Low Levels ofLRRK2Gene Expression are Associated withLRRK2SNPs and Contribute to Parkinson's Disease Progression

Abstract

Parkinson's disease (PD) is a chronic neurodegenerative disease that has relatively slow progression with motor symptoms.Leucine-rich repeat kinase 2 (LRRK2)gene mutations and polymorphisms are suggested to be associated with PD. In this study, we aimed to investigate the association between single-nucleotide polymorphisms (SNPs) of theLRRK2gene, namely, rs11176013, rs10878371, rs11835105, and PD. Genotypes of 132 PD cases and 133 healthy individuals were determined by qRT-PCR. Haplotype analysis was performed. Additionally,LRRK2mRNA expression levels were determined in 83 PD cases and 55 healthy subjects. The relationship betweenLRRK2mRNA levels, the target SNPs, and clinical data was also investigated. Our results indicated that the "GG" genotype and "G" allele of rs11176013 and the "CC" genotype and "C" allele of rs10878371 were more frequent in cases. The "GCG" haplotype was significantly more frequent in cases.LRRK2mRNA expression levels in patients were significantly lower than those in healthy individuals. The patients with the "CC" genotype for rs10878371 and the "GG" genotype for rs11176013 had decreasedLRRK2mRNA levels. We found that the rs11176013 "GG" genotype and the rs10878371 "CC" genotype were less frequently seen in cases with akinetic rigid or combined akinetic rigid and tremor-dominant initial symptoms. Consequently, our results demonstrate that the rs11176013 and rs10878371 polymorphisms are associated with PD in a Turkish cohort, and moreover, these results suggest that these polymorphisms may affect the expression of theLRRK2gene and disease progression and thus play a role in the pathogenesis of PD.