1. Fetal Medicine Center, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province, China
2. Clinical Laboratory of BGI Diagnostics, BGI-Shenzhen, Shenzhen, China
3. BGI-Research, BGI-Shenzhen, Shenzhen, China
4. Shenzhen Birth Defect Screening Project Lab, BGI-Shenzhen, Shenzhen, China
5. Fetal Medicine Centre, Paramount Medical Centre, Hong Kong