[1] Akershus Univ Hosp, Dept Pediat, Lorenskog, Norway
[2] Univ Oslo, Oslo, Norway
[3] Univ Oslo, Inst Basic Med Sci, Fac Med, Oslo Ctr Biostat & Epidemiol OCBE, Oslo, Norway
[4] Univ Oslo, Dept Clin Mol Biol EpiGen, Lorenskog, Norway
[5] Akershus Univ Hosp, Lorenskog, Norway
[6] Univ Oslo, Inst Clin Med, Fac Med, Oslo, Norway
[7] Oslo Metropolitan Univ, Fac Hlth Sci, Dept Behav Sci, Oslo, Norway