Torsion dystonia is an autosomal dominant
movement disorder characterized by involuntary, repetitive muscle contractions and twisted postures. The most severe early onset form of
dystonia has been linked to mutations in the human
DYT1 (TOR1A) gene encoding a
protein termed torsinA. Moreover,
dystonia and
Parkinson disease share the common feature of reduced
dopamine neurotransmission in the striatum, so we assumed that mutations in the
DYT1 gene might have the same role in cases of early onset
primary torsion dystonia (EOPTD) and early onset
Parkinson disease (EOPD) that present
dystonia. In this present study, 17 patients with EOPTD, 221 patients with EOPD and 164 control subjects were screened for mutations of the
DYT1 gene by denaturing high performance liquid chromatography (DHPLC), polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis and
DNA sequencing. Our results showed that the GAG deletion was identified in 7 EOPTD patients, which results in Glu302del of
DYT1 gene. No mutations were found in EOPD patients and control subjects. By carefully reviewing the available literature on studies of sporadic, non-Ashkenazi Jewish populations, the results showed that the prevalence rate of
DYT1 mutation was not significantly different (p=0.267) between European (27.3%) and Asian (22.2%) patients with early onset
primary torsion dystonia.