Last Saturday, June 13th, marked the centenary of the birth of Professor  Jérôme Lejeune . His exemplary life began in Montrouge, near Paris, a town on the border between the capital and the rural world where Jérôme took his first steps. His parents, Pierre and Massa, practicing Catholics and well-known, cultured, and respected individuals, ensured a Christian education for their sons, Jérôme and Philippe, first at the Sainte-Jean-de-Arc school in Montrouge, and later, upon entering primary school, at the prestigious private Catholic school Stanislaus in Paris.

When Jérôme was 13, he read Honoré de Balzac’s *Le Médecins Patrière* (The Country Doctor ), written in 1833. Its protagonist, Dr. Benassis, cared for and healed the poorest and most needy out of love, which shaped his understanding of medicine. This reading marked his destiny as a person dedicated to serving others. In 1944, Jérôme began his medical studies at the Sorbonne in Paris, and a year later, at the end of World War II, inspired by the country doctor, he combined his studies with volunteer work in charitable hospitals.

Upon completing his studies, he defended his doctoral thesis on June 15, 1951, and a year later joined the Centre National de la Recherche Scientifique (CNRS). In 1956, Jérôme Lejeune attended a scientific congress where the Swedish cytogeneticist Albert Levan (1905–1998) announced that humans have 46 chromosomes, not 48 as had been erroneously published previously. Levan’s discovery had been made in Zaragoza, at the CSIC’s Aula Dei research center, where the Indonesian researcher Joe Him Tjio (1919–2001) worked, and was confirmed in Lund, Sweden, by Tjio and Levan. Later, Lejeune spent time in the United States with Tjio, which allowed him to learn new techniques for chromosome observation.

The discovery of trisomy 21 and scientific recognition

With the approval of Dr. Raymond Turpin (1895-1988), he decided to investigate whether the cause of Down syndrome was related to the chromosomal makeup. In collaboration with pediatrician Marthe Gautier (1925-2022), he applied and improved chromosomal staining and observation techniques, which allowed him to better visualize the karyotype of his patients. Finally, after many attempts, he discovered in one of his patients the presence of three copies of chromosome pair 21 instead of the two in the normal set. This important finding was published in a short note co-authored with Gautier and Turpin in January 1959, after confirming the finding in several patients  ^[1] . Two months later, they confirmed the finding through a new publication based on the karyotypic analysis of many more cases  ^[2] . Spurred by this groundbreaking discovery, Lejeune dedicated himself to studying the causes of other pathologies and diagnosed that Cri du Chat syndrome is due to the loss of a region of chromosome 5. Later, he discovered other pathologies caused by chromosomal aberrations that lead to spontaneous abortions and other syndromes. For these discoveries, Jérôme Lejeune is considered the “father of human cytogenetics.”

For his research, he received the highest distinctions awarded in the field of human genetics, of which he is considered one of the modern founders. His international renown grew as a result of his constant travels and presentations at various academic forums. In 1982, he was admitted to the French Academy of Moral and Political Sciences, and the following year, to the French National Academy of Medicine. In 1962, the World Health Organization appointed him an expert in Human Genetics, and he received the prestigious Kennedy Center Honors.

In 1964, he was appointed director of the CNRS (French National Centre for Scientific Research) and awarded the Chair of Fundamental Genetics at the Sorbonne Faculty of Medicine. A year later, he was appointed head of the Genetics Department at the Necker-Enfants Malades Hospital in Paris. From his appointment onward, he combined teaching with research and clinical practice, convinced that discovering the cause of a disease is only the first step… but that the most difficult part, curing it, remains. He was also a member of foreign academies, such as the Royal Swedish Academy of Sciences, the American Academy of Humanities and Sciences (Boston), and the Royal Society of Medicine in London. He was a strong candidate for the Nobel Prize in Medicine, which he never received. Regarding this, the writer and journalist José Javier Esparza, in his work  “Jérôme Lejeune: To Love, To Fight, To Cure, ” compares him to Galileo, who was condemned in a villa in Florence for his defense of heliocentrism. Unlike the practices of the 17th-century Inquisition, the practices of the 20th century were more subtle, consisting of isolation. Those who refused to acknowledge that human life begins with the formation of the zygote, which is already a human reality, simply turned their backs on him. They demanded that he sell his soul and renounce the notion of the embryo as a human being in the womb  ^[4] .

In January 1994, Saint John Paul II appointed him the first president of the Pontifical Academy for Life, but two months after his appointment, on April 3, 1994, Easter Sunday, Jérôme Lejeune died in Paris from lung cancer at the age of 67. He was survived by his wife, five children, and 28 grandchildren.

The patient above the disease

In commemorating this centenary, I believe it is fitting to highlight his qualities as a scientist and as a physician. It is essential to acknowledge Jérôme Lejeune’s scientific curiosity, his interest in understanding the causes of his young patients’ health problems, his unwavering commitment to his scientific, ethical, and spiritual convictions, and his dedication to his medical profession, convinced that at its core lies respect for human dignity and the care of his patients’ health. While expanding his research and traveling the world to attend numerous conferences, he cared for his patients, especially sick children, and remained available to their families.

As his daughter Clara noted in her biography of her father, one of his greatest concerns was healing his young patients  ^[5] . Clara says that her father was first and foremost a doctor, and that he based his defense of life primarily on his profession, not on his faith. She said of her father that he believed that when you are a doctor, you have sworn the Hippocratic Oath to do no harm. Lejeune always said that respect for life had nothing to do with faith, although, of course, respecting life is inherent in faith. This is why he was so unpopular with  abortion advocates .

