Dopaminergic pathway is the most disrupted pathway in the pathogenesis of Parkinson's disease. Several studies reported associations of dopaminergic genes with the occurrence of adverse events of dopaminergic treatment. However, none of these studies adopted a pathway based approach. The aim of this study was to comprehensively evaluate the influence of selected single nucleotide polymorphisms of key dopaminergic pathway genes on the occurrence of motor and non-motor adverse events of dopaminergic treatment in Parkinson's disease. In total, 231 Parkinson's disease patients were enrolled. Demographic and clinical data were collected. Genotyping was performed for 16 single nucleotide polymorphisms from key dopaminergic pathway genes. Logistic and Cox regression analyses were used for evaluation. Results were adjusted for significant clinical data. We observed that carriers of at least one COMT rs165815 C allele had lower odds for developing visual hallucinations (OR = 0.34; 95% CI = 0.16–0.72; p = 0.004), while carriers of at least one DRD3 rs6280 C allele and CC homozygotes had higher odds for this adverse event (OR = 1.88; 95% CI = 1.00–3.54; p = 0.049 and OR = 3.31; 95% CI = 1.37–8.03; p = 0.008, respectively). Carriers of at least one DDC rs921451 C allele and CT heterozygotes had higher odds for orthostatic hypotension (OR = 1.86; 95% CI = 1.07–3.23; p = 0.028 and OR = 2.30; 95% CI = 1.26–4.20; p = 0.007, respectively). Heterozygotes for DDC rs3837091 and SLC22A1 rs628031 AA carriers also had higher odds for orthostatic hypotension (OR = 1.94; 95% CI = 1.07–3.51; p = 0.028 and OR = 2.57; 95% CI = 1.11–5.95; p = 0.028, respectively). Carriers of the SLC22A1 rs628031 AA genotype had higher odds for peripheral edema and impulse control disorders (OR = 4.00; 95% CI = 1.62–9.88; p = 0.003 and OR = 3.16; 95% CI = 1.03–9.72; p = 0.045, respectively). Finally, heterozygotes for SLC22A1 rs628031 and carriers of at least one SLC22A1 rs628031 A allele had lower odds for dyskinesia (OR = 0.48; 95% CI = 0.24–0.98, p = 0.043 and OR = 0.48; 95% CI = 0.25–0.92; p = 0.027, respectively). Gene-gene interactions, more specifically DDC-COMT, SLC18A2-SV2C, and SLC18A2-SLC6A3, also significantly influenced the occurrence of some adverse events. Additionally, haplotypes of COMT and SLC6A3 were associated with the occurrence of visual hallucinations (AT vs. GC: OR = 0.34; 95% CI = 0.16–0.72; p = 0.005) and orthostatic hypotension (ATG vs. ACG: OR = 2.48; 95% CI: 1.01–6.07; p = 0.047), respectively. Pathway based approach allowed us to identify new potential candidates for predictive biomarkers of adverse events of dopaminergic treatment in Parkinson's disease, which could contribute to treatment personalization.

Background Inflammation and oxidative stress are recognized as important contributors to Parkinson’s disease pathogenesis. As such, genetic variability in these pathways could have a role in susceptibility for the disease as well as in the treatment outcome. Dopaminergic treatment is effective in management of motor symptoms, but poses a risk for motor and non-motor adverse events. Our aim was to evaluate the impact of selected single-nucleotide polymorphisms in genes involved in inflammation and oxidative stress on Parkinson’s disease susceptibility and the occurrence of adverse events of dopaminergic treatment. Methods In total, 224 patients were enrolled, and their demographic and clinical data on the disease course were collected. Furthermore, a control group of 146 healthy Slovenian blood donors were included for Parkinson’s disease’ risk evaluation. Peripheral blood was obtained for DNA isolation. Genotyping was performed for NLRP3 rs35829419, CARD8 rs2043211, IL1β rs16944, IL1β rs1143623, IL6 rs1800795, CAT rs1001179, CAT rs10836235, SOD2 rs4880, NOS1 rs2293054, NOS1 rs2682826, TNF-α rs1800629, and GPX1 rs1050450. Logistic regression was used for analysis of possible associations. Results We observed a nominally significant association of the IL1β rs1143623 C allele with the risk for Parkinson’s disease ( OR = 0.59; 95%CI = 0.38–0.92, p = 0.021). CAT rs1001179 A allele was significantly associated with peripheral edema (OR = 0.32; 95%CI = 0.15–0.68; p = 0.003). Other associations observed were only nominally significant after adjustments: NOS1 rs2682826 A allele and excessive daytime sleepiness and sleep attacks (OR = 1.75; 95%CI = 1.00–3.06, p = 0.048), SOD2 rs4880 T allele and nausea/vomiting (OR = 0.49, 95%CI = 0.25–0.94; p = 0.031), IL1β rs1143623 C allele and orthostatic hypotension (OR = 0.57, 95%CI = 0.32–1.00, p = 0.050), and NOS1 rs2682826 A allele and impulse control disorders (OR = 2.59; 95%CI = 1.09–6.19; p = 0.032). We did not find any associations between selected polymorphisms and motor adverse events. Conclusions Apart from some nominally significant associations, one significant association between CAT genetic variability and peripheral edema was observed as well. Therefore, the results of our stud...

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This is the first report on the epidemiology and prevalence of HD in Slovenia. The prevalence of HD is comparable with previously reported data in other European countries. In Slovenia, a higher proportion of individuals at risk for HD decide on predictive mutational testing as compared with the estimated numbers for Europe, United States, Canada and Australia.