Phenotypic expression of the DYT1 mutation: a family with writer's cramp of juvenile onset.

Recently, the mutation causing early-onset generalized torsion dystonia has been identified as a GAG deletion in the gene for an adenosine triphosphate-binding protein named torsinA. We describe a German family with 5 clinically affected individuals carrying this mutation. In at least 4 of the 5 patients, the disease presented as a dystonic writer's cramp during late childhood or adolescence, which affected sequentially both sides but did not progress to a generalized form of dystonia. We conclude that familial writer's cramp may be a manifestation of the DYT1 mutation.