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New cystic fibrosis screening test developed at Stanford

LungsStanford researchers have invented a new technique to detect cystic fibrosis in infants. The test, described in a paper published today in The Journal of Molecular Diagnostics, is more comprehensive, faster and cheaper than current newborn screening methods.

CF, which causes buildup of sticky mucus in the lungs and digestive organs, is the country's most common fatal genetic disease. Newborn screening for the disease has been conducted in every U.S. state since 2010 and has mostly been a success story: Early diagnosis helps doctors start CF therapy more quickly, which can keep patients healthier longer. With good medical care, such as that provided by the CF experts at Lucile Packard Children's Hospital Stanford, many people with CF now live into their 40s or beyond.

"Kids who are diagnosed early [with genetic screening tests] do not have a symptom-based diagnosis, so they don’t have to recover from any health insults," study co-author Iris Schrijver, MD, told me when we discussed the research.

But there are limitations to the current screening tests. One big problem is that they can miss rare mutations in the CF gene, particularly those that prevail in nonwhite populations about whose CF changes scientists have limited knowledge. That's especially an issue in California, where the 500,000 babies born each year have very diverse heritages. In fact, to help illuminate the problems of older CF tests, Schrijver recently published another study about the difficulty nonwhite CF patients face in receiving timely diagnosis.

In contrast to the current screening tests, the new test will detect virtually all CF-causing mutations in one step, which should make it far easier to find every affected newborn.

Our press release explains how the new method works:

To enable these improvements, the team developed a new way to extract and make many copies of the CF gene from a tiny sample of DNA — about 1 nanogram — from the dried blood spots that are collected on cards from babies for newborn screening. “These samples are a very limited and precious resource,” senior author Curt Scharfe, MD, PhD said. The entire CF gene then undergoes high-throughput sequencing. This is the first time scientists have found a way to reliably use dried blood spots for this type of sequencing for CF, which typically requires much more DNA.

“In our new assay, we are reading every letter in the book of the CF gene,” Schrijver said. “Whatever mutations pop up, the technique should be able to identify. It’s a very flexible approach.”

And the technique could be adapted to other genetic diseases, too. “Ultimately, we would like to develop a broader assay to include the most common and most troublesome newborn conditions, and be able to do the screening much faster, more comprehensively and much more cheaply,” Scharfe said.

Previously: Cystic fibrosis is deadlier for Hispanic patients, Stanford study finds, Cystic fibrosis patient on her 20+ years of care and New Stanford-developed sweat test may aid in development of cystic fibrosis treatments
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