SNCA and Parkinson disease: 6207 CpGs in PD showing hemispheric asymmetry in DNA methylation (3894 CpGs showed a greater hemispheric asymmetry in PD compared to controls). These targeted 4691 genes, including PD risk genes.More DNA methylation and transcriptomic differences seen in hemisphere matched to symptom-dominant sideAbove findings validated in replication cohort37 PD risk genes showing more hemispheric asymmetry in PD and/or greater differences in symptom-dominant hemisphere, including SNCA, ITPKB, SATB1, ANK2 and CAMK2D