The reason I became interested in Jér ôme Lejeune had little to do directly with my work. While Lejeune was a geneticist who discovered trisomy 21 as the cause of Down's syndrome, I lead a research laboratory studying the molecular changes in breast tumours. However, a friend who is a scientist told me about her rediscovery of Jér ôme Lejeune, whose cause for beatification was being opened. How rare to find a scientist who may one day become a saint. Who was Jér ôme Lejeune? Upon further reading, I became increasingly fascinated with this scientific giant and defender of truth, a man of whom Pope John Paul II would say, "He took on fully the responsibility specific to that of a scientist, ready to become a ‘sign of contradiction' without caring about the pressures exercised by a permissive society or of the ostracism of which he was an object," and whom he called a "great Christian of the 20th century."

Jér ôme Lejeune was born in the French country-side near Paris and wanted to become a country doctor. Gifted manually, he then desired to become a surgeon but missed the qualifying exam when he fell asleep on the Paris metro heading in the wrong direction. A surgeon was lost, but a geneticist was born. He began working at Raymond Turpin's laboratory at the Université Paris, and decided to study the basis of Down's syndrome.

The syndrome, named after John Langdon Down, a British physician, was thought to be due to a venereal disease contracted by the mother, since children were born with its unmistakable features. As a result, both mother and child were ostracized not only by society but also by medical practitioners. Lejeune, who began to attend to these patients, had several hints that it could be otherwise. Like all scientific discoveries, this one built on previous discoveries and insights.

First, it had been shown that changing the genetic information—that is, the DNA—that was packaged into chromosomes could alter the appearance of organisms such as fruit flies. Second, Lejeune recognized that Down's syndrome were almost never shared between fraternal twins, but almost always shared between identical twins and that the patterns of the lines on the hands of these children were different. Since these patterns appear early on in the womb during embryonic development, and since twins are formed at the earliest moments after conception, Lejeune and his mentor, Turpin, thought that there could be a genetic basis for Down's. Moreover, the fact that complex activities such as brain function were affected suggested to Lejeune that it was more than one gene, and perhaps whole chromosomes, that were altered in some way. But he had to wait for technology to catch up. In 1956, the technology was finally developed that allowed the counting of human chromosomes: and the number was 46. Lejeune learned how to use this technique and immediately counted the chromosomes from the cells of a patient with Down's, expecting to find a missing chromosome or two. The answer was unexpected. There was an extra chromosome 21. Since chromosome 21 is one of the smallest chromosomes, he was worried that it could be a fragment of another chromosome. So he looked at other patients, and each time, the number of chromosomes was 47, with an extra chromosome 21. It is fascinating that his first impulse was to "spread the news."

Indeed, he was to fly to Canada and the United States within a few days and took with him a photomicrograph of the extra chromosome, showing it to all his collaborators. For Lejeune, the first priority was not "publish or perish" but to advance the science as quickly as possible, to remove obstacles to finding a cure for his patients. Lejeune is the model of a true clinician-scientist, one whose research is driven by love for his patients. He did not care about the glory but about accelerating the process of research for his patients' sake.

The first consequence of his discovery was that the dignity of Down's families was returned to them. Indeed, they were no longer ostracized as symbols of impurity. Lejeune's discovery opened up a novel field of research. It was the birth of medical cytogenetics. His team discovered other chromosomal abnormalities that form the basis of diseases such as Cri du chat syndrome. And like any scientific discovery, it led to further questions. The first and most obvious one was why is it that one extra, and not one missing, chromosome leads to Down's syndrome? Lejeune expected to find missing genetic material, not excess. His prescient explanation took the form of a metaphor. He said that it is like a musician in an orchestra. When a musician plays fast, it is not a problem if the musician is playing a solo. However, a single musician playing faster than the others in an orchestra will destroy the sound. In this way, Lejeune foresaw the interplay of genes and proteins that make up cells. Indeed, he drew what was known as the Lejeune machine, an apparatus of cogs, each of which represented a different protein in the body. Now it is the fashion to conceive of cells as biological systems. At that time, however, it was a new way of thinking of biology, different from the standard "one gene, one protein, one function" approach. Typical of Lejeune's thought was the way he would generalize to the bigger picture. The fact that each human being has the same number of chromosomes, such that a single change in one of the smallest causes so much disturbance, was a sign to him "that mankind is a biological unit of which races are variations with no precise boundaries. Hence the old idea that human beings are brothers is not an ethical hypothesis or a purely moral goal, but simply a correct expression of plain reality." He does not stop there. "The recognition of such brotherhood is very comforting, but increases our concern as human geneticists for the destiny of those unfortunate children who do not share equitably our chromosomal heritage."

