Funding for this research was provided by:
National Natural Science Foundation of China (81472888)
Received: 1 November 2018
Revised: 29 January 2019
Accepted: 30 January 2019
First Online: 13 February 2019
Ethics approval and consent to participate
: Skin biopsies were obtained from all subjects with their written informed consent. The protocol was approved by the Medical Ethics Committee of Taiyuan City Centre Hospital (approval number 2014015) in Taiyuan, China, and the study was conducted according to the principles expressed in the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.
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