Clinical characteristics of carriers of a GAG deletion in the DYT1 gene amongst Polish patients with primary dystonia.

DYT1 primary torsion dystonia is an autosomal dominant disorder caused by deletion of a GAG triplet in exon 5 of the DYT1 gene. A significant proportion of individuals with early-onset generalized dystonia is believed to be DYT1 mutation carriers. We assessed the frequency of the GAG deletion in the DYT1 gene in a group of 61 Polish probands with clinical diagnosis of primary dystonia. The deletion was identified in four probands presenting with early-onset generalized disease (7%). Further studies in probands' families revealed two symptomatic and nine asymptomatic mutation carriers. We tested all mutation-positive individuals for the presence of some common polymorphisms within the DYT1 gene. Two of the 15 mutation-positive individuals additionally carried polymorphisms in 3'-UTR of the gene. Early onset in a limb and progression toward a generalized form, but not family history of dystonia, are indicative of DYT1 dystonia in Polish dystonic individuals.