Medical Pioneer. Montrouge born Jérôme Jean Louis Marie Lejeune became a researcher at the National Center of Scientific Research (CNRS) in Paris in 1952 upon finishing his studies, discovering soon the chromosome abnormality in humans that causes Down Syndrome, establishing thus a link between an intellectual disability and its genetic cause. Founding the first specialized clinic for Down Syndrome patients at Necker Children's Hospital in Paris, he would go on to discover the genetic cause of Cri-du-Chat Syndrome and to also advance understanding of Fragile X Syndrome and others. Named the first professor of Fundamental Genetics at the Faculty of Medicine of Paris in recognition of his discoveries, while increasing his research he continued to remain available to families, caring for disabled children and traveling the world giving thousands of lectures on genetics. A well-known geneticist, he was called to the United States of America to testify in court in Davis v. Davis, the Tennessee Frozen Embryo Case, in Maryville, Tennessee in 1989. Receiving through the years numerous awards, he was elected member of several academies. President John F. Kennedy awarded him with the first Kennedy Prize for his research into genetic intellectual disability and for finding the genetic cause of Down Syndrome. In 1969 he received the William Allen Award from the American Society of Human Genetics, the highest award possible for a geneticist. Succumbing to lung cancer shortly after its diagnosis having been a lifelong heavy smoker, Pope John Paul II who shortly before his death had him named the first president of the Pontifical Academy for Life, visited his grave while in Paris for the World Youth Day in 1997. The cause for his beatification was introduced a decade later by the Archdiocese of Paris.