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.