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FDA approves blood test for babies

Detects mental disabilities early

WASHINGTON — The Food and Drug Administration cleared a first-of-a-kind blood test Friday that can help diagnose mental disabilities in babies by analyzing their genetic code.

The laboratory test from Affymetrix detects variations in patients’ chromosomes that are linked to Down syndrome, DiGeorge syndrome, and other developmental disorders. About 2 to 3 percent of US children have some sort of intellectual disability, according to the National Institutes of Health.

The test, known as the cytoscan dx assay, is designed to help doctors diagnose children’s disabilities earlier and get them appropriate care and support. It is not intended for prenatal screening or for predicting other genetically acquired diseases and conditions, such as cancer.

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While there are already genetic tests used to detect such conditions as Down syndrome, doctors usually have to order them individually and they can take several days to develop. Pediatricians said Friday that Affymetrix’s test should offer a faster, more comprehensive screening approach.

Dr. Annemarie Stroustrup emphasized that such tests are generally only used after children exhibit certain physical or behavioral signs that suggest a disorder.

‘‘When there’s something about the child that strikes us as unusual or pointing to a potential genetic disease, that’s when we would use this testing,” said Stroustrup, an assistant professor of pediatrics at Mount Sinai Hospital in New York.

‘‘This is not a screening test to be done on all newborns to predict how they are going to do in school when they are 5,” she said.

Hospitals in all 50 states are required to screen newborns for at least 29 disorders that can be detected though lab testing, including sickle cell anemia and cystic fibrosis. Generally those tests pickup irregularities in metabolism, not genetic variations.

This mandatory screening program is considered one of the nation’s most successful public health programs.