The LRRK1 gene gives cells instructions for a signaling protein that is especially important in bone, where it helps bone removing cells reshape and renew the skeleton. This gene helps your body keep bone building and bone breakdown in balance. When both copies of the gene do not work properly, bones can become unusually dense yet still break more easily than expected. Some people may also have delayed tooth eruption and changes seen on bone scans or X-rays.
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 instructions for producing proteins, which are the working parts of cells. Others mainly help determine when certain processes occur, where they take place, and how strongly they operate. Taken together, genes affect how the body develops and works, and they can also shape how you respond to food, stress, or medications. To go deeper into this topic, you can find more in the LearnHub.
Overview
LRRK1Gene function
What if the gene works
The LRRK1 gene helps cells send signals and move materials inside the cell. It is especially important in bone, where it supports osteoclasts, the cells that break down old bone during normal bone remodeling.
Risk
What if the gene does not work
More disruptive variants in the LRRK1 gene can cause a rare bone growth condition with overly dense bones and changes at the ends of long bones. Milder variants may cause milder skeletal changes or symptoms that appear later.
Treatment
What does that mean for your treatment
No LRRK1-specific treatment or drug choice approach is currently established in clinical guidelines for people with a pathogenic or loss-of-function variant in the LRRK1 gene. The LRRK1 gene is being studied in bone remodeling pathways, but this has not yet led to a targeted therapy.
Conditions associated with LRRK1
Gene function
What if the gene works
The LRRK1 gene helps cells pass along signals and organize movement inside the cell. It is especially active in cells that reshape bone as part of normal bone renewal. Understanding how the LRRK1 gene works in bone cells helps explain how your skeleton stays balanced over time.
Cells use the LRRK1 gene to pass along chemical messages that guide routine activity. Its protein adds small chemical tags to other proteins, helping turn cell pathways on at the right time.
Inside cells, the LRRK1 gene helps direct tiny transport sacs to the right place. This supports the steady movement and recycling of cell materials.
The protein made from the LRRK1 gene helps organize the cell’s inner framework. This lets cells change shape, attach, and move in a controlled way when needed.
In bone tissue, the LRRK1 gene supports osteoclasts (cells that clear away old bone). This helps normal bone remodeling, the ongoing process that replaces worn bone with new bone.
What is a variant?
A genetic variant is a slight difference in the DNA sequence of a gene. These differences are common and help shape normal human diversity, such as variation in appearance, metabolism, or the way the body responds to environmental influences. Many do not have any noticeable effect and are simply part of natural genetic variation. Sometimes, though, a variant changes how a gene works more substantially and may contribute to or cause a genetic condition.
Genetic variants
What if the gene does not work
Variants in the LRRK1 gene can change the LRRK1 protein’s shape, stability, or signaling activity. In understanding how variants in the LRRK1 gene affect protein function, milder changes may leave some activity, while more disruptive variants that cut the protein short can greatly reduce or remove it. Greater loss of LRRK1 activity can disrupt bone cell signaling more strongly and may be linked to earlier or more marked osteosclerotic metaphyseal dysplasia.
How variants are linked to conditions
Pathogenic variants in both copies of the LRRK1 gene cause osteosclerotic metaphyseal dysplasia, a rare inherited condition that affects bone growth and leads to unusually dense bones. People with this diagnosis may have short stature, bone pain, delayed walking, fractures, and bone changes seen on X-rays, especially near the ends of the long bones. This is a confirmed genetic diagnosis rather than a general risk association.
A variant is not necessarily a diagnosis
Variants in genes are a routine feature of human biology and occur widely across the population. Most do not directly affect health and simply reflect natural variation among people. For many genes, having a variant associated with a condition points to a possible link rather than a confirmed diagnosis, particularly when several genes and environmental influences are involved. In certain situations, though, one well-characterized variant in a particular gene is enough to establish a diagnosis.
Are there things that can increase or change my risk?
There is not yet broadly confirmed evidence on specific factors that increase or reduce health risk related to the LRRK1 gene. If LRRK1 is relevant in your family or test results, a doctor or genetic counselor can help explain what it may mean for your personal risk.
Inheritance of LRRK1 variants
For families looking into how LRRK1 gene variants are inherited, the established pattern is autosomal recessive. This means a person usually needs to inherit two disease causing variants in the LRRK1 gene, one from each parent, to have the related condition. Parents who each carry one variant are often unaffected carriers. With each pregnancy, two carrier parents have a 25% chance of having an affected child, a 50% chance of having a child who is a carrier, and a 25% chance of having a child without either variant.
What does my LRRK1 result mean for my family?
For families with a disease-causing change in the LRRK1 gene, the pattern is usually recessive, which means close relatives may also be carriers even if they do not have symptoms. Brothers and sisters could be affected or could carry the same gene change, while parents are often healthy carriers. Family members may want to talk with a genetics specialist about what this result could mean for them.
Genetic information
Genetic testing
How you find out about variants
LRRK1 genetic testing looks for changes in the LRRK1 gene using a blood sample, saliva, or sometimes a cheek swab. A lab reads the DNA and compares it with the usual sequence to see whether a variant is present, then reports whether the finding is likely health related, uncertain, or not currently linked to health problems.
When should I consider getting a genetic test?
Genetic testing for the LRRK1 gene may be worth considering when a child has unexplained very dense bones, frequent fractures, bone pain, or unusual bone growth seen on X-rays, especially if similar problems run in the family. In this setting, testing can help confirm whether LRRK1 is the cause.
A genetic result is only one part of your health story
Genetic findings can be informative, but how much they reveal varies by the condition and the type of variant involved. Many factors, including age, environment, lifestyle, and medical history, shape how the body functions over time. For some conditions, especially those influenced by many genes, genetic information offers context rather than certainty and is best understood together with other parts of care. In other situations, a genetic result can give a clear answer. In areas like medication response, these results may help place personal experiences in context.
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, seems weaker for another, or causes more side effects in someone else. Small differences in genes can change how the body breaks down a drug, moves it through the body, or responds to it at its target. These differences are common and can influence both how well a medicine works and how sensitive a person is to it.
What is Pharmacogenetics?
Pharmacogenetics is the area of medicine that looks at how genetic differences affect the way people respond to medications. It studies the relationship between genes and drugs to better explain why the same treatment may work differently from one person to another. For many medicines, genes can influence how strongly a drug works or how the body handles it. This information can help support more informed, more personalized treatment decisions. More detail on this topic is available in the LearnHub.
Drugs influenced by the LRRK1 gene
When should I seek medical advice?
There is no broadly confirmed role for this gene in guiding how medicines are used, so questions about symptoms, treatment changes, or side effects are best discussed with your doctor.
History
LRRK1 entered the genetics literature in the early 2000s, when researchers identified it as part of a small family of related genes. Interest grew further after the closely related LRRK2 gene became important in Parkinson disease research. Building on this early work, scientists studied LRRK1 in animals and saw that changes in the gene could affect bone development and remodeling over time. A major step came later when rare inherited variants in the LRRK1 gene were linked to a human skeletal condition with unusually dense bones. This connection gave the gene a clearer place in medical genetics. Over time, descriptions became more precise as sequencing made it easier to match rare family patterns to specific gene variants.