[1] Leiden Univ, Med Ctr, Dept Neurol, NL-2300 RC Leiden, Netherlands
[2] Leiden Univ, Med Ctr, Dept Clin Epidemiol, NL-2300 RC Leiden, Netherlands
[3] Univ Oxford, John Radcliffe Hosp, Weatherall Inst Mol Med, Dept Clin Neurol,Neurosci Grp, Oxford OX3 9DS, England
[4] Leiden Univ, Med Ctr, Dept Pediat, Sect Immunol Hematol Oncol Bone Marrow Transplant, NL-2300 RC Leiden, Netherlands
[5] Haga Hosp, Dept Neurol, NL-2504 LN The Hague, Netherlands