Guo, Chao
Li, Dongmei
Liu, Cuimei
Guo, Zhenpeng
Chen, Yi
Article History
Received: 27 February 2018
Revised: 3 April 2018
Accepted: 11 April 2018
First Online: 11 May 2018
Compliance with ethical standards
: Informed consent was obtained from all participants who provided saliva samples.
: The authors declare that they have no competing interests.