Hereditary Ataxia

Hereditary ataxia represents a complex group of genetic disorders that cause progressive problems with balance, coordination, and movement, affecting thousands of people and their families around the world.

Table of contents

• What is Hereditary Ataxia?
• Signs and Symptoms
• Main Types of Hereditary Ataxia
• How Hereditary Ataxia is Inherited
• Diagnosis
• Treatment and Management
• Living with Hereditary Ataxia

What is Hereditary Ataxia?

Hereditary ataxias are a group of genetic conditions that affect how your body coordinates movement. The word ataxia means poor muscle control, which causes clumsy or awkward movements^[1]. These disorders are characterized by slowly progressive problems with walking and balance, along with difficulty coordinating hands, speech, and eye movements^[2].

In hereditary ataxia, changes in certain genes cause damage to the part of the brain called the cerebellum, which controls muscle coordination^[4]. The cerebellum can actually shrink over time in people with these conditions^[2]. The disorders can also affect the spinal cord and nerves throughout the body.

• Cerebellum (part of the brain)
• Spinal cord
• Peripheral nerves

Signs and Symptoms

The symptoms of hereditary ataxia vary from person to person, but they generally affect coordination and balance. Many of these conditions become noticeable between ages 30 and 50 years, though some appear before age 25 or even before age five^[1].

The most common first sign is a slowly progressive walking problem that appears unsteady and makes falls more likely^[1]. People might notice they walk with their feet set wide apart to maintain balance^[3].

Other symptoms can include:

• Poor coordination of hands and fingers, making tasks like buttoning a shirt or writing difficult^[3]
• Slurred, slow, or unclear speech (called dysarthria)^[2]
• Difficulty swallowing (called dysphagia)^[5]
• Eye movement problems, including back-and-forth movements that cannot be controlled^[3]
• Dizziness or a feeling of being unbalanced^[1]
• Numbness, tingling, or burning sensations in the legs and arms (called peripheral neuropathy)^[4]
• Muscle weakness^[4]
• Vision and hearing problems^[5]

Some types of hereditary ataxia can also affect other parts of the body beyond the nervous system, including the heart, eyes, and spine^[4].

Main Types of Hereditary Ataxia

There are more than 35 different types of hereditary ataxia^[2]. They are grouped by how they are inherited and which genes are affected.

Autosomal Dominant Ataxias

Spinocerebellar ataxias (SCAs) are the most common autosomal dominant types, and they typically begin in adulthood^[2]. The most common subtypes are SCA1, SCA2, SCA3, SCA6, and SCA7, all of which are caused by repeated sections of DNA expanding abnormally^[2]. These usually start affecting people from age 25 to 80, depending on the specific type^[5].

There is also a type called episodic ataxia, which causes brief repeating episodes of ataxia and dizziness, often triggered by exercise, stress, or caffeine^[5]. This type usually first develops during the teenage years, and episodes can last from several minutes to hours^[5].

Autosomal Recessive Ataxias

These types usually begin in childhood^[2]. The most common include:

• Friedreich ataxia is the most common type of hereditary ataxia overall^[5]. Symptoms usually start before age 25 and include problems with balance, weakness in the legs, slurred speech, and difficulty swallowing^[5]. It can also affect the heart and spine^[5].
• Ataxia-telangiectasia is a rarer type that usually begins in early childhood^[5]. Along with walking difficulties and speech problems, people develop small spider-like clusters of red blood vessels in their eyes and on their cheeks^[5]. They also have a weakened immune system and are more vulnerable to infections^[5].
• Ataxia with oculomotor apraxia types 1 and 2^[2]

Four autosomal recessive types have dietary or biochemical treatment options available: ataxia with vitamin E deficiency, cerebrotendinous xanthomatosis, Refsum disease, and coenzyme Q10 deficiency^[2].

How Hereditary Ataxia is Inherited

Hereditary ataxia can be inherited in four main ways^[4]:

Autosomal dominant inheritance means you only need to inherit one abnormal gene from either parent to develop the condition. A person with the abnormal gene has a 50% chance of passing the gene to each child^[4].

Autosomal recessive inheritance means you must inherit an abnormal gene from both parents. If each parent has one abnormal gene, each child has a 25% chance of inheriting both abnormal genes and developing the disease^[4]. Usually, parents are just carriers and are healthy with no signs of the disease.

