ePub 版

we were called upon to perform abortions, we were also performing the first intrauterine fetal transfusions in Colorado for Rhesus disease, a procedure developed by Dr. Liley, who is with us today. How was I to rationalize vigorous efforts to treat and save one human fetus with a congenital disorder on one day and on the next kill the fetus with a congenital disorder that I could not correct?

The scientific evidence for the growth and development of human life before birth is incontrovertible. Today you will hear that evidence presented by two outstanding scientists with international reputations in their fields.

Dr. Jerome Lejeune is professor of fundamental genetics, faculty of medicine, at the Universite Rene Descartes in Paris. His many contributions to fundamental human genetics are recognized throughout the world. His descriptions of the chromosome abnormalities in Down's Syndrome, Mongolism, were instrumental in our understanding of chromosomal disorders. He is the author of a widely acclaimed textbook of human chromosomes, as well as innumerable contributions to scientific journals. His accomplishments have been acknowledged by awards from prestigious societies, both in our country and his own, including the Kennedy Award and the William Allen Memorial Medal from the American Society of Human Genetics.

I have known Sir William Liley since 1965 because of our mutual interest in fetal transfusion for the treatment of Rhesus affected infants. Dr. Liley has degrees in both medicine and neurophysiology. He is perhaps most widely known for having first successfully performed a transfusion for the fetus in utero. But his numerous contributions in the field of human fetal physiology have enormously broadened our understanding of intrauterine life. Dr. Liley's research has been conducted at the Postgraduate School of Medicine in Auckland, New Zealand, from which have come his extensive contributions to the scientific literature.

It is a great pleasure to present to the committee Dr. Jerome Lejeune and Dr. William Liley.

Senator Bayi. Gentlemen, have you decided how you are going to proceed?

Is there some seniority system in international expertise such as is represented here?

Dr. Bowes. Senator Bayh, in the development of a human being, Dr. Lejeune comes first.

Senator BAYH. All right.



Dr. LEJEUNE. Mr. Chairman and members, please excuse my poor English.

I am a doctor of medicine, and I take care of disabled children in the Sick Children's Hospital in Paris. After 10 years of pure scientific research, I became professor of fundamental genetics.

I am a human geneticist, and that is the reason why I try to remain human when I am dealing with genetics. Having found with

my coworkers that there was an extra chromosome which was producing a disease called mongolism, I had the great honor to receive the Kennedy Award here in this country from the late President. And also I had the great honor of having the William Allen Memorial Medal from the Society of Genetics of America. That is one of the reasons why I feel that I am here trying to give back to the United States some scientific data. I owe so much to your country for our scientific research.

The point which is the main point for geneticists is that the transmission of life is a very paradoxical phenomenon. We are entirely sure that the link between the parents and the children is at every moment material, because it is from the ovum fertilized by the sprmatazoa from the father that the new human being will emerge. But we know with exactly the same degree of certainty that no molecule, no particle of matter, which was in the first cell will be transmitted to the next generation. Then, obviously, what is transmitted is not matter by itself, but is something which is supported by the matter, that is, bits of information.

I do not think it is necessary that we review the whole machinery of the coded molecule, DNA, RNA, protein, and so on, to understand that this paradox of reproduction is found, not only in living things but in every system of reproduction. To take an example, when you want to reproduce a statue, during the process of casting, there is always a contiguity of molecules, or particles of matter, between first the statue and the cast, and secondarily between the cast and the replica. But what is replicated! It is not the matter, because the statue was, for example, of marble and the replica will be of plastic. What is replicated is a form that the genius of the sculptor had imprinted on the matter.

Another, maybe more familiar example, would be to look at what happens when we record a symphony on a magnetic tape. Let us suppose that you record the Little Night Music of Mozart on a tape. If you put the tape on the machine, then the machine will play the Little Night Music. But what is important is that which is on the tape; there are no musicians and there are even no notes of music. What is there is just a minute change of magnetism making a code which is read by the machine.

And it is exactly in that same way that the human existence is played. That is, once the full information is in the system, then the system is triggered, and the human is formed in perfect conformity to its own program. But here, this analogy vanished, because the tape which dictates all our specifications is incredibly small, because it is reduced to a molecule of DNA. To give an idea of this minuteness, we should remember that this thread is 1 yard long but is coiled so tightly that it would fit very neatly on the point of a needle.

