The PFKM gene helps muscle cells turn sugar into usable energy, especially during exercise. If the PFKM gene does not work well, muscles may run short of energy, leading to early fatigue, cramps, pain, or dark urine after hard activity, and some people also develop anemia because red blood cells rely on the same energy process. Understanding this gene can help make sense of why symptoms often appear with exercise rather than at rest. The PFKM gene is mainly known in medicine as the gene linked to Tarui disease.
What is a gene?
A gene is a section of DNA that carries instructions your cells use to make molecules or regulate processes in the body. Some genes provide the instructions for building proteins, the parts of cells that do much of the work. Other genes mostly control when certain processes happen, where they happen, and how strongly they are carried out. Together, genes affect how the body grows and works, and they can influence how you respond to food, stress, or medications. To go further into this topic, you can find more in the LearnHub.
Overview
PFKMGene function
What if the gene works
The PFKM gene helps muscle cells turn sugar into usable energy, especially during exercise. Its protein carries out a key step in the pathway that breaks down glucose for energy.
Risk
What if the gene does not work
Variants in the PFKM gene can cause glycogen storage disease type VII, often with exercise intolerance, muscle cramps, and dark urine after exertion. Milder or more severe variants can affect symptom onset and whether anemia occurs.
Treatment
What does that mean for your treatment
For people with a pathogenic or loss-of-function variant in the PFKM gene, no gene-specific treatment or drug-selection approach is currently established. Care is supportive, with activity pacing and symptom-based nutrition strategies, and medicines are not routinely chosen based on PFKM status.
Conditions associated with PFKM
Gene function
What if the gene works
Your muscles need a fast, steady way to turn stored sugar into usable energy. It provides instructions for a key enzyme in that process. This enzyme helps control one of the main steps your cells use to release energy from glucose, especially during movement and exercise. This is central to how the PFKM gene helps muscles use sugar for energy.
The PFKM gene helps drive a key step in turning glucose into usable energy. Its enzyme adds a phosphate group (a small chemical tag) to a sugar molecule, which keeps the pathway moving.
This step acts as an important control point for energy production in muscle cells. The enzyme responds to signals about the cell’s energy state, helping sugar use rise when demand goes up and ease when demand is lower.
During movement, the PFKM gene supports fast energy release from glucose and stored glycogen. This is part of how the PFKM gene helps muscles use sugar for energy during brief, higher effort activity.
What is a variant?
A genetic variant is a minor change in the DNA sequence of a gene. These changes are common and are part of normal human diversity, including differences in appearance, metabolism, and 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 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
Variants in the PFKM gene can lower the amount of working enzyme in cells or change its shape so it folds poorly, breaks down sooner, or has much less activity. This is how PFKM gene variants affect muscle enzyme activity and, in some people, red blood cell energy handling. Milder variants may leave some enzyme function, while more severe variants can cause little to none, which often lines up with earlier or more noticeable features of glycogen storage disease type VII.
How variants are linked to conditions
Two pathogenic variants in the PFKM gene can cause glycogen storage disease type VII (Tarui disease), a rare inherited condition linked to exercise intolerance, muscle cramps, and dark urine after strenuous activity. Some people also have ongoing tiredness, elevated bilirubin, or hemolytic anemia, which means red blood cells break down faster than usual. In this setting, a PFKM gene variant helps confirm the diagnosis rather than showing a small change in risk.
A variant is not necessarily a diagnosis
Genetic variants are common in the general population and are a normal feature of human biology. Most have no direct effect on health and simply reflect natural human diversity. For many genes, carrying a variant associated with a condition indicates a possible link rather than a definite diagnosis, especially when multiple genes and environmental factors play a role. In some cases, though, a single well understood variant in a specific gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
For PFKM-related muscle disease, the main risk comes from inheriting two changed copies of the PFKM gene, so family history and whether both parents carry a PFKM variant matter most. Once someone has the condition, hard exercise can trigger symptoms and muscle breakdown, but there is not enough evidence to say lifestyle changes prevent the condition itself.
Inheritance of PFKM variants
PFKM-related conditions are inherited in an autosomal recessive pattern. This means a child usually develops PFKM-related disease only if they inherit one changed copy of the PFKM gene from each parent. Parents who each carry one variant are usually unaffected, and with each pregnancy there is a 25% chance their child will inherit both variants, a 50% chance the child will be a carrier, and a 25% chance the child will inherit neither variant. This PFKM inheritance pattern affects sons and daughters equally.
What does my PFKM result mean for my family?
For PFKM, family impact is usually discussed in terms of a recessive inherited condition. Parents of someone with a disease-causing PFKM result are often healthy carriers, and brothers or sisters may also have the condition or be carriers. Other close relatives, such as aunts, uncles, and cousins, may carry the same gene change in the family.
Genetic information
Genetic testing
How you find out about variants
To find out whether you carry a change in the PFKM gene, a lab can do genetic testing for PFKM variants using a blood sample or saliva. The test reads the DNA code in the PFKM gene and may look for missing or extra pieces. Results can confirm whether a variant linked to glycogen storage disease type VII is present.
When should I consider getting a genetic test?
Genetic testing for the PFKM gene may be worth considering if someone has lifelong trouble with exercise, painful muscle cramps, episodes of dark urine after activity, or unexplained breakdown of red blood cells. It can also help when there is a family history of this inherited muscle energy condition.
A genetic result is only one part of your health story
Genetic results can be informative, but how much they explain varies by the condition and the kind of variant involved. Over time, the body is also shaped by factors like lifestyle, environment, age, and medical history. In some conditions, especially those influenced by many genes, genetic information provides context rather than certainty and is best considered alongside other parts of care. In other situations, it may offer a clear answer. In areas like medication response, genetic results can also help put personal experiences in context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Small inherited differences can change how the body absorbs, breaks down, transports, or responds to a drug, so the same treatment may work well for one person but less well for another. This is a common part of normal human variation and can influence how much benefit someone gets from a medicine or how sensitive they are to side effects.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences can shape the way a person responds to medicines. It studies links between genes and drugs to better understand why the same treatment can affect people differently. For many medicines, genes influence both how strongly a drug works and how the body handles it. This information can support treatment choices that are more informed and more individualized. More detail on this topic is available in the LearnHub.
Drugs influenced by the PFKM gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication response. If you have questions about medicines, side effects, or changes in how you feel, discuss them with your doctor or pharmacist.
History
In 1965, Japanese physician Seiichiro Tarui described a group of people with exercise related muscle symptoms and an unusual sugar storage pattern, a condition now known as Tarui disease. This was one of the key early clues that a change in the PFKM gene could affect muscle energy use. Initially understood only through visible traits, later recognized as tied to a specific gene, the condition helped connect clinical medicine with modern biochemical genetics. From these first observations, research expanded steadily. By the late 20th century, scientists had identified the PFKM gene and linked specific variants to glycogen storage disease type VII. These historical steps shaped today’s understanding of this rare inherited condition.