Jérôme Jean Louis Marie Lejeune was a French pediatrician and geneticist. He is best known for his work on the links between chromosome abnormalities like Down syndrome (trisomy-21) and cri du chat syndrome. He is also known for his subsequent strong opposition to the use of amniocentesis prenatal testing for eugenic purposes through selective and elective abortion. He was declared Venerable by Pope Francis on 21 January 2021.