[1] Natl Publ Hlth Inst, Dept Mol Med, Helsinki, Finland
[2] Univ Helsinki, Dept Med Genet, Helsinki, Finland
[3] Univ Helsinki, Hosp Children & Adolescents, Unit Child Neurol, Helsinki, Finland
[4] Univ Calif Los Angeles, Dept Human Genet, Los Angeles, CA USA
[5] Univ Helsinki Hosp, Genet Mol Lab, Helsinki, Finland