Acknowledgements
The authors thank all of the physicians and staff at the hospital and the cord blood banks in Japan for their help in this study. We also thank Chisato Kohara and Mika Ito for technical help.
Author contributions
T.K. conceived the project, designed the research, analyzed data, and wrote the paper. K.Y. collected DNA samples and contributed to the critical review of the manuscript. N.Y. collected DNA samples. All the other authors participated in the treatment of the patients, acquired the clinical data, and contributed to writing the paper. All authors approved the final version.
Disclosure statement
No potential conflict of interest was reported by the authors.