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Article History

Received: 16 November 2017

Accepted: 1 February 2018

First Online: 12 February 2018

Ethics approval and consent to participate

: The study protocol was approved by Ethics Committee of Harbin Medical University and all experimental procedures (DNA extraction and genotyping) complied with the Declaration of Helsinki (2003). All participates gave written informed consent to take part in the present study.

: Not applicable.

: The authors declare that they have no competing interests.

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