Is TOR1A a risk factor in adult-onset primary torsion dystonia?

BACKGROUND: Studies of genetic association between TOR1A and adult-onset primary torsion dystonia have contradictory results.METHODS: The authors genotyped TOR1A single nucleotide polymorphisms rs1801968, rs2296793, rs1182 and rs3842225 in a cohort of clinically well characterized cervical dystonia patients (n=367) and constructed haplotypes. The authors systematically reviewed the published case-control TOR1A association studies in adult-onset primary torsion dystonia.RESULTS: In this Dutch cervical dystonia cohort, no significant association was found with TOR1A variants. In the meta-analysis (eight studies, 1332 adult-onset primary dystonia patients) no variant reached overall significance. However, in a selection of familial cases the functional variant p.Asp216His (rs1801968) was associated with increased dystonia risk (odds ratio 1.43; 95%CI 1.01-2.02).CONCLUSIONS: Meta-analysis does not show association with common variants in TOR1A in adult-onset primary dystonia, except for the functional variant rs1801968 in familial focal dystonia cases.