[1] Univ Tsukuba Hosp, Dept Pediat, Ibaraki, Japan
[2] Univ Tsukuba, Dept Child Hlth, Fac Med, 1-1-1 Tennodai, Tsukuba, Ibaraki, Japan
[3] Showa Univ, Dept Pediat, Sch Med, Tokyo, Japan
[4] Yamagata Univ, Dept Pediat, Fac Med, Yamagata, Japan
[5] JA Toride Med Ctr, Dept Pediat, Ibaraki, Japan
[6] Keio Univ, Ctr Med Genet, Sch Med, Tokyo, Japan