Mr. Chairman and Members,
My name is Jérôme Lejeune. i am a doctor of medicine, taking care of
disabled children at the Hôpital des Enfants Malades (Sick Children Hospital).
I have spent ten years in full-time scientific research, and am now Professor
of Fundamental Genetics at theniversity René Descartes in Paris. Having always
been a human geneticist, I try to remain human in dealing with genetics.
After working specifically with mongoloid children, I demonstrated that
this disease was due to an extra chromosome. For this work, I had the great
honor of receiving the Kennedy award from the late President.
Specializing in the study of the human chromosomes, i have frequently
visited thenited States, and had the honor in 1970 of receiving the William
Allen Memorial Medal in San Francisco from the Maerican Soceity of Human
With my colleagues in Paris, we have particularly described many
different chromosomal conditions in man, and also compared the chromosomes of
man and of primates like the great apes.
We are deeply involved in new techniques of analysis, and have achieved
specific recognition of the old and the new chromosomes during celle
We are also working on the effect of super-numerary chromosomes. in
mongoloid children, we have recently demonstrated an excess of a specific
enzyme, superoxyde dismutase. the eventual relationship between this trouble
and the mental retardation of the affected children is under investigation.
The transmission of life is quite paradoxical. We know with certainty
that the link wich relates parents to children is at every moment a material
link, for we know it is from the encounter of the female celle (the ovum) and
the male cell (the spermatozoa), that a new individual will emerge.
But we know with the same degree of certitude that no molecule, no
individual particle of matter enclosed in the fertilized egg has the slightest
chance of being transmitted to the next generation. Hence, what is really
transmitted is not the matter assuch but a specified conformation of the
matter, or more precisly, an "information".
Without receiving the complex machinery of coded molecules like DNA,
RNA, proteins, and so on, wich are the vehicle of heredity, we can see that
this paradox is common to all the process of reproduction, wheter natural or
man-made. For example, a statue must be built out of some material, and could
not exist if made of pure void? During the casting process, there exist at
every moment a contiguity of molecules between the statue and the cast, and,
later, between the cast and the replica. But obviously, no matter is
reproduced, for the replica could be plaster, or bronze, or anything else. What
is indeed reproduced is not the matter of the statue, but the form imprinted in
the matter by the genius of the sculptor.
Indeed, the reproduction of living beings is infinitely more delicate
than the reproduction of an inanimate form, but the process follows a very
similar path, as we will see by antother familial example. On the magnetic tape
of a tape recorder, it is possible to inscribe by minute alterations of local
magnetism, a series of signals corresponding, for example, to the execution of
a symphony. Such a tape, if introduced in the appropriate machine, will play
the symphony, although there are no musicians in the machine and even no notes
written on the tape. that's the way existence is played.
But in this analogy, the mangetic tape is incredibly thin, for it is
reduced to the size of a DNA molecule, the miniaturization of which is
bewildering. To give an idea of this minuteness, we should remember that in
this thread every character of each of us is exactly described. Thou sahll have
blond hair, hazel eyes ; thou shall be six feet tall, and thou shall live some
eighty years, if no road accidents interven ! All these instructions giving a
full description of a man are written in a thread one yard long. But the thread
is so thin and so carefully packed inside the nucleus of the celle, that it
would stay at ease on the point of a needle.
To give another impression, if we were to reassemble on this table all
these threads wich will specify each and every quality of the next three
thousan million men who will replace us on the surface of this planet, this
quantity of matter would fit nicely in an aspirin tablet. The fertilized egg is
comparable to a tape recorder loaded. As soon the mechanism is triggered, the
human work is lived, in strict conformity to its program.
The very fact that we have to develop ourselves during nine months
inside the bodily protection of our mother does not change anything, as you can
easily observe by looking at the egg of the hen, from wich the chicken will
emerge. It makes no difference wheter he was incubated by the fowl, or by an
electric heating device ! The chicken is stilla chicken. If one day a children
can be entirely grown in a test tube, the test tube will never believ that the
child is its property !
Such a reduction of the human being to its very nature may not be
palatable, or intuitively stisfactory, but it accurately reflects the present
state of our scientific knowledge. When a new student hears for the first time
a symphony, let us say the Little Night Music by Mozart, he must listen to the
whole in order to know it. But if he is a music lover, he will recognize Mozart
at the first bars, and could tell the title at the second or third bar. It is
the same with the human symphony? the specialist can recognize it at its first
accents, even if a great number of various movements are required so that its
general form becomes evident to everyone.
