Funding for this research was provided by:
Ministry of Health, Labour and Welfare (H24-nanchitou (nan)-ippan-041)
Text and Data Mining valid from 2019-04-01
Received: 27 November 2018
Revised: 18 January 2019
Accepted: 7 March 2019
First Online: 1 April 2019
Compliance with ethical standards
: The study was conducted in accordance with the ethical principles set out in the Declaration of Helsinki and the ethical guidelines for Medical and Health Research Involving Human Subject created of the Ministry of Health, Labour and Welfare in Japan. The study was approved by the ethics board of National Center for Child Health and Development (ID:1606).
: The authors declare that they have no conflict of interest.
: The authors have no financial relationships relevant to this article to disclose.
: Informed consent for participating in this study was not required in agreement with the above-mentioned guidelines. For individual gene analysis, informed consent was obtained from all individual participants or their parents.