1 Porphyria Center, Center for Lysosomal and Metabolic Disease, Department of Internal Medicine, Erasmus Medical Center, PO Box 2040, 3000, CA, Rotterdam, the Netherlands.
2 Department of Internal Medicine, Isala Clinics, Zwolle, the Netherlands.
3 Porphyria Center, Center for Lysosomal and Metabolic Disease, Department of Internal Medicine, Erasmus Medical Center, PO Box 2040, 3000, CA, Rotterdam, the Netherlands. j.langendonk@erasmusmc.nl.