sch, Beijing, Peoples R China
[5] North China Univ Sci & Technol, Grad Sch, Tangshan, Peoples R China
[6] Natl Res Inst Family Planning, Natl Human Genet Resources Ctr, 12 Dahuisi Rd, Beijing 100081, Peoples R China