CHM and Parkinson disease: Maraganore et al. led the International Consortium of Genetic Epidemiology of PD (GEO-PD) to validate the association of αSyn promoter region and the SNP (single nucleotide polymorphism) dinucleotide repeat sequence (REP1), in which particularly longer alleles with more than 263 base-pair were associated with increased risk of sporadic PD [26].