Early-onset isolated dystonia is one of many forms of dystonia, which is a group of conditions characterized by 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. An isolated dystonia is one that occurs without other abnormal movements or other neurological symptoms, such as seizures, a loss of intellectual function, or developmental or intellectual delay. Early-onset isolated dystonia does not affect a person's intelligence.

A particular variant (also called a mutation) in the TOR1A gene (also known as DYT1) is responsible for most cases of early-onset isolated dystonia. Variants in other genes cause other forms of dystonia, such as dystonia 6.

Early-onset isolated 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.

Variants 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 variant in this gene are not affected by the disorder and may never know they have the altered gene. Only 30 to 40 percent of people who inherit a TOR1A gene variant will ever develop signs and symptoms of early-onset isolated dystonia.

Published Date: April 22, 2022
Published By: National Institutes of Health