1. The Center of Gerontology and Geriatrics and West China Biomedical Big Data Centre, West China Hospital, Sichuan University , Chengdu , Sichuan 610041 , PR China
2. Center for Computational Systems Medicine, School of Biomedical Informatics, The University of Texas Health Science Center at Houston , Houston , TX 77030 , USA
3. Med-X Center for Informatics, Sichuan University , Chengdu , Sichuan 610041 , PR China
4. School of Life Science and Technology, Xidian University , Xi’an, Shaanxi 710071 , PR China
5. McGovern Medical School, The University of Texas Health Science Center at Houston , Houston , TX , USA
6. School of Dentistry, The University of Texas Health Science Center at Houston , Houston , TX 77030 , USA