[1] Childrens Hosp, Dept Med, Div Genet, Inborn Errors Metab Serv, Boston, MA 02115 USA
[2] Childrens Hosp, Dept Psychiat, Boston, MA 02115 USA
[3] Shinshu Univ, Sch Med, Dept Biochem, Matsumoto, Nagano 390, Japan
[4] Dartmouth Hitchcock Med Ctr, Dept Pediat, Lebanon, NH 03766 USA