What Is Ataxia-Telangiectasia? Symptoms, Causes, and Treatment
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is ataxia-telangiectasia and how serious is it?
Ataxia-telangiectasia is a rare, inherited, degenerative condition that progressively affects movement, coordination, speech and the immune system. Symptoms usually appear in early childhood as unsteady walking and slurred speech, along with visible clusters of dilated blood vessels on the skin and eyes. There is no cure, but treatment helps. Because immunity is weakened, signs of infection need prompt care. [1]
Key Takeaways
Ataxia-telangiectasia (A-T), or Louis-Bar Syndrome, is a rare genetic condition affecting the nervous and immune systems. [1]
Its two defining features are unsteadiness of movement (ataxia) and zig-zag clusters of dilated blood vessels (telangiectasia). [1]
It is caused by an ATM gene mutation inherited in an autosomal recessive pattern; about 1% of Americans carry one copy. [1]
A-T occurs in roughly 1 in 40,000 to 100,000 people worldwide and usually appears in early childhood. [1]
The condition is progressive and degenerative; most children need mobility assistance by early adolescence. [1]
There is no cure, but symptom-directed treatment — physical therapy, immune therapy, antibiotics, and cancer care — can prolong life and comfort. [1]
Life expectancy varies by severity; most people with A-T live into early adulthood, with a median around 25 years. [1]
What the research says
A-T is rare, and treatment targets symptoms rather than the nerve loss itself. A clinical review puts A-T at 1 in 40,000 to 1 in 100,000 live births, with neurological symptoms usually first appearing in early childhood. The authors note that no treatments are known to slow or stop the neurodegeneration, while immunodeficiency, lung disease, poor growth, and diabetes can be treated effectively. (Rothblum-Oviatt et al., Orphanet J Rare Dis, 2016) [2]
Cancer and lung infections are the main drivers of early death. In a French cohort of 240 patients, 20-year survival was 53.4%; cancer (hazard ratio 2.7, 95% CI 1.6–4.5) and respiratory tract infections (hazard ratio 2.3, 95% CI 1.4–3.8) were each independently linked to mortality. (Micol et al., J Allergy Clin Immunol, 2011) [3]
Cancer surveillance matters. In a single-center study of 69 patients, 19 cancers were diagnosed in 17 patients (25%), and a cancer diagnosis was linked to a markedly higher risk of death (hazard ratio 6.9, 95% CI 3.1–15.2). (Bakhtiar et al., Br J Haematol, 2021) [4]
What Is Ataxia-Telangiectasia?
Ataxia-telangiectasia (A-T), also known as Louis-Bar Syndrome, is a rare genetic condition that targets the nervous system, immune system, and other systems throughout the body. [1]
The condition is neurodegenerative. That means cells in your body’s central nervous system progressively stop working over time. [1]
People diagnosed with A-T most commonly have trouble with movement and coordination — a symptom called ataxia — which begins in early childhood. A notable characteristic of the condition is the appearance of small clusters of dilated blood vessels in the eyes and on the skin, called telangiectasia. [1]
Who Does Ataxia-Telangiectasia Affect?
A genetic mutation causes ataxia-telangiectasia. Anyone can inherit the condition if both parents carry a copy of the ATM gene mutation and pass it on to their child — a pattern called autosomal recessive. [1]
Parents can each carry one copy of the gene without showing any symptoms, because two copies are needed for a diagnosis. An estimated 1% of people in the U.S. carry a mutated copy of the ATM gene. [1]
How Common Is It?
Ataxia-telangiectasia is rare. It occurs in an estimated 1 out of every 40,000 to 100,000 people worldwide. [1]
What Are the Symptoms of Ataxia-Telangiectasia?
Two defining characteristics of ataxia-telangiectasia are difficulty with coordination (ataxia) and small zig-zag clusters of blood vessels forming in the eyes and on the skin (telangiectasia). [1]
The condition also affects movement in several other ways:
Symptom | Medical Term | What It Looks Like |
Difficulty walking | — | Off-balance, unsteady gait |
Trouble with balance | — | Frequent stumbles, poor stability |
Eye movement problems | Oculomotor apraxia / nystagmus | Inability to move eyes side-to-side; “eye jumping” movements |
Involuntary jerking movements | Chorea | Jerky, uncontrolled movements of arms and legs |
Muscle twitching | Myoclonus | Small, sudden muscle twitches |
Declining nerve function | Neuropathy | Reduced sensation and nerve signaling |
Slurred speech | Dysarthria | Problems articulating words; emphasis on wrong syllables |
Poor growth | Endocrine dysfunction | Worsened by frequent infections and growth hormone changes |
Most children with A-T never obtain fully “normal” speech, because of problems articulating and placing emphasis on the wrong syllables or parts of words. [1]
The condition also affects the function of the immune system, weakening it as the disease develops over time. [1]
How Does A-T Affect the Immune System?
