Author contributions:
Tetsuro Uchida: Study design (SD), data collection (DC), manuscript writing (MW), critical revision (CR), and approval of the manuscript for submission (AS)
Atsushi Yamashita: AS, DC
Ai Ishizawa: AS, DC
Mitsuaki Sadahiro: SD, CR, AS
Nobuyoshi Azuma: SD, CR, AS
Tadashi Kaname: SD, CR, AS, genetic analysis