1. Medical University Sofia, Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Sofia, Bulgaria
2. Medical University Sofia, Department of Dermatology and Venereology, University Hospital Alexandrovska, Clinic of Dermatology and Venereology, Sofia, Bulgaria
3. Department of Neurology, Hôpitaux Drôme Nord, Romans-sur-Isère, France
4. Department of Internal Medicine, University Hospital St. Ivan Rilski, Clinic of Nephrology, Sofia, Bulgaria