FAH gene
The FAH gene provides instructions for producing the enzyme fumarylacetoacetate hydrolase, which is essential for breaking down the amino acid tyrosine.
Normal Function
The FAH gene provides instructions for making an enzyme called fumarylacetoacetate hydrolase. This enzyme is abundant in the liver and kidneys, with smaller amounts found in many other tissues throughout the body. It is the final enzyme in a series of five that work to break down the amino acid tyrosine, a protein building block found in many foods. Specifically, fumarylacetoacetate hydrolase converts a tyrosine byproduct called fumarylacetoacetate into smaller molecules that are either excreted by the kidneys or used to produce energy or make other substances in the body.
Health Conditions Related to Genetic Changes
Tyrosinemia
At least 86 FAH mutations have been found that cause tyrosinemia type I. This condition is characterized by severe liver and kidney disease, neurological problems, and other signs and symptoms that begin in infancy. The altered FAH gene produces an unstable or inactive enzyme, resulting in reduced or absent fumarylacetoacetate hydrolase activity. Without sufficient activity, tyrosine and its byproducts are not properly broken down, causing fumarylacetoacetate to accumulate in the liver and kidneys, where it is thought to be toxic to cells.
In some cases, FAH gene mutations have been observed to revert to the normal state in certain liver cells. Researchers have found a correlation between the severity of symptoms and the extent of this reversion: people with severe symptoms have few reverted cells, while those with milder symptoms have many cells with the reverted FAH gene.
Other Names for This Gene
- beta-diketonase
- FAA
- FAAA_HUMAN
- fumarylacetoacetase
- fumarylacetoacetate hydrolase (fumarylacetoacetase)