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Jerome Lejeune with a Little Child

The Venerable Father of Modern Genetics

February 23, 2023


The Roman Catholic Church can boast of many notable Catholic scientists and medical professionals going all the way back to Albert the Great in the 13th century. Among the more recent and well known are Fr. Georges Lemaître (1894-1966), who developed the “Big Bang Theory” of the origin of the universe, and Louis Pasteur (1822-1895), who is considered the inventor of vaccines and, of course, pasteurization. Gregor Mendel (1822-1884), whose name appears in every biology textbook, was also a Catholic. In fact, like several others, he was a priest. Through Fr. Mendel, all high school biology students learn how dominant and recessive genes are responsible for their blond hair and blue eyes, or, tragically, their cystic fibrosis or Huntington’s disease.

There is another Catholic physician and scientist whose name should be—and one day will be—just as familiar as these: Dr. Jerome Lejeune (1926-1994), or rather, the Venerable Jerome Lejeune. At one time, Professor Lejeune was quite well known in the United States. He received the first Kennedy Prize in 1962 for his discoveries and, in 1969, the William Allen Memorial Award, the highest award a geneticist could receive. In fact, it was in San Francisco during his acceptance of this award that he sealed his fate. Because of its support for prenatal diagnosis and abortion, he said that the National Institutes of Health should be renamed the National Institutes of Death. It was no surprise to him when he left the podium that his comments hadn’t been well received. He wrote to his wife that night that he had ruined his chance of ever receiving a Nobel Prize.

Jerome Lejeune speaking

Lejeune was one of the most important figures in the history of modern medicine. With his discovery in 1958 that Down syndrome is caused by an extra copy of chromosome 21, he became the first to correlate a disability to a genetic anomaly. Like Anton von Leeuwenhoek (who peered through a microscope and for the first time saw bacteria and protozoa, realizing they were the culprit in some illnesses), Dr. Lejeune was the first to peer into the nucleus of a cell and discover that chromosomes were the cause of a disability. From that discovery, medicine turned to the genome to seek understanding and treatment for inherited as well as many non-inherited diseases. He had launched the field of cytogenetics, the study of how chromosomes regulate cell behavior and can be the cause of disease.

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Jerome Lejeune was born in 1926 in a suburb just south of Paris called Montrouge. He was one of three boys in a tight-knit and very religious family. His father was a third-order Franciscan. Jerome was especially close to his older brother, Phillippe, and their close friendship would endure until Jerome’s death in 1994. Pierre, the boys’ father, was determined that his sons would not just have a bookish education but be formed in the Western intellectual tradition. He taught them Latin and Greek and encouraged their imaginations by reciting Homer and Aesop’s Fables to them on their drives to school each day. The boys put their imaginations to creative use by producing and starring in various dramatic productions for their friends and neighbors. When World War II came closer to their home, Pierre pulled his sons out of school for their safety and opened a library of Latin, Greek, and French literature to them. They became self-learners, and when Jerome took his baccalaureate exams in school, his examiner commented that he read Cicero in Latin “the way people read the newspaper.”

Lejeune family lore has it that during this time, Jerome was inspired to become a doctor by reading the story of the remarkable physician Dr. Benassis in Balzac’s novel The Country Doctor. He was also deeply influenced by Blaise Pascal, who he would continue to quote throughout his life. Pascal was an especially beneficial reference point in his arguments against a scientism that excludes metaphysics and religion and therefore deforms the practice of medicine and, indeed, all truly human pursuits.

Jerome Lejeune’s natural gifts were formed from his earliest years into a keen intellect, a compassionate heart, and a creative and curious mind. After completing his medical training, he began working in the pediatric clinic of Dr. Raymond Turpin. There, he encountered several patients with Down syndrome and became convinced that there was something in their genetic makeup that was the cause of their disability.

In post-war France, resources were scarce. Turpin’s lab had one very old, worn-out microscope with gears Lejeune padded with the foil wrapper from a chocolate bar so that they would hold focus. He was determined to prove that Down syndrome had a genetic cause. Thanks to a new technique of culturing cells and staining tissue brought back to France from the United States by his colleague Marthe Gautier, they were able to look within the nucleus of the cell and sort out the tangle of DNA to see the individual chromosomes.

By further developing the technique of karyotyping (creating a photographic image of chromosomes), Dr. Lejeune realized he could enlarge the image and then cut and paste the paired chromosomes onto a sheet of paper from largest to smallest. In following this process on a particular tissue sample taken from a child with Down syndrome, he set about organizing the chromosomes, et voilá! There were not just two, but three chromosomes 21 present. This groundbreaking discovery was made and verified in his lab in 1958, and the findings were published in the Annales de génétique in 1959 with Lejeune as the principal author, followed by Drs. Turpin and Gautier. History had been made and the field of cytogenetics born. In addition to the understanding that some disabilities have a genetic origin, the pathway to understanding the development and treatment of certain diseases was forever changed.

Lejeune would go on to discover other genetically caused disabilities like Cri-du-chat syndrome, 18q deletion syndrome, and trisomies of chromosomes 8 and 9. Because of his discoveries, many came to refer to him as “the Father of Modern Genetics.”

Jerome Lejeune smiling

There is no question of Jerome Lejeune’s brilliance as a physician and medical researcher, nor is there dispute of his worthy claim to the title “the Father of Modern Genetics.” But brilliance isn’t a virtue or what the Church seeks to verify in the grueling process of the discernment of holy lives in the process of canonization.

Then what of this “Venerable” title that Dr. Lejeune has been awarded by the Church, and why was this Fellowship named after him? I have answered that question in general terms, but there is so much to the story. We will have to save the discussion of Jerome Lejeune’s heroic virtues for another article.

It is a coincidence that the Word on Fire Institute brought the name of the Venerable Jerome Lejeune forward with this Fellowship almost at the same time of our first Wonder Conference, but there could be no better figure in modern history to represent our commitment to teaching the compatibility of faith and science. However, that isn’t the role of this fellowship. The role of the Venerable Jerome Lejeune Fellowship is to bring Lejeune’s love and concern for those with intellectual and developmental disabilities into the mission of the Institute and more fully into the evangelical mission of the Church. Jerome Lejeune dedicated his entire life to bringing God’s healing love to his little ones, as he called them. He knew the difficulties they faced both medically and socially, and he was their greatest advocate for their place in society and for the preservation of their lives from prenatal diagnosis and abortion.

Those who are interested in Jerome Lejeune’s life have two great resources to read in English. One of Lejeune’s daughters, Clara Gaymard, wrote a beautiful, intimate, short biography of her father called Life Is a Blessing that was re-published in English by the National Catholic Bioethics Center in 2011. Aude Dugast, the postulator for Lejeune’s cause, has also written an extensively researched biography that was translated and published in English in 2021 called Jerome Lejeune: Man of Science and Conscience. Both are easily available for those interested in the life, work, and heroic virtue of this fascinating, Venerable Father of Modern Genetics.