The LRRK2 gene provides instructions for a protein that helps certain cells, including nerve cells, manage signaling and routine cleanup inside the cell. This gene plays an important role in keeping these cells working smoothly over time. When LRRK2 does not work as intended, it can contribute to problems in brain circuits that control movement, which may show up as symptoms linked to Parkinson’s disease. Some changes in the LRRK2 gene can raise the chance of Parkinson’s disease, and a smaller number can run in families and be enough to explain an inherited form. Many variants are harmless and do not lead to health problems.
What is a gene?
Genes are stretches of DNA that carry instructions your cells use to make molecules or manage activities in the body. Many genes provide the code for proteins, which do much of the day-to-day work inside cells. Other genes mostly regulate processes by affecting when they happen, where they occur, and how strongly they operate. As a group, genes shape how your body grows and works, and they can also influence how you react to things like food, stress, or medications. For a more detailed look at this subject, you can find additional information in the LearnHub.
Overview
LRRK2Gene function
What if the gene works
The LRRK2 gene makes a protein that helps nerve cells manage transport and recycling inside the cell, supporting healthy communication. It also supports routine activity in immune cells and helps cells respond to stress.
Risk
What if the gene does not work
Changes in LRRK2 can increase Parkinson’s disease risk, which may cause tremor, stiffness, and slow movement. Effects range from milder variants to pathogenic mutations, influencing whether symptoms appear and the age and severity of onset.
Treatment
What does that mean for your treatment
For most people with variants in the LRRK2 gene, Parkinson’s treatments stay the same, including medicines like levodopa to ease movement symptoms. Some LRRK2 gene changes may make you eligible for research studies of LRRK2 targeted treatments, such as LRRK2 inhibitors. Genetic results can help guide trial selection and counseling.
Conditions associated with LRRK2
Gene function
What if the gene works
Brain and immune cells are busy, long-lived cells that need reliable systems for moving materials and keeping internal compartments clean. The LRRK2 gene provides instructions for a protein that helps coordinate these everyday tasks by acting like a molecular switch inside cells. Understanding LRRK2 gene function can clarify how cells manage routine maintenance and communication from hour to hour.
The LRRK2 protein adds a tiny chemical tag called a phosphate to other proteins, which can change how they behave. This helps cells pass signals along at the right time and in the right place.
LRRK2 helps organize how small packages move within cells, including delivery to compartments that sort and recycle materials. This supports steady transport of proteins and membranes so cell parts stay supplied and organized.
LRRK2 supports the pathways cells use to break down and recycle worn-out proteins and cell components. This helps keep cell interiors orderly, especially in cells that must function for many years.
LRRK2 is active in several immune cells and helps shape how they respond to internal and external cues. This supports a balanced, coordinated immune response during normal day-to-day immune surveillance.
What is a variant?
A genetic variant is a minor alteration in the DNA code within a gene. These differences are widespread and help explain normal variation among people, such as differences in appearance, metabolism, or how the body reacts to environmental influences. Many variants do not cause any noticeable changes and are part of typical genetic diversity. Sometimes, though, a variant can more strongly affect how a gene works and may play a role in, or lead to, a genetic condition.
Genetic variants
What if the gene does not work
Changes in the LRRK2 gene can shift how strongly its protein signals inside nerve cells, which may influence movement symptoms such as stiffness or tremor in some people. Many well-studied LRRK2 variants act as “overactive” changes, increasing the protein’s enzyme activity, and LRRK2 gene mutation and Parkinson’s disease risk often rises but does not become certain. Other DNA changes may have milder effects or act mainly as small risk modifiers. Variant severity can shape whether symptoms appear earlier or later, how noticeable they are, and which features show up.
How variants are linked to conditions
Certain changes in the LRRK2 gene can cause a hereditary form of Parkinson’s disease, often with adult onset. Other, more common LRRK2 gene variants and Parkinson’s disease risk are linked in population studies, meaning they can raise or lower risk without guaranteeing that someone will develop Parkinson’s. Scientific studies have also associated some LRRK2 variants with inflammatory bowel disease, including Crohn’s disease, with patterns that can differ by ancestry.
A variant is not necessarily a diagnosis
Differences in DNA are a typical feature of being human, and they are widespread across the population. The majority of these variants do not directly affect health and instead represent normal human variation. For many genes, having a variant that has been linked to a condition points to a potential association, not a certain diagnosis, particularly when the outcome depends on multiple genes along with environmental influences. Still, in certain situations, one well-studied variant in a particular gene can be enough to confirm a diagnosis.
