1. Prenatal Diagnosis Centre, Women and Children's Hospital, School of Medicine, Xiamen University, Xiamen, Fujian 361003, P.R. China
2. Department of Obstetrics and Gynecology, Women and Children's Hospital, School of Medicine, Xiamen University, Xiamen, Fujian 361003, P.R. China
3. Department of Experimental Medicine, United Diagnostic and Research Center for Clinical Genetics, School of Public Health, Xiamen University, Xiamen, Fujian 361102, P.R. China