AGXT: A gene that provides instructions for making a liver enzyme called alanine-glyoxylate aminotransferase (AGXT). Inside liver cells, this enzyme is found in peroxisomes, structures that contain many different enzymes used to produce energy and the basic materials important for cellular activities. AGXT converts a compound called glyoxylate to glycine, an amino acid that is a building block for making enzymes and other proteins
More than 150 AGXT mutations responsible for a disease called type 1 primary hyperoxaluria have been identified. In some type 1 primary hyperoxaluria cases, AGXT enzyme activity is partially or entirely absent because of a mutation. As a result of this enzyme shortage, glyoxylate accumulates and is converted to a compound called oxalate instead of glycine. Oxalate, in turn, combines with calcium to form calcium oxalate, which the body cannot readily eliminate. Deposits of calcium oxalate can lead to kidney stones, kidney damage or failure, and injury to other organs, which are characteristic features of primary hyperoxaluria.
In other patients, the AGXT gene mutation results in an abnormal location of the enzyme. Instead of locating in peroxisomes, the enzyme is misdelivered to mitochondria, the energy-producing centers of cells. Even though the enzyme retains some of its activity, it cannot make contact with glyoxylate, which is located in peroxisomes. As a result, glyoxylate accumulates, leading to the signs and symptoms of primary hyperoxaluria. The AGXT gene is located on the long (q) arm of chromosome 2 in 2q36-q37. See: hyperoxaluria.
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