Wednesday, June 17, 2009

Why Human Cloning is Undesirable?

There is a series of scientific reasons for not cloning human beings. Although many scientists and most of the public share this point of view, it is feared that personal ambition of unscrupulous scientists would make them blind to the scientific reasons for not cloning man. The success in animal cloning is evidence that this technology might be ready to justify its application to humans. In 2000, Dr. Panayiotis Zavos, an Israeli specialist in in vitro fertilization, and Dr. Severino Antinori, an Italian specialist in reproductive physiology, announced their intention to clone humans. In April 2002, Antinori claimed that he had two women carrying cloned babies.

After the birth of Dolly and the successful cloning of mice, cattle, monkeys, goats, and pigs, it is evident that cloning is not a completely safe procedure. Cloning of mammals is considered highly inefficient, and this is unlikely to change in the foreseeable future. Many cloning experiments have resulted in developmental flaws either during gestation or in the neonatal period. Even in the best cases, only a small percentage of cloned embryos survive to birth and, of those, many die shortly after birth. There is no reason to believe this would be any different with humans. This means that to achieve the successful generation of a human clone, many others will have been sacrificed in the developmental phases.

The few animal clones that have survived and been born show abnormal size, a phenomenon called increased offspring syndrome. It is believed that incorrect functioning of the placenta is one of the main causes of embryonic death. The suspected causes of newborn death are respiratory and circulatory problems. Some seemingly healthy survivors might possess immune system dysfunction or kidney and brain malformation. Those problems have been detected in practically all species in which cloning has been accomplished. Therefore, if an attempt to clone a human is made, the concern is not just with the embryos, but also with those that will live to be abnormal children and adults.

The abnormalities in the fetuses and in those few clones that are born alive cannot be easily traced to the nucleus of the donor. The most probable explanations are flaws in the genetic reprogramming or timing and expression of the correct developmental genes. Normal development depends on a necessary sequence of changes in the configuration of DNA and proteins coded by developmental genes. Those developmental changes control the specific genetic expression in the specialized tissues.

Genetic reprogramming of the entire genome is a natural process that happens during spermatogenesis and oogenesis, which can span over months and years in humans. During cloning, reprogramming of the donor's DNA must be done within minutes or, at the most, in a few short hours, during the period of time that nuclear transfer is completed and cell division begins to form the zygote.

Prenatal mortality in clones can occur due to inadequate reprogramming that results in improper gene expression. Some surviving clones have subtle genetic defects that, over time, result in life-threatening conditions. There is no information on genetic regulation in clones, but some evidence seems to indicate errors in gene expression in cloned animals. The expression of marked genes is significantly altered when embryos are cultivated in vitro before they are implanted in the uterus, indicating that even a minimal disturbance of the embryo's environment can have profound effects on gene regulation during development.

All the current evidence now suggests that the experiments on human cloning announced by Zavos and Antinori will have the same failure rates and occurrences of abnormalities that have been detected in animal cloning. Zavos tried to calm the public, informing them their research would use genetically perfect embryos to be implanted as a quality control. However, the public perception of reproductive biotechnology will be seriously damaged if the research fails and defective babies are born from human cloning experimentation. This would likely negatively affect other areas of research, such as the advancements being made with stem cells.

The National Bioethical Advisory Commission in the United States reached the following conclusion six years ago: "At the present, the use of cloning to generate a child would be a premature experiment, and would expose the fetus and the child in development to unacceptable risks." All the data gathered since seems to reinforce this point of view. In many countries, it is unlawful to perform research with human reproductive cells, thereby forbidding embryonic cloning.

Tags: Bio Technology, Bio Genetics, Cloning

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