ARL13B helps cells build and run tiny structures called cilia, which guide signals that shape early development. If the ARL13B gene does not work properly, those signals can be disrupted, and this can affect the brain, eyes, kidneys, and other organs. Pathogenic variants in this gene are linked to Joubert syndrome and related conditions, often causing differences in balance, movement, breathing control, and development. ARL13B is mainly known in genetics and neurology rather than in popular culture.
What is a gene?
Genes are stretches of DNA that carry instructions your cells use to make molecules or manage processes in the body. Some genes provide the directions for producing proteins, which are the working parts of cells. Others mainly control when certain processes happen, where they happen, and how active they are. Taken together, genes affect how the body develops and works, and they can also shape how you respond to food, stress, or medications. For a more detailed look at this subject, you can find more in the LearnHub.
Overview
ARL13BGene function
What if the gene works
The ARL13B gene helps cells build and maintain cilia, tiny structures that sense signals. Cilia support normal development and help tissues such as the brain and kidneys respond to chemical messages.
Risk
What if the gene does not work
Variants in the ARL13B gene can cause Joubert syndrome, affecting brain development, balance, muscle tone, and eye movements. Milder and more severe variants can influence how early signs appear and which features develop.
Treatment
What does that mean for your treatment
No ARL13B-specific treatment or management approach is currently established. Research on the ARL13B gene mainly focuses on how cilia work and how cilia related conditions develop, rather than on a current drug target used in care.
Conditions associated with ARL13B
Gene function
What if the gene works
Tiny antenna-like structures on cells help the body sense signals and organize growth. The ARL13B gene supports these structures, called primary cilia, and helps them work in an orderly way. This matters during early development and in many tissues throughout life.
The ARL13B gene helps build and maintain primary cilia, tiny antenna-like structures on cells. When these structures are well organized, cells can sense their surroundings and respond in a controlled way.
Inside cilia, the ARL13B gene helps guide where important proteins go and how long they stay. This steady movement supports normal cilia shape and smooth signal flow.
The ARL13B gene supports signaling systems such as Hedgehog, which helps guide growth and body patterning during development. This is part of how the ARL13B gene supports primary cilia function in human cells.
What is a variant?
A genetic variant is a small difference in the DNA sequence of a gene. These differences are common and are part of normal human diversity, such as variation in appearance, metabolism, or the way 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 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 ARL13B gene can change the protein's shape, stability, or ability to reach the primary cilium, an antenna on the cell surface. This helps explain how variants in the ARL13B gene affect cilia signaling: milder variants may partly reduce protein activity, while more severe variants can leave little or no working protein. In people with pathogenic variants, that larger functional loss is linked to Joubert syndrome and often goes with earlier or more marked features.
How variants are linked to conditions
Pathogenic variants in the ARL13B gene cause a rare inherited condition called Joubert syndrome, a link often described as ARL13B gene variants and Joubert syndrome in medical reports. People with this diagnosis may have low muscle tone, developmental delay, balance and coordination problems, and unusual breathing or eye movements early in life. Some may also have changes affecting the eyes, kidneys, or liver.
A variant is not necessarily a diagnosis
Genetic variants are a normal feature of human biology and are widespread 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 multiple genes and environmental factors contribute. 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?
There is not yet broadly confirmed evidence that lifestyle or environmental factors meaningfully change health risks related to the ARL13B gene. For the rare condition linked to ARL13B, risk is mainly determined by whether someone is born with disease-causing changes in both copies of the gene, often inherited from carrier parents.
Inheritance of ARL13B variants
ARL13B-related conditions are inherited in an autosomal recessive pattern. This means a child usually inherits one altered copy of the ARL13B gene from each parent, and the parents are often healthy carriers. When both parents carry an ARL13B gene variant, each pregnancy has a 25% chance of the child inheriting both altered copies, a 50% chance of being a carrier, and a 25% chance of inheriting neither altered copy. In practical terms, how ARL13B gene variants are inherited usually follows this two-carrier parent pattern.
What does my ARL13B result mean for my family?
ARL13B results linked to disease are usually connected with an inherited condition that runs in families in a recessive pattern, so close relatives may also carry the same gene change without having symptoms. Brothers and sisters could be affected or be carriers, and other family members may also carry it. For future children, the family impact depends on whether both parents carry an ARL13B change.
Genetic information
Genetic testing
How you find out about variants
To look for changes in this gene, genetic testing for ARL13B variants uses a blood sample, saliva, or a cheek swab. A lab reads the ARL13B gene letter by letter and compares it with the usual sequence to see whether a variant is present. Results can help clarify whether an inherited condition linked to ARL13B is the cause of symptoms.
When should I consider getting a genetic test?
Consider genetic testing for the ARL13B gene if someone has signs of Joubert syndrome, such as low muscle tone in infancy, delayed development, unusual eye movements, or the typical brain scan finding, or if there is a family history of it. Testing can help confirm the cause and clarify family planning risks.
A genetic result is only one part of your health story
Genetic results can provide meaningful information, but how much they reveal depends on the condition and the specific type of variant involved. Over time, many factors, including lifestyle, environment, age, and medical history, influence how the body functions. In some conditions, especially those shaped by many genes, genetic information offers context rather than certainty and makes the most sense when considered with other parts of care. In other situations, a genetic result may give a clear answer. In areas like medication response, genetic results 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 through the body, or responds to it at its target, so the same treatment may work better for some people than for others. This is common and can influence how much benefit a medicine provides or how sensitive someone is to side effects.
What is Pharmacogenetics?
Pharmacogenetics examines how genetic differences can affect a person’s response to medications. It focuses on the relationship between genes and drugs to help explain why the same treatment may work differently from one person to another. For many medicines, genes influence how strongly a drug works or how the body handles it. This information can support more informed and individualized treatment decisions. You can read more about this topic in the LearnHub.
Drugs influenced by the ARL13B gene
When should I seek medical advice?
There is no broadly confirmed evidence that changes in this gene should guide medication choices at this time, so questions about side effects, new symptoms, or how a medicine is working are best discussed with your doctor.
History
The ARL13B gene entered medical genetics through research on tiny cell structures called cilia, especially in animal models that showed distinctive developmental changes when this gene was altered. From these first observations, research expanded steadily. In the late 2000s, scientists linked variants in the ARL13B gene to Joubert syndrome, helping place it within the growing group of conditions now known as ciliopathies. That discovery was part of a broader shift in genetics, when many rare childhood conditions were being traced to genes involved in cilia. Since then, ARL13B has remained an important gene in the history of cilia research and in understanding how rare inherited conditions are identified.