Academy of Sciences urges ban on human cloning

Dr. Irving Weissman chaired the panel that looked at the safety of human cloning.

(CNN) -- The National Academy of Sciences recommended Friday that human reproductive cloning -- cloning to create a baby -- be legally banned.

"Human reproductive cloning should not now be practiced. It is dangerous and likely to fail," Dr. Irving Weissman, the chairman of the panel that made the recommendation, said while presenting the findings at a news conference.

Despite these misgivings, the panel said the issue of human reproductive cloning should be revisited in five years if a medical and scientific review suggests techniques may be safer, and if there is a public consensus that a review is warranted.

While the panel called for human cloning to be banned, it said that ban should not extend to the nuclear transfer technique, or cloning embryos for the purpose of extracting stem cells for the treatment of disease, "because of its considerable potential for developing new medical therapies for life-threatening diseases."

The group cited an earlier Academy of Sciences report that also supported this technique -- also called theuraputic cloning -- for stem cell research.

RESOURCES Read the report online: Scientific and Medical Aspects of Human Reproductive Cloning

Dr. Bruce Alberts, president of the National Academy of Sciences, said the group decided to tackle the subject of human reproductive cloning to help inform public debate on the issue. He said the panel looked only at medical and scientific aspects of cloning, including protection of human subjects; it did not consider the ethical or moral implications of the research.

In a Friday news conference, Weissman explained that the panel had consulted experts in animal cloning, assisted reproductive technologies, medical and legal policy, and groups who want to clone a human, before coming to its conclusion.

It focused, he said, on the safety of the woman carrying the clone, the safety of the baby, and the risk to the egg donor. Data from animal studies show that there are serious risks to the mother, and that many cloned animals die or have severe abnormalities.

The rate of animal cloning successes, said panelist Dr. Mark Siegler, is "astonishingly low."

"There's no reason to believe that if carried out on human cells that (cloning) would be successful," he said.

Behavioral abnormalities are another concern, said panelist Dr. Maxine Singer. There is no animal data to determine whether clones might have behavioral problems, which would be of serious concern in any human cloning attempt.

To be considered safe, the panel said, cloning techniques must be improved so that the rate of abnormalities in the fetus is no more than that seen with assisted reproductive technologies such as in-vitro fertilization.

In addition, tests would have to be developed to show that the embryos to be implanted are normal, and tests must be developed to monitor the fetus in utero for cloning-related defects.

Groups that say they are working to clone a human now lack the fundamental biological knowledge to do so, the panel said. They also have not demonstrated the safety of animal cloning nor developed appropriate testing methods to assure safety.