Hereditary ataxia is a group of neurological disorders marked by progressive degeneration of the cerebellum, and eventually leads to problems with voluntary muscle movement, balance, and coordination. Let’s look at the condition in detail, and understand the various types, symptoms, causes, as well as available treatment options.
What is Hereditary Ataxia?
Hereditary ataxia is essentially an umbrella term for a group of genetically heterogeneous disorders that affect the nervous system, specifically the cerebellum. This part of the brain is responsible for coordinating voluntary movements, maintaining balance, and controlling muscle tone. Since ataxia is degenerative, the functions of the cerebellum also progressively deteriorate with time.
Types of Hereditary Ataxia
Hereditary Ataxia is divided according to the mode of inheritance gene – autosomal dominant, autosomal recessive, X-linked, and mitochondrial. Certain types of ataxia are indicative of the presence of a mutated gene that secretes irregular proteins. These proteins then go on to disrupt the regular functioning of nerve cells, especially those in the cerebellum and spinal cord.
Autosomal Dominant Ataxias
In these types of ataxia, the individual can inherit the mutated gene from either parent. They are usually slowly progressive, and typically result in cerebellar atrophy. For the purpose of this blog, we’ll look at two types of autosomal dominant ataxias:
Spinocerebellar Ataxia (SCA)
Spinocerebellar ataxia, spinocerebellar atrophy, or spinocerebellar degeneration is a genetic disease caused by either a recessive or dominant gene. SCA may result in non-coordinated gait, impaired hand-eye coordination, and abnormal speech. Cerebellar degeneration and cerebellar ataxia are common symptoms of all types of SCA, with other symptoms being:
- Slurred speech
- Poor coordination of movement
- Inability to perform basic fine motor movements
- Dysphagia (difficulty in swallowing)
- Unsteady gait
- Tendency to trip
- Rapid back-and-forth eye movements
There are 40 types of SCA discovered so far. Each type is named SCA1, SCA2, and so on, to indicate the order in which they were discovered.
SCA3 is the most common type of Spinocerebellar Ataxia. It is also known as Machado-Joseph Disease.
Read more about Plexus’ Regenerative Rehabilitation for SCA here.
Episodic Ataxia (EA)
EA1 to EA7 along with late-onset episodic ataxia are like their name suggests, episodic and not progressive. EA1 and EA2 are the most common, with the former involving short ataxic episodes which can last from seconds to over two minutes. Stress, sudden movement, or even getting startled are considered triggers to such episodes. EA1 also manifests as muscle twitching. EA2 can have much longer episodes – 30 minutes to 6 hours. Also triggered by stress, EA2 can result in dizziness, muscle weakness, and fatigue. Since EA is not progressive, it does not shorten life span.
Autosomal Recessive Ataxias
In these types of ataxia, the mutated gene is inherited from both parents. With both parents as carriers, 1 in 4 children can inherit two copies of the mutated gene and develop ataxia.
Friedreich’s Ataxia
The most common type of hereditary ataxia, Friedreich’s Ataxia, is caused by the mutated FXN gene, and is characterized by damage to the cerebellum, spinal cord, and peripheral nerves which carry signals to the brain and spinal cord from the arms and legs. The earliest signs of this type of ataxia manifests before 25 years of age at least, with the first symptom being difficulty in walking. Gradually this difficulty of movement progresses to the arms and trunk. Some people also develop high arches (feet deformity) and scoliosis.
Friedreich’s Ataxia also shares some common symptoms with SCA, including:
- Slurred speech
- Rapid back-and-forth eye movements
- fatigue
Additionally, Friedreich’s Ataxia can also result in hearing loss, diabetes, cardiomyopathy, and heart failure.
RFC1 Associated Ataxia
RFC1 is a gene that encodes one of the subunits of Replication Factor C Complex. This is a five-subunit protein that is critical for DNA replication and repair. Any changes or mutations in these genes can have serious consequences, such as neurological disorders.
Mutations in the RFC1 gene (inherited from both parents) can result in late-onset ataxia, in fact this is one of the latter’s most common causes. The symptoms typically include dizziness, tingling sensation or numbness in the body, erratic bouts of coughing.
