[1] Univ Helsinki, Pediat Res Ctr, Childrens Hosp, Helsinki, Finland
[2] Helsinki Univ Hosp, Helsinki, Finland
[3] Univ Helsinki, Fac Med, Res Program Clin & Mol Metab CAMM, Helsinki, Finland
[4] Natl Inst Hlth & Welf THL, Populat Hlth unit, Helsinki, Finland
[5] Oulu Univ Hosp, MRC Oulu, PEDEGO Res Unit, Oulu, Finland
[6] Univ Oulu, Oulu, Finland
[7] Folkhalsan Inst Genet, Helsinki, Finland
[8] Norwegian Univ Sci & Technol, Dept Clin & Mol Med, Trondheim, Norway
[9] Karolinska Inst, Dept Mol Med & Surg, SE-17176 Stockholm, Sweden
[10] Karolinska Univ Hosp, Karolinska Univ Lab, Clin Genet, SE-17176 Stockholm, Sweden