Genetic testing for early-onset torsion dystonia (DYT1): introduction of a simple screening method, experiences from testing of a large patient cohort, and ethical aspects

Genet Test. 1999;3(4):323-8. doi: 10.1089/gte.1999.3.323.


Early-onset, generalized primary torsion dystonia (PTD) is an autosomal dominantly inherited disorder, characterized by involuntary movements and abnormal postures. The majority of cases are caused by a 3-bp deletion in the DYT1 gene on chromosome 9q34 that allows for specific genetic testing. We developed a simple, reliable, and cost-effective, PCR-based screening method for this mutation. Testing results from a cohort of 550 cases, including patients with different forms of dystonia and unclassified movement disorders, revealed that 72.2% of the patients with typical early-onset generalized PTD carried the GAG deletion in the DYT1 gene. Among 300 cases with late-onset focal/segmental dystonia, only 3 patients tested positive for the GAG deletion whereas 12.8% of the patients with an unclassified movement disorder were GAG positive. Our results confirm a genotype/phenotype correlation in early-onset PTD and show that application of strict clinical criteria leads to accurate prediction of carrier status in more than two-thirds of patients with this type of dystonia. Currently, we suggest that testing be recommended in individuals with age of onset of dystonia below 30 years and/or a positive family history of early-onset PTD. Testing is not recommended in patients with onset of symptoms after 30 years or in asymptomatic individuals under the age of 18.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Age of Onset
  • Aged
  • Carrier Proteins / genetics*
  • Child
  • Child, Preschool
  • Dystonia / ethnology
  • Dystonia / genetics*
  • Ethics, Medical
  • Female
  • Genetic Testing / methods*
  • Genetic Testing / psychology
  • Heterozygote
  • Humans
  • Infant
  • Jews
  • Male
  • Molecular Chaperones*
  • Pedigree
  • Polymerase Chain Reaction / methods
  • Prenatal Diagnosis
  • Sequence Deletion
  • Trinucleotide Repeats / genetics


  • Carrier Proteins
  • Molecular Chaperones
  • TOR1A protein, human