Lack of Association Between MIR155 Gene Variant rs767649 and Risk for Parkinson's Disease

An important role of neuroinflammation in the pathogenesis of Parkinson's disease (PD) has been proposed. Since some microRNAs (miRNAs), and miR-155 in particular, are involved in neuroinflammatory processes, a previous study reported an association between one of the most common single nucleotide variants (SNVs), rs767649, in the MIR155 gene, and risk for PD. The aim of the current study was to replicate this finding in a larger Spanish population case-control series. We analyzed genotype and allele frequencies of the MIR155 rs767649 SNV in a Spanish Caucasian cohort consisting of 459 PD patients and 460 age- and sex-matched healthy controls, using a TaqMan allelic discrimination assay specifically designed for rs767649. The genotype frequencies of the MIR155 rs767649, under codominant, dominant, recessive, and overdominant inheritance models, as well as allelic frequencies, showed no significant differences between PD patients and healthy controls. Likewise, the age at PD onset did not differ among the three MIR-155 rs767649 genotypes. These data did not identify a statistically significant association between MIR155 rs767649 variants and PD risk. However, the low frequency of the variant allele resulted in limited statistical power, and modest genetic effects cannot be excluded.