Chicago Center for Jewish Genetics Disorders - Ashkenazi Disorders: Torsion Dystonia

Ashkenazi Disorders: Mendelian

Gene: Torsion dystonia is caused by mutations in the DYT1 gene, which is located at 9q34. It encodes torsinA, an ATP-binding protein that resembles a heat-shock protein. It is dominantly inherited.

Mutations and testing: More than 90% of early-onset cases of torsion dystonia in the Ashkenazi Jewish population are caused by a GAG deletion. This deletion is estimated to have low penetrance and only produces symptoms in 30% of the people who carry it.

Traits: Torsion dystonia is caused by a defect in the DYT1 gene, which may be a heat shock protein. Heat shock proteins act as thermoregulators for other proteins and protect them from temperature fluctuations in the cell which might change their conformation and function. By helping proteins maintain their strength and resiliency, heat shock proteins protect cells from deadly environmental, biological, and chemical stress. Clinical manifestations of Torsion dystonia are involuntary sustained contractions of opposing muscles that cause posturing, initially of the foot, leg, or arm. Occasionally the dystonia may initiate in the neck or cranial muscles. Regardless of the site of initial involvement, the contractions usually generalize to other body regions. They may be slow or rapid, shock-like jerks, are repetitive and may be rhythmic, and are often made worse by voluntary movement, stress and fatigue. Average age of onset depends upon the site of initial symptoms, with an average age of 9 years with onset in the leg and 15 years with onset in the arm. If a person has not developed contractions by the age of 30, they are unlikely to do so later in life. Overall, 60 to 70% of patients will have progression to more generalized dystonia involving limb and axial musculature. Cranial muscles are involved in only 11 to 18% of cases. No other neurological abnormalities are present except for postural arm tremor. Once symptoms appear, they are present for life, but there is no shortening of the lifespan.

Treatment: Treatment is aimed predominately at the relief of symptoms. Medications may be used to block the transmission of the nerve impulses that initiate the contractions. Surgery may be helpful in more serious cases. To reduce the number and severity of contractions caused by stress, hypnosis, sleep, and relaxation may help.

Torsion Dystonia from Geneclinics.org
http://www.genetests.org/profiles/dystonia

Reviewed by Dr. Joel Charrow, Children's Memorial Hospital.
1/03

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This page last updated on January 10, 2003.