Funding for this research was provided by:
Beijing Key Laboratory (BZ0317)
Received: 14 November 2017
Accepted: 22 January 2018
First Online: 30 January 2018
Ethics approval and consent to participate
: The study was approved by the clinical research ethics committee of Peking University First Hospital. Written informed consents were obtained from the parents.
: Not applicable.
: The authors declare that they have no competing interests.
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