Cloning's cousin

Culture | Haploidization-a new kind of genetic manipulation-could radically change the institution of the family

Issue: "The 2002 vote," Nov. 2, 2002

Cloning-making genetic Xeroxes of an individual and generating children without benefit of a father and a mother-is hard for most people to wrap their minds around. But geneticists are now going far beyond cloning, opening up the prospect of an even braver new world.

Every cell in the body contains the entire genetic code of the living animal or person. In cloning, the nucleus of an ordinary cell-from a piece of skin, or a hair, or a drop of blood-is injected into an egg that has been emptied of its own nucleus, whereupon it is made to multiply. The result is an embryo that, if it is allowed to live and grow up, will be genetically identical to whoever donated the cell. The donor is thus, biologically, a sibling rather than a parent.

Mass-producing identical twins over multiple generations, though, is not terribly useful, except for animal breeders who want carbon copies of an outstanding meat producer. Cloning does not bring out new and different genetic traits. In natural conception, the sperm and the egg combine into a unique individual whose full set of genes derives from the equal contribution of both parents. The resulting "genetic diversity" is far healthier for any species and any organism.

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But now scientists have found a way, using cloning techniques, to make an embryo out of two separate cells. This involves taking that ordinary cell from skin, hair, or blood, and causing its DNA to split in half. This half-cell, with exactly one half of the genetic code, can then be used to fertilize an egg, in the way that a sperm does. Or, two of these half-cells can be joined together, providing a full genetic blueprint that can then constitute a living embryo.

This process is called "haploidization," which was the focus of the latest conference of the American Society for Reproductive Medicine. Scientists at the Cornell University medical school reported success in generating both mouse embryos and human embryos, though they were frozen for further study, rather than allowed to be born. The next step, according to Cornell researcher Gianpiero Palermo, is to produce live mice.

Peter Nagy, of Georgia's Reproductive Biology Associates, told of using haploidization on a Brazilian woman whose own egg cells were damaged. The doctor replaced the genes from someone else's donated egg with intact DNA from one of the woman's normal cells, then fertilized it with her husband's sperm. But Mr. Nagy's conscience woke up and, feeling ethical concerns, he decided not to implant the embryo. He froze it instead.

Like similar medical breakthroughs, the moral questions raised by haploidization are being trumped with waves of sentimental, "caring" emotionalism. The procedure is being hailed as "the next major breakthrough" in fertility treatments. A man with infertile sperm can just use a skin cell to engender his child. A woman whose biological clock has run down will be able to have a baby after all, by using a cell from a piece of her hair. Infertile couples will have their little bundle of joy. What tears of happiness will be shed. Who would be so cold-hearted as to be against something that would help people have a little baby?

Never mind the babies that are found to be defective, killed, and disposed of, or the extra embryos that are engendered only to be put into a freezer. Those do not evoke the same sympathetic emotionalism as a couple that demands a baby no matter what.

Haploidization would also allow children to be bred for desirable traits, just as farmers devise hybrid corn and animal breeders raise champion stock by manipulating dominant and recessive genes. Since sex would no longer be necessary for having children, the institution of the family could radically change.

Mr. Palermo told The Wall Street Journal that same-sex couples could use the technique to become parents. A woman could have a baby with her lesbian partner, who could donate a half-cell. Heather really could have two mommies. Even more wondrous to contemplate, two men could have a baby. By manipulating the X and Y chromosomes and using a surrogate's womb, two homosexual men could have a baby of either sex. Heather could not only have two daddies, they would also be her mommies.

Some biologists do not believe a live child could be born from haploidization. Of course, some of those same biologists did not think cloning would ever be possible. Everyone admits that genetic defects are inevitable, at least for the trial runs until the technique is perfected.


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