Genetic variants in sporadic Parkinson's disease: East vs West.

A number of gene variants or single nucleotide polymorphisms (SNPs) have been shown to modulate the risk of Parkinson's disease (PD). These variants are identified from genetic association studies of familial PD and candidate genes, and from genome wide association studies (GWAS). These include REP1 dinucleotide repeat polymorphism within the promoter region of the SNCA gene, and SNPs within the vicinity of SNCA and LRRK2 genes. A number of exonic variants of LRRK2 (G2385R, R1628P, S1647T, M1646T, A419V, R1398H, N551K, Y2189C) have been shown to influence PD risk in various ethnic populations. Numerous GWAS linked loci including BST1 (bone marrow stromal cell antigen 1), PARK16 (parkinson disease 16 susceptibility), GAK (cyclin G associated kinase), and HLA (human leukocyte antigen) have also been identified. The genetic variants have differential effect on PD risk in Eastern and Western populations. Knowing the basis behind ethnic-specific variances would further our understanding of the pathophysiologic mechanisms and help planning of genetic testing programmes.