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CAT gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

CAT gene

The CAT gene encodes the enzyme catalase, which detoxifies hydrogen peroxide in cells. Mutations in this gene can cause acatalasemia and may increase the risk of type 2 diabetes and other complex diseases.

Normal Function

The CAT gene provides instructions for making pieces (subunits) of an enzyme called catalase. Four identical subunits, each attached (bound) to an iron-containing molecule called a heme group, form the functional enzyme.

Catalase is active in cells and tissues throughout the body, where it breaks down hydrogen peroxide (H2O2) molecules into oxygen (O2) and water (H2O). Hydrogen peroxide is produced through chemical reactions within cells. At low levels, it is involved in several chemical signaling pathways, but at high levels it is toxic to cells. If hydrogen peroxide is not broken down by catalase, additional reactions convert it into compounds called reactive oxygen species that can damage DNA, proteins, and cell membranes.

Health Conditions Related to Genetic Changes

Acatalasemia

At least 13 mutations in the CAT gene have been found to cause acatalasemia, a condition characterized by very low catalase activity. Many people with acatalasemia never have any related health problems, although the condition has occasionally been associated with open sores (ulcers) inside the mouth leading to the death of soft tissue (gangrene). Acatalasemia also appears to increase the risk of developing type 2 diabetes (the most common form of diabetes) and is a potential risk factor for other common, complex diseases.

The mutations that cause acatalasemia occur in both copies of the CAT gene in each cell, and they reduce the activity of catalase to less than 10 percent of normal. A shortage of this enzyme can allow hydrogen peroxide to build up to toxic levels in certain cells. For example, hydrogen peroxide produced by bacteria in the mouth may accumulate in and damage soft tissues, leading to mouth ulcers and gangrene. A buildup of hydrogen peroxide may also damage beta cells of the pancreas, which release a hormone called insulin that helps control blood glucose, also called blood sugar. Malfunctioning beta cells are thought to underlie the increased risk of type 2 diabetes in people with acatalasemia. It is unclear why some people have no health problems associated with a shortage of catalase activity.

A related condition called hypocatalasemia occurs when only one of the two copies of the CAT gene in each cell has a mutation. This single mutation reduces the activity of catalase by approximately half. Like acatalasemia, hypocatalasemia usually does not cause any health problems.

Other disorders

Common variations (polymorphisms) in the CAT gene and in regions of DNA that regulate the gene's activity may be associated with the risk of developing certain common, complex diseases. For example, researchers are studying these polymorphisms as potential risk factors for type 2 diabetes and other disorders of blood glucose regulation. CAT gene polymorphisms may also be associated with high blood pressure (hypertension), a skin condition called vitiligo, thinning of the bones (osteoporosis), and elevated levels of cholesterol and other fats (lipids) in the blood, which increase the risk of heart attack and stroke. However, it is unclear how polymorphisms in the CAT gene impact catalase activity, and how changes in the activity of this enzyme might influence a person's risk of developing these diseases. A large number of genetic and lifestyle factors, many of which remain unknown, likely determine the risk of developing most common, complex conditions.

Other Names for This Gene

  • CATA_HUMAN
  • EC 1.11.1.6

Additional Information & Resources

  • Tests of CAT

Scientific Articles on PubMed

  • PubMed

Catalog of Genes and Diseases from OMIM

  • CATALASE; CAT

Gene and Variant Databases

  • NCBI Gene
  • ClinVar

References

  • Goth L, Eaton JW. Hereditary catalase deficiencies and increased risk of diabetes. Lancet. 2000 Nov 25;356(9244):1820-1. doi:10.1016/S0140-6736(00)03238-4. Citation on PubMed
  • Goth L, Nagy T. Inherited catalase deficiency: is it benign or a factor in various age related disorders? Mutat Res. 2013 Oct-Dec;753(2):147-154. doi:10.1016/j.mrrev.2013.08.002. Epub 2013 Sep 8. Citation on PubMed
  • Goth L, Rass P, Pay A. Catalase enzyme mutations and their association with diseases. Mol Diagn. 2004;8(3):141-9. doi: 10.1007/BF03260057. Citation on PubMed
  • Hebert-Schuster M, Fabre EE, Nivet-Antoine V. Catalase polymorphisms and metabolic diseases. Curr Opin Clin Nutr Metab Care. 2012 Jul;15(4):397-402. doi:10.1097/MCO.0b013e328354a326. Citation on PubMed
  • Kirkman HN, Gaetani GF. Mammalian catalase: a venerable enzyme with new mysteries. Trends Biochem Sci. 2007 Jan;32(1):44-50. doi:10.1016/j.tibs.2006.11.003. Epub 2006 Dec 8. Citation on PubMed

Genomic Location

The CAT gene is found on chromosome 11.

MEDICAL ENCYCLOPEDIA

  • Genes
  • Genetics

Understanding Genetics

  • What is DNA?
  • What is a gene?
  • What is a gene variant and how do variants occur?

Frequently Asked Questions

Most individuals with acatalasemia are asymptomatic and do not require specific dietary restrictions or lifestyle modifications. Because the condition involves a lack of catalase activity, which breaks down hydrogen peroxide, patients are generally advised to avoid excessive exposure to oxidative stressors, such as heavy smoking or high levels of environmental pollutants, though strict avoidance is not typically mandated. Regular dental hygiene is crucial, as the rare complication of oral ulcers and gangrene is a primary concern; any persistent mouth sores should be evaluated promptly by a healthcare provider. What are the long-term health risks associated with acatalasemia, particularly regarding the increased risk of type 2 diabetes?::Acatalasemia is associated with an increased risk of developing type 2 diabetes, likely due to the accumulation of reactive oxygen species that can damage pancreatic beta cells and impair insulin function over time. While not every person with acatalasemia will develop diabetes, clinicians may recommend more frequent monitoring of blood glucose levels and HbA1c tests compared to the general population, especially if there are other risk factors such as obesity or family history. Early detection allows for timely intervention to manage blood sugar levels effectively. Can acatalasemia be inherited, and what is the probability of passing the condition to children?::Acatalasemia is an autosomal recessive condition, meaning an individual must inherit two mutated copies of the CAT gene, one from each parent, to have the condition. If both parents are carriers (heterozygous), there is a 25 percent chance with each pregnancy that the child will have acatalasemia, a 50 percent chance the child will be a carrier, and a 25 percent chance the child will not inherit the mutation. Genetic counseling can help families understand these risks and discuss testing options for at-risk relatives. Why might a person with acatalasemia experience severe oral ulcers, and how are these typically treated?::The severe oral ulcers associated with acatalasemia, which can progress to gangrene, are thought to result from the inability to neutralize hydrogen peroxide produced by bacteria in the mouth. This leads to an accumulation of toxic reactive oxygen species that damage soft tissue. Treatment focuses on aggressive wound care, antimicrobial therapy to control bacterial load, and pain management. In some cases, surgical debridement may be necessary to remove dead tissue and promote healing, and patients are often referred to specialists in oral medicine or wound care for management.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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