SNCA and Parkinson disease: Here using a much large sample size (N control subject = 144) we demonstrate for the first time the regulatory effect of Rep1 alleles in vivo in human brain structures relevant to the disease providing further direct, functional evidence for the reported genetics associations; i.e. in PD-affected brain regions the ‘protective’ genotype correlated with lower SNCA-mRNA levels compared with all the other genotypes carrying one or two PD-risk alleles (261 and 263) [18], [26]–[29].