MET-14

Inborn errors of metabolism are a group of disorders characterized by a block in a metabolic pathway. They are caused by mutations (or alterations) in the genes that direct the production of enzymes and the co-factors for metabolism. A mutation causes a gene to not function at all or function poorly. Most often these altered genes are inherited from one or more parent.

In general, the treatment of these metabolic disorders is to minimize or eliminate the buildup of toxic metabolites that result from the block in metabolism while maintaining growth and development. This may be accomplished by special modified diets, supplements, and medications. For example, in the disorder phenylketonuria (PKU) there is a defect in the gene that produces the enzyme that breaks down the amino acid phenylalanine. As a result, there is a buildup of that amino acid in the body. Individuals with PKU must limit phenylalanine in the diet for their lifetime.

Another example is maple syrup urine disease in which the body cannot break down the amino acids leucine, isoleucine, and valine. The urine of people with this condition can smell like maple syrup. Long-term treatment is a diet that is low in the problematic amino acids.