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Expanded testing better for newborns

/ Source: The Associated Press

Technology that allows the screening of newborns for several rare genetic diseases at once can help prevent mental retardation and other complications more effectively than conventional tests done after symptoms develop, researchers say.

A study found that because the technology allows earlier diagnosis and prompt treatment, retardation among infants was much less common and hospitalization was less frequent.

All states require testing of newborns for phenylketonuria and hypothyroidism, which can cause retardation if untreated, but not all use the newer method. States differ on the other diseases for which testing is required.

The new technology, called tandem mass spectrometry, uses a single drop of blood to screen for at least 20 diseases and is either in use or under consideration in about 25 states, said Dr. Nancy Green, medical director of the March of Dimes. The technology has been around since the 1990s.

More false-positive findings

The expanded testing can cause more false-positive findings, but overall it led to less stress for the babies’ parents, the government-funded study found.

The findings appear in Wednesday’s Journal of the American Medical Association.

One of the researchers is a founder of Neo Gen Screening, a company that does the expanded tests, but the company, now called Pediatrix Screening, was not directly involved in the research and provided no funding, said lead author Dr. Susan Waisbren of Harvard University and Children’s Hospital in Boston.

Parents of affected children have strongly pushed for the expanded screening, which requires a $400,000 machine and special training.

The March of Dimes supports the expanded screening method, especially for a rare metabolic disease called MCAD, an inherited enzyme deficiency that is easily treated with diet if detected early but can otherwise cause death or severe retardation.

But expanded testing can also sometimes “open a can of worms” because infants might have mild cases of disease that do not require any treatment or they might have ailments for which early diagnosis makes no difference, Green said.

The study included families of 50 infants whose diseases were identified at birth through the expanded screening and 33 infants diagnosed by doctors after symptoms developed.

Only one ill child diagnosed through expanded screening developed mental retardation, compared with eight in the non-screened group, Waisbren said.

Screened infants were 5 days old on average at diagnosis versus 4 months in the non-screened group. And within the first six months of life, 28 percent of the screened infants were hospitalized compared with 55 percent of the non-screened infants.

Waisbren said longer-term follow-up is needed to better evaluate expanded screening.