Funding for this research was provided by:
National Natural Science Foundation of China (nos. 81370327)
Text and Data Mining valid from 2018-11-03
Received: 9 August 2018
Accepted: 22 October 2018
First Online: 3 November 2018
Ethics approval and consent to participate
: Approval of the Ethics Committee of Peking Union Medical College Affiliated Fuwai Hospital was obtained before the start of the work, and each participant signed written consent form.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.