Complex segregation analysis of dystonia pedigrees suggests autosomal dominant inheritance.

We reanalyzed data collected in a large family study of idiopathic torsion dystonia (ITD) using complex segregation analysis. Previous investigators concluded that the mode of inheritance of ITD differed between Jews and non-Jews. The results from our segregation analyses suggest that ITD is inherited as an autosomal dominant trait, with low penetrance (0.255 to 0.333), regardless of ethnic origin. The low penetrance implies that, although a major gene is important for the expression of the illness, other factors also contribute to the manifestations of ITD.