The Food and Drug Administration (FDA) approved the marketing of a new laboratory blood test that will help doctors screen newborn infants for a variety of inherited diseases.

The test is done on blood from newborn heel-stick samples-the same kind of sample used for state-mandated newborn screening tests. The blood sample is measured for levels of amino acids and substances called free carnitine and acylcarnitines.

FDA cleared the test based on results of a study of blood samples taken from more than 200,000 babies. The study was a part of a large multi-centre, epidemiologic study performed by the sponsor. Blood samples from newborns were tested by current methods and by the new test, the NeoGram Amino Acids and Acylcarnitines Tandem Mass Spectrometry Kit.

While small amounts of these substances are found in everyone, abnormally high amounts, or abnormal patterns, may indicate different disease states called inborn errors of metabolism. They include, but are not limited to, phenylketonuria (PKU) and maple syrup urine disease (MSUD), medium chain Acyl-CoA dehydrogenase deficiency (MCAD), isovaleric acidemia, homocystinuria and hereditary tyrosinemia.

While each of these individual disorders is relatively rare, as a group they are fairly common. These diseases can cause developmental delay, seizures, mental retardation and death, FDA says in its release.

With early identification, many of the effects of these diseases can be significantly reduced, with improved long-term outcome and improved quality of life.

The NeoGram Amino Acids and Acylcarnitines Tandem Mass Spectrometry Kit is not a stand-alone test for predicting these kinds of inborn errors of metabolism. The test provides screening information when used with clinical evaluation and other tools to determine a newborn baby's risk for disorders of amino acid and/or carnitine and/or acylcarnitine metabolism. Abnormalities are distinguished by elevated levels or abnormal patterns of amino acids, free carnitine, and acylcarnitines.