The UGT2A1 gene helps cells in the nose and airway process odor molecules and other chemicals so they can be cleared. If it does not work well, smell signaling and chemical handling in the nasal lining may be altered. This gene plays an important role in how some people experience loss of smell, especially during viral illness. Public awareness rose during the COVID-19 pandemic, when studies linked variants near the UGT2A1 gene and UGT2A2 gene to a higher chance of losing smell or taste with infection.
What is a gene?
Genes are stretches of DNA that carry instructions cells use to make molecules or regulate processes in the body. Some provide the code for producing proteins, which are the active components of cells. Others mostly guide when certain processes happen, where they happen, and how active they are. As a group, genes affect how the body grows and works, and they can also influence how you respond to food, stress, or medicines. For a deeper look at this topic, you can find more in the LearnHub.
Overview
UGT2A1Gene function
What if the gene works
Your cells use the UGT2A1 gene to help process smell related chemicals and other small molecules. Its protein tags these substances so the body can clear them more easily, especially in the nose.
Risk
What if the gene does not work
Variants in the UGT2A1 gene can range from milder to more severe and may reduce how well cells tag certain odor related compounds for processing and removal, especially in the nose.
Treatment
What does that mean for your treatment
No UGT2A1-specific treatment or drug choice guideline is currently established for people with a pathogenic or loss-of-function variant in the UGT2A1 gene. The UGT2A1 gene is being studied in smell-related biology and as a possible biomarker in some cancers, but this has not led to routine treatment changes.
Gene function
What if the gene works
In the lining of the nose, cells use the UGT2A1 gene to process odor molecules and other small chemicals you breathe in. Its protein adds glucuronic acid, a small chemical tag that helps make these substances easier to handle and clear. This supports day to day smell signaling and routine chemical cleanup in nearby tissues. This helps explain how the UGT2A1 gene affects smell in daily life.
UGT2A1 helps nasal cells attach glucuronic acid, a small chemical tag, to odor molecules after they enter the nose. This can change those molecules so they are easier for the body to manage and move along.
By clearing used odor compounds from the nasal lining, this gene helps smell signals fade in an orderly way. That helps your nose stay ready to detect new scents, such as noticing food aromas after a previous smell has passed.
Its protein also helps process other small airborne chemicals that reach the upper airway. Making these compounds more able to mix with water helps the body handle them more easily in mucus and nearby tissues.
What is a variant?
A genetic variant is a slight change in the DNA sequence within a gene. These changes are common and are part of 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 simply represent natural genetic variation. In some cases, though, a variant can affect how a gene functions more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
UGT2A1 gene variants can change how much enzyme a cell makes or how well the protein folds, stays stable, and carries out its chemical tagging activity. In this way, UGT2A1 gene variants may have a mild effect that slightly lowers activity, or a more severe effect that greatly reduces protein production or leaves little usable enzyme in the cell. Some variants may also alter how the protein interacts with its usual small molecule targets.
How variants are linked to conditions
Research on how variants in the UGT2A1 gene are linked to conditions is still developing. The UGT2A1 gene does not yet have a broadly confirmed link to a specific inherited health condition, so anyone with a reported finding in the UGT2A1 gene should rely on guidance from their doctor or genetic counselor for interpretation.
A variant is not necessarily a diagnosis
Genetic variants are common across the general population and are a normal feature of human biology. Most do not directly affect health and simply reflect natural variation among people. For many genes, having a variant associated with a condition points to a possible link rather than a confirmed diagnosis, particularly when more than one gene and environmental influences play a part. In some situations, though, one well-characterized variant in a particular gene is enough to establish a diagnosis.
Are there things that can increase or change my risk?
Some changes in the UGT2A1 gene have been linked with a higher chance of losing smell or taste during COVID-19, but this effect is only one small part of the picture. Overall risk is also shaped by the virus itself, age, health, and other genes, and there is not enough evidence to say that any specific lifestyle step changes UGT2A1-related risk.
Inheritance of UGT2A1 variants
There is not yet a broadly confirmed Mendelian inheritance pattern tied to a specific UGT2A1-related condition. In practice, how UGT2A1 gene variants are inherited is usually discussed as part of general family inheritance rather than a clearly established dominant, recessive, or X-linked syndrome. The UGT2A1 gene is located on chromosome 4, which is an autosome, so you inherit one copy from each parent. Any effect of a UGT2A1 variant may depend on the specific change and on other genetic and non-genetic factors.
What does my UGT2A1 result mean for my family?
There is not yet a broadly confirmed inheritance pattern tied to a specific medical condition for UGT2A1. A result in this gene usually does not, by itself, show a clear inherited condition for relatives, and the meaning for family members depends on the exact finding and the health issue being looked at.
Genetic information
Genetic testing
How you find out about variants
To look for changes in the UGT2A1 gene, doctors use UGT2A1 genetic testing, which reads your DNA from a saliva sample or blood sample. A lab checks the gene’s code for variants and reports whether a specific change was found, usually alongside an explanation of what that result may mean.
When should I consider getting a genetic test?
There is not yet a broadly established, UGT2A1-specific medical reason for genetic testing. Testing choices are best made with a doctor or genetic counselor, based on your symptoms, overall health, and family history.
A genetic result is only one part of your health story
Genetic results can provide useful insight, although how much they reveal varies by the condition and the kind of variant present. Over time, the way the body works is also shaped by many factors, including lifestyle, environment, age, and medical history. For some conditions, especially those influenced by many genes, genetic information offers context rather than certainty and is most helpful when considered alongside other parts of care. In other situations, a genetic result may give a clear answer. In areas like medication response, genetic results can also help put personal experiences into context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Some people break down a drug more quickly, while others process it more slowly, so the same dose can lead to different effects. This kind of variation is common and can influence how well a treatment works or how likely someone is to notice side effects.
What is Pharmacogenetics?
Pharmacogenetics examines the ways genetic differences shape a person’s response to medications. By studying links between genes and drugs, it helps explain why the same treatment can affect people differently. For many medicines, genes influence either how strongly a drug works or how the body processes it. This information can support treatment decisions that are more informed and more individualized. More detail on this topic is available in the LearnHub.
Drugs influenced by the UGT2A1 gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication choices, so questions about medicines, side effects, or your overall health are best discussed with your doctor.
History
The UGT2A1 gene entered the scientific literature as researchers mapped members of the UGT family and sorted out which tissues used each one. Early work drew attention to UGT2A1 because it was active in the lining of the nose, which made it a distinctive gene within this family. Building on this early work, scientists also studied the nearby UGT2A2 gene and the broader chromosome region around both genes. In recent decades, awareness of this gene’s role has grown. A major jump in public and research attention came during the COVID-19 pandemic, when large genetic studies linked the UGT2A1 and UGT2A2 region to a person’s chance of losing smell or taste during infection.