Ataxia-Telangiectasia vs. Friedreich Ataxia: Differences and More

If you or your child have recently received a rare ataxia diagnosis, two names may have come up: ataxia-telangiectasia (sometimes abbreviated A-T) and Friedreich ataxia (sometimes abbreviated FA or FRDA). Both are inherited neurological conditions — conditions related to the nervous system — that worsen over time, affecting movement, coordination, and balance.

But these two conditions are not the same. They’re caused by mutations (variations) in different genes and affect the body in very different ways.

This article covers what these conditions have in common, the key differences between them, and how doctors can tell which one is causing a person’s symptoms.

What Do Ataxia-Telangiectasia and Friedreich Ataxia Have in Common?

Ataxia-telangiectasia and Friedreich ataxia have a lot in common.

Both conditions are passed down in families through an autosomal recessive inheritance pattern. This means a person develops either condition only when they inherit disease-causing variants in both copies of the condition-related gene — one from each parent. Parents who carry one changed copy are often healthy and may not know they’re carriers.

Both conditions are cerebellar ataxias, meaning they affect the cerebellum, the part of the brain that controls balance and coordination. Because of this, the early warning signs are very similar.

People with either condition often share similar early symptoms — an unsteady walk, muscle weakness, dysarthria (slurred speech), and difficulty coordinating movements. For both diseases, these problems slowly get worse over time.

How Are Ataxia-Telangiectasia and Friedreich Ataxia Different?

Despite sharing the same inheritance pattern and many early symptoms, these two conditions diverge in important ways. Here are seven key differences.

Friedreich ataxia is the most common form of inherited ataxia worldwide, accounting for roughly half of all hereditary ataxia cases. It impacts an estimated 1 in 30,000 to 1 in 50,000 people in the United States.

Ataxia-telangiectasia is rarer, affecting an estimated 1 in 40,000 to 1 in 100,000 people. After Friedreich ataxia, ataxia-telangiectasia is the second most common inherited cerebellar ataxia that begins in childhood. Both are uncommon, but Friedreich ataxia is far more prevalent.

Friedreich ataxia results from a genetic mutation in the frataxin (FXN) gene, located on chromosome 9. An unusual DNA pattern called a GAA repeat stops the body from making enough of a protein called frataxin. This lack of frataxin damages heart muscles, the spinal cord, cerebellum, and peripheral nerves.

Ataxia-telangiectasia results from mutations in the ATM gene, located on chromosome 11. This gene normally acts like a repair crew for broken DNA. When both copies are faulty, DNA damage accumulates across the nervous system and other tissues over time.

The age of onset for ataxia-telangiectasia is typically between 1 and 4 years. The first signs are often clumsiness and an unsteady walk, noticed shortly after a child starts walking. Most children with ataxia-telangiectasia need a wheelchair by around ages 10 to 12.

In Friedreich ataxia, symptoms typically appear between ages 8 and 15, though onset as late as the mid-20s has been documented. People with Friedreich ataxia generally become wheelchair-dependent within 10 to 15 years after symptoms first begin.

On average, people with ataxia-telangiectasia live to be 19 to 25 years old, while people with Friedreich ataxia live into their late 30s. Both of these timelines can vary widely depending on the person.

One of the most recognizable signs of ataxia-telangiectasia is telangiectasias — tiny, dilated blood vessels that create visible markings.

On lighter skin tones, these tend to appear as bright red clusters; on medium to deeper skin tones, they may look more purple or be harder to spot. They most often develop in the whites of the eyes between ages 4 and 6.

The ATM gene normally helps repair DNA damage throughout the body. When both copies are faulty, damaged cells may be more likely to grow out of control — raising the risk of certain cancers.

Around 30 percent of people with ataxia-telangiectasia may develop cancer in their lifetime. The most common types are leukemia and lymphoma, often appearing during childhood. Adults with ataxia-telangiectasia may also face an increased risk of breast, ovarian, and skin cancers.

This same genetic disruption also causes immune impairment in most people with ataxia-telangiectasia, increasing their likelihood of getting lung infections. Neither elevated cancer risk nor immune deficiency is a feature of Friedreich ataxia.

Heart disease is one of the most serious concerns in Friedreich ataxia. More than half of people with the condition develop hypertrophic cardiomyopathy — a thickening of the heart muscle that makes it harder to pump blood effectively. Some people also develop arrhythmias (irregular heart rhythms).

Beyond the heart, Friedreich ataxia also uniquely affects the skeletal system and the way the body regulates blood glucose (sugar). Many people with Friedreich ataxia develop scoliosis, an abnormal curvature of the spine. Some also develop diabetes or impaired glucose tolerance, meaning the body has trouble keeping blood glucose in a healthy range.

While ataxia-telangiectasia comes with its own systemic (whole-body) risks, these specific cardiac, skeletal, and metabolic concerns are far less prominent or entirely absent in ataxia-telangiectasia.

In 2023, the U.S. Food and Drug Administration (FDA) approved omaveloxolone (Skyclarys) for Friedreich ataxia — the first and only approved medication for this condition, available to people 16 years of age and older.

Omaveloxolone targets a protein called NRF2, which helps cells respond to oxidative stress — a key driver of nerve and heart cell damage in Friedreich ataxia. In clinical studies, the drug improved neurological function scores at one year with benefits continuing until at least three years.

There’s currently no approved medication to slow ataxia-telangiectasia. Care for ataxia-telangiectasia includes physical therapy, symptom management, infection prevention, and regular cancer monitoring.

How Do Doctors Tell the Difference Between These Two Conditions?

Because ataxia-telangiectasia and Friedreich ataxia share several early symptoms, doctors rely on a combination of visual clues and specialized tests to reach an accurate diagnosis.

• Clinical signs — Telangiectasias on the whites of the eyes or skin are one of the strongest visual clues for ataxia-telangiectasia, as they do not appear in Friedreich ataxia.
• Blood and lab tests — Blood tests checking for elevated alpha-fetoprotein (AFP) and immune deficiencies can point toward ataxia-telangiectasia rather than Friedreich ataxia. A separate lab test that finds no detectable ATM protein in a person’s cells also strongly supports an ataxia-telangiectasia diagnosis.
• Brain imaging — An MRI can provide useful supporting evidence by revealing shrinkage in the cerebellum, though this can occur in both conditions.
• Genetic testing — This provides the definitive confirmation. Doctors will look for specific mutations in the ATM gene to confirm ataxia-telangiectasia or the FXN gene to confirm Friedreich ataxia.

Together, these tests help build a clear clinical picture — and an accurate diagnosis is the foundation of good care.

Taking the Next Step

Ataxia-telangiectasia and Friedreich ataxia share the same inheritance pattern and some early symptoms, but they are distinct conditions with different causes, timelines, and health risks. Understanding those differences helps people with the conditions and their families talk more effectively with their healthcare team.

Because early symptoms overlap, your daily observations matter. If you notice redness in the whites of the eyes or small discolored markings on the skin, mention it at the next appointment. These visible blood vessels are a critical clue pointing specifically to ataxia-telangiectasia.

From there, ask your child’s neurologist if genetic testing has been ordered. While physical signs guide the doctor, a genetic test is the only way to confirm the exact condition and shape their care moving forward.

Every person navigating ataxia-telangiectasia or Friedreich ataxia has a different path, but an accurate diagnosis is the essential first step. It allows you to build a suitable care team, access the appropriate resources, and make informed decisions for the future.

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