AGXT

The AGXT gene provides instructions for making a liver enzyme called alanine-glyoxylate aminotransferase. 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. Alanine-glyoxylate aminotransferase converts a compound called glyoxylate to glycine, an amino acid that is a building block for making enzymes and other proteins.

hyperoxaluria, primary - caused by mutations in the AGXT gene

More than 40 AGXT mutations that cause type 1 primary hyperoxaluria have been identified. In about two-thirds of type 1 primary hyperoxaluria cases, alanine-glyoxylate aminotransferase 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 about one-third of people with type 1 primary hyperoxaluria, the alanine-glyoxylate aminotransferase enzyme is misplaced within the cell. Misplacement happens when certain mutations occur with a natural variation (polymorphism) in the gene. In most cases, a mutation replaces the amino acid glycine with arginine at position 170 in the enzyme's chain of amino acids (also written as Gly170Arg). The mutation is found with a polymorphism that replaces the amino acid proline with leucine at position 11 (or Pro11Leu). The combined effect of the mutation and the polymorphism alters the structure of alanine-glyoxylate aminotransferase and changes the cellular shipping address 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.

2q36-q37

The AGXT gene is located on the long (q) arm of chromosome 2 between positions 36 and 37.

See How do geneticists indicate the location of a gene? in the Handbook.

You and your healthcare professional may find the following resources about AGXT helpful.

• Gene Reviews - Clinical summary
• Gene Tests - DNA tests ordered by healthcare professionals

You may also be interested in these resources, which are designed for genetics professionals and researchers.

• PubMed - Recent literature
• OMIM - Genetic disorder catalog
• Research Resources - Tools for researchers (3 links)

See How are genetic conditions and genes named? in the Handbook.

The Handbook provides basic information about genetics in clear language.

• What is DNA?
• What is a gene?
• How does a gene make a protein?
• How can gene mutations cause disorders?

These links provide additional genetics resources that may be useful.

• Genetics education
• Human Genome Project
• Resources for Genetic Researchers

amino acid ; compound ; enzyme ; gene ; mitochondria ; mutation ; peroxisomes ; polymorphism ; protein ; serine ; sign ; symptom

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.