1. Key Laboratory for Major Obstetric Diseases of Guangdong Province, Key Laboratory for Reproduction and Genetics of Guangdong Higher Education Institutes, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, People's Republic of China.
2. Department of Laboratory Medicine, Boston Children's Hospital, Boston, Massachusetts.
3. Department of Laboratory Medicine, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
4. Department of Pathology, Harvard Medical School, Boston, Massachusetts.