Researchers have developed a new test designed to simultaneously detect genetic mutations involved in more than 400 severe diseases. The test, which was shown to be highly accurate, is initially aimed at screening prospective parents for mutations linked to rare inherited disorders.
Thanks to inexpensive sequencing technology, scientists aim to offer the test for just a few hundred dollars, similar to the cost of tests currently available for detecting individual diseases or a handful of disorders.
“We want this test to become available in the same way Tay-Sachs and cystic-fibrosis testing has,” says Stephen Kingsmore, chief scientific officer of the National Center for Genome Resources and senior author on the study. Tay-Sachs, a rare inherited disorder, strikes in infancy and is typically fatal within the first few years of life. “Forty years of experience with Tay-Sachs resulted in that awful disorder becoming pretty much eradicated in North America,” he says. “This is just on a grander scale.”
The new test, which reads the sequence of about 2 million letters of DNA spread out over 7,000 different chunks, is designed to detect mutations in genes that have been linked to so-called recessive Mendelian disorders, including cystic fibrosis and Tay-Sachs. People who inherit two mutant copies of the relevant gene are guaranteed to develop the disease, while people with only one copy will not. These diseases often strike early in life with severe consequences, including severe disability and death. And while they are individually rare, together they account for about 20 percent of infant mortality.
Testing prospective parents for these mutations can help them prevent or plan for the diseases. Couples who are both carriers of mutations in a particular disease-linked gene could choose to adopt, to conduct genetic tests on in-vitro-fertilized embryos, or to do prenatal testing and terminate affected pregnancies.
While more than 1,000 genes have been linked to recessive Mendelian disorders, the tests now available to prospective parents screen for only the most common, such as cystic fibrosis, and are mainly offered to parents in high-risk groups. Ashkenazi Jews are at particular risk of carrying Tay-Sachs mutations, for example.
“To be able to screen for more than 400 rare conditions is really an important advance,” says Eric Topol, director of the Scripps Translational Science Institute, who was not involved in the study. “We don’t have anything near that today.”