X-linked ataxia means the abnormal gene is on the X chromosome and passes from the mother (usually healthy) to the child^[4].

Mitochondrial ataxia develops when mitochondrial DNA (the genetic material in the energy-producing parts of cells) has an abnormal gene. This is usually passed on by the mother^[4].

Diagnosis

Establishing a diagnosis of hereditary ataxia requires several steps. First, a doctor performs a neurological examination to detect typical signs including poorly coordinated walking, finger and hand movements, speech problems, and eye movement abnormalities^[2]. During the exam, the doctor checks vision, balance, coordination, and reflexes^[7].

The doctor must also rule out other causes of ataxia that are not genetic, such as stroke, tumors, multiple sclerosis, alcohol misuse, vitamin deficiencies, or certain medications^[2].

Several tests may be ordered to help with diagnosis:

• Blood tests can help find treatable causes of ataxia^[7]
• An MRI (magnetic resonance imaging) scan of the brain can show shrinkage of the cerebellum and other brain structures, or reveal other treatable findings^[7]
• A spinal tap (also called lumbar puncture) may be done if an infection or inflammation could be causing ataxia^[7]
• Genetic testing can identify specific gene changes that cause hereditary ataxia. Tests are available for many, but not all, hereditary ataxias^[7]

Finding a positive family history of ataxia also helps establish that the condition is hereditary^[2]. However, sometimes there is no family history at all, even when the condition is genetic^[4].

Treatment and Management

Currently, there is no effective treatment to cure most hereditary ataxias, and management focuses on relieving symptoms and maintaining quality of life^[8]. However, for people with Friedreich ataxia, an oral medicine called omaveloxolone (Skyclarys) has been approved for treatment^[7].

If ataxia is caused by a treatable condition such as vitamin deficiency or celiac disease, treating that condition may help improve symptoms^[7]. For the types that have biochemical treatments available (such as ataxia with vitamin E deficiency), specific supplements or dietary changes can be beneficial^[2].

Symptom Management

Various therapies and treatments can help manage specific symptoms:

Physical therapy helps maintain the use of arms and legs and prevents muscles from weakening or getting stuck in one position^[9]. A physiotherapist can teach exercises to strengthen and stretch muscles and may recommend walking aids^[9]. Regular exercise is encouraged for all types of hereditary ataxia^[14].

Speech and language therapy can help with slurred speech and swallowing problems. A therapist may teach exercises to strengthen the muscles used when speaking and breathing techniques to improve speech^[9]. They can also teach swallowing exercises and provide dietary advice about foods that are easier to swallow^[9].

Occupational therapy teaches you how to adapt to gradual loss of mobility and develop new skills for daily activities^[9]. An occupational therapist can teach you how to use mobility devices and advise about home modifications like guide rails or stair lifts^[9].

Medications can help control specific symptoms like muscle spasms, cramps, and stiffness. Muscle relaxants or botulinum toxin (Botox) injections may be used^[9]. Bladder problems and eye movement issues may also be treated with specific medications^[9].

Multidisciplinary Care

People with hereditary ataxia are usually cared for by a team of healthcare professionals, including a neurologist, physiotherapist, speech therapist, occupational therapist, and specialist nurse^[9]. This team works together to create a care plan that addresses physical, social, and psychological needs^[9].

Living with Hereditary Ataxia

Living with hereditary ataxia means adapting as the condition changes over time. The symptoms usually get progressively worse, but the rate of progression varies greatly from person to person^[1].

Many people with hereditary ataxia can live fulfilling lives with the right support and care. Some practical tips include:

• Using assistive devices such as walkers, wheelchairs, or hearing aids as needed^[4]
• Maintaining independence by asking for help only when needed, rather than having others take over all tasks^[15]
• Building a strong support network of family, friends, and healthcare providers^[15]
• Taking care of mental health, as living with a chronic condition can be challenging^[12]
• Staying informed about your specific type of ataxia and available treatments^[1]

For caregivers, it’s important to maintain open communication, recognize your limitations, and ask for help when needed. Working with a social worker can help access additional support services^[15].

Life expectancy varies depending on the type of hereditary ataxia. Some types may shorten lifespan, while others do not affect life expectancy. Many people with hereditary ataxia now live longer than in the past due to improvements in supportive care^[1].