Nevertheless, in this tape is written all our characteristics. If we could read it directly, we would see, for example, that it is written: Thou shalt be blond; thou shalt have hazel eyes; and thou shall Jive, say, 80 years, if no road accidents end it; and so on. All these instructions give the full description of a human being.

To give you a physical impression of this minuteness, I could take another example. If we had all the threads which will deter

mine every one of the qualities of every person, let us say 3 billion of them, this quantity of matter if we were putting it on the table here would fit neatly in one aspirin tablet.

The very fact that we develop ourselves during 9 months under the bodily protection of our mother does not change anything, as you could immediately notice looking at the egg of a hen. It does not matter if the egg is incubated by the fowl or by an electrically heated device. The chicken is there, and it is the same chicken. That means that if someday somebody was able to grow a human being inside a test tube, the test tube would never believe that it is the proprietor of this tiny human being.

Maybe such a reduction of the human being to its very nature does not look very acceptable, not very palatable, and maybe not intuitively acceptable. But this is a description of molecular genetics; it is not a pretension of the scientist. Let us suppose that a new student has to listen to the Little Night Music of Mozart; then he must listen to the whole thing in order to understand what it is and to recognize it. But, now, if he is a professional, a music lover, after the first bar he will

say, “Oh, that is Mozart,” and after the third he could tell you the title. It is exactly the same with scientists. Because they know the human symphony, they can recognize it at its first actions, even if it needs a lot of various movements until everybody can understand it.

Those infinitesimal threads in which all the genetic information of every human being is carefully spelled out are coiled tightly in little bodies that we call chromosomes, exactly like a magnetic tape inside the cartridge of a minicassette. And, let us say, 15 years ago nobody in the world would have been able to tell the difference between a cell of man and a cell of a chimpanzee. Around 10 years ago, just the counting of the chromosomes would have told, if there are 46, it is a man; if there are 48, it is a chimpanzee. But, since a year ago, we are able to decipher inside the chromosome, to recognize their particular patterns. To give you a simple example, if a student now was presented a dividing egg, at the first division, if the preparation was good, and put under the microscope, he should be able to tell this one is a human being and this one is a chimpanzee. If he could not recognize that, he would not be licensed as a good cytogeneticist. That was not true 10 years ago, but it is true now.

But can we say—and it is possibly the most important pointthat this tiny human being, which is entirely spelled out in the genetic code, is already an individual? An individual can be defined by two qualtites; an individual is one in the sense that it is the same individual in every part of its body; and secondly, an individual is unique in the sense that no one else in the world is so identical to him that he could replace him exactly.

Then we have to ask whether this unity and uniqueness is present at the beginning of the human being. Obviously, it must be present, but what is important is that pathology can tell us what happens when those qualities are not there. We know that very rarely, maybe once in every million births, people are born with a mixture of cells. Some cells are of the male type; they have X and Y chromosomes—we can recognize them safely—and others are XX, they have two X's, they are the female type. And those people built with

those two populations of cells are simultaneously furnished, if I can say, with the male attributes of Hermes and the feminine ones of Aphrodite; then we call them hermaphrodites.

What is important is that those people have two different genetic contributions, because there appears to have been the fission of two fertilized eggs, one which would have given a boy, one which would have given a female.

Now, we must ask at what moment this fission of two different natures in one individual is still possible. From what we know at the moment in science, we are reasonably sure that this accident occurred in man at the moment of the production of the female cell. And instead of losing a tiny cell which should be lost, which we call the polar body, the first primary cell splits into two cells of the same size which are fertilized each by different spermatazoa; hence, this exception to unity of the organism.

The contrary, that is the exception to uniqueness, that no other is like him, is much more common, like the one of the twins. Twins are two persons coming from one fertilized egg which has split and given two individuals. Now, we must ask at what moment that can still occur. We know for sure that after the neural crest, which is the beginning of our nervous system, has been delineated in the embryo, no splitting of the embryo into two embryos is possible. That puts the latest possibility at 13 days after fecundation. But it is very likely from what we know that, in fact, the splitting occurs much earlier than that. It is very likely that it occurs at the time of the two or four cells of the dividing embryo; that means 24 hours or maybe 2 days after fertilization.