Ataxia Telangiectasia
This is a very rare form of hereditary ataxia. It is a multisystem ataxia because it impacts different organs and tissues. It develops in individuals who inherit the ataxia-telangiectasia mutated from both their parents. Its symptoms include:
- Unsteady gait (ataxia)
- Small dilated blood vessels near surface of the skin, especially around the eyes and on the earlobes (telangiectasia)
- Red or dilated blood vessels in the eyes (oculocutaneous telangiectasia)
- Increased susceptibility to infections because of weakened immune system
- Increased sensitivity to ionizing radiation
- Elevated risk of certain cancers, especially leukemia and lymphoma (increased risk in children with ataxia telangiectasia)
- Progressive neurological degeneration
Congenital Cerebellar Ataxia
Present at birth, this type of ataxia is a result of damage to the cerebellum. Its symptoms include:
- Unsteady gait
- Hypotonia (low muscle tone)
- Floppy and weak muscles
- Delayed motor development
- Dysphagia
- Speech delays and difficulties
- Cognitive impairment
Wilson’s Disease
This condition is a result of toxic buildup or accumulation of copper in various tissues, especially in the liver and brain. This accumulation is caused by the inheritance of two copies of ATP7B which is responsible for encoding a critical protein that supports copper transport within the body. Its symptoms include:
- Unsteady gait
- Fatigue
- Abdominal pain
- Jaundice
- Muscle stiffness
- Tremors
- Speech difficulties
- Mood swings
- Depression
- Cognitive impairment
Hereditary Ataxia Diagnosis
In order to accurately diagnose the type of hereditary ataxia, your doctor may perform a comprehensive evaluation that includes:
- Clinical assessment: Medical history, family history, detailed assessment of symptoms
- Genetic testing: Identification of specific gene mutation to plan treatment and management of condition
- Neurological examination: Testing coordination, reflexes, muscle strength, etc.
- Imaging studies: MRI (magnetic resonance imaging) to evaluate structure of cerebellum and check for abnormalities, EMG (electromyography) to assess nerve and muscle function
Hereditary Ataxia Treatment at Plexus
At our centres in Bangalore and Hyderabad, we offer advanced regenerative rehabilitation for ataxia. This customisable program comprises stem cell therapy, physiotherapy, occupational therapy, as well as speech and language therapy.
At Plexus, we use mesenchymal stem cells (MSCs) that possess the ability to transform into different kinds of human cells. Through suitable application, MSCs can be turned into neurons to replace the ones lost or damaged in ataxia, thereby restoring neural function to a point where the patient recovers enough mobility and function to live a more independent life.
Apart from stem cell therapy, our rehabilitation program focuses on:
Physiotherapy
- Coordination training
- Balance training
- Trunk stability training
- Trunk rehabilitation
- Core strengthening
- Locomotor exercises
Occupational therapy
- Activities for Daily Living (ADL)
- Handwriting training
- Hand function training
- Balance training
Speech therapy
- Swallowing techniques
- Articulation techniques
- Pronunciation exercises
- Assistive communication devices
- Oral musculature strengthening exercises
Although, there is little one can do to avoid inheriting ataxia, timely diagnosis and early intervention can go a long way in managing the condition. At Plexus, we provide state-of-the-art therapeutic care to provide you the best chance at living a life of dignity and purpose.
FAQs
What are the 3 types of ataxia?
The 3 types of ataxia are:
- Sensory Ataxia: Caused by a dysfunction in the sensory nerve pathways, leading to problems with joint position sense.
- Vestibular Ataxia: Linked to issues with the inner ear’s vestibular system, affecting balance and coordination.
- Cerebellar Ataxia: Associated with damage to the cerebellum, impacting coordination, balance, and voluntary muscle movements.
What is the most common type of hereditary ataxia?
Friedreich’s Ataxia is one of the most common types of hereditary ataxia, caused by mutations in the FXN gene.
How do you diagnose hereditary ataxia?
Diagnosing hereditary ataxia involves genetic testing to identify specific gene mutations, clinical neurological examinations, MRI to check for abnormalities in the cerebellum, as well as EMG to evaluate nerve and muscle function.
What is the difference between ataxia and apraxia?
Ataxia refers to a lack of coordination in voluntary muscle movements. It affects gait, balance, and fine motor skills. It is typically a progressive neurological condition that is caused by damage to the brain, spinal cord, and peripheral nerves.
Apraxia on the other hand involves a difficulty in planning and executing purposeful movements despite having the physical ability to perform them.
Is ataxia similar to Parkinson’s?
Although ataxia and Parkinson’s are characterized by impaired movement, ataxia primarily affects coordination and balance due to cerebellar dysfunction, while Parkinson’s involves tremors, stiffness, and bradykinesia resulting from dopamine deficiency in the basal ganglia.
They have different causes and symptoms.
