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DNA Test May Detect Immune Disorder in Infants

TUESDAY Dec. 8, 2009 -- A DNA test can identify newborns with T-cell lymphopenia, a blood disorder that affects the immune system, U.S. researchers say.

Infants with T-cell lymphopenia -- an abnormally low level of white blood cells -- often appear normal and have no family history of immunodeficiency.

"Consequently, many infants with severe T-cell deficiencies are not identified until life-threatening infections occur," wrote Dr. John M. Routes, of the Medical College of Wisconsin and Children's Research Institute in Milwaukee, and colleagues.

Early diagnosis greatly improves the long-term prognosis of infants with T-cell lymphopenia. The researcher also noted that some vaccines recommended in early infancy can cause serious infections in infants with T-cell lymphopenia. Early detection of the immune system disorder could help prevent such infections.

In the new study, all infants born in Wisconsin in 2008 were screened for T-cell lymphopenia using a test that determines the number of T-cell receptor excision circles (TRECs) in DNA extracted from dried blood spots on newborn blood screening cards.

Of the 71,000 infants screened, 17 of the infants of at least 37 weeks' gestation had at least one abnormal TREC test result. Samples from 11 of those 17 infants were analyzed to count T cells. Eight were found to have T-cell lymphopenia and evaluated by a clinical immunologist, the study authors reported.

The findings, published in the Dec. 9 issue of the Journal of the American Medical Association, demonstrate the value of state screening programs for T-cell lymphopenia, the researchers wrote.

Posted: December 2009


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