1. Biomedicum Helsinki (T.R., J.J.P., O.A.J.), Institute of Biomedicine, University of Helsinki, FIN-00014 Helsinki;
2. Institute of Biotechnology (J.J.P.), University of Helsinki, FIN-00014 Helsinki;
3. Department of Pediatrics (S.K., R.V.), Kuopio University Hospital, FIN-70211 Kuopio;
4. Department of Clinical Chemistry (O.A.J.), University of Helsinki, and Helsinki University Central Hospital, FIN-00014 Helsinki, Finland