The Role of SNCA Rep1 Microsatellite in Parkinson’s Disease Progression

α-synuclein is a constituent of Lewy bodies and mutations of its gene cause familial PD. A previous study showed that a variant of α-synuclein gene (SNCA), namely the 263bp allele of Rep1 was associated to faster motor progression in PD. On the contrary, a recent report failed to detect a detrimental effect of Rep1 263 on both motor and cognitive outcomes in PD. Aim of this study was to evaluate the influence of the Rep1 variants on disease progression in Parkinson’s Disease (PD) patients. We recruited and genotyped for SNCA-Rep1 426 PD patients with age at onset ≥40 years and disease duration ≥4 years. We then analyzed frequency and time of occurrence of wearing-off, dyskinesia, freezing of gait, visual hallucinations and dementia. SNCA Rep1 263 carriers showed increased risk of both dementia (HR=3.03) and visual hallucinations (HR=2.69) compared to 263 non-carriers. In conclusion, SNCA Rep 1 263 allele is associated to a worst cognitive outcome in PD.