 Also in 1983, he started to work as a junior assistant at the Department of Medical Genetics at the Pediatrics Institute in Kraków.In 1988, he took a three-month intership at Harvard University.In 1991, he received a one-year scholarship from the Ministry of Scientific Research and Technology of the Republic of France, in the unit U-12 of the Institute of Medical Research (INSERM), located in the Necker Hospital in Paris and headed by Arnold Munnich and Marie-Claude Hors-Cayla.