Rare Oncology News

Disease Profile

Ataxia with Oculomotor Apraxia Type 2

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.

Unknown

Age of onset

Adolescent

ICD-10

G60.2

Inheritance

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

no.svg

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

rnn-autosomalrecessive.svg

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.

no.svg

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

no.svg

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.

no.svg

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.

no.svg

Not applicable

no.svg

Other names (AKA)

AOA2; SCAN 2; SCAR1;

Categories

Congenital and Genetic Diseases; Eye diseases; Nervous System Diseases

Summary

Ataxia with oculomotor apraxia type 2 (AOA2) is a rare condition that affects muscle control and coordination. Ataxia (difficulty coordinating movements) is generally the earliest sign of the condition and is often diagnosed between age seven and 25 years. Other signs and symptoms may include sensorimotor neuropathy, mild cognitive impairment and less commonly, movement disorders. Approximately half of affected people also experience, oculomotor apraxia which makes it difficult to move the eyes from side-to side in the desired direction. AOA2 is caused by changes (mutations) in the SETX gene and is inherited in an autosomal recessive manner.[1][2][3] Treatment is based on the signs and symptoms present in each person.[2]

Symptoms

The signs and symptoms of ataxia with oculomotor apraxia type 2 (AOA2) generally become apparent between age 7 and twenty five years. Ataxia is often the first symptom and is a major cause of disability in the early stages of the condition. Most people with AOA2 also experience sensorimotor neuropathy which is associated with a decreased ability to move or feel (sensation) in certain parts of the body, especially the lower limbs. Other symptoms can include oculomotor apraxia, movement disorders, and mild cognitive impairment.[2][3][1]

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
80%-99% of people have these symptoms
Areflexia
Absent tendon reflexes
0001284
Ataxia
0001251
Cerebellar vermis atrophy
0006855
Sensorimotor neuropathy
Nerve damage causing decreased feeling and movement
0007141
30%-79% of people have these symptoms
Elevated alpha-fetoprotein
0006254
Gait imbalance
Abnormality of balance
Abnormality of equilibrium
Imbalanced walk

[ more ]

0002141
Gaze-evoked nystagmus
0000640
Oculomotor apraxia
0000657
Saccadic smooth pursuit
0001152
Sensory impairment
0003474
5%-29% of people have these symptoms
Babinski sign
0003487
Choreoathetosis
0001266
Conjunctival telangiectasia
Small dilated blood vessels near membrane covering front of eye and eyelids
0000524
Dysphagia
Poor swallowing
Swallowing difficulty
Swallowing difficulties

[ more ]

0002015
Dystonia
0001332
Elevated serum creatine kinase
Elevated blood creatine phosphokinase
Elevated circulating creatine phosphokinase
Elevated creatine kinase
Elevated serum CPK
Elevated serum creatine phosphokinase
High serum creatine kinase
Increased CPK
Increased creatine kinase
Increased creatine phosphokinase
Increased serum CK
Increased serum creatine kinase
Increased serum creatine phosphokinase

[ more ]

0003236
Head tremor
0002346
Hypercholesterolemia
Elevated serum cholesterol
Elevated total cholesterol
Increased total cholesterol

[ more ]

0003124
Hypoalbuminemia
Low blood albumin
0003073
Postural tremor
0002174
Strabismus
Squint eyes
Squint
Cross-eyed

[ more ]

0000486
Urinary bladder sphincter dysfunction
0002839
1%-4% of people have these symptoms
Cerebellar atrophy
Degeneration of cerebellum
0001272
Chorea
0002072
Distal amyotrophy
Distal muscle wasting
0003693
Distal muscle weakness
Weakness of outermost muscles
0002460
Dysarthria
Difficulty articulating speech
0001260
Gait ataxia
Inability to coordinate movements when walking
0002066
Hyporeflexia
Decreased reflex response
Decreased reflexes

[ more ]

0001265
Impaired distal tactile sensation
Decreased touch sensation in extremities
0006937
Impaired proprioception
0010831
Nystagmus
Involuntary, rapid, rhythmic eye movements
0000639
Peripheral axonal neuropathy
0003477
Pes cavus
High-arched foot
0001761
Scoliosis
0002650
Tremor
0001337
Percent of people who have these symptoms is not available through HPO
Abnormal pyramidal sign
0007256
Autosomal recessive inheritance
0000007
Chronic axonal neuropathy
0007267
Decreased motor nerve conduction velocity
0003431
Impaired distal vibration sensation
0006886
Increased circulating antibody level
0010702
Limb ataxia
0002070
Polyneuropathy
Peripheral nerve disease
0001271
Pontocerebellar atrophy
0006879
Progressive
Worsens with time
0003676
Progressive gait ataxia
0007240
Variable expressivity
0003828

Cause

Spinocerebellar ataxia with axonal neuropathy type 2 (SCAN2) is caused by changes (mutations) in the SETX gene, which provides instructions for making a protein that is involved in DNA repair. People with a mutation in SETX make a reduced amount of this important protein. This leads to an accumulation of damaged DNA which can cause cells to become unstable and die. Certain cells in the brain, such as those involved in coordinating movements (the cerebellum), appear to be most affected by cell death because these cells do not copy themselves to replace cells that have been lost. Scientists suspect that the loss of brain cells in the cerebellum causes the many signs and symptoms associated with SCAN2.[4]

Diagnosis

A diagnosis of spinocerebellar ataxia with axonal neuropathy type 2 is often suspected based on the presence of characteristic signs and symptoms. Additional testing may then be ordered to confirm the diagnosis and to rule out other conditions that are associated with similar features. This testing may include:[5][2]

Treatment

Although there is no cure for spinocerebellar ataxia with axonal neuropathy type 2 (SCAN2), treatments are available to help manage the signs and symptoms of the condition. For example, affected people may benefit from physical therapy and speech therapy. A wheelchair or other devices may be necessary to help maintain mobility. Children with SCAN2 may also need additional help in school since they may have difficulties with reading, writing and other activities. In some cases, a low-cholesterol diet may be recommended.[2][6]

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

    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

    • Genetics Home Reference (GHR) contains information on Ataxia with Oculomotor Apraxia Type 2. This website is maintained by the National Library of Medicine.

      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.
      • 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.

        References

        1. Pera J, Lechner S, Biskup S, Strach M, Grodzicki T, Slowik A. Two novel mutations of the SETX gene and ataxia with oculomotor apraxia type 2. Clin Neurol Neurosurg. January 2015; 128:44-46.
        2. Moreira MC & Koenig M. Ataxia with Oculomotor Apraxia Type 2. GeneReviews. 2018; https://www.ncbi.nlm.nih.gov/books/NBK1154.
        3. SPINOCEREBELLAR ATAXIA, AUTOSOMAL RECESSIVE 1. OMIM. August 2016; https://www.omim.org/entry/606002.
        4. ataxia with oculomotor apraxia. Genetics Home Reference. April 2015; https://ghr.nlm.nih.gov/condition/ataxia-with-oculomotor-apraxia.
        5. Mignarri A, Tessa A, Federico A, Santorelli FM, Dotti MT. Ataxia with oculomotor apraxia type 2: not always an easy diagnosis. Neurol Sci. August 2015; 36(8):1505-1507. https://www.ncbi.nlm.nih.gov/pubmed/25787807.
        6. Spinocerebellar ataxia with axonal neuropathy type 2. Orphanet. May 2015; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=64753.

        Rare Oncology News