A country-wide search for idiopathic torsion dystonia (ITD) in Israel between 1969 and 1975 revealed 42 patients (41 Jewish and 1 Druze Arab). Prevalence of ITD per million population, age-adjusted to the United States population in 1970, was 10.8 in the total Jewish population (22.0 among Jews of European extraction contrasted with 1.5 among Jews with Afro-Asian forebears). Among Europeans, the highest prevalence was among Jews from Eastern Europe.
The average age-adjusted annual incidence rates per million population were 0.43 in the total Jewish population, 0.98 in the Europeans, and 0.11 in the Afro-Asians. Among the 40 patients for whom familial data were available, the majority of cases (26) were sporadic. The other 14 belonged to four unrelated European families, all of Russian-Polish origin. The pattern of inheritance in these four families fits an autosomal dominant model with incomplete penetrance.