[1] Oulu Univ, Dept Pathol, FIN-90014 Oulu, Finland
[2] Tampere Univ, Dept Pediat, FIN-33101 Tampere, Finland
[3] Baylor Coll Med, Dept Biochem, Houston, TX 77030 USA
[4] Baylor Coll Med, Howard Hughes Med Inst, Houston, TX 77030 USA
[5] Univ Helsinki, Dept Pathol, FIN-00014 Helsinki, Finland