Primary torsion dystonia (PTD) is a clinically and genetically heterogeneou
s movement disorder. DYT1 on chromosome 9q34 was the first PTD gene to be m
apped. A 3-bp (GAG) deletion in this gene was reported to account for almos
t all early limb-onset generalized PTD, No relationship has been found with
DYT1 in patients with prominent craniocervical involvement. To elucidate t
he DYT1-associated phenotype, we analysed the DYT1 mutation in 150 PTD pati
ents, either sporadic or index cases from small PTD families. Twenty-two pa
tients were positive for the GAG deletion in the DYT1 gene. Fifteen of them
presented with the typical DYT1 phenotype (early, limb-onset generalized d
ystonia without spread to craniocervical muscles), four had limb-onset dyst
onia with spread to craniocervical muscles, two patients had arm-onset segm
ental dystonia and one had focal right-arm dystonia, One-hundred and twenty
-eight patients were negative for the DYT1 mutation. Forty-six of them had
segmental dystonia and 59 had focal dystonia, The other 23 patients present
ed with generalized dystonia, either with craniocervical involvement (13 pa
tients) or without spread to the craniocervical region (typical DYT1 phenot
ype-10 patients). These data confirm the importance of the GAG deletion in
European cases of PTD, and indicate phenotypic and genotypic heterogeneity.