Jérôme Lejeune was born in 1926 in Montrouge, a Parisian suburb.
He studied medicine and became a researcher at the CNRS in 1952. This led him to be an international expert for France on atomic radiation.
In July 1958, during a study of chromosomes of a so-called “mongoloid” child, he discovered the existence of an extra chromosome on the 21st pair. For the first time ever a link was established between a state of mental retardation and a chromosomal anomaly.
In 1962, this extraordinary discovery was greeted with the award of the Kennedy Prize which Jérôme Lejeune received personally from President John F. Kennedy.
In 1964, the first chair of fundamental genetics was created for him at the Faculté de Médecine de Paris. While remaining very available to families of the handicapped children he treated, he gave thousands of conferences around the world.
In 1969, his work on chromosomal pathologies was rewarded with the William Allen Memorial Award.
In 1974, he became a member of the Pontifical Academy of Sciences.
In 1981 he was elected to the Académie des Sciences Morales et Politiques.
In 1983 he joined the Académie Nationale de Médecine. He was an honorary doctor, member or laureate of many other foreign academies, universities and scholarly societies.
In 1993 he received the Griffuel Prize for his pioneering work on chromosomal anomalies in cancer.
In 1994 he was named president of the Pontifical Academy for life.
He died on 3 April 1994, saddened at the thought he had not fulfilled his mission: “I was a physician who should have cured them and I am leaving them. I have the impression I am abandoning them.”
In 2007 the case for beatification of Jérôme Lejeune was opened.