The DNMT3B gene helps place small chemical tags on DNA that guide when other genes are active, especially during early development and in immune cells. If this process is disrupted, the body may have trouble building and regulating parts of the immune system, and some people develop a rare inherited condition called ICF syndrome, with frequent infections, growth or learning differences, and characteristic facial features. This gene plays an important role in keeping gene activity well timed across the body.
What is a gene?
A gene is a stretch of DNA that carries instructions your cells use to make molecules or regulate activities in the body. Some genes provide the code for proteins, which are the parts of cells that do much of the work. Others are used mainly to control when certain activities happen, where they take place, and how active they are. Taken together, genes affect how the body grows and works, and they can also influence how you react to food, stress, or medicines. To look at this topic more closely, you can read more in the LearnHub.
Overview
DNMT3BGene function
What if the gene works
The DNMT3B gene helps place chemical tags on DNA that turn some genes on or off. This supports normal early development and helps cells keep genetic activity organized.
Risk
What if the gene does not work
Changes in the DNMT3B gene can cause ICF syndrome, which often involves immune weakness with repeated infections, developmental differences, and distinctive facial features. Effects can range from milder to more severe, influencing when problems begin and how broad they are.
Treatment
What does that mean for your treatment
No treatment or drug choice is currently guided specifically by a pathogenic variant in the DNMT3B gene. The DNMT3B gene is being studied in cancer research as an epigenetic biomarker and possible drug target, but this has not led to established DNMT3B-specific care.
Conditions associated with DNMT3B
Gene function
What if the gene works
Your cells use the DNMT3B gene to place small chemical tags on DNA. These tags help decide which genes stay active and which stay quieter as cells grow, divide, and take on specific jobs. This is a key part of how the DNMT3B gene helps control other genes in your body.
One of the main jobs of the DNMT3B gene is to add methyl groups (small chemical tags) to DNA. These tags help set up normal patterns of gene activity.
By placing these tags, the DNMT3B gene helps some genes stay quieter while others remain available for use. This gives cells a clear way to follow the right instructions at the right time.
This gene is especially important early in life, when cells are taking on specific roles. It helps build lasting gene activity patterns so tissues can develop in an organized way.
DNMT3B also helps keep repeated stretches of DNA under control, especially in regions that are usually kept quiet. This supports stable DNA behavior as cells copy and divide.
What is a variant?
A genetic variant is a small difference 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 cause any noticeable effect and simply represent 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
Variants in the DNMT3B gene can change the enzyme’s shape, stability, or active site, so it adds fewer methyl groups, small chemical tags on DNA. In how DNMT3B gene variants affect protein function, milder variants may leave some activity, while more severe variants can greatly reduce or stop this process, especially in repeat-rich DNA near centromeres. That loss of control can make chromosomes less stable during cell division. When both copies are affected, greater loss of activity is often linked to earlier or more pronounced ICF syndrome features.
How variants are linked to conditions
Pathogenic variants in the DNMT3B gene cause ICF syndrome type 1, a rare inherited condition linked to immune problems, repeated infections, low antibody levels, developmental delay, and characteristic facial features. In clinical genetics, the link between the DNMT3B gene and ICF syndrome is well established. A confirmed disease-causing DNMT3B variant can establish this diagnosis.
A variant is not necessarily a diagnosis
Variants in genes are a routine feature of human biology and are widely found across the population. Most do not directly affect health and instead represent normal human variation. For many genes, a variant associated with a condition points to a possible link rather than a certain diagnosis, particularly when several genes and environmental influences also play a part. In some situations, though, one well understood variant in a particular gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
For DNMT3B-related conditions, risk is mostly determined by whether someone inherits harmful changes in both copies of the DNMT3B gene, usually because both biological parents carry one changed copy. There is not broadly confirmed evidence that diet, exercise, or other everyday exposures meaningfully change this genetic risk.
Inheritance of DNMT3B variants
Variants in the DNMT3B gene linked to ICF syndrome are inherited in an autosomal recessive pattern. This means a child usually inherits one nonworking copy from each parent, and parents are often healthy carriers. When both parents carry a disease causing DNMT3B variant, each pregnancy has a 25% chance of the child having the condition, a 50% chance of being a carrier, and a 25% chance of inheriting neither variant. In practical terms, the inheritance of DNMT3B gene variants does not differ between sons and daughters because this gene is on chromosome 20, one of the autosomes.
What does my DNMT3B result mean for my family?
For families with a disease-causing DNMT3B change linked to ICF syndrome, parents are usually healthy carriers, and brothers or sisters may also be affected or be carriers. Other relatives on both sides of the family may carry the same change without knowing it. This can matter most for family planning, because carrier relatives could have a child with the condition if their partner also carries a disease-causing DNMT3B change.
Genetic information
Genetic testing
How you find out about variants
Genetic testing for DNMT3B variants usually uses a blood or saliva sample to read the DNMT3B gene and look for changes linked to certain inherited conditions. Results can show whether a variant is present, absent, or uncertain, which helps clarify diagnosis and family testing.
When should I consider getting a genetic test?
Consider testing the DNMT3B gene if someone has a pattern of repeated serious infections, low antibody levels, growth or developmental differences, and a doctor suspects ICF syndrome, a rare inherited condition. Testing can also help when there is a known DNMT3B change in the family or for family planning.
A genetic result is only one part of your health story
A genetic result can provide useful insight, but what it can tell you varies with the condition and the type of variant involved. Lifestyle, environment, age, and medical history, among other factors, also shape how the body functions over time. In some conditions, especially those influenced by many genes, genetic information provides context rather than certainty and is most useful when viewed alongside other parts of care. In other situations, a genetic result may offer a clear answer. In areas such as medication response, genetic findings can also help put individual experiences in context.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. Small differences in DNA can change how the body absorbs, breaks down, or uses a drug, so the same treatment may work better for one person than for another. These differences are common and can influence how much benefit someone gets from a medicine or how sensitive they are to side effects. Medication response also depends on other factors, including age, liver and kidney function, and other medicines a person takes.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences shape a person’s response to medications. By looking at the relationship between genes and drugs, it helps explain why treatments can work differently from one person to another. For many medicines, genes influence how strongly a drug works and how the body processes it. This information can support more informed, individualized treatment decisions. More detailed information on this topic is available in the LearnHub.
Drugs influenced by the DNMT3B gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in predicting how medicines will work or which side effects may happen, so general questions about treatment are best discussed with your doctor or pharmacist. Seek medical advice if you develop new or worsening symptoms after starting a medicine, have side effects that worry you, or feel a treatment is not helping as expected.
History
In the late 1990s, researchers identified the DNMT3B gene during a period of rapid progress in epigenetics, the study of chemical marks that help regulate genes. Soon after, variants in the DNMT3B gene were linked to ICF syndrome, a rare inherited condition with immune system problems and distinctive chromosome findings. This connection gave the gene an important place in early human epigenetics research. Building on this early work, scientists uncovered more about the gene’s role in development and inherited disease. Over time, DNMT3B became one of the key genes that helped researchers connect changes in gene regulation with real clinical conditions.