1 Institute of Laboratory Medicine, Municipal Hospital Zurich Triemli, Zurich, Switzerland.
2 Swiss Reference Centre for Porphyrias, Municipal Hospital Zurich Triemli, Zurich, Switzerland.
3 Division for Endocrinology, Diabetology and Porphyria, Municipal Hospital Zurich Triemli, Zurich, Switzerland.
4 Institute of Translational Immunology and Research Center for Immune Therapy, University Medical Centre, Johannes Gutenberg University, Mainz, Germany.
5 Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
6 Porphyria Centre, Department of Internal Medicine II, Klinikum Chemnitz, Chemnitz, Germany.