title: Phenotypes and genetic architecture of focal primary torsion dystonia.
abstract: BACKGROUND
  The focal primary torsion dystonias (FPTDs) form a group of clinical heterogeneous syndromes and can be considered a genetic complex disease; it is thought to be primed by genetic variants with variable impact and triggered by non-genetic factors. Thorough clinical description of FPTDs cohorts is sparse but essential for further progress in genetic research.
  
  
  OBJECTIVE
  To establish suggested relations between age at onset (AaO), site and family history in a large focal dystonias cohort and gain more insight into familial clustering for genetic research.
  
  
  METHODS
  A prospective cohort study between March 2008 and March 2011, including 676 FPTD patients attending the botulinum toxin outpatient clinics of six Dutch movement disorder centres.
  
  
  CONCLUSIONS
  Of all of the FPTD patients, 25% had a familial predisposition; in 2.4% a Mendelian inheritance pattern was noted. With a stronger family history, a significantly lower AaO was seen in all focal dystonias. In both the sporadic and familial focal dystonia groups, AaO had an effect on the distribution of dystonia, with a caudal to cranial tendency. In all focal dystonia forms, women were more frequently affected, except for writer's cramp. Careful clinical characterisation will allow the formation of phenotype subgroups. We suggest that genetic research into FPTDs will benefit from this approach and discuss genetic research strategies to decipher the complex background of focal dystonias.
authors: Department of Neurology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
authors: Justus L
authors: JL
authors: Groen
authors: Marlot C
authors: MC
authors: Kallen
authors: Bart P C
authors: BP
authors: van de Warrenburg
authors: J D
authors: JD
authors: Speelman
authors: Jacobus J
authors: JJ
authors: van Hilten
authors: Majid
authors: M
authors: Aramideh
authors: Agnita J W
authors: AJ
authors: Boon
authors: Christine
authors: C
authors: Klein
authors: Johannes H T M
authors: JH
authors: Koelman
authors: Ton P
authors: TP
authors: Langeveld
authors: Frank
authors: F
authors: Baas
authors: Marina A J
authors: MA
authors: Tijssen
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D015331:Cohort Studies; D020821:Dystonic Disorders / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D006801:Humans; D008297:Male; D057182:Mendelian Randomization Analysis; D008875:Middle Aged; D009426:Netherlands; D010641:Phenotype; D011446:Prospective Studies; D012107:Research Design; D012307:Risk Factors