Ataxia-telangiectasia weakens the immune system over time. Symptoms of a weakened immune system in people diagnosed with A-T include:
Immune-Related Symptom | Description |
Chronic lung infections | Ongoing respiratory infections |
Fatigue | Persistent tiredness |
Feeling sick more often | Increased frequency of illness |
Frequent infections and delayed wound healing | The body fights infection and repairs tissue more slowly |
Higher cancer risk | Increased susceptibility to leukemia and lymphoma |
Radiation sensitivity | Heightened sensitivity to radiation exposure, including X-rays |
Another sign of A-T is high levels of alpha-fetoprotein (AFP), a protein in the blood. The cause of increased AFP levels is unknown, but it serves as a useful diagnostic marker. [1]
What Causes Ataxia-Telangiectasia?
A mutation of the ATM gene causes ataxia-telangiectasia. [1]
To understand how, it helps to understand how genes work. Most people have 46 chromosomes that divide into 23 pairs. Chromosomes carry DNA — the instruction manual that tells your body how to form and function. Genes are segments of DNA that contain chapters in that manual. You receive one chromosome from each parent to form a pair. [1]
When cells divide, genetic mutations can occur at random — similar to a printer getting a paper jam. Some copies of the instruction manual print perfectly; others print askew.
The ATM gene is responsible for creating proteins that tell your body how to repair broken strands of DNA. ATM proteins locate damaged cells and DNA strands and recruit enzymes to fix them, keeping the pages of your body’s instruction manual turning smoothly. ATM proteins also keep the nervous and immune systems active so they can do their jobs. [1]
A mutation of the ATM gene reduces the function of the ATM protein over time. Cells lose pieces of their instruction manual and become unable to complete their function — which ultimately causes the symptoms of ataxia-telangiectasia. [1]
Inheritance Pattern | What It Means for Your Child |
One mutated copy from one parent | Child is a carrier; no symptoms of A-T |
Mutated copies from both parents | Child receives two copies and can be diagnosed with A-T |
How Is Ataxia-Telangiectasia Diagnosed?
Diagnosis begins with a physical examination of symptoms, followed by imaging and blood tests to verify the genetic mutation responsible for the symptoms. Healthcare providers also gather detailed information about the child’s health and family history before confirming the diagnosis. People with suspected A-T should see an immunologist for a complete workup and evaluation. [1]
Diagnostic Test | What It Looks For |
Genetic testing | A blood test that pinpoints the exact gene mutation causing symptoms |
MRI (magnetic resonance imaging) | Brain images that look for weakened neurons or cerebellar cells (cerebellar atrophy), a sign of progressive ataxia |
Karyotyping | A blood test that examines chromosomes for genetic conditions |
Blood tests | Increased levels of alpha-fetoprotein (AFP) |
Many states offer newborn screenings that can detect ataxia-telangiectasia at birth. Otherwise, healthcare providers usually diagnose the condition in early childhood. [1]
How Is Ataxia-Telangiectasia Treated?
Treatment for ataxia-telangiectasia addresses the symptoms of the condition. There is no cure for A-T, and treatment is unique for each person diagnosed with it. [1]
Treatment | Purpose |
Avoiding overexposure to sunlight | Controls dilated blood vessels (telangiectasia) |
Chemotherapy | Treats cancer, such as leukemia or lymphoma |
Physical therapy | Strengthens muscles |
Gammaglobulin injections | Addresses respiratory infections |
Immunoglobulin therapy | Addresses a weakened immune system |
Antibiotics | Treats infections |
Diazepam | Controls slurred speech and involuntary muscle movements |
What Is the Outlook?
Ataxia-telangiectasia is a degenerative condition that worsens as it progresses. Mild symptoms affecting movement arise during childhood, along with visible blood vessel clusters on the skin. As a child ages, their cells lose the ability to function as their instruction manual indicates, so symptoms increase in severity. Most children will likely need a wheelchair to help them become more mobile by early adolescence. [1]
The weakened immune system can make small infections detrimental to a child’s health. It also makes people diagnosed with A-T more susceptible to cancers like leukemia and lymphoma. Treatment is available to improve immune system function and help your child stay healthy. [1]
Life expectancy varies based on the severity of symptoms, but most people diagnosed with the condition live into early adulthood — up to about 30 years of age, with the median age around 25. Early treatment for recurrent infections and preventative screenings can help prolong life expectancy. [1]
Can Ataxia-Telangiectasia Be Prevented?