Jérôme Lejeune practiced medicine with great humanity. He is a model that should be promoted in medical schools, nursing schools, and all other institutions whose mission is the health and care of the most vulnerable and defenseless human beings. From the perspective of one who knows the truth better than anyone, he staunchly defended the irreducible value and dignity of every human being from conception to natural death. In a debate on French television, he confronted other medical colleagues who advocated for the abortion of children diagnosed with Down syndrome before birth. Lejeune told them:  “We are doctors. I am not speaking from a pulpit. I am speaking of children of flesh and blood, and I do not want to kill them because they are sick.”  True to his principles, he often said that the enemy of the doctor is the disease, not the patient. In this vein, full of humanity, she publicly spoke out against contraception, eugenics, in vitro fertilization, cloning, abortion, and euthanasia, and in favor of family, love, comfort, care, and life.

Jean Marie Le Méné, son-in-law of Jérôme Lejeune, Magistrate of the French State Court of Auditors and President of the Jérôme Lejeune Foundation, in his work “ Professor Lejeune: Founder of Modern Genetics ”  ^[6],  points out four qualities of the French scholar and physician. First, his “simplicity” in his way of life and in his interactions with people, whom he addressed with respect and utmost consideration, elegantly elevating them to his own level. Second, his “intelligence,” which those who knew him always acknowledged, regardless of any disagreement. Third, his “kindness,” which, together with his intelligence, made Jérôme an upright person whom it was difficult to contradict. And finally, his extraordinary “fecundity,” which has resulted in an extraordinary legacy of knowledge as a scientist who researches, a physician who heals, and a humanist who loves humanity and recognizes its dignity.

Lejeune always based his defense of human beings on scientific arguments, rather than on any other social or religious consideration, but he was a ” man of scientific faith ,” as his friend Pope Saint John Paul II described him.

Aude Dugast, philosopher and postulator of Jérôme Lejeune’s cause for canonization, emphasizes Jérôme’s life-giving hope in his dual role as physician and researcher. In her book, ” Jérôme Lejeune: A Spiritual Portrait ”  ^[7] , she notes that, convinced, as Benedict XVI pointed out, that ” heaven is not empty… life is not simply the product of the laws and chance of matter “… Jérôme fought for his patients. He was the first to believe there was hope for them and embarked on the search for a treatment when others abandoned him, even against the current of the scientific community and the public health system, which opted for eugenic selection. Only Christian hope explains the care and advocacy that many of his patients’ families acknowledge.

In an interview in Madrid in early 2016 with his wife, Birthe Bringsted, Madame Lejeune recalled how a father confessed to Jérôme that for years he had been ashamed of his daughter, who had Down syndrome, but that something had changed his perspective:  “This gentleman told Jérôme that for a long time he hadn’t accepted his daughter’s condition, that he didn’t love her. But that, after his wife’s death, he had become aware of the immense love this little girl gave to everyone, including him, every day. ‘Now she is my whole life, I don’t know what I would do without my daughter,’ the father said.”  Madame Lejeune added that:  “The vast majority of parents of children with Down syndrome love their children immensely.”

It is evident that the love Lejeune lavished on sick children was a Christian love, based on God’s love for all creatures. At the end of the biographical film produced by the Jérôme Lejeune Foundation  ^[8] , these words he spoke in one of his lectures are highlighted:  “Those of us in this profession, what must we do to know what should be done and what should be refused? We need a reference point, and perhaps a much stronger one than natural law… and this reference point is very simple… you all know it. Or rather, it is a phrase, but a phrase that judges everything and explains everything, that contains everything… and this phrase is: ‘Whatever you do for the least of these brothers and sisters of mine, you do for me.’”

After all the wonderful things Jérôme Lejeune left us, we should have no doubt that the best argument, the principal intellectual weapon for loving life and defending it as he did, is reason. A reason that loves, and a reason that is based on the truth of science and on revealed Truth, both perfectly compatible.

Nicolás Jouve. Emeritus Professor of Genetics at the University of Alcalá. Member of the Bioethics Observatory. Catholic University of Valencia

***

[1] J. Lejeune, M. Gautier, R. Turpin. “Les chromosomes humains en culture de tissus”. Comptes Rendus de l’Académie des Sciences 248, 1959, pp. 602–603.
[2] J. Lejeune J, J. Lafourcade, R. Berger, J. Vialatte, M. Boeswillwald, P. Seringe, R. Turpin R. “Trois cas de délétion partielle du bras court d’un chromosome 5“. CR Acad Sci (D) 257, 1963, pp. 3098–3102.
[3] J. Lejeune, R. Berger, J. Lafourcade, MO Rethore. “La délétion partielle du bras long du chromosome 18. Individualization d’un nouvel état morbide.” Ann, Génét. 9, 1963, pp.32–38.
[4] JJ Esparza. « Jérôme Lejeune: to love, to fight, to heal. The fascinating life of the discoverer of the origin of Down syndrome.” Libros Libres. Madrid, 2019.
[5] C. Lejeune, Life is a blessing, Jérôme Lejeune, my father (Critérion, Paris, 1997) (Dr. Lejeune. The love of life. (Ediciones Palabra. Madrid, 1999.)
[6] JM Le Méné. Professor Lejeune. Founder of Modern Genetics. Ed. Marova, Madrid, 2023.
[7] A. Dugast. Jérôme Lejeune. A spiritual portrait. Ediciones Palabra, Madrid. 2022.
[8] J. Lejeune Foundation. Jérôme Lejeune: To the smallest of mine. Biographical film. 2017.