Familial Writer's Cramp with DYT1 Mutation: A Clinical and Genetic Analysis of a New Kindred

Lee, Joon K; Im, Joo Hyuk; Lee, Myoung Chong

Abstract

BACKGROUND: Recently a non-Jewish German family with writer's cramp was reported to have DYT1 mutation, expanding the phenotypic spectrum of DYT1. Although functional brain surgery has been tried for generalized dystonia, surgical outcome in focal dystonia patients with DYT1 mutation has not yet been reported. We investigated the clinical features and response to thalamotomy in familial writer's cramp with DYT1 mutation.
METHODS
Family members were examined and clinically affected cases were video-taped. For the detection of DYT1 mutation, PCR-RFLP(restriction fragment length polymorphism) and heteroduplex analyses were performed as screening tests. Additional DNA sequencing was performed for the proband case to confirm the GAG deletion.
RESULTS
Among this clinically homogeneous non-Jewish Korean family, five members in three generations were affected. Age of onset ranged from 7 to 20 years. Writing difficulty was the initial and the main disabling problem for all the affected individuals. All had the bilateral writer's cramp in succession. Dystonia remained focal and task-specific for the entire period after onset. Unilateral thalamotomy was performed in three patients, with remarkable improvement. Surgical benefit remained unchanged during the follow-up period of 6-8 years. DYT1 mutation cosegregated with the affected members.
CONCLUSIONS
This study adds another evidence that DYT1 phenotype can present with purely focal and task-specific dystonia in all the affected members of a family. Marked and sustained improvement following thalamotomy in three of our patients suggests that stereotaxic thalamotomy is beneficial in familial focal dystonia with DYT1 mutation. (J Korean Neurol Assoc 19(2):110~115, 2001)