"This test represents a significant advance in the application of genetic technology and paves the way for similar genetic diagnostic tests to be developed in the future," said Daniel Schultz, MD, director of FDA ™s Center for Devices and Radiological Health.

Cystic fibrosis is a serious genetic disorder affecting the lungs and other organs that often leads to an early death. It is the number one cause of chronic lung disease in children and young adults, as well as the most common fatal hereditary disorder affecting Caucasians in the United States. The disease affects about one in 2500-3300 Caucasian babies. Half of the people with cystic fibrosis die by the age of 30.

The Tag-It test identifies a group of variations in a gene called the "cystic fibrosis transmembrane conductance regulator" or CFTR gene that causes cystic fibrosis. FDA approved Tag-It based on a manufacturer study of hundreds of DNA samples showing that the test identifies the CFTR gene variations with a high degree of certainty. The manufacturer also provided FDA with a broad range of supporting peer-reviewed literature.

Since Tag-It detects a limited number of the more than 1300 genetic variations identified in the CFTR gene, the test should not be used alone to diagnose cystic fibrosis. Physicians should interpret test results in the context of the patient ™s clinical condition, ethnicity, and family history. Also, patients may need genetic counseling to help them understand their test results.

The Tag-It Cystic Fibrosis Kit is manufactured by Tm Bioscience Corporation of Toronto, Canada.

fda

Receptors are made up of protein building blocks, each of which is coded for by a specific gene. TRECs form during a mix-and-match rearrangement of these genes into any one of countless combinations. The rings represent sections of DNA cut out of chromosomes during the mixing and matching of genes that are chosen to build a particular receptor. Each T cell uses the resulting combination of genes to make a receptor that lets the cell recognize a specific target. When stimulated to multiply, each parent T cell produces an army of identical cells against a designated target.

Previously, a team led by Handgretinger showed that a high level of TRECs in the blood of children means that the thymus has converted a large number of stem cells into parent T cells ”each of which targets a specific foreign substance.

The NOD-scid IL2R null model combines the crucial characteristics of other models that, by themselves, were inadequate to study HSC engraftment and the different functions of an intact human immune system, according to Stanley Chaleff, M.D., a clinical fellow who did much of the work on the project. This combination of characteristics permits the successful engraftment of HSCs, Chaleff said. Because our models don ™t develop cancer like other models do, they are more efficient tools for studying the human immune system.

Other authors of the study include Leonard D. Shultz, Bonnie L. Lyons, Lisa M. Burzenski and Bruce Gott (The Jackson Laboratory, Bar Harbor, ME); Xiaohua Chen and Stanley Chaleff (St. Jude); Malak Kotb (University of Tennessee, Memphis); Stephen D. Gillies (EMD Lexigen Research Center, Billerica, MA); and Marie King, Julie Mangada and Dale L. Greiner (University of Massachusetts, Worcester, MA).

This work was supported in part by the National Institutes of Health, the Diabetes Endocrinology Research Center (NIH), Juvenile Diabetes Research Foundation, the Assisi Foundation of Memphis and ALSAC.

stjude