Rare Neurology News

Disease Profile

Friedreich ataxia

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
1-9 / 100 000

3,310 - 29,790

US Estimated

1-9 / 100 000

5,135 - 46,215

Europe Estimated

Age of onset

Childhood

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ICD-10

G11.1

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

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Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

Friedreich's ataxia; Hereditary spinal sclerosis; Hereditary spinal ataxia;

Categories

Congenital and Genetic Diseases; Eye diseases; Heart Diseases;

Summary

Friedreich ataxia is an inherited condition that affects the nervous system and causes movement problems. People with this condition develop impaired muscle coordination (ataxia) that worsens over time. Other features include the gradual loss of strength and sensation in the arms and legs, muscle stiffness (spasticity), and impaired speech. Many individuals have a form of heart disease called hypertrophic cardiomyopathy. Some develop diabetes, impaired vision, hearing loss, or an abnormal curvature of the spine (scoliosis). Most people with Friedreich ataxia begin to experience the signs and symptoms around puberty. This condition is caused by mutations in the FXN gene and is inherited in an autosomal recessive pattern.[1]

Symptoms

Symptoms usually begin between the ages of 5 and 15 but can, on occasion, appear in adulthood or even as late as age 75. The first symptom is usually difficulty walking (gait ataxia). The ataxia gradually worsens and slowly spreads to the arms and then the trunk. Over time, muscles begin to weaken and waste away, especially in the feet, lower legs, and hands. Other symptoms include loss of tendon reflexes, especially in the knees and ankles. There is often a gradual loss of sensation in the extremities, which may spread to other parts of the body. Slurred speech (dysarthria), fatigue, and involuntary eye movements (nystagmus) are also common. Most people with Friedreich's ataxia develop scoliosis (a curving of the spine to one side), which, if severe, may impair breathing.[2]

Other symptoms that may occur include chest pain, shortness of breath, and heart palpitations. These symptoms are the result of various forms of heart disease that often accompany Friedreich ataxia, such as cardiomyopathy (enlargement of the heart), myocardial fibrosis (formation of fiber-like material in the muscles of the heart), and cardiac failure. Heart rhythm abnormalities such as tachycardia (fast heart rate) and heart block (impaired conduction of cardiac impulses within the heart) are also common. About 20 percent of people with Friedreich ataxia develop carbohydrate intolerance and 10 percent develop diabetes mellitus. Some people lose hearing or eyesight.[2]

The rate of progression varies from person to person. Generally, within 10 to 20 years after the first symptoms appear, people with Friedreich ataxia need to consistently use a wheelchair. Life expectancy may be affected, and many people with Friedreich ataxia die in adulthood from the associated heart disease. However, some people with less severe symptoms of Friedreich ataxia live much longer, sometimes into their sixties or seventies[2].

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
HPO ID
100% of people have these symptoms
Gait ataxia
Inability to coordinate movements when walking
0002066
80%-99% of people have these symptoms
Babinski sign
0003487
Dysarthria
Difficulty articulating speech
0001260
Gait imbalance
Abnormality of balance
Abnormality of equilibrium
Imbalanced walk

[ more ]

0002141
Hand muscle atrophy
Hand muscle degeneration
0009130
Impaired proprioception
0010831
Limb ataxia
0002070
30%-79% of people have these symptoms
Abnormal saccadic eye movements
0000570
Areflexia of lower limbs
0002522
Cardiomyopathy
Disease of the heart muscle
0001638
Cervical spinal cord atrophy
0010873
Dysmetria
Lack of coordination of movement
0001310
Falls
0002527
Impaired visually enhanced vestibulo-ocular reflex
0030183
Intention tremor
0002080
Muscle weakness
Muscular weakness
0001324
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Optic atrophy
0000648
Pes cavus
High-arched foot
0001761
Poor fine motor coordination
0007010
Scoliosis
0002650
Sensory axonal neuropathy
0003390
Urinary bladder sphincter dysfunction
0002839
5%-29% of people have these symptoms
Chorea
0002072
Decreased motor nerve conduction velocity
0003431
Diabetes mellitus
0000819
Dysphagia
Poor swallowing
Swallowing difficulties
Swallowing difficulty

[ more ]

0002015
Dystonia
0001332
Hearing impairment
Deafness
Hearing defect

[ more ]

0000365
Inability to walk
0002540
Incomprehensible speech
0002546
Reduced visual acuity
Decreased clarity of vision
0007663
Spasticity
Involuntary muscle stiffness, contraction, or spasm
0001257
Percent of people who have these symptoms is not available through HPO
Abnormal echocardiogram
Abnormal echocardiography
0003116
Abnormal EKG
Abnormal ECG
0003115
Abnormality of visual evoked potentials
0000649
Autosomal recessive inheritance
0000007
Congestive heart failure
Cardiac failure
Cardiac failures
Heart failure

[ more ]

0001635
Decreased amplitude of sensory action potentials
0007078
Decreased pyruvate carboxylase activity
0003209
Decreased sensory nerve conduction velocity
0003448
Hypertrophic cardiomyopathy
Enlarged and thickened heart muscle
0001639
Impaired vibratory sensation
Decreased vibration sense
Decreased vibratory sense
Diminished vibratory sense
Impaired vibratory sense

[ more ]

0002495
Juvenile onset
Signs and symptoms begin before 15 years of age
0003621
Mitochondrial malic enzyme reduced
0003232
Sensory neuropathy
Damage to nerves that sense feeling
0000763
Visual field defect
Partial loss of field of vision
0001123

Cause

Friedreich ataxia is caused by mutations in the FXN gene. This gene provides instructions for making a protein called frataxin. One region of the FXN gene contains a segment of DNA known as a GAA trinucleotide repeat. This segment is made up of a series of three DNA building blocks (one guanine and two adenines) that appear multiple times in a row. Normally, this segment is repeated 5 to 33 times within the FXN gene. In people with Friedreich ataxia, the GAA segment is repeated 66 to more than 1,000 times. The length of the GAA trinucleotide repeat appears to be related to the age at which the symptoms of Friedreich ataxia appear.[1]

The abnormally long GAA trinucleotide repeat disrupts the production of frataxin, which severely reduces the amount of this protein in cells. Certain nerve and muscle cells cannot function properly with a shortage of frataxin, leading to the characteristic signs and symptoms of Friedreich ataxia.[1]

Diagnosis

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
  • Spinocerebellar Ataxia: Making an Informed Choice about Genetic Testing is a booklet providing information about spinocerebellar ataxia and is available as a PDF document on the University of Washington Medical Center Web site. Click on the title above to view this resource.

    Treatment

    The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your healthcare professional.

    Management Guidelines

      Organizations

      Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

      Organizations Supporting this Disease

        Organizations Providing General Support

          Learn more

          These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

          Where to Start

            In-Depth Information

            • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
            • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
            • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
            • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
            • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
            • PubMed is a searchable database of medical literature and lists journal articles that discuss Friedreich ataxia. Click on the link to view a sample search on this topic.

              References

              1. Friedreich ataxia. Genetics Home Reference. May 2010; https://ghr.nlm.nih.gov/condition/friedreich-ataxia. Accessed 5/22/2015.
              2. Friedreich's Ataxia Fact Sheet. The National Institute of Neurological Disorders and Stroke (NINDS). April 16, 2014; https://www.ninds.nih.gov/disorders/friedreichs_ataxia/detail_friedreichs_ataxia.htm. Accessed 5/22/2015.

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