The MYO5B gene helps cells move and position important proteins, especially in the lining of the gut and liver. This gene plays an important role in helping these cells absorb nutrients and move bile. When it does not work properly, a person may develop severe diarrhea in infancy, poor growth, or liver problems such as cholestasis. Doctors most often link pathogenic variants in both copies of the MYO5B gene to microvillus inclusion disease and some inherited conditions that slow bile flow.
What is a gene?
Genes are sections of DNA that carry instructions your cells use to make molecules or regulate processes in the body. Some genes provide the information needed to make proteins, the parts of cells that do much of the work. Others mainly help determine when certain processes happen, where they happen, and how strongly they are carried out. Taken together, genes affect how the body develops and works, and they can influence how you respond to food, stress, or medications. To go into this topic in more detail, you can find more in the LearnHub.
Overview
MYO5BGene function
What if the gene works
The MYO5B gene helps cells move and recycle tiny membrane packages to the right place. This supports normal cell surface organization, especially in the intestine and liver.
Risk
What if the gene does not work
Variants in the MYO5B gene can affect both the gut and liver. More severe variants often cause early microvillus inclusion disease with ongoing diarrhea, while milder or different variants may mainly cause cholestatic liver disease, with timing and severity varying.
Treatment
What does that mean for your treatment
No treatment or drug-choice approach specific to the MYO5B gene is currently established in clinical guidelines. Research is exploring ways to correct the cell-transport problems linked to MYO5B variants, but this is still early-stage and has not changed standard care.
Conditions associated with MYO5B
Gene function
What if the gene works
Your cells constantly move tiny packages of proteins and fats from one place to another. The MYO5B gene supports this delivery system, especially when cells need to recycle items and place them on the right part of their surface. Understanding how the MYO5B gene helps cells recycle surface proteins makes its day to day role easier to picture.
Cells use instructions from the MYO5B gene to make a motor protein that carries tiny membrane packages along fine protein tracks inside the cell. This steady transport helps proteins and fats reach the places where the cell needs them.
Inside many cells, the MYO5B gene helps sort and return used surface proteins from internal storage areas back to the membrane. This is part of how the MYO5B gene helps cells recycle surface proteins and keep supplies ready for reuse.
In cells with a clear top and bottom side, the MYO5B gene helps deliver proteins to the correct part of the cell surface. That careful placement supports absorption, secretion, and barrier functions in many lining tissues.
By guiding where membrane packages go, the MYO5B gene helps cells maintain polarity (an organized top and bottom layout). This organized layout lets neighboring cells work together in a coordinated way.
What is a variant?
A genetic variant is a small difference in the DNA sequence within a gene. These differences are common and help shape normal human diversity, including differences in appearance, metabolism, or the way the body responds to environmental influences. Many variants do not cause any noticeable effect and simply represent natural genetic variation. In some cases, though, a variant can change a gene’s function more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the MYO5B gene can make the protein unstable, shorten it, or weaken how it binds to the cell's transport machinery, disrupting how surface proteins are delivered inside intestinal and liver cells. This helps explain how variants in the MYO5B gene affect cell transport. Milder variants may leave some activity, while more severe variants can greatly reduce it. That difference often shapes whether symptoms start earlier and involve the intestine, the liver, or both.
How variants are linked to conditions
Pathogenic MYO5B gene variants cause microvillus inclusion disease, a rare inherited condition with ongoing diarrhea that often starts in infancy. The MYO5B gene is also linked to cholestatic liver disease, where bile does not flow normally, including forms described as progressive familial intrahepatic cholestasis. Some people have mostly intestinal symptoms, some mostly liver symptoms, and some have both.
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 have a 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 certain diagnosis, especially when several genes and environmental factors also play a role. 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?
For MYO5B, risk is mainly shaped by the changes inherited in this gene rather than by lifestyle. People who inherit harmful changes in both copies are much more likely to develop related bowel or liver problems, while carriers with one changed copy usually do not. There is not enough evidence to say that diet, exercise, or other everyday habits meaningfully change this genetic risk.
Inheritance of MYO5B variants
MYO5B-related conditions are inherited in an autosomal recessive pattern, which means a person usually inherits one MYO5B variant from each parent. In families wondering how MYO5B gene variants are inherited, parents are often healthy carriers, and when both parents carry a variant, each pregnancy has a 25% chance of a child inheriting both altered copies, a 50% chance of being a carrier, and a 25% chance of inheriting neither variant. Because the MYO5B gene is on chromosome 18, inheritance is the same for males and females.
What does my MYO5B result mean for my family?
For families with a disease-causing MYO5B result, parents are often healthy carriers, and brothers or sisters may also be affected or may be carriers. Other close relatives on both sides of the family may carry the same gene change even if they have no symptoms. What this means for relatives depends on whether someone has one changed copy or two.
Genetic information
Genetic testing
How you find out about variants
To find variants in the MYO5B gene, genetic testing uses DNA from a blood or saliva sample. This explains what genetic testing is and how it works: a lab reads the gene’s sequence and looks for changes that may help clarify whether a MYO5B related condition is present.
When should I consider getting a genetic test?
Testing for changes in the MYO5B gene may be worth considering when a baby or child has severe diarrhea starting very early in life, poor growth, or ongoing liver bile-flow problems without a clear cause. It can also help when there is a family history of these conditions or when parents want clearer information about future pregnancy risks.
A genetic result is only one part of your health story
A genetic result can be informative, but what it can tell you varies with the condition and the kind of variant that is present. Over time, many factors, including lifestyle, environment, age, and medical history, influence how the body functions. For some conditions, particularly those shaped by many genes, genetic information provides context rather than certainty and is most useful when considered together with other parts of care. In other situations, a genetic result can offer a clear answer. In areas like medication response, it 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 into tissues, or responds to it at its target. This helps explain why the same medication may work well for one person but seem weaker or cause more side effects in another. These differences are common and are one part of the bigger picture, along with age, liver and kidney function, other medicines, and overall health.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences can shape a person’s response to medication. It looks at relationships between genes and drugs to help explain why the same treatment can work differently from one person to another. For many medicines, genes affect how strongly a drug works or how the body handles it. This information can support more informed, more individualized treatment choices. You can learn more about this topic in the LearnHub.
Drugs influenced by the MYO5B gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medicine choices, so questions about side effects, new symptoms, or how a treatment is working are best discussed with your doctor.