American researchers: the cloning process itself causes genetic defects - and its application in humans would be a bad idea
Tamara Traubman
While scientists around the world announce one after the other that they have succeeded in cloning various animals, and while the ethical debate on the question of human cloning is in full swing, yesterday a team of American researchers came out with pessimistic news - which brings back and sharpens the problems and dangers involved in the cloning of living beings in general, and humans in particular.
In the most comprehensive study of its kind, the researchers showed that cloned animals suffer from many genetic defects. According to the team, its findings imply that even in cloned animals that appear healthy at birth, genetic defects exist. Human cloning, the researchers say, would probably be a very bad idea.
The researchers, Prof. Rudolph Jinisch and my colleague from the Whitehead Institute at BM-IT, tested the genes of cloned mice that were born. They discovered that one out of every 25 genes in the placenta, which envelops the cloned mouse during its development in the womb, does not function properly. Genes whose activity is not normal were also found in genes from the liver of the mice, although the scope of the defects was smaller than in the placenta. The findings were published yesterday in the scientific journal." Sciences National Academy of "Proceedings of the
Researchers observed that many of the cloned fetuses die before or shortly after their birth. To try and explain this phenomenon, Prof. Jinish and his colleagues decided to examine in detail the effect of the cloning process on the genetic development of the cloned animals. Even cloned animals that survived after birth suffered in many cases from various problems - including greater than normal birth weight, breathing problems, repeated pneumonia, failures in liver function and a short life expectancy. Another study on a smaller scale, which examined 12 genes, also pointed to the genetic defects caused by the cloning process.
The team's findings are published as the public debate on the question of human cloning reaches its peak. Even before the ethical debate ended, two doctors - the American Dr. Panos Zavos and the Italian Dr. Severino Antinori - announced that they had begun attempts to clone children for couples with fertility problems. Another group known as the "Heral Movement", an American religious movement whose branch also operates in Israel, also announced that it is working on cloning a wealthy businessman, who is dying and wants to create another person in his image - who will live on after him. Both groups have announced in recent months that they have implanted cloned embryos into women's wombs, however, neither group has presented evidence of their attempts.
In the cloning process, the nucleus is removed from an egg (almost all the genes are in the nucleus) and a nucleus from a mature cell of the animal you want to clone is inserted in its place. The egg "resets" the development clock of the adult cell, and reprograms it, so that it returns to its embryonic state. The egg begins to divide and develop into an embryo. The animal that will be born will be a genetic twin of the animal from which the adult cell was taken.
It turns out that countless things can go wrong when reprogramming the kernel. "The procedure of transferring the nucleus to the egg interferes with the normal programming process, and causes many genes to operate abnormally," said Prof. Jinish in a statement published by the team. "Our research is further confirmation of the many problems inherent in cell reprogramming."
The first mammal born from a mature cell, Dolly the sheep, cloned from an udder cell. The animals born after her - including pigs, rabbits, mice and cows - were cloned from cells taken from different parts of the body. Some of these animals were not cloned from adult cells but from fetal cells. Some scientists have already suggested that the type of cell and the conditions in which it is kept in the laboratory flasks before being cloned, have a great influence on the amount of defects that will be created in the cloned animal. However, according to Jinish, the new research indicates that "the cloning process itself, regardless of the cell type, leads to problems".
The test conducted by the team was indeed a sample, but Prof. Jinish believes that all the surviving cloned animals contain genetic defects. "I believe that all cloned animals have abnormalities, but to a different degree," he said. According to him, "those who survived have less serious abnormalities and for this reason they survived".
And on the same topic, Alex Doron writes, Ma'ariv, on 23/9/2002
Genetics/human cloning: "a very bad idea"
A study published in the American journal "Records of the National Academy of Sciences" claims: "It is very possible that humans are not qualified/suitable for the process of 'genetic replication' (cloning) in order to create 'copies' of them. It may very well be a bad idea to try and clone humans. The procedure is neither perfectly safe nor ethical."
The article started a new debate among the scientists, which will certainly become more heated in the near future. Leading the research: Prof. Rudolf Janisch from the "Whitehead" Institute for Biomedical Research in Boston. He analyzed ten thousand genes - he was therefore the most comprehensive so far on this subject - and found that animal cloning of all kinds almost always produced abnormal phenomena in the cloned animals. This is how it started with the sheep "Dolly". The genetic makeup in the cloned animals was shocked and damaged. Various diseases appeared in the animals: arthritis, premature aging, lung and liver diseases, the litter fell. Even in cloned mice - and the mice are used as models for research related to diseases and human genes - serious medical problems have been discovered in the placenta.
Researchers who reviewed the research report said: "It may be another nail in the coffin of the idea of cloning humans for the purpose of creating 'copies' of people." There seems to be no dispute about the need to perform cloning for organ reserves for transplantation.
Nobel laureate in biochemistry, Prof. Paul Berg from Stanford University said: "If we do not know how to safely clone animals, we must not try to clone humans." Other researchers: "It doesn't matter how normal the cloned animal looks, as soon as it comes into the world - after a while, very serious diseases will begin to appear in it."
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