THE VIRGINIAN-PILOT
Copyright (c) 1996, Landmark Communications, Inc.
DATE: Sunday, January 14, 1996 TAG: 9601140057
SECTION: LOCAL PAGE: B1 EDITION: FINAL
SOURCE: BY MARIE JOYCE, STAFF WRITER
LENGTH: Medium: 97 lines
Scientists at Norfolk's Jones Institute for Reproductive Medicine say they have overcome most technical hurdles to screening embryos for Down syndrome and many other chromosomal defects before the embryos are implanted in a woman's uterus.
This spring, the institute, part of Eastern Virginia Medical School, hopes to try out the technique with a handful of high-risk couples who come to the institute for in-vitro fertilization, said Dr. William E. Gibbons, chairman of reproductive endocrinology and infertility.
Eventually, all couples who go through the Jones Institute may have the option to screen for Down and most of the other conditions caused by an extra chromosome on one of 23 pairs that make up the normal complement.
The technique has been developed in part to help parents avoid a difficult moral decision - what to do if the fertility techniques cause the mother to become pregnant with many children at once. At the same time, it opens up a host of other ethical questions for parents and society as a whole, say people who have children with Down.
Down syndrome is caused by an extra chromosome on the 21st pair. The condition can cause retardation, which is usually mild; certain facial characteristics; and, often, defects in the heart and intestines. Life expectancy is about 55.
In-vitro fertilization is a technique in which eggs are removed from a woman's ovaries and combined with sperm in a dish. The resulting embryos are transplanted into the woman's uterus.
Before transplant, a single cell will be removed and exposed to probes made up of genetic material treated with fluorescent dye. Each probe has been designed to attach to a specific chromosome in the nucleus.
Using a special microscope, a scientist can count the dots of various colors. Three of a specific color means that there is one extra chromosome of that type.
The institute will test five pairs that account for most chromosomal defects. The first cases will be done for free. When the procedure becomes common, the procedure will add about $2,000 to the cost of IVF, about $7,500.
Gibbons said the procedure was developed primarily to avoid the multiple births that sometimes happen with IVF.
Most transplanted embryos, and many naturally conceived ones, never take root and grow because they have the wrong number of chromosomes. In IVF, doctors try to improve the odds by implanting three or more, assuming that some will be lost.
But sometimes, many or all of the embryos are viable. The parents then must decide - do they selectively abort some, or do they take on the hugely demanding task of having many babies at once?
``It's kind of Russian roulette,'' said Gibbons.
If doctors could screen the embryos, he said, they could limit themselves to implanting two and still enjoy a high probability that the embryos will survive.
Nevertheless, the ability to screen out embryos with Down syndrome still worries families of people with the condition.
The option not to have a child with Down already exists. Tests during pregnancy can detect the condition. Parents may choose an abortion.
But James Wheaton, father of a child with Down syndrome, says that parents who choose to discard an embryo in a laboratory are further removed from the implications of their decision.
``It's a lot easier . . . and I'm not sure it's a good thing,'' said the Chesapeake resident. ``I want very much for people confronting the decision to understand that having a child with Down syndrome can be very fulfilling.''
Gibbons says the Jones Institute isn't trying to devalue people with Down syndrome by offering the test.
``They are special. I don't argue that,'' he said. But ``it has such important ramifications for the family. If we had that information, we would give it to them.'' The couple, he said, will make the choice.
John Arras, a philosophy professor at the University of Virginia and a specialist in medical ethics, says the two points of view don't have to compete. We can have a society that offers parents this choice but still values and cares for members of the community with Down syndrome, he said.
``I understand what (parents) are saying when they suggest we're heading down a slippery slope leading to a quality-control mentality,'' he said. On the other hand, ``I don't think it's selfish or irrational for people to want to avoid this if they possibly can . . .
``What the Jones clinic is contemplating is probably no worse than what goes on now, and it's probably better.''
The Jones Institute's most celebrated success involved screening for a fatal disease. Several years ago, work there led to the birth of the world's first baby guaranteed free of Tay-Sachs, a genetic disorder.
Since then, the institute has tried two other times to screen embryos for Tay-Sachs, as well as once for cystic fibrosis and once for sickle cell anemia. In all of the other attempts, no children were conceived.
The institute gets lots of calls from people who want some type of pre-implantation diagnosis, Gibbons said. Most of the time, it's for a condition that current science can't address.
``These are people who won't abort'' if testing during pregnancy shows a problem. Typically, he said, they've already given birth to a child with a genetic disorder. ``It isn't theoretical. It's a very real process for them.'' by CNB