Love and concern for his patients always dominated Lejeune's thoughts. In fact, Lejeune's main goal was not to make discoveries. It was to find a way to cure his little patients. "If I could find a cure for trisomy 21, this would lead to a cure for all of the other diseases that have a genetic origin. My patients are waiting for me." He began to explore various approaches. The first and most obvious one was to decode chromosome 21, which contains the "extra" genetic information, in Down's cells. He knew that it would happen one day (in fact it happened shortly after his death), but he foresaw that it would not be the final answer. "What will remain to be understood are the properties of the proteins coded, the functions of the enzymes and the complex activity of… activators, repressors, enhancers, etc...." Scientists would need to understand how the information is being processed to affect cellular function. In fact, we now know that there are between 300 and 400 genes on chromosome 21, but the gene or group of genes that is responsible for the clinical manifestations of Down's has not yet been identified. As Lejeune wrote, "The whole difficulty in the research is to discover the discordant musician, because the orchestra of life has about 50,000 musicians." He turned to the chemical approach, asking, "Why is it that trisomic 21 children are mentally retarded?" Or, in more operational terms, "How could a gene overdose hamper the functioning of their brains?"

Lejeune needed to learn about the metabolism of cells, and so he went back to university to study biochemistry. He realized that folic acid deficiency could play an important role in brain development and was one of the first to advocate for folic acid supplementation in pregnancy. This idea came to him from observing how children with a genetic disease that was due to the abnormal function of folic acid metabolism exhibited similar self-mutilation behaviour as some Down's children. He realized that Down's adults tend to get Alzheimer's dementia earlier than other adults and began to look for similarities between the two syndromes. He recognized that nature shuts down entire chromosomes, as observed in the so-called Barr body, which results from the shutdown of the second X chromosome in females. Therefore, he thought that the obvious treatment would be to suppress or silence the chromosome, but he did not have the technology to do it. Recently, a group of scientists reported the experimental silencing of chromosome 21 in animal cells, fulfilling Lejeune's prophecy.

The most striking aspect of Lejeune's research approach was his absolute optimism. He was convinced that a cure for Down's would be found. "We will find it, it is impossible not to find it. It is an intellectual effort that is much less difficult than sending a man to the moon. The skill of a researcher when confronted with a difficulty is to keep turning around until he finds the door that opens."

If one thinks about it, however, such optimism appears unreasonable. Either one must find the first embryonic cell when the chromosomal separation that causes trisomy 21 occurs (which is quite impossible because it is too small, and it is impossible to know when exactly it happens), or cure all cells in the body and the brain that have the extra chromosome. Yet Lejeune persisted. His last regret was that he was abandoning his patients without having found a cure. He provided clues as to the origin of this optimism: "If we believe, if we have faith… this requires us to put forward another postulate: that there is a Spirit that has not only written the laws of the Universe, but has created us men in His image. Thus, if it truly is like this, the one with faith has a great advantage, because he is an optimist for the following reason: Since his mind is limited, as it has been made partially in the image of the Spirit that made the laws of the Universe, it is reasonable to hope that his limited mind will come to understand, in a limited way, the laws of the Universe." Thus, faith potentiates reason.

As Pope John Paul II said, Lejeune's sense of responsibility was complete. He became the advocate of his patients. His daughter, Clara, recalls, "One day, a 10-year-old child with Down's came to the clinic. He was crying and was inconsolable. His mother explained, ‘He saw yesterday's [abortion] debate on TV with us.' The child threw his arms around my father's neck and said, ‘They want to kill us. You must defend us. We are too weak. We are not able to do it alone.'" Lejeune decided to defend them and the following day warned his team members, "I will be forced to publicly take a stand to defend our patients. If I didn't defend them, I would betray them and would renounce what I have in fact become: their natural advocate."

His gaze encompassed the individual and the society in which he lived. "It cannot be denied that the price [of genetic diseases] is great, in terms of suffering for the individual and of troubles for society. That is without mentioning what the parents have to bear. If these individuals could be eliminated early, the savings would be enormous. But we can assign a value to this price: it is exactly that which a society has to pay to remain fully human." So characteristic of Lejeune's views is how he sees everything together from the DNA to the human being carrying it. It is precisely this unity in looking at reality that is the most amazing aspect of this thinking.

