1. Department of Dermatology Second Affiliated Hospital of Xi'an Jiaotong University Xi'an China
2. Department of Infectious Diseases Second Affiliated Hospital of Xi'an Jiaotong University Xi'an China
3. Department of Dermatology University of California, San Francisco San Francisco California USA
4. School of Mathematics and Statistics Xi'an Jiaotong University Xi'an China
5. Department of Dermatology First Affiliated Hospital of Xi'an Jiaotong University Xi'an China
6. Bristol Medical School University of Bristol Bristol UK
7. Dermatology Services Veterans Affairs Medical Center and University of California San Francisco California USA
8. Karsh Division of Gastroenterology and Hepatology Cedars‐Sinai Medical Center Los Angeles California USA