The infinitesimal threads of the genetic information are carefully
coiled in little rods, the chromosomes, easily visible with an ordinary
microscope. they are something like the magnetic tape inside the cartridge of a
minicassette. Some twenty years ago, nobody could have told the celle of a man
from the cell of a chimpanzee. Ten years ago, a simple counting of the
chromosomes would have given the answer, 46 if a man, 48 if chimp. Since last
year, if a student looking at a divinding fertilized egg or at the divinding
celle of a blastocyst, could not telle them apart saying "this one is a
chimpanzee being, this one is a human being", he would fail the examination for
But can we say that the early human being is an individual just after
fecundation? Does he have the two qualities of an individual : its unity and
its uniqueness? Exceptions to unity are known : maybe once in every million
births, some subjects carry , side by side, male cells (recognized by their X
and Y chromosomes). Thus these subjects are simultaneously provided mith the
masculine attributes of Hermes and those feminine of Aphrodite, hence the name
hermaphroditism. one would believe that two fertilized egges, one bound to be a
boy, and the other bound to be a girl, have united together intimately, and it
is quite the case. In the hermaphrodite, the mistake is extremely precocious,
and seems to happen at the second division of maturation of the egge. Two
reciprocal celles are produced, the ovum and its polar body, which would be
here just as voluminous as the ovum. Both of them are simultaneously
fertilized, each one by a different spermatozoa. Hence, exceptions to unity can
happen very rarely at the time of fecundation.
Exception to uniqueness is more common : the identical twins coming from
the same fertilized egg, share exactly the same genetic patrimony, but each of
them is obviously an individual by itself. From embryological knowledge, it
seems impossible to separate one nature int two (or more) persons after the
neural crest, that is, the first appearance of the nervous system, has
differentiated. Hence, after the 13ty day, no twins could occur. But, by
inference, for the experimentation is not at hand at this time, it seems that
the splitting must be extemely precocious, probably at the moment of the
division of the first few cells of the embryo, that is, at the first encounter
of the paternal and maternal stes of chromosomes.
These remarks on the exceptions of the individual "one and unique"
corroborate the notions that every man begins at his very beginning. These
theoretical ans experimental notions can sometimes be directly felt by the
persons themselves in exceptionnal situations. A very rare accident can occur
at the moment the identical twins are formed. From ans XY fertilized egg, bound
to be a boy, two celles are produced: one XY will continue its masculine
destiny, the other having received only the X chromosome (the Y being lost
during the separation process) will develop itself as an imperfect girl. Two X
chromosomes are required for a complete and harmonious feminity. Hence, the
identical twins will be different : one normal boy and frail and strerile
In the fist case we observed of such a young gril, she was some 18 years
old and complained of a strange trouble. She feared to look at herself in a
mirror because she pretended she was seeing her brother. Such an impression,
far from anomalous, was an extraordinary intuition, very feminine indeed, of a
very complex situation entirely undetected at that time. At the exception of
the lost Y chromosome, she was effectively a piece of her brother from whom she
These facts of human genetics can appear a little theoretical, and the
question must be asked wheter common sense can recognize as such a tiny human
being. if very early, only the scientist aided by refined techniques can tell.
If, let us say, at two months everybody knows, and has known for thousands of
At two months of age, the human being is less than one thumb's lenght
from the head to the rump. He would fit neatly into a nutshell, but everything
is there - hands, feet, head, organs, brain - all are in place. If you look
very closely, you would see the palm creases, and if you were a fortune teller,
you could read the good adventure of that person. looking still closer with a
microscope, you could detect the finger prints like Sherlock Holmes - every
document is available to give him his national identity card!
The incredible Tom Thumb really does exist. Not the one of the fairy
tale, but the one each of us has been. For it is from this true story that
fairy tales were invented.
If thom Thumb's adventure have always enchanted the children, if they
cans still evoke emotion on grown-ups, it is because all the children of the
world, all the grown-ups they have turned into, were one day a Tom Thumb in
their mother's womb.
But can we scientists accept these fairy tales? The truth is indedd that
Nature itself does. For instance, abortion is a normal process in imperfect
mammals called marsupials. They have a special pouch on the abdomen,
conveniently accomodated to nurture the little. In the giant kangaroo, the
abortion occurs at the same stage as the little Tom Thumb in man, and is
roughly the same size. The aborted fetus then climbs into the fur of its mother
to reach the pouch. The bewildering fact is that the kangaroo mother will let
him do so, although she would not allow any other kind of animal drop in! If
the poor brain of a female kangaroo can recognize the tiny creature as a
kangaroo being, there is no wonder that geneticists can safely assure you that
Tom Thumb is indeed a true human being.
From moleculat genetics to comparative reproduction, nature has taught
us that from its very beginning the "thing" we started with is a member of our
kind. Being its own, human by its nature, never a tumor, never an amoeba, fish
or quadruped, it is the same human being from fecundation to death. he will
develop himself if the surrounding world is not too hostile. And the sole roel
of medicine is to protect the indivodual from accidents as much as possible
during the long and dangerous road of life.