A method for earlier genetic testing.After plucking a single cell from an eight-celled embryo conceived through in vitro fertilization in vitro fertilization (vē`trō, vĭ`trō), technique for conception of a human embryo outside the mother's body. Several ova, or eggs, are removed from the mother's body and placed in special laboratory culture dishes (Petri dishes); (IVF IVF in vitro fertilization.
in vitro fertilization
IVF 1 In vitro fertilization, see there 2. Intravascular fluid ), geneticists have successfully determined whether the embryo carries the genetic mutation that causes cystic fibrosis.
The advance offers a means of detecting some genetic diseases much earlier than is possible using amniocentesis amniocentesis (ăm'nēō'sĕntē`sĭs), diagnostic procedure in which a sample of the amniotic fluid surrounding a fetus is removed from the uterus by means of a fine needle inserted through the abdomen of the pregnant woman (see or chorionic villus sampling chorionic villus sampling (CVS) or chorionic villus biopsy (CVB) (kōr'ē-ŏn`ĭk, kôr'–), diagnostic procedure in which a sample of chorionic villi from the developing placenta is removed from the , two widely used techniques for diagnosing common genetic abnormalities. Unlike these tests, the new technique -- called preimplantation diagnosis -- is performed before a pregnancy begins.
A team led by Alan H. Handyside of Hammersmith Hospital in London, England, removed a cell from each of five embryos that had been conceived in a laboratory dish three days earlier. Both parents were carriers of the mutation responsible for cystic fibrosis and therefore had a one-in-four chance of having a child affected by the disorder, which clogs vital organs such as the lungs with infection-prone mucus.
Handyside collaborated with a group led by Mark R. Hughes of the Baylor College of Medicine Baylor College of Medicine is a private medical school located in Houston, Texas, USA on the grounds of the Texas Medical Center. It has been consistently rated the top medical school in Texas and among the best in the United States. in Houston to examine the five isolated cells for mutations. They found that two contained two copies of the mutant gene responsible for cystic fibrosis, one was a carrier of the disorder, and two others were unaffected.
Handyside's group implanted a carrier and an unaffected embryo into the womb of the mother. One developed, and the woman gave birth to a healthy baby, both teams of researchers report in the Sept. 24 NEW ENGLAND JOURNAL OF MEDICINE The New England Journal of Medicine (New Engl J Med or NEJM) is an English-language peer-reviewed medical journal published by the Massachusetts Medical Society. It is one of the most popular and widely-read peer-reviewed general medical journals in the world. .
Preimplantation diagnosis "represents substantive progress" in genetic testing, Joe Leigh Simpson and Sandra Ann Carson of the University of Tennessee The University of Tennessee (UT), sometimes called the University of Tennessee at Knoxville (UT Knoxville or UTK), is the flagship institution of the statewide land-grant University of Tennessee public university system in the American state of Tennessee. in Memphis comment in an editorial accompanying the report. Because the technique involves embryos that have not yet been implanted in the mother's womb, they write, couples may avoid the agonizing decision of whether to abort an affected fetus.
Simpson and Carson caution, however, that preimplantation diagnosis is technically difficult. They also question whether the technique's $2,000 price tag makes it a practical way to conceive a baby -- especially since it can only be administered to embryos conceived through the already costly IVF process.