Val158Met polymorphism of COMT gene and Parkinson’s disease risk in Asians

Does COMT Play a Role in Parkinson's Disease Susceptibility Across Diverse Ancestral Populations?

Background

The catechol-O-methyltransferase (COMT) gene is involved in brain catecholamine metabolism, but its association with Parkinson's disease (PD) risk remains unclear.

Objective

To investigate the relationship between COMT genetic variants and PD risk across diverse ancestries.

Methods

We analyzed COMT variants in 2,251 PD patients and 2,835 controls of European descent using whole-genome sequencing from the Accelerating Medicines Partnership-Parkinson Disease (AMP-PD), along with 20,427 PD patients and 11,837 controls from 10 ancestries using genotyping data from the Global Parkinson's Genetics Program (GP2).

Results

Utilizing the largest case-control datasets to date, no significant enrichment of COMT risk alleles in PD patients was observed across any ancestry group after correcting for multiple testing. Among Europeans, no correlations with cognitive decline, motor function, motor complications, or time to LID onset were observed.

Conclusions

These findings emphasize the need for larger, diverse cohorts to confirm the role of COMT in PD development and progression.

Addressing the Ethnicity Gap in Catechol O-Methyl Transferase Inhibitor Trials in Parkinson's Disease: A Review of Available Global Data

Catechol-O-methyltransferase inhibitors (COMT-Is) have significantly improved the quality of life and symptom management for those at advanced stages of Parkinson's Disease (PD). Given that PD is one of the fastest-growing neurodegenerative diseases worldwide, there is a need to establish a clear framework for the systematic distribution of COMT-Is, considering inter-individual and intra-individual variations in patient response. One major barrier to this is the underrepresentation of ethnic minority participants in clinical trials investigating COMT-Is. To investigate this, we performed a narrative review. We searched PubMed for clinical trials investigating COMT-Is in patients with PD and examined the ethnic diversity of cohorts. A total of 63 articles were identified, with 34 trials found to match our inclusion criteria. Among the 34 trials meeting our inclusion criteria, only 8 reported participants' ethnic backgrounds. Our findings reveal a consistent underrepresentation of ethnic minority groups in trials investigating COMT-Is in PD cohorts-a trend that reflects broader concerns across clinical research. In this review, we explore potential reasons for the underrepresentation of ethnic minorities in clinical trials and propose strategies to address this issue.

Association of Catechol-O-Methyltransferase Gene rs4680 Polymorphism and Levodopa Induced Dyskinesia in Parkinson's Disease: A Meta-Analysis and Systematic Review

INTRODUCTION

Long-term levodopa therapy for Parkinson's disease (PD) can cause levodopa induced dyskinesia (LID). Genetic predisposition has a significant role to play in inter-individual heterogeneity in the clinical manifestation of LID. Despite accumulating evidence for the role of COMT gene polymorphism (rs4680) as a genetic basis for LID, to date results have been inconsistent. Early assessment of the Catechol-O-Methyltransferase (COMT) genotype might be helpful to stratify PD patients concerning their individual risk for LID.

METHOD

In this meta-analysis, we have used 9 studies, which were selected through online databases. Statistical analysis was performed