The MPO gene helps certain white blood cells make myeloperoxidase, an enzyme they use to kill germs. If this gene does not work properly, these cells are less effective at destroying some bacteria and fungi, which can lead to MPO deficiency. Many people with MPO deficiency feel well, but some have a higher chance of infections, especially Candida yeast infections. Most variants in this gene have little effect on how your body handles everyday health.
What is a gene?
A gene is a stretch of DNA that holds instructions your cells use to make molecules or regulate processes in the body. Some genes provide the directions for producing proteins, which are the parts of cells that do much of the work. Others are mainly involved in controlling when certain processes happen, where they happen, and how active they are. Taken together, genes affect how the body grows and works, and they can also influence how you respond to food, stress, or medications. To look into this subject more closely, you can find more in the LearnHub.
Overview
MPOGene function
What if the gene works
The MPO gene helps certain white blood cells make myeloperoxidase, an enzyme that helps kill bacteria and fungi. It supports the body’s early defense against infection during inflammation.
Risk
What if the gene does not work
Variants in the MPO gene can cause myeloperoxidase deficiency. Many people have no symptoms, while more severe variants can reduce infection-fighting activity further and, in some cases, raise the chance of Candida fungal infections.
Treatment
What does that mean for your treatment
No treatment or drug choice approach specific to a pathogenic variant in the MPO gene is currently established. The MPO gene is being studied as a biomarker and possible drug target in inflammatory and cardiovascular conditions, but this has not changed routine care.
Conditions associated with MPO
Gene function
What if the gene works
Your white blood cells use the MPO gene as part of their fast first-line defense against germs. It helps them turn routine cell chemicals into stronger germ-fighting substances in the small compartments where microbes are trapped. Understanding what the MPO gene does in the body makes its role in everyday immune protection easier to picture.
The MPO gene gives certain white blood cells the instructions to make myeloperoxidase, a germ-fighting protein. These cells store it in internal packets so it is ready when a microbe is swallowed.
Inside those packets, myeloperoxidase uses hydrogen peroxide and chloride to create bleach-like substances that help kill bacteria and fungi. This action works mainly in the enclosed space around a trapped germ.
This system supports the body's quick first response to infection. It helps white blood cells act early, often before the rest of the immune system fully joins in.
What is a variant?
A genetic variant is a slight change in the DNA sequence within a gene. These changes are very common and help shape normal human diversity, including differences in appearance, metabolism, or how the body responds to environmental influences. Many variants do not have any noticeable effect and are simply part of natural genetic variation. In some situations, though, a variant can change how a gene functions more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Many MPO gene variants change how the myeloperoxidase protein folds, matures, or is delivered inside white blood cells, which can reduce enzyme activity or stop it completely. Some variants also disrupt the protein’s iron-containing center or make it less stable, so it breaks down more easily. Understanding how MPO gene variants affect enzyme activity helps explain why some changes have a mild effect, while more severe variants can lead to little or no working protein.
How variants are linked to conditions
Pathogenic variants in the MPO gene cause myeloperoxidase deficiency, a rare inherited condition that is often found by chance because many people have no clear symptoms. Some people with this diagnosis have a higher chance of certain infections, especially Candida yeast infections. Beyond this well-established MPO gene variant and condition link, studies have explored ties to other inflammatory or heart-related conditions, but those findings are less consistent and do not confirm a diagnosis on their own.
A variant is not necessarily a diagnosis
Variants in genes are a normal feature of human biology and are common across the general population. Most have no direct impact on health and simply reflect natural human diversity. For many genes, carrying a variant associated with a condition suggests a possible link rather than a definite diagnosis, especially when more than one gene and environmental factors contribute. In some situations, though, a single well-characterized variant in a specific gene can be 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 clearly increase or reduce health risk related to the MPO gene. Risk can vary depending on the exact gene change and a person’s overall health, so anyone worried about personal risk should speak with a doctor or genetic counselor.
Inheritance of MPO variants
For families looking into MPO gene inheritance, the inheritance pattern for myeloperoxidase deficiency is autosomal recessive. This means a person usually inherits one MPO gene variant from each parent. Parents who each carry one variant are often unaffected, but with each pregnancy there is a 25% chance the child will inherit both variants and have the condition, a 50% chance the child will be a carrier, and a 25% chance the child will inherit neither variant. Because the MPO gene is on an autosome, this pattern is the same for males and females.
What does my MPO result mean for my family?
For families of people with an MPO result linked to myeloperoxidase deficiency, close relatives may also carry the same gene change. Brothers and sisters may sometimes have the condition or be carriers, even if they feel well, and future children in the family could also inherit it if both parents carry an MPO change. What this means for relatives depends on the exact MPO result and whether it is tied to this known inherited condition.
Genetic information
Genetic testing
How you find out about variants
To look for changes in the MPO gene, labs usually analyze DNA from a blood sample or saliva. A genetic test for MPO variants may sequence the gene on its own or include it in a broader panel. Results can show whether a variant is present and how clearly it is linked to MPO deficiency.
When should I consider getting a genetic test?
Testing may be considered if other tests suggest an inherited lack of the MPO protein in white blood cells, especially with repeated fungal infections or a family history of this finding. A doctor or genetic counselor can help decide whether MPO testing is likely to be useful.
A genetic result is only one part of your health story
A genetic finding can provide useful insight, but how much it explains varies with the condition and the kind of variant involved. Over time, many factors, including lifestyle, environment, age, and medical history, affect how the body functions. For some conditions, especially those shaped by many genes, genetic information offers context rather than certainty and is most useful when considered alongside other parts of care. In other situations, a genetic result can give a clear answer. In areas like medication response, these results can also help make sense of individual experiences.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Some people break down or handle a drug a bit differently, so the same treatment may work better for one person, have less effect in another, or cause more side effects. These differences are common and are one reason medication response can vary even when two people take the same dose. Genetics is only one part of the picture, alongside age, kidney and liver function, other medicines, and overall health.
What is Pharmacogenetics?
Pharmacogenetics examines how differences in genes can affect the way a person responds to medicines. By looking at connections between genes and drugs, it helps explain why treatments may work differently from one person to another. For many medicines, genes can influence both how strongly a drug works and how the body processes it. This information can help support treatment decisions that are more informed and more individualized. More on this topic is available in the LearnHub.
Drugs influenced by the MPO gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication choices. If you have questions about side effects, drug interactions, or the best treatment for your health needs, talk with your doctor or pharmacist.
History
Researchers first described myeloperoxidase in white blood cells in the early 20th century, long before the MPO gene itself was mapped and sequenced. Inheritance patterns were noticed long before the gene was identified, especially in families with myeloperoxidase deficiency found during blood testing. By the 1980s, scientists had isolated and characterized the MPO gene, which helped connect unusual lab findings to inherited gene variants. This became an important step in blood and immune system genetics because it linked a specific enzyme deficiency to a defined genetic cause. Over time, descriptions became more precise as testing distinguished harmless variation from rarer changes tied to clearer clinical findings. These historical steps shaped today’s understanding of the MPO gene in laboratory medicine and inherited immune traits.