Brain-derived neurotrophic factor and risk for primary adult-onset cranial-cervical dystonia

Background and purpose: Adult-onset dystonia may be related, amongst other factors, to abnormal neuronal plasticity in cortical and subcortical structures. Brain-derived neurotrophic factor is a major modulator of synaptic efficiency and neuronal plasticity. Recent works documented that a single nucleotide polymorphism (SNP) of the BDNF gene, the Val66Met SNP, modulates short-term plastic changes within motor cortical circuits. In this study we aimed at exploring the effect of this SNP upon the risk of developing common forms of primary adult-onset dystonia. Methods: We explored the influence of the Val66Met SNP of the BDNF gene on the risk of cranial and cervical dystonia in a cohort of 156 Italian patients and 170 age- and gender-matched healthy control subjects drawn from the same population. Results: The presence of the rare Met allele was not significantly associated with the diagnosis of dystonia (age- and gender-adjusted odds ratios of 1.22, P = 0.38). The study had a > 90% power to detect a 50% change in the risk of developing cranial-cervical dystonia associated with the presence of the Met allele. Moreover, there was no relationship between Val66Met SNP and age at dystonia onset or type of dystonia. Conclusion: Our data do not support the common variant Val66Met of the BDNF gene as an etiologic factor shared by the various forms of primary adult-onset dystonia.