Because ataxia-telangiectasia results from a genetic mutation, there is no way to prevent it from occurring. [1]
You can take general steps to reduce your risk of having a child with a genetic condition by avoiding smoking and avoiding exposure to chemicals. If you plan on becoming pregnant, talk with your healthcare provider about genetic testing to understand your risk of having a child with a genetic condition like A-T. [1]
How Do I Take Care of a Child With A-T?
After a diagnosis, it can be difficult to understand the full scope of the condition and to know exactly how to help. The healthcare provider will recommend treatment unique to the child’s symptoms and will be available to answer questions.
Your provider might suggest talking with a genetic counselor — an expert in genetics who can help your family learn more about ataxia-telangiectasia and how to help your child live a comfortable and fulfilling life. A genetic counselor can also provide emotional support as you navigate your child’s diagnosis. [1]
When Should I See a Healthcare Provider?
Since A-T affects the immune system, visit a healthcare provider right away if you notice your child showing signs of an infection. Treatment is available, and prompt care matters.
Sign of Infection | Description |
Change in skin color | The affected area changes color |
Chills | Feeling cold and shivering |
Coughing | New or persistent cough |
Fever | Elevated body temperature |
Pain or soreness | In a specific area or throughout the body |
Swelling | Raised skin around an area of the body |
Shortness of breath | Difficulty breathing |
Vomiting or diarrhea | Digestive symptoms |
What Questions Should I Ask My Doctor?
Useful questions to bring to your provider include: Does my child need to see a physical therapist to improve their muscle strength? Are there any side effects to the treatment you prescribed for my child’s symptoms? And am I at risk of having a child diagnosed with ataxia-telangiectasia if I carry the mutated gene? [1]
Conclusion: A Rare Diagnosis — But a Clear Plan of Care
Ataxia-telangiectasia is one of the rarest conditions you will ever read about — affecting roughly 1 in 40,000 to 100,000 people — yet its story is strikingly concrete. One mutated gene (ATM) gradually silences the cells that repair DNA, and the results show up where families can see them: unsteady first steps, jerky movements, slurred words, and tiny zig-zag blood vessels on the skin and eyes.
The honest truth is that there is no cure for A-T, and the condition is progressive. But the treatment picture is far from empty. Physical therapy strengthens muscles. Immunoglobulin therapy and gammaglobulin injections support a weakening immune system. Antibiotics fight infections early. Cancer care is available when leukemia or lymphoma arises. And early treatment for recurrent infections, combined with preventative screenings, can meaningfully prolong life.
If you have noticed these signs in a child — unsteadiness when walking, jerky movements, unusual eye movements, or clusters of small blood vessels on the skin or eyes — speak with a healthcare provider and ask for a referral to an immunologist. If your child is already diagnosed, lean on the care team and a genetic counselor; you do not have to navigate A-T alone. For more clear, verified health information, explore the rest of Rinnit.com.
Frequently Asked Questions
What is ataxia-telangiectasia?
Ataxia-telangiectasia (A-T), also known as Louis-Bar Syndrome, is a rare genetic condition that targets the nervous system, immune system, and other body systems. It is neurodegenerative — cells in the central nervous system progressively stop working over time. [1]
What does “ataxia-telangiectasia” mean?
The name describes its two defining features: “ataxia” means difficulty with movement and coordination, and “telangiectasia” refers to small clusters of dilated, zig-zag blood vessels that appear in the eyes and on the skin. [1]
How rare is ataxia-telangiectasia?
Ataxia-telangiectasia is rare — occurring in an estimated 1 out of every 40,000 to 100,000 people worldwide. [1]
What causes ataxia-telangiectasia?
A mutation of the ATM gene. ATM proteins normally repair broken DNA strands and keep the nervous and immune systems active. When the gene is mutated, those proteins gradually lose function, cells lose pieces of their “instruction manual,” and symptoms develop. [1]
How is ataxia-telangiectasia inherited?
Ataxia-telangiectasia follows an autosomal recessive pattern: both parents must carry a copy of the ATM gene mutation and pass it on for a child to be diagnosed. Carrying one copy makes someone a symptom-free carrier. About 1% of people in the U.S. carry one mutated copy. [1]
When do symptoms of A-T appear?