And so Jér ôme Lejeune spoke out against abortion, against killing "us" in the womb. His voice was the only scientific voice against abortion at the time. He was severely criticized for his position and was ostracized by the medical, academic and political elite in France. He faced harassment from university and State officials, and did not receive an increase in salary for nearly 20 years. His research grants were withdrawn, and he was forced to close his laboratory. American and English laboratories, indignant at this treatment, granted him no-cost private loans. This solidarity allowed him to rebuild a team of researchers inspired by the same motivations. Tragically, excellent students avoided him, as a letter of recommendation from Lejeune would only hurt their ambitions. But he persisted, frequently speaking out against abortion. And he redoubled his research efforts, recognizing that just as Pasteur's discovery of bacteria eventually rendered the suffocation of persons with rage or the burning of plague victims unnecessary, so would a cure for Down's render their intrauterine elimination unwarranted.

In 1969, he received the highest accolade from the American Society of Human Genetics—the William Allan Memorial Award. He arrived in San Francisco, greeted, as is the custom, by a young, ambitious and bright geneticist, Charles Epstein. Dr. Epstein proudly told Lejeune that his discovery had made possible the opening of the first prenatal screening clinic in California, which had just recently legalized abortion. The next day, Lejeune delivered his plenary talk, and titled it "On the Nature of Man, or To Kill or Not to Kill, That Is the Question." He asked the question: What is man, and when does a human being begin? He surveyed many approaches to the issue and, although genetically all the information was there at the beginning, and therefore a human being was present at conception, he concluded that science could not tell when a human person was present. Thus it behooved the scientist to treat the unfortunate victims of genetic accidents with "humility and compassion."

In later interventions, including at a trial challenging the legality of abortion in Saskatchewan in 1984, Lejeune would state that he could not understand how a geneticist could not affirm that a human life was present at the time of the creation of the genetic information specific to that human being. "I would say that a child in utero is a human being to the best of the scientific knowledge we have, that its genetic endowment is human. He is living by himself, then he is a being, and being a human is a human being." At that time, he went on to state that the birth of the first test-tube baby, Louise Brown, was experimental proof that human life begins at fecundation. His profound anti-abortion positions were thus motivated purely by scientific reasons.

"If—and I hope God will never permit that—the Pope was saying that abortion was killing nobody, I would stop being a Catholic for scientific reasons, because no moral authority can make me believe that discarding an early human being is not discarding a human being."

This viewpoint, though controversial in the scientific milieu, nevertheless left its imprint. In 2003, Charles Epstein, the same scientist who hosted Lejeune in San Francisco in 1969, would himself receive the Allan Memorial Award. In his acceptance talk, he said he had witnessed almost all of the Allan Memorial winners giving their talks, and the one that was "particularly vivid" in his mind was Lejeune's. He compared the effect of Lejeune's speech with that of the earthquake that shook San Francisco during the conference they were attending. He admitted his position remained in favour of the right of abortion for women, but he recognized the dismay that the availability of abortions caused the disabled. Indeed, "as much as we talk about neutrality and non-di-rectiveness in genetic counselling, the message that these programs convey is that it is really not all right to give birth to a child with serious abnormalities." Keeping in mind Lejeune's emphasis on the human, Epstein wished to remind geneticists that "human genetics is about human beings—about humanity and humaneness."

As a final example of Lejeune's wonderful all-encompassing gaze on reality, we can turn to his prophecy of the availability of DNA sequencing. "Intelligence…teaches us that the number of possible combinations of the various genes transmitted to us from our father and mother surpasses the number of humans who are alive today or who have ever lived on Earth. It teaches us that each one of us possesses and is endowed with an absolutely original composition that has never before occurred and that will never occur again.… When we look at this genetic identity card, we not only see that every human being is unique, but that he or she was born from a father and a mother who in turn were also unique. In a few years from now, machines like those in supermarkets will be able to read [this identity card]."

We are now in the era of the $1,000 human genome, available directly to the consumer. But, as Lejeune put it, "the machine will never be able to give the price of human life." For Lejeune, science confirmed the great uniqueness and dignity of each individual human being.

Lejeune remains an outstanding example of a true physician-scientist, a model of love for truth and reason, one for whom the words of the recent papal encyclical, Lumen Fidei, are true. "The gaze of science thus benefits from faith: faith encourages the scientist to remain constantly open to reality in all its inexhaustible richness. Faith awakens the critical sense by preventing research from being satisfied with its own formulas and helps it to realize that nature is always greater. By stimulating wonder before the profound mystery of creation, faith broadens the horizons of reason to shed greater light on the world, which discloses itself to scientific investigation."

As Lejeune wrote: "For millennia, medicine has striven to fight for life and health and against disease and death. Any reversal of the order of these terms of reference would entirely change medicine itself. It happens that nature does condemn. Our duty has always been not to inflict the sentence but to try to commute the pain. In any foreseeable genetic trial, I do not know enough to judge, but I feel enough to advocate."