These remarks can really make you feel that it is too theoretical. But what is very remarkable is that human beings who do not know anything about genetics can feel directly those realities if they are in special

situations. For example, it happens sometimes that an egg which is XY and is bound to be a boy, and which will split to give two twins-it should be two boys-it happens sometimes that at the moment of the splitting, one of the chromosomes is lost, and if it is a Y chromosome—the one which gives maleness—then the two twins coming from the same cell will be different. One will be a boy, as it should, and the other will lack the masculine shift, and it will be an imperfect feminine person, which we call the Turner syndrome. They are obviously normal individuals as far as their intelligence is concerned, bodily development is concerned, which is very important.

One girl affected by that disease, who was a cotwin of a normal boy, was suffering from a very curious psychological trouble. She was complaining that she did not want to look at herself in a mirror, because, she said, “I am afraid that I will see my brother.” And it was not a kind of abnormality of mind; she had an extraordinary intuition, and a very typically feminine one, because she was really a part of her brother, with a Y chromosome excluded. So she could feel the reality of her own history, and at that moment nobody in the world knew how those extraordinary twins could have happened.

That proves that as far as human genetics is concerned, we know that a human begins at the beginning. And what is more important, that if you need to have all the scientific data to be a scientist at all to know it with certainty a little later.

I will take an example, and I will finish with that. When the little human being is 2 months old—that is, 2 months after fecundationits length from the head to the rump is something like 3 centimeters, half of my thumb. At that moment, the whole individual would fit neatly inside a nutshell. If I had it in my fist you could not notice I had anything in my fist, and I could even squash him and you would not see it. But if I were to open my hand, you could see the whole, tiny human being there—hands, feet, head, organs, brain, everything in place. If you looked very closely at this very tiny fellow, you could look, for example, at the palms, you could detect the creases of the palms, and you could tell the fortune, if you were a fortuneteller.

Now, if you looked closer, with a tiny microscope, you would detect the fingerprints as if you were Sherlock Holmes. That means that every evidence is there to give him his national identity card. The very fact is that the incredible Tom Thumb is not an invention of fairy tales. Tom Thumb exists really; not the one of the tale, the one each of us has been, because it is from that true story

that the fairy tales have been invented. And if the story of Tom Thumb is still amusing for all the children and for all the grownups they have turned into, it is just because each of us has been a Tom Thumb in his mother's womb.

But you could ask me, do the scientists really believe in fairy tales ! The very fact is that nature does, indeed, believe. For instance, abortion is a normal process in some low mammals that we call marsupials. They are called marsupials because they have a pouch on the abdomen which is conveniently provided by nature so that they can accommodate the little ones. For example, the giant kangaroo when it is grown up is roughly the size of a man. When a kangaroos has its normal, its physiological abortion, the tiny kangaroo is exactly the same size as the Tom Thumb I was telling you about; it is around 3 centimeters. It has no eyes, it has no ears, and it has only a big mouth, some legs, and the capability to suckle.

What is really bewildering is that this tiny creature, when it is just outside the genitalia, climbs into the fur of the mother and drops in the pouch. And what is a surprise is that the female kangaroo would never allow any other animal to drop in but will carefully let the tiny kangaroo go inside the pouch.

Now, when you see that nature was careful enough to put the wiring in the very poor brain of the kangaroo complicated enough so that the female kangaroo can understand that this tiny creature is a little kangaroo being, there is no wonder that geneticists can also understand that the tiny Tom Thumb is a true human being.

From what we know of molecular genetics to comparative reproduction of all the mammals, nature has taught us that from its very beginning, the thing which is developed in the womb of the mother is a member of our kin. Being by its own virtue, human by its own nature, never a tumor, never an amoeba, never a fish or a quarduped, the human being will develop by itself if, and only if, the outside world is not too hostile to him. And the sole role that medicine exists is to protect from its beginning to its end this human being developing in this very long road, very long and very dangerous road, that we call life.

Thank you, sir.

« 上一頁繼續 »