Funding for this research was provided by:
Capital Health Research and Development of Special (2018-2-1073)
Medical Epigenetics Research Center (2019PT310017)
Received: 15 October 2019
Accepted: 6 January 2020
First Online: 28 January 2020
Ethics approval and consent to participate
: This study has been approved by the ethics committee of Beijing Tiantan Hospital, Capital Medical University. All samples and records were de-identified and anonymized prior to the study. Consent was obtained from all individuals for publication. No individual-level data are reported.
: Not applicable.
: The authors declare that they have no competing interests.