Jérôme Jean Louis Marie Lejeune (13 June 1926 – 3 April 1994) was a French pediatrician and érôgeneticist, best known for his work on the link of diseases to chromosome abnormalities, most especially the link between Down Syndrome and trisomy-21 and cri du chat syndrome, amongst several others, and for his subsequent strong opposition to, in his opinion, the improper and immoral use of amniocentesis prenatal testing for eugenic purposes through selective and elective abortion. He is venerated in the Catholic Church, having been declared Venerable by Pope Francis on 21 January 2021.
Career
Discovering trisomy 21
In 1958, while working in Raymond Turpin’s laboratory with Marthe Gautier, Jérôme Lejeune reported that he had discovered that Down syndrome was caused by an extra copy of chromosome 21. According to Lejeune's laboratory notebooks, he made the observation demonstrating the link on 22 May 1958. The discovery was published by the French Academy of Sciences with Lejeune as first author, Gautier as second author, and Turpin as senior author. In 2009, co-author Gautier claimed that the discovery was based on fibroblast tissue samples that she had prepared and noticed the discrepancy in chromosome count on. This discovery was the first time that a defect in intellectual development was shown to be linked to chromosomal abnormalities.
Origins of the discovery
In the early 1950s, Lejeune joined the department headed by Turpin, who suggested that Lejeune focus his research on the causes of Down syndrome. As early as 1953, the two men showed a connection between an individual's characteristics and his or her dermatoglyphs–the fingerprints and lines on the hand. The structure of these lines, which remain the same throughout the individual's life, is determined during the earliest stages of embryo development. As Lejeune and Turpin studied the hands of children with Down syndrome, they deduced that their dermatoglyphic anomalies appeared during embryo formation.
In 1956, biologists from Lund University in Sweden announced that humans have exactly 46 chromosomes. Turpin had many years earlier proposed the idea of culturing cells to count the number of chromosomes in trisomy. Gautier had recently joined the pediatrics group he headed at the Armand-Trousseau Hospital, and she offered to attempt this, since she had been trained in both cell culture and tissue staining techniques in the United States. Turpin agreed to provide her with tissue samples from patients with Down syndrome. With very limited resources Gautier set up the first in vitro cell culture laboratory in France.
At the time, the laboratories at the Armand-Trousseau hospital did not have a microscope capable of capturing images of the slides. Gautier entrusted her slides to Lejeune, a fellow researcher at CNRS, who offered to take pictures in another laboratory better equipped for this task. In August 1958 the photographs identified the supernumerary chromosome in Down syndrome patients.
The laboratory notebook begun by Lejeune on 10 July 1957 indicates that on 22 May 1958 he succeeded in showing, for the first time, the presence of 47 chromosomes in a child with Down syndrome. This was two years after Tjio and Levan had proven that the human species has 46 chromosomes. On 13 June 1958, Lejeune identified an additional case, and a photo of the karyotype met with skeptical interest at the International Congress of Genetics in Montreal. The international community did not grasp the full impact of his discovery until 26 January 1959, when the French Academy of Sciences published the team's first paper presenting three case studies of children with Down syndrome.
In January 1959, by studying new cases and to forestall similar research by the English, the Trousseau laboratory announced the results of the analysis of the slides in the Proceedings of the Academy of Sciences through a paper published with Lejeune as first author, Gautier second (her surname misspelled as Gauthier) and Turpin last author.
On 16 March 1959, another presentation to the Academy of Sciences confirmed the team's initial publication, this time covering nine cases. In April 1959, the English team of Brown and Jacobs corroborated these results, citing the initial January 1959 publication by Lejeune, Gautier, and Turpin. “Mongolism” had become trisomy 21. The discovery opened up a new field of investigation for modern genetics and laid the foundation for a new discipline: cytogenetics.