1. Children's Healthcare Institute, Hunan Children's Hospital, University of South China, Changsha, Hunan 410007, P.R. China
2. The Laboratory of Genetics and Metabolism, Hunan Children's Research Institute, Hunan Children's Hospital, University of South China, Changsha, Hunan 410007, P.R. China
3. Department of Radiology, Hunan Children's Hospital, University of South China, Changsha, Hunan 410007, P.R. China