[1] Univ Oslo, Inst Clin Med, N-0424 Oslo, Norway
[2] Oslo Univ Hosp, Dept Dermatol, Oslo, Norway
[3] Oslo Univ Hosp, Dept Paediat, Oslo, Norway
[4] Innlandet Hosp Trust, Elverum Hosp, Dept Paediat, Elverum, Norway
[5] Karolinska Univ Hosp, Karolinska Inst, Dept Mol Med, Stockholm, Sweden