Early-onset Primary Dystonia

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This entry is adapted from the peer-reviewed paper https://medlineplus.gov/genetics/condition/early-onset-primary-dystonia

Early-onset primary dystonia is a condition characterized by progressive problems with movement, typically beginning in childhood. Dystonia is a movement disorder that involves involuntary tensing of the muscles (muscle contractions), twisting of specific body parts such as an arm or a leg, rhythmic shaking (tremors), and other uncontrolled movements. A primary dystonia is one that occurs without other neurological symptoms, such as seizures or a loss of intellectual function (dementia). Early-onset primary dystonia does not affect a person's intelligence.

genetic conditions

1. Introduction

On average, the signs and symptoms of early-onset primary dystonia appear around age 12. Abnormal muscle spasms in an arm or a leg are usually the first sign. These unusual movements initially occur while a person is doing a specific action, such as writing or walking. In some affected people, dystonia later spreads to other parts of the body and may occur at rest. The abnormal movements persist throughout life, but they do not usually cause pain.

The signs and symptoms of early-onset primary dystonia vary from person to person, even among affected members of the same family. The mildest cases affect only a single part of the body, causing isolated problems such as a writer's cramp in the hand. Severe cases involve abnormal movements affecting many regions of the body.

2. Frequency

Early-onset primary dystonia is among the most common forms of childhood dystonia. This disorder occurs most frequently in people of Ashkenazi (central and eastern European) Jewish heritage, affecting 1 in 3,000 to 9,000 people in this population. The condition is less common among people with other backgrounds; it is estimated to affect 1 in 10,000 to 30,000 non-Jewish people worldwide.

3. Causes

A particular mutation in the TOR1A gene (also known as DYT1) is responsible for most cases of early-onset primary dystonia. The TOR1A gene provides instructions for making a protein called torsinA. Although little is known about its function, this protein may help process and transport other proteins within cells. It appears to be critical for the normal development and function of nerve cells in the brain.

A mutation in the TOR1A gene alters the structure of torsinA. The altered protein's effect on the function of nerve cells in the brain is unclear. People with early-onset primary dystonia do not have a loss of nerve cells or obvious changes in the structure of the brain that would explain the abnormal muscle contractions. Instead, the altered torsinA protein may have subtle effects on the connections between nerve cells and likely disrupts chemical signaling between nerve cells that control movement. Researchers are working to determine how a change in this protein leads to the characteristic features of this disorder.

4. Inheritance

Mutations in the TOR1A gene are inherited in an autosomal dominant pattern, which means one of the two copies of the gene is altered in each cell. Many people who have a mutation in this gene are not affected by the disorder and may never know they have the mutation. Only 30 to 40 percent of people who inherit a TOR1A mutation will ever develop signs and symptoms of early-onset primary dystonia.

Everyone who has been diagnosed with early-onset primary dystonia has inherited a TOR1A mutation from one parent. The parent may or may not have signs and symptoms of the condition, and other family members may or may not be affected.

5. Other Names for This Condition

Dystonia musculorum deformans 1
DYT1
Early-onset generalized torsion dystonia
Oppenheim dystonia
Oppenheim's dystonia
Primary torsion dystonia

References

Bragg DC, Slater DJ, Breakefield XO. TorsinA and early-onset torsion dystonia.Adv Neurol. 2004;94:87-93. Review.
Breakefield XO, Blood AJ, Li Y, Hallett M, Hanson PI, Standaert DG. Thepathophysiological basis of dystonias. Nat Rev Neurosci. 2008 Mar;9(3):222-34.doi: 10.1038/nrn2337. Review.
Bressman SB. Dystonia genotypes, phenotypes, and classification. Adv Neurol.2004;94:101-7. Review.
Geyer HL, Bressman SB. The diagnosis of dystonia. Lancet Neurol. 2006Sep;5(9):780-90. Review.
Grundmann K, Laubis-Herrmann U, Bauer I, Dressler D, Vollmer-Haase J, Bauer P,Stuhrmann M, Schulte T, Schöls L, Topka H, Riess O. Frequency and phenotypicvariability of the GAG deletion of the DYT1 gene in an unselected group ofpatients with dystonia. Arch Neurol. 2003 Sep;60(9):1266-70.
Kamm C. Early onset torsion dystonia (Oppenheim's dystonia). Orphanet J RareDis. 2006 Nov 27;1:48. Review.
Ozelius L, Lubarr N. DYT1 Early-Onset Isolated Dystonia. 1999 Apr 14 [updated 2016 Nov 17]. In: Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University ofWashington, Seattle; 1993-2020. Available fromhttp://www.ncbi.nlm.nih.gov/books/NBK1492/
Tarsy D, Simon DK. Dystonia. N Engl J Med. 2006 Aug 24;355(8):818-29. Review.

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Nicole Yin

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Table of Contents

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1. Introduction

2. Frequency

3. Causes

4. Inheritance

5. Other Names for This Condition

References

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1. Introduction

2. Frequency

3. Causes

3.1. The Gene Associated with Early-onset Primary Dystonia

4. Inheritance

5. Other Names for This Condition

References