Our meta-analysis revealed a significant implication of rs1182 and rs1801968TOR1A variants in the development of focal dystonia and writer's cramp respectively.
TOR1A (torsinA, DYT1) is the leading cause of early-onset generalized dystonia, however, the associations between common TOR1A single nucleotide polymorphisms (SNPs) and primary adult-onset focal dystonia are controversial.
In light of these findings, a more comprehensive genetic effort is warranted to identify the role of this and other rare TOR1A variants in the expression of late onset, focal dystonia.
Polymorphisms of the genes encoding TorsinA (DYT1) and the D5 dopamine receptor (DRD5) have previously been associated with lifetime risk for focal dystonia.
Taken together, these results suggest that most cases of focal dystonia in patients of northern German or central European origin are due neither to the GAG deletion in DYT1 nor to a proposed founder mutation on chromosome 18p but must be caused by other genetic or environmental factors.