Polymorphism of neurodegeneration-related genes associated with Parkinson's disease risk

Neurodegenerative genes are critical in neuronal loss in Parkinson's disease (PD). We performed a systematic meta-analysis including all the studies published on PD risk related to genes encoding enzymes vital for dopamine metabolism and neuron survival.

We included neurodegeneration-related genes which were divided into four groups according to their functions: main enzymes in dopamine metabolism, receptors and transporters for dopamine or other metabolites, neuroprotective factors for dopaminergic neurons, and genes associated with dopaminergic neurons survival reported in other neurological diseases. We collected original articles from PubMed, Embase, and Web of Science databases. Revman 5.3 software was used to analyze data. The allele model (AM) was used to test the effect size of the effect allele between the case group and the control group and secondary analysis using the dominant model (DM) and recessive model (RM) to analyze the contributions from heterozygote and homozygote to the allele risk. Odds ratio (OR) and 95% confidence interval (CI) were used to present the pooled results.

We included 31 variants in 20 genes for the final pooled analysis. Consequently, SLC6A4/5-HTT HTTLPR, BDNF rs56164415, FGF20 rs1721100, PARK16 rs823128, rs823156, rs947211, APOE e2, A2M rs669, RIT2 rs12456492, MAPT intron 9 H1H2, and STH rs62063857 variants were statistically associated with PD risk while researched variants in COMT, DBH, MAO, DAT/SLC6A3, DRD2, GRIN2B, GSK3β, ATP13A2, LINGO1, PICALM, and GRN were not related to PD risk.

Several variants from neurodegeneration-related genes are associated with PD risk, which may help deepen the understanding of PD pathogenesis and improve clinical treatment strategies.