Are there things that can increase or change my risk?
With some LRRK2 gene changes, the chance of developing Parkinson’s disease can rise with age and can be higher with a strong family history, but many people with LRRK2 never develop symptoms. Evidence is limited on what clearly changes risk specifically for LRRK2. Avoiding repeated head injuries and long-term exposure to certain pesticides is sensible for brain health, but there is not enough evidence to say this lowers risk for LRRK2.
Inheritance of LRRK2 variants
Many people with a disease-causing change follow an autosomal dominant LRRK2 gene inheritance pattern, meaning one altered copy can be enough to raise the chance of Parkinson’s disease, although some carriers never develop symptoms. A variant can be passed down from either parent to any child. If you carry a pathogenic LRRK2 variant, each pregnancy has a 50% chance of inheriting it.
What does my LRRK2 result mean for my family?
Talk with a genetics-trained clinician if an LRRK2 result raises worries about Parkinson’s disease in your family, especially if several relatives have tremor, stiffness, slowed movement, or symptoms starting before age 50. Medical advice can clarify how this result may affect close relatives and what steps make sense for family planning and communication. It’s also important to review an LRRK2 result before joining a research study or starting new treatments for movement symptoms.
Genetic information
Genetic testing
How you find out about variants
Genetic testing for LRRK2 variants looks for inherited DNA changes that can be linked to certain forms of Parkinson’s disease risk in some families. A lab analyzes DNA from a blood draw or saliva sample, usually by sequencing, and reports whether a specific variant is found, not found, or is of uncertain significance. Results are interpreted alongside personal and family history.
When should I consider getting a genetic test?
Consider genetic testing for the LRRK2 gene if Parkinson’s disease runs in your family, especially if a close relative had symptoms at a younger age. Testing can also help if you have Parkinson’s and want to know whether a known family gene change may be involved. Some people also test when planning a family and wanting clearer information for relatives.
A genetic result is only one part of your health story
Genetic test results can be very informative, but what they can tell you varies based on the health condition and the specific kind of genetic variant. How your body functions over the years is also shaped by many factors, including lifestyle, environment, age, and your medical history. For some conditions, particularly those affected by many genes, genetic information offers helpful context rather than a definite prediction and makes the most sense when considered together with other parts of your care. In other situations, a genetic finding may give a straightforward answer. For things like how you respond to medications, genetic results can also help you better understand your individual experiences.
Pharmacogenetics
How variants shape your response to medicine
Genetic variation can affect how people respond to medicines, and this is one reason the same treatment can work well for one person but cause side effects or limited benefit for another. Many gene differences change how quickly the body breaks down a drug, how much of it reaches the bloodstream, or how strongly it interacts with its target. For the LRRK2 gene specifically, genetic testing is not routinely used to guide medication choice or dosing, although LRRK2 is an active area of research in Parkinson’s disease and in the development of targeted therapies. Overall, genetics is one piece of the picture alongside age, other health conditions, diet, and other medicines you take.
What is Pharmacogenetics?
Pharmacogenetics focuses on the ways inherited genetic differences can affect how you respond to medications. Researchers study relationships between specific genes and particular drugs to understand why the same treatment can have different effects in different people. With many medicines, your genes can influence how intensely a drug works or how your body breaks it down. This information can support more personalized and better informed choices about treatment. More details on this subject are available in the LearnHub.
Drugs influenced by the LRRK2 gene
When should I seek medical advice?
Seek medical advice if you develop ongoing shaking, stiffness, slowed movement, balance problems, or handwriting changes that affect daily life. If you know your family carries a change in the LRRK2 gene and you feel worried, or if Parkinson’s treatment causes new side effects or mood changes, talk with your clinician so care can be adjusted safely.
History
The LRRK2 gene became a major focus in Parkinson’s research after families with inherited Parkinson’s were mapped to a region called PARK8. In recent decades, awareness of this gene’s role has grown as researchers identified LRRK2 changes as one of the more common genetic contributors to Parkinson’s in several populations. A key milestone was the discovery of the LRRK2 G2019S variant, which helped explain why Parkinson’s can cluster in some families while still appearing in people without a strong family history. These findings pushed genetic testing forward and shaped how clinicians discuss inherited risk. The gene also became a practical target for new medicines, helping drive long-term efforts to develop LRRK2 focused treatments.