[Genetic study of idiopathic torsion dystonia in Russia]

Inheritance of idiopathic torsion dystonia (ITD) was studied in 41 Russian families including 41 probands with generalized, focal, and segmental dystonia and 140 recurred cases. Affected relatives appeared in two or more generations in 31 families analyzed. It was shown that in 76% of segregated cases, ITD was inherited as an autosomal dominant trait with a penetrance of 40% and varying expression. An autosomal recessive type was observed in 24% of the cases. Approximately 10% of the cases of disease could be caused by a new mutation and 14.6% by a nongenetic phenotype similar to genetic forms in its clinical symptoms. ITD with the X-linked recessive type of inheritance did not occur in the families studied. The recurrence risk was 20% in autosomal dominant forms. The risk correlated with age the relative's: clinical symptoms developed in 98.4% of patients by the age of 30.