The CAT gene gives your body instructions to make catalase, an enzyme that breaks down hydrogen peroxide, a normal waste chemical that can harm cells if it builds up. This gene helps your body protect tissues from oxidative stress, which is cell damage caused by reactive chemicals. If the CAT gene does not work well, hydrogen peroxide may linger longer, and some people have low catalase levels, called acatalasemia or hypocatalasemia. Many people have no symptoms, though some may develop mouth sores or gum problems.
What is a gene?
Genes are stretches of DNA that carry instructions your cells use to make molecules or regulate processes in the body. Some genes provide the directions for producing proteins, the parts of cells that do much of the work. Others mainly control when certain processes happen, where they happen, and how strongly they are carried out. As a group, genes affect how the body develops and works, and they can also influence how you respond to food, stress, or medications. For a deeper look at this topic, you can find more in LearnHub.
Overview
CATGene function
What if the gene works
The CAT gene makes catalase, an enzyme that breaks down hydrogen peroxide, a normal waste chemical from cell activity. This helps protect cells from oxygen-related stress, especially in the liver, kidneys, and red blood cells.
Risk
What if the gene does not work
Variants in the CAT gene can cause catalase deficiency, called acatalasemia or hypocatalasemia. Many people have no symptoms, while more severe variants can cause very low enzyme activity and, in some cases, mouth ulcers or tissue damage after infection.
Treatment
What does that mean for your treatment
No treatment or drug choice strategy tied to pathogenic variants in the CAT gene is currently established. The CAT gene is being studied as a marker of oxidative stress and in some cancers, but this has not led to guideline based treatment decisions.
Conditions associated with CAT
Gene function
What if the gene works
Your cells make energy constantly, and that creates hydrogen peroxide, a common chemical byproduct. The CAT gene helps clear this substance by making catalase, an enzyme that turns it into water and oxygen. This is a central part of what the CAT gene does in the body each day.
The CAT gene provides instructions for catalase, which breaks down hydrogen peroxide into water and oxygen. This quick cleanup helps cells handle a normal byproduct of everyday metabolism.
By removing extra hydrogen peroxide, this gene helps cells keep a healthy balance of oxygen related chemicals. That supports routine protection of DNA, proteins, and cell membranes during normal daily activity.
Catalase works mainly inside peroxisomes, small parts of cells that process certain fats and chemicals. This helps cells manage the byproducts made during those routine reactions.
What is a variant?
A genetic variant is a minor change in a gene’s DNA sequence. These changes are common and help explain normal differences between people, such as appearance, metabolism, or the way the body responds to environmental influences. Many variants have no noticeable effect and are simply part of natural genetic variation. In some cases, though, a variant can change how a gene works more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
How variants influence the CAT gene's function depends on the type of DNA change. Some CAT gene variants slightly lower the amount or activity of catalase, while more disruptive variants can create an unstable or shortened enzyme that breaks down much less hydrogen peroxide. This range can lead to milder hypocatalasemia or more marked acatalasemia, and greater loss of activity may be linked to earlier or more noticeable features in some people.
How variants are linked to conditions
Among CAT gene variants linked to conditions, the clearest association is with acatalasemia, a rare inherited condition, and its milder form, hypocatalasemia. These pathogenic variants can confirm the diagnosis and are often found in people who have very low catalase activity, though many remain well in daily life. Some may be more prone to mouth ulcers, gum problems, or slow healing after irritation or infection.
A variant is not necessarily a diagnosis
Genetic variants are a routine part of human biology and are widely found in the general population. Most do not directly affect health and instead reflect normal human diversity. For many genes, carrying a variant associated with a condition suggests a possible link rather than a confirmed diagnosis, especially when several genes and environmental factors are involved. In some situations, though, a single well-characterized variant in a specific gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
There is not yet broadly confirmed evidence on specific factors that increase or reduce health risk related to the CAT gene. If a CAT change is found, its effect can vary from one family to another, and personal risk is usually shaped by many other genes and everyday health factors as well.
Inheritance of CAT variants
CAT gene inheritance is usually autosomal recessive for catalase deficiency, so a person typically inherits one altered copy of the CAT gene from each parent. Parents who each carry one variant usually do not have symptoms themselves, but with each pregnancy they have a 25% chance of having a child with the condition and a 50% chance of having a child who is a carrier. This pattern means CAT gene inheritance can affect sons and daughters equally, and either parent can pass the variant to a child.
What does my CAT result mean for my family?
Changes in the CAT gene are linked to a rare inherited condition called acatalasemia, which usually runs in families in a recessive pattern. This means brothers and sisters may also have the condition or be carriers, and parents are often carriers without having symptoms. Other close relatives may also carry the same gene change, so a family result can matter beyond just one person.
Genetic information
Genetic testing
How you find out about variants
To look for changes in the CAT gene, doctors use CAT gene genetic testing on a blood or saliva sample. A lab reads the gene’s DNA sequence and compares it with the usual pattern to identify variants, then reports whether a variant is found and if it is known to be linked to health effects.
When should I consider getting a genetic test?
Genetic testing for the CAT gene may be worth discussing if you or a close relative has a rare family history of acatalasemia, a condition where the body has very low catalase enzyme activity. Testing is usually considered alongside symptoms, enzyme test results, and family history with a doctor or genetic counselor.
A genetic result is only one part of your health story
A genetic result can provide valuable insight, but how much it reveals depends on the condition and the type of variant involved. Over time, many factors, including lifestyle, environment, age, and medical history, also shape how the body works. For some conditions, especially those influenced by many genes, genetic information provides context rather than certainty and is most useful when considered alongside other parts of care. In other situations, a genetic result may offer a clear answer. In areas like medication response, genetic results can also help put individual experiences into context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Small differences in genes can change how the body breaks down a drug, moves it through the blood, or responds at the drug’s target, so the same treatment may work better for one person than another. These differences are common and can influence how much benefit someone feels or how likely they are to have side effects.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences affect the way a person responds to medication. It studies links between genes and drugs to help explain why the same treatment may work differently from one person to another. For many medicines, genes influence how strongly a drug works or how the body handles it. This information can support treatment decisions that are more informed and more individualized. You can learn more about this topic in the LearnHub.
Drugs influenced by the CAT gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication choices, so any concerns about medicines, side effects, or your overall health are best discussed with your doctor.
History
Research on the CAT gene grew out of early studies of catalase, an enzyme identified in the late 1800s as scientists began sorting out how cells handle hydrogen peroxide. In 1948, Japanese doctor Shigeo Takahara described people with very low catalase activity, a finding that brought lasting medical attention to this gene. From these first observations, research expanded steadily as inherited catalase deficiency, often called acatalasia, was recognized in affected families. Later genetic studies linked these family patterns to variants in the CAT gene. By the late 20th century, the gene had become part of broader research on oxidative stress, aging, and common disease risk. This history helped move CAT from a laboratory finding to a gene with clear clinical and biological relevance.