title: Clinical and genetic evaluation in a French population presenting with primary focal dystonia.
abstract: Primary focal dystonia (PFD) is known to be a clinically and genetically heterogeneous group of movement disorders. To evaluate the frequency of familial focal dystonia in a French population presenting with PFD, we screened 197 patients (150 index cases and 47 affected family members) presenting focal primary dystonia for the GAG deletion in the DYT1 gene and analyzed linkage to the DYT6, DYT7, and DYT13 loci in those who presented a family history. Fourteen families could be recruited and, among them 47 new symptomatic individuals could be identified by clinical examination. A group of 104 patients were without family history and 46 patients (30.7%) were found to have at least one first-degree relative with dystonia. Mean age at onset was significantly later (55.4 +/- 14.0 years) in the blepharospasm group and earlier in patients with writer's cramp (35.8 +/- 14.0 years). The group of patients with family history showed a mean age at onset significantly earlier (39.2 +/- 18.0) than in patients without family history (47.4 +/- 14.4 years). Fourteen families demonstrated an autosomal mode of transmission and five families were studied further for genetic linkage analysis, but no significant linkage to one of the three loci could be observed. Our results illustrate the importance of genetic factors and the clinical heterogeneity of PFD. They indicate the existence of one or several as yet unmapped genes responsible for these diseases.
authors.affiliation: Department of Biochemistry and Molecular Biology, Institut National de la Santé et de la Recherche Médicale (IFR 114), Centre Hospitalier Universitaire de Lille, France.
authors.forename: Claire-Marie
authors.initials: CM
authors.lastname: Dhaenens
authors.forename: Pierre
authors.initials: P
authors.lastname: Krystkowiak
authors.forename: Xavier
authors.initials: X
authors.lastname: Douay
authors.forename: Pierre
authors.initials: P
authors.lastname: Charpentier
authors.forename: Sylvain
authors.initials: S
authors.lastname: Bele
authors.forename: Alain
authors.initials: A
authors.lastname: Destée
authors.forename: Bernard
authors.initials: B
authors.lastname: Sablonnière
mesh_terms: D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D001764:Blepharospasm / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics*; D002874:Chromosome Mapping; D002899:Chromosomes, Human, Pair 9; D004252:DNA Mutational Analysis; D020821:Dystonic Disorders / Q000145:classification / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018911:Trinucleotide Repeats
chemical_list: D002352:Carrier Proteins