Interleukin-18 promoter polymorphisms and idiopathic Parkinson disease: an Egyptian study

Genetic Testing in Parkinson's Disease

Genetic testing for persons with Parkinson's disease is becoming increasingly common. Significant gains have been made regarding genetic testing methods, and testing is becoming more readily available in clinical, research, and direct-to-consumer settings. Although the potential utility of clinical testing is expanding, there are currently no proven gene-targeted therapies, but clinical trials are underway. Furthermore, genetic testing practices vary widely, as do knowledge and attitudes of relevant stakeholders. The specter of testing mandates financial, ethical, and physician engagement, and there is a need for guidelines to help navigate the myriad of challenges. However, to develop guidelines, gaps and controversies need to be clearly identified and analyzed. To this end, we first reviewed recent literature and subsequently identified gaps and controversies, some of which were partially addressed in the literature, but many of which are not well delineated or researched. Key gaps and controversies include: (1) Is genetic testing appropriate in symptomatic and asymptomatic individuals without medical actionability? (2) How, if at all, should testing vary based on ethnicity? (3) What are the long-term outcomes of consumer- and research-based genetic testing in presymptomatic PD? (4) What resources are needed for clinical genetic testing, and how is this impacted by models of care and cost-benefit considerations? Addressing these issues will help facilitate the development of consensus and guidelines regarding the approach and access to genetic testing and counseling. This is also needed to guide a multidisciplinary approach that accounts for cultural, geographic, and socioeconomic factors in developing testing guidelines. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Functional variant rs17525453 within RAB35 gene promoter is possibly associated with increased risk of Parkinson's disease in Taiwanese population

Our previous study suggests that upregulated RAB35 is implicated in etiology of Parkinson's disease (PD). We hypothesized that upregulated RAB35 results from single nucleotide polymorphisms (SNPs) in RAB35 gene promoter. We identified SNPs within RAB35 gene promoter by analyzing DNA samples of discovery cohort and validation cohort. SNP rs17525453 within RAB35 gene promoter (T>C at position of -66) was significantly associated with idiopathic PD patients. Compared to normal controls, sporadic PD patients had higher C allele frequency. CC and CT genotype significantly increased risk of PD compared with TT genotype. SNP rs17525453 within RAB35 gene promoter leads to formation of transcription factor TFII-I binding site. Results of EMSA and supershift assay indicated that TFII-I binds to rs17525453 sequence of RAB35 gene promoter. Luciferase reporter assays showed that rs17525453 variant of RAB35 gene promoter possesses an augmented transcriptional activity. Our results suggest that functional variant rs17525453 within RAB35 gene promoter is likely to enhance transcriptional activity and upregulate RAB35 protein, which could lead to increased risk of PD in Taiwanese population.

Inflammation-related gene polymorphisms associated with Parkinson’s disease: an updated meta-analysis

Background

Strong evidence supports the involvement of inflammation processes in the development and progression of Parkinson’s disease (PD), where increasingly correlations have been identified between genetic variations in inflammation-related genes and PD. However, data varies between studies. Therefore, we conducted a meta-analysis to clarify associations between inflammation-related gene polymorphisms and PD risk.

Methods

All studies were identified through online databases. Pooled and stratified groups based on racial descent were assembled to evaluate associations between polymorphisms and PD.

Results

The pooled results showed that protective effects for PD were observed for (1) IL-1α -889 C/T in Asian populations (T vs. C, OR = 0.831, P = 0.031; TT + CT vs. CC, OR = 0.827, P = 0.049); (2) IL-6 -176 G/C in Caucasian populations (CC + GC vs. GG, OR = 0.656, P = 0.000; GC vs. GG, OR = 0.673, P = 0.000); (3) IL-8 -251 A/T (T vs. A, OR = 0.812, P = 0.041; TT vs. AT + AA, OR = 0.663, P = 0.012), particularly in Caucasian populations (TT vs. AT + AA, OR = 0.639, P = 0.010); (4) IL-10 -819 T/C (C vs. T, OR = 0.742, P = 0.034); (5) IL-18 -607 C/A (AA + CA vs. CC, OR = 0.597, P = 0.015; CA vs. CC, OR = 0.534, P = 0.005), and (6) CCR2 +190 G/A (AA vs. GA + GG, OR = 0.552, P = 0.018; AA vs. GG; OR = 0.554; 95% CI 0.336–0.914, P = 0.005). An increased risk of PD was associated with IL-10 -1082 G/A in Asian populations (A vs. G, OR = 1.731, P = 0.000; AA + GA vs. GG, OR = 1.910, P = 0.000). No significant associations with PD were observed for polymorphisms in IL-1β -511 C/T, IL-10 -592 C/A, IL-18 -137 G/C, TNFα -863 C/A, TNFα -857 C/T, TNFα -308 G/A, IFNΥ +874 T/A, and MCP1/CCL2 +2518 A/G.

Conclusions

We suggest that IL-1α -889, IL-6 -176, IL-8 -251, IL-10 -1082, IL-10 -819, IL-18 -607, and CCR2 +190 polymorphisms may be associated with PD risk; however, further studies must verify these conclusions.