National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Harding ataxia


Other Names:
Cerebellar ataxia early onset with retained tendon reflex; EOCA; Ataxia, harding type
Categories:
The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.
orphanet

Orpha Number: 1177

Definition
Early onset cerebellar ataxia with retained reflexes (EOCARR) or Harding ataxia is a cerebellar ataxia characterized by the progressive association of a cerebellar and pyramidal syndrome with progressive cerebellar ataxia, brisk tendon reflexes, and sometimes profound sensory loss.

Epidemiology
The prevalence of EOCARR ataxia has been estimated to be around 1/100,000, and the birth prevalence at 1/48,000 births in North-western Italy.

Clinical description
EOCARR is a progressive cerebellar ataxia, with disease onset occurring in childhood or in juveniles (ranging from 3 to 20 years with a mean age of 9 years). EOCARR is characterized by dysarthria, gait ataxia, nystagmus, brisk tendon reflexes in the upper and lower limbs, absent ankle reflexes, and discrete or absent deep sensory loss. The association of brisk jerks and absent ankle reflexes may occur. Oculomotor disturbances, dysphagia, tremor, scoliosis, pes cavus, extensor plantar response, and lower limb wasting and weakness may be observed while amyotrophy is rarely observed. Moreover, spasticity may become progressively severe.

Etiology
The exact etiology of EOCARR is still unknown. However, molecular genetic analysis in a Tunisian family confirmed the genetic heterogeneity of this syndrome and mapped the gene locus to chromosome 13q11-12.

Diagnostic methods
Diagnosis relies on physical examination as well as on imaging findings (magnetic resonance imaging (MRI) or computed tomography (CT)) revealing cerebellar atrophy. Peripheral nerve conduction and nerve biopsy findings may show moderate to severe axonal sensory-motor neuropathy with axonal regeneration.

Differential diagnosis
Differential diagnosis includes Friedreich ataxia (FRDA; in contrast to EOCARR shows cardiomyopathy, diabetes mellitus, scoliosis, skeletal deformities or optic atrophy), autosomal dominant cerebellar ataxia (ADCA), autosomal recessive spastic ataxia of Charlevoix-Saguenay, ataxia with vitamin E deficiency (see these terms), and inherited metabolic disorders that may express ataxia.

Genetic counseling
Transmission is autosomal recessive. The parents of an affected child should be informed of the 25% chance of transmitting the disease to future offspring.

Management and treatment
Treatment is symptomatic, aimed towards the control of spasticity, and should include physiotherapy and pharmacotherapy (that may include spasmolytic drugs such as baclofen).

Prognosis
The period of latency before becoming wheelchair-bound is significantly longer in EOCARR than in FRDA, resulting in a better prognosis in patients with EOCARR than in those with FRDA.

Visit the Orphanet disease page for more resources.
Last updated: 1/1/2014

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.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Progressive cerebellar ataxia 0002073
30%-79% of people have these symptoms
Abnormal pyramidal sign 0007256
Dysarthria
Difficulty articulating speech
0001260
Dysphagia
Poor swallowing
Swallowing difficulties
Swallowing difficulty
[ more ] 		0002015
Hyperactive patellar reflex
Overactive knee reflex
0007083
Hyperreflexia in upper limbs 0007350
Jerky ocular pursuit movements 0008003
Lower limb hypertonia 0006895
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Progressive gait ataxia 0007240
Sensory impairment 0003474
5%-29% of people have these symptoms
Abnormal EKG
Abnormal ECG
0003115
Cognitive impairment
Abnormality of cognition
Cognitive abnormality
Cognitive defects
Cognitive deficits
Intellectual impairment
Mental impairment
[ more ] 		0100543
Decreased/absent ankle reflexes 0200101
Generalized amyotrophy
Diffuse skeletal muscle wasting
Generalized muscle degeneration
Muscle atrophy, generalized
[ more ] 		0003700
Impaired visuospatial constructive cognition 0010794
Lower limb muscle weakness
Lower extremity weakness
Lower limb weakness
Muscle weakness in lower limbs
[ more ] 		0007340
Lower limb spasticity 0002061
Pes cavus
High-arched foot
0001761
Scoliosis 0002650
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Last updated: 7/1/2020

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • The Centers for Mendelian Genomics program is working to discover the causes of rare genetic disorders. For more information about applying to the research study, please visit their website.

Patient Registry

  • Coordination of Rare Diseases at Sanford (CoRDS) hosts a specific registry for patients with ataxia in partnership with the National Ataxia Foundation. The goal of the CoRDS registry is to connect as many patients and researchers as possible to help advance treatments and cures for rare diseases. The CoRDS registry is free for patients to enroll and for researchers to access.

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

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.

In-Depth Information

  • 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 Harding ataxia. Click on the link to view a sample search on this topic.

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