Newborn Screening for Genetic and Metabolic Disorders

The maternity service
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In many genetic and metabolic disorders, symptoms don’t begin until days or weeks after an infant is born. By the time symptoms appear, damage may already have been done to the nervous system, kidneys, vision, hearing, and other body systems. That's why early detection of these serious disorders in all infants is very important. Diagnosis and treatment of these disorders can reduce the risk of disease, disability, and even death.

Beginning of Newborn Screenings

The idea of testing all newborn babies for disorders began in the 1960s with the development of a screening test for phenylketonuria, a metabolic disorder. A method of collecting and transporting blood samples on filter paper was developed that made wide-scale screening cost-effective.

Since then many more screening blood tests have been developed, and now an infant can be tested for more than 30 different genetic or metabolic disorders. New technology using tandem mass spectrometry can screen for many disorders using only a few drops of the baby’s blood.

Newborn Screening in the United States

All 50 states in the United States offer newborn screening tests, but not all states require newborn screening by law. Although newborns can be screened for as many as 29 disorders, only 13 states and the District of Columbia require all 29 screenings. An additional 27 states require more than 20 screenings. Five states screen for 10 to 20 disorders, and five states screen for fewer than 10 disorders. A list of screening tests provided by each state is available.

Each year the March of Dimes issues a Newborn Screening Report Card that analyzes newborn screening requirements in the United States. In 2007, 90 percent of all babies born in the United States lived in states that required screening for at least 21 disorders.

The March of Dimes estimates that 6.2 percent of newborns in the United States will get screening for fewer than 10 disorders. The March of Dimes is working to reduce this disparity in newborn screening in the country, with the goal of having all babies screened for 20 or more disorders by 2008.

Newborn Screening-Around the World

Screening for disorders is part of newborn healthcare in all developed countries. Most countries screen for phenylketonuria, congenital hypothyroidism, and cystic fibrosis. Many also screen for congenital adrenal hyperplasia, galactosemia and sickle cell disease, as well as other disorders. The U.S. National Newborn Screening & Genetics Resource Center has links to international programs for more information.

How the Tests Are Done

Within the first few days of life (between 24 hours to 7 days after birth), a few drops of blood are taken from an infant’s heel (see photo) and placed on a special card. The paper is sent to a laboratory for testing. The results of the blood tests are sent to the infant’s pediatrician. If any of the tests come back positive, further testing is done to make a diagnosis.

Disorders Screened For

The most common disorders newborns are screened for include:

  • Phenylketonuria
  • Congenital hypothyroidism
  • Cystic fibrosis
  • Congenital adrenal hyperplasia (CAH)
  • Galactosemia
  • Sickle cell disease
  • Biotinidase deficiency
  • Congenital toxoplasmosis
  • Homocystinuria
  • Maple syrup urine disease (MSUD)
  • Medium-chain acyl-coA dehydrogenase deficiency (MCAD)

A full list of the disorders that can be screened for, including information about each disorder, is available.

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