1. Department of Genetics, Faculty of Biology, Sofia University St. Kliment Ohridski, 8 Dragan Tzankov Str., 1164 Sofia, Bulgaria
2. Pediatric Department, University Hospital “N. I. Pirogov”, 21 “General Eduard I. Totleben” Blvd, 1606 Sofia, Bulgaria
3. Health Care Department, Faculty of Public Health, Medical University Sofia, Bialo More 8 Str., 1527 Sofia, Bulgaria
4. Medical Faculty, Sofia University St. Kliment Ohridski, 1 Kozyak Str., 1407 Sofia, Bulgaria