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New Test Warns Couples of Genetic Illnesses

Scientists say a new blood test could be available by the end of the year that would help couples thinking about having children to screen for hundreds of genetic illnesses that might threaten the health of their offspring. The test is an outgrowth of the revolution in human genetics sequencing.

So-called recessively inherited disorders, such as Tay-Sachs disease, cystic fibrosis and red blood cell disorders known as thalessemias are rare. But when they strike newborns, they can be devastating, accounting for an estimated 20 percent of infant deaths.

Tay-Sachs is most common among Askenazi Jews and French Canadian populations, while cystic fibrosis is mostly seen in people of Northern European descent. The thalessemia belt passes through the Mediterranean and West and Central Asian countries.

Now, researchers have developed a pre-conception carrier test capable of telling would-be parents whether they carry genetic abnormalities for almost 450 inherited childhood diseases. If both parents carry the same mutated genes, there's a one-in-four chance they will pass that disease on to their baby.

Lead researcher Stephen Kingsmore of the Center for Genomics at Children's Mercy Hospital in Kansas City, Missouri, says investigators used the test to screen the DNA of 100 unrelated people and discovered that each one carried two to three severe childhood mutations in their DNA. "By and large, all of one of us have these mutations in our genetic code, and every time a baby is born, there's a game of Russian roulette on a certain level. And we hope to take the element of chance out of it," he said.

Because recessive genetic mutations appear to be so common in the general population, Kingsmore says pre-conception screening - along with genetics counseling - ought to be carried out routinely before couples decide to conceive a child of their own..

Researchers say their next step is to finalize development of the test and focus on making the results understandable to physicians and patients. Kingsmore says investigators are also looking at ways to make it available to the public for little or no cost. "Our goal, though, is to do this on a non-profit basis. We think that this type of information is something that is important from a humanitarian standpoint. We'd like to come up with a strategy where we can do this on pretty much anybody so that we can offer this free to those that can't afford it," he said.

Decoding the human genome a decade ago has disappointed some people who were hoping for the speedy development of cures for devastating illnesses.

But DNA sequencing has revolutionized the field of diagnostics, according to Laird Jackson, a geneticist at Drexel University College of Medicine in Philadelphia, Pennsylvania.

Jackson says a comprehensive screening test for prospective parents could avert a lot of pain and suffering. "If people were identified as carriers, and used that information to modify their reproductive behavior, (that) would aid in saving costs of caring for affected children, the emotional cost of families having such children and the debility, pain and suffering that the child would suffer."

An article describing the pre-conception screening test is published this week in the journal Science Translational Medicine.