DefinitionInborn errors of metabolism are rare genetic disorders in which the body cannot properly turn food into energy. The disorders are usually caused by defects in specific proteins (enzymes) that help break down (metabolize) parts of food.See: Newborn screening testsAlternative NamesMetabolism - inborn errors ofSide EffectsA food product that is not metabolized (broken down into energy) can build up in the body and cause a wide array of symptoms. Several inborn errors of metabolism cause developmental delay if not controlled. There are wide number of inborn errors of metabolism. This article offers a general overview.Specific information is available on the following forms of inborn errors of metabolism:Fructose intoleranceGalactosemiaMaple sugar urine disease (MSUD)Phenylketonuria(P