1. Ultrasound Department, He Xian Memorial Hospital, Panyu, Guangzhou, Guangdong 511400, P.R. China
2. Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China
3. Guangzhou Huayin Medical Laboratory Center, Co., Ltd., Guangzhou, Guangdong 510663, P.R. China