Funding for this research was provided by:
Beijing Hospitals Authority Youth Programme (QML20191205)
Received: 20 December 2019
Accepted: 27 May 2020
First Online: 4 June 2020
Ethics approval and consent to participate
: The work has been approved by the Ethical Committees of Beijing Children’s Hospital. Written informed consent was obtained from the parents.
: Not applicable.
: The authors declare that they have no competing interest.