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New Technology Allows Doctors to Detect Diseases Before ConceptionAired June 27, 2000 - 1:36 p.m. ET
THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
NATALIE ALLEN, CNN ANCHOR: Yesterday, we heard how advances in sequencing the human genome will someday help us prevent and treat disease. Now, a look at how that know-how could be applied before babies are even a glint in their parents' eyes.
CNN medical correspondent Rhonda Rowland explains.
RHONDA ROWLAND, CNN MEDICAL CORRESPONDENT (voice-over): When some couples decide to have a baby in the future, this is where it will likely begin: behind closed doors with a genetic counselor. Within a decade or two, it may be possible to screen couples for risk of disease before conception even occurs.
DR. NATHAN SLOTNICK, GENETICIST, EASTERN VA MEDICAL SCHOOL: I anticipate that, you know, in 15 to 20 years from now, we'll be able to really know what we're predisposed for in terms of reproductive abnormalities.
ROWLAND: A new technology introduced in the mid-1990s already allows doctors to study an embryo's genetics to a certain extent before pregnancy ever occurs. The procedure: pre-implantation genetic diagnosis. Couples electing pre-implantation genetic diagnosis must have children through in vitro fertilization.
The male's sperm and female's eggs are placed together in the laboratory, incubated outside of the body. When the embryos are three days old and consist of just eight cells, one cell containing all the genetic information is carefully removed and analyzed for abnormalities.
Then only those embryos that appear healthy and free of genetic defects are returned to the woman's uterus. The Jones Institute at Eastern Virginia Medical School is one of a handful of infertility clinics in the United States using pre-implantation genetic diagnosis to screen for diseases linked to particular genes.
SUE GITLIN, JONES INSTITUTE, EASTERN VA MEDICAL SCHOOL: This particular mutation that we're looking at is for cystic fibrosis, but we can look at mutations for other diseases: Tay-Sachs; hemophilia; sickle cell anemia; X-link (ph) diseases. DR. WILLIAM GIBBONS, MEDICAL DIRECTOR, JONES INSTITUTE: From the standpoint of looking at single gene defects, the list grows every single day.
ROWLAND: Only about 300 babies have been born worldwide with the help of pre-implantation genetic diagnosis. The oldest children are three or four. All indications are they're normal, but questions linger about the safety of the procedure.
(on camera): Today, doctors are using reproductive technology to prevent devastating diseases of childhood. But soon, scientists predict, they'll be able to test for a number of diseases of adulthood. In fact, the Genetics & IVF Institute, in Virginia, already tests embryos for Huntington's disease. Only those embryos free of the disease are put back in the mother.
(voice-over): Because of the cost, $10,000 a try, risks from fertility drugs, emotional stress, and limited success rate, infertility specialists don't expect these technologies, which can prevent devastating health problems, to be used routinely in the near future.
Today, most defects are discovered during pregnancy with routine genetic screening tests, tests which are still imperfect. If the news is bad, couples are left with the decision to continue or end the pregnancy.
But scientists expect that to change with the unraveling of the human genome.
DR ALAN FLAKE, CHILDREN'S HOSPITAL OF PHILADELPHIA: I think, looking years into the future, we might very well treat all human genetic disease in the fetus.
ROWLAND: They'll use what's known as gene therapy, delivering the desirable gene to the patient through what is hopefully an innocuous viral vector. Fetal gene therapy is already being done successfully in laboratory animals. Gene therapy has been used in children and adults for the past decade with mixed results. Scientists predict it will be more successful when they're able to do it safely in the human fetus.
DR. SCOTT ADZICK, CHILDREN'S HOSPITAL OF PHILADELPHIA: There are compelling reasons to want to do gene therapy before birth, before the disease manifestations start. I mean, wouldn't it be wonderful to be able to treat cystic fibrosis before birth, before the disease affects the lungs? I think it's not a matter of if; it's just a matter of when.
ROWLAND: Being born already cured of disease, eliminating human suffering caused by the devastating medical consequences -- it may sound like science fiction.
ADZICK: Well, 15 or 20 years ago it was science fiction and what we're talking about now sounds like science fiction. But I am quite sure that it's the future reality. ROWLAND: The question no longer is if science will have the ability to use genes, not only to cure disease, but to enhance generations to come, but when and will we be ready?
Rhonda Rowland, CNN.
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