Inheritance of idiopathic torsion dystonia among Ashkenazi Jews.
The mechanism(s) of inheritance of primary dystonia are unclear. An autosomal recessive form among Ashkenazi Jews and an autosomal dominant form among non-Jews have been proposed. However, the patterns of inheritance, particularly among Ashkenazim, are controversial. In this report we have reviewed the literature particularly as it pertains to the mode of inheritance among Ashkenazim. We also report the results of a pilot study of the families of 25 independently ascertained Ashkenazi probands with onset of primary dystonia before age 27 years. A total of 91/98 living first-degree relatives were examined; of these 91, 86 were greater than or equal to 8 years of age at time of examination and were included in our analysis. Overall, 14/86 (16.3%) of first-degree relatives were affected. We found 11.4% (4/35) of parents, 22.2% (8/36) of siblings, and 13.3% (2/15) of offspring were definitely affected. This finding of an approximately equal risk to parents, siblings, and offspring is consistent with autosomal dominant transmission with a minimum penetrance of 32.6%. Our findings do not support autosomal recessive or multifactorial inheritance.