SNCA and Parkinson disease: CpG islands arelocated in the promoter region and intron 1 of the SNCA gene.Given that exon 1 of the alpha-synuclein gene is non-transcribed, andtranscription begins with exon 2, located immediately after intron 1, it wassuggested that the methylation level of these regions may affect transcription,the alpha-synuclein expression level and, possibly, the risk of developing thesporadic form of PD [24].