Children diagnosed with A-T show signs as early as age 5, including being off-balance when walking, jerking their arms and legs, muscle twitching, and slurred speech. Many states’ newborn screenings can detect A-T at birth. [1]
What are the main symptoms of ataxia-telangiectasia?
The two defining characteristics are difficulty with coordination (ataxia) and zig-zag clusters of dilated blood vessels (telangiectasia). Other symptoms include difficulty walking, trouble with balance, oculomotor apraxia and nystagmus (eye movement problems), chorea (jerking movements), myoclonus (muscle twitching), neuropathy, slurred speech, and poor growth. [1]
Does ataxia-telangiectasia affect the immune system?
Yes. A-T weakens the immune system over time, leading to chronic lung infections, fatigue, feeling sick more often, frequent infections, delayed wound healing, increased cancer susceptibility (leukemia and lymphoma), and sensitivity to radiation exposure, including X-rays. [1]
What is alpha-fetoprotein (AFP) and why does it matter in A-T?
AFP is a protein in the blood. People with A-T have high levels of AFP, though the cause of the increase is unknown. Elevated AFP serves as a helpful diagnostic marker. [1]
How is ataxia-telangiectasia diagnosed?
Diagnosis begins with a physical examination, then imaging and blood tests: genetic testing to pinpoint the mutation, MRI to look for cerebellar atrophy, karyotyping to examine chromosomes, and blood tests for elevated AFP. People with suspected A-T should see an immunologist for a complete workup. [1]
Is there a cure for ataxia-telangiectasia?
No. There is no cure for A-T. Treatment addresses symptoms — physical therapy, gammaglobulin injections, immunoglobulin therapy, antibiotics, chemotherapy when cancer develops, diazepam for movement and speech symptoms, and sun protection to control telangiectasia. [1]
Can children with A-T talk normally?
Most children with A-T never obtain fully normal speech, due to problems articulating and placing emphasis on the wrong syllables or parts of words. Diazepam may help control slurred speech. [1]
Will my child need a wheelchair?
Because A-T is progressive, symptoms increase in severity over time. Most children diagnosed with A-T will likely need mobility assistance, such as a wheelchair, by early adolescence. [1]
What is the life expectancy for someone with ataxia-telangiectasia?
Life expectancy varies based on symptom severity, but most people diagnosed with A-T live into early adulthood — up to about 30 years of age, with the median around 25. Early treatment of recurrent infections and preventative screenings can help prolong life. [1]
Can ataxia-telangiectasia be prevented?
Not directly — it results from a genetic mutation, so it cannot be prevented from occurring. General steps include avoiding smoking and chemical exposure, and discussing genetic testing with a healthcare provider before pregnancy. [1]
When should I contact a doctor if my child has A-T?
Contact a healthcare provider promptly if you notice signs of infection: skin color changes, chills, coughing, fever, pain or soreness, swelling, shortness of breath, or vomiting and diarrhea. People with A-T should also avoid radiation exposure (X-rays) when possible.
Should I see a genetic counselor?
Yes — genetic counselors are experts who can help your family understand A-T, discuss carrier status and risks for future children, and provide emotional support as you navigate the diagnosis. [1]
Related Reading
References
Cleveland Clinic. Ataxia-Telangiectasia. Cleveland Clinic Health Library. Last updated July 6, 2022. https://my.clevelandclinic.org/health/diseases/23415-ataxia-telangiectasia
Rothblum-Oviatt C, Wright J, Lefton-Greif MA, et al. Ataxia telangiectasia: a review. Orphanet J Rare Dis. 2016;11(1):159. PMID 27884168. https://doi.org/10.1186/s13023-016-0543-7
Micol R, Ben Slama L, Suarez F, et al. Morbidity and mortality from ataxia-telangiectasia are associated with ATM genotype. J Allergy Clin Immunol. 2011;128(2):382-389.e1. PMID 21665257. https://doi.org/10.1016/j.jaci.2011.03.052
Bakhtiar S, Salzmann-Manrique E, Donath H, et al. The incidence and type of cancer in patients with ataxia-telangiectasia via a retrospective single-centre study. Br J Haematol. 2021;194(5):879-887. PMID 34337741. https://doi.org/10.1111/bjh.17736
Medical disclaimer
This article is for informational purposes only and is not medical advice. Always consult a qualified healthcare provider — including an immunologist or medical geneticist — for diagnosis, testing, and treatment decisions related to ataxia-telangiectasia.
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