what is "cloning"?

In the cloning procedure the nucleus of a fully differentiated donor cell — such as the udder cell used in Dolly’s case — is inserted into an egg cell after removing the egg’s own nucleus. The altered egg cell is stimulated to divide, developing into an embryo made up of cells that genetically match the donor organism that had supplied the nucleus. Therapeutic or reproductive cloning can be done when the cloned embryo is about a week old.

Certain animals before Dolly had been cloned using the nuclei of embryonic cells; Dolly made science history because, for the first time, adult cells had been used. Since 1997, several other species — including mice, goats, cattle, pigs, and cats — have been successfully cloned from adult cell nuclei, often in order to replicate animals of superior commercial value (such as cows that are above-average milk producers). Recent announcements in the press that human clones have been born await confirmation.

At this conference, advances in both therapeutic and reproductive cloning will be explained in plain English. Speakers will discuss the ethical and legal questions raised by human cloning, whatever its purpose.

What are the potential benefits and risks of human cloning?

In 1997 the birth of the first cloned animal, Dolly the sheep, unleashed a flood of public curiosity and concern: If animals could be successfully cloned, why not clone humans? Suddenly this question, formerly the stuff of science fiction and fantasy, was worthy of serious consideration — and heated debate.

In the years since Dolly’s birth, interest in human cloning has focused on its two known uses. Therapeutic cloning involves harvesting stem cells from cloned human embryos at a very early stage and directing the stem cells to differentiate into specific replacement cells. These replacement cells may then be grafted into human patients. For example, insulin-producing pancreatic cells may be used to treat diabetes; replacement nerve cells may be used to treat Parkinson’s disease.
The second, more controversial type of cloning involves using DNA from an adult or child to create a human being who is genetically identical to that person. Such reproductive cloning may enable infertile or gay couples to have children without the use of a surrogate, or couples with inherited genetic disorders to avoid passing genetic disease to their children.

Both therapeutic and reproductive cloning, however, have significant medical and ethical risks. Cloning-based stem cell therapies carry the risk of tumor formation, and cloning experiments in animals have been met with alarmingly high birth defect and mortality rates. Ethical issues associated with human cloning include embryonic rights, issues of individuality, the impact on traditional parent-child relationships, and the slippery slope towards “designer” babies with made-to-order genetic traits.



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