Jérôme Lejeune

Jérôme Lejeune (1926 to 1994) was a French pediatrician and geneticist, best known for his work on the links between chromosome abnormalities and disease. In 1958, working in the laboratory of Raymond Turpin with Marthe Gautier, he reported that Down syndrome is caused by an extra copy of chromosome 21. This was the first time a defect in intellectual development was shown to be tied to a chromosomal abnormality, and it helped found the field of cytogenetics. The credit has been disputed, since Gautier has said she prepared the cell cultures and noticed the extra chromosome first. Lejeune later described cri du chat syndrome in 1963 and other chromosomal syndromes, and he became a strong opponent of prenatal testing used for selective abortion. He was declared Venerable by Pope Francis in 2021. This entry records the history of the work and the dispute and gives no medical advice.