The TREM2 gene helps immune cells in the brain clear debris and respond to injury in a balanced way. Some people first learn about this gene when Alzheimer’s disease is discussed, because certain variants in the TREM2 gene can raise the chance of developing it. When the gene works poorly, brain cleanup becomes less effective and inflammation may be harder to control. Rare severe variants can cause an inherited condition with changes in thinking and sometimes bone health.
What is a gene?
Genes are stretches of DNA that carry instructions your cells use to make molecules or regulate activities in the body. Some genes hold the instructions for making proteins, which are the working parts of cells. Others mainly help control when certain processes happen, where they happen, and how strongly they occur. Taken together, genes affect how the body develops and functions, and they can also influence how you respond to food, stress, or medications. For a more detailed look at this topic, you can find more information in the LearnHub.
Overview
TREM2Gene function
What if the gene works
The TREM2 gene helps certain immune cells, especially in the brain, clear waste, damaged cells, and fatty debris. This supports healthy brain upkeep and a balanced response to injury.
Risk
What if the gene does not work
More severe variants in the TREM2 gene can cause a rare condition with bone cysts and early dementia, while milder variants may mainly raise the chance of Alzheimer disease and related brain changes.
Treatment
What does that mean for your treatment
No TREM2-specific treatment or drug choice is currently established in clinical guidelines. The TREM2 gene is being studied as a biomarker and potential drug target in Alzheimer disease and other neurodegenerative conditions, especially in treatments aimed at changing immune cell activity in the brain.
Conditions associated with TREM2
Gene function
What if the gene works
In the brain and other tissues, the TREM2 gene helps certain immune cells respond to their surroundings in an organized way. It is especially active in microglia, the brain’s cleanup and support cells. Understanding what the TREM2 gene does in the brain helps explain how these cells clear debris and support healthy tissue.
This gene helps microglia detect signs of cell stress, fatty material, and debris in nearby tissue. That allows them to focus their attention where support and cleanup are needed.
After sensing debris, the TREM2 gene supports taking in and clearing away damaged cell parts and other waste. This cleanup helps keep the tissue environment more orderly.
In microglia, the TREM2 gene helps shape a measured immune response rather than a broad one. This supports steady communication between these cells and nearby tissue.
The TREM2 gene supports the energy use and day to day activity of microglia as they carry out routine maintenance. It helps these cells stay ready to move toward areas that need attention.
What is a variant?
A genetic variant is a minor change in the DNA sequence of a gene. These changes are 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 simply represent natural genetic variation. In some cases, though, a variant can more substantially affect how a gene works and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Changes in the TREM2 gene can disrupt protein folding, keep the protein from reaching the cell surface, weaken binding, or blunt signaling in immune cells. This is how TREM2 variants affect protein function: some are milder and partly lower activity, while more disruptive variants can leave little or no working protein. That range can influence whether a variant mainly shifts disease risk or, with two severe variants, causes a rare condition linked to the TREM2 gene.
How variants are linked to conditions
Rare pathogenic variants in both copies of the TREM2 gene cause Nasu-Hakola disease, a condition that affects thinking, behavior, and bones. Some TREM2 gene variants linked to Alzheimer’s disease are associated with a higher chance of developing late onset Alzheimer’s, but they do not make it certain. A few rare changes have also been reported in people with other forms of dementia, although the clearest and most widely accepted links are with Alzheimer’s disease and Nasu-Hakola disease.
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 contribute to natural differences between people. 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 play a role. In some situations, though, one well-studied variant in a particular gene is enough to confirm a diagnosis.
Are there things that can increase or change my risk?
Some TREM2 changes are linked with a higher chance of late-onset Alzheimer’s disease, but they do not make it certain. Age, family history, and everyday factors that affect brain and blood vessel health, such as smoking, high blood pressure, diabetes, and low physical activity, can also shape overall risk.
Inheritance of TREM2 variants
How TREM2 variants are inherited depends on the health effect involved. For the rare TREM2-related condition that affects bone and brain, the pattern is autosomal recessive, which means a person inherits one variant in the TREM2 gene from each parent. If both parents carry one variant, each pregnancy has a 25% chance of an affected child, a 50% chance of a child who is a carrier, and a 25% chance of a child with no inherited variant. Some single-copy TREM2 variants are linked to a higher chance of conditions such as Alzheimer disease, but those risk-linked variants do not follow a simple Mendelian inheritance pattern.
What does my TREM2 result mean for my family?
For the rare TREM2 changes linked to a recessive condition that affects the brain and bones, parents are often healthy carriers, and brothers or sisters may also be carriers or, more rarely, have the condition. Other relatives on both sides of the family may carry the same change. Some TREM2 findings are linked more to Alzheimer’s risk than to a single inherited condition, so what a result means for family members depends on the exact result.
Genetic information
Genetic testing
How you find out about variants
Finding TREM2 variants usually involves a blood or saliva sample that is analyzed with DNA sequencing, a method that reads your DNA. TREM2 genetic testing looks for changes in the TREM2 gene and may be part of a broader inherited dementia panel. Results may show no relevant variant, a benign variant, a variant of uncertain significance, or a pathogenic variant.
When should I consider getting a genetic test?
Testing for the TREM2 gene may be considered if there is a strong family history of inherited dementia, especially when memory decline starts unusually early or happens alongside bone cysts or repeated fractures. Some TREM2 changes raise Alzheimer’s risk, but they do not by themselves diagnose the disease.
A genetic result is only one part of your health story
Genetic results can be informative, but what they reveal depends on the condition and on the type of variant involved. How the body works over time is also shaped by many other factors, including 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, a genetic result may offer a clear answer. In areas such as medication response, these results can also help put individual experiences into perspective.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines. This helps explain why the same treatment works well for one person, has less effect in another, or causes more side effects in someone else. Part of the difference comes from how the body absorbs, breaks down, and uses a drug, and these inherited differences are common.
What is Pharmacogenetics?
Pharmacogenetics examines how differences in a person’s genes can affect the way they respond to medications. It focuses on patterns between genes and drugs to clarify why the same treatment may work differently in different people. For many medicines, genes influence either how strongly a drug works or how the body handles 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 TREM2 gene
When should I seek medical advice?
There is not yet a broadly confirmed role for this gene in guiding medication choices, so general concerns about medicines, side effects, or memory-related symptoms are best discussed with your doctor. TREM2 is being studied in Alzheimer’s disease research, including whether it may influence response to some newer treatments, but this is not part of routine care.
History
The TREM2 gene entered medical genetics through studies of families with a rare inherited condition affecting bone and brain health, historically called Nasu-Hakola disease. In the early 2000s, researchers identified disruptive variants in the TREM2 gene as a cause of this condition, marking an important step in linking immune related genes to brain disease. From these first observations, research expanded steadily. A major turning point came in 2013, when large genetic studies showed that certain TREM2 variants are linked to a higher risk of Alzheimer’s disease. That finding drew broad scientific attention because the risk increase was stronger than for many other newly discovered Alzheimer’s genes. Since then, TREM2 has become a key part of research into dementia and age related brain conditions.