New genetic tests for women who are expecting

Women expecting a baby or planning a pregnancy are being pitched a fast-growing array of tests to check if they are carriers for hundreds of mostly rare genetic diseases.

Such genetic testing, called carrier screening, has long been targeted mainly at people of certain ethnic groups such as Ashkenazi Jews, who are at higher risk for some conditions such as Tay-Sachs disease. Now, companies that offer carrier screening are promoting the idea that testing everyone for many diseases is a more effective way to reduce the number of babies born with serious disorders, including cystic fibrosis, a life-limiting lung condition, and Canavan disease, a fatal neurological disorder.

“We have the technology and it’s affordable enough that we don’t need to put people into ethnic categories,” says Shivani Nazareth, director of women’s health for Counsyl Inc., in South San Francisco, Calif., one of the largest carrier-screening companies. “If we can offer the same panel to everyone, it’s so much more efficient.”

Scientists keep identifying new gene mutations, or variations, associated with specific diseases. Advances in DNA technology allow companies to quickly screen large numbers of people, using saliva or blood samples, to determine if parents could pass the genetic variations to their children.

Counsyl offers tests that aim to detect heightened genetic risk for at least 98 different diseases, for between $599 and $999. Another company, Gene by Gene Ltd., of Houston, plans in the next few months to introduce First Look, a test billed as the most comprehensive on the market that can screen for more than 300 diseases. The company expects the price could be close to $1,500.

Carrier screening is usually covered by health insurance. Counsyl says the average out-of-pocket bill for its insured patients is between $150 and $300.

There are almost 7,000 known rare diseases, which are defined by the National Institutes of Health as affecting fewer than 200,000 people. Most rare diseases have no known treatment or cure.