New CF screen expected to improve accuracy: genotyping test may allow more labs to perform CF screening and allow greater uniformity of result reports.(Obstetrics)

The Food and Drug Administration's approval of a genotyping test for cystic fibrosis detection should improve screening accuracy and availability and could result in more uniform reporting of test results to physicians, experts say.

The new test--coined the "Tag-It Cystic Fibrosis Kit"--is the first multiplexed genotyping test to be cleared by the FDA as an in vitro device for diagnosing human disease.

Laboratories traditionally have purchased what are known as "analyzed specific reagents" and then have had to establish and validate assays and test kits themselves. The newly approved device, on the other hand, is a "standardized, validated testing kit.... It moves us past the 'home brews,' and makes for a more accurate test," said Michael Watson, Ph.D., executive director of the American College of Medical Genetics.

Dr. Watson was a lead author of the clinical and laboratory guidelines for cystic fibrosis (CF) carrier screening that were published in 2001, and updated in 2004, by the ACMG and the American College of Obstetricians and Gynecologists (ACOG).

The kit is approved for use in carrier testing, as an aid in newborn screening, and in confirmatory diagnostic testing in newborns and children.

It can be used to detect and identify simultaneously 39 mutations in the gene for CF--known as the cystic fibrosis transmembrane conductance regulator (CFTR) gene--as well as 4 polymorphisms.

These variations include the 23 mutations recommended in the updated ACOG-ACMG guidelines as a "core mutation panel" for carrier screening in the general population. According to the manufacturer, the kit covers additional mutations seen in the African American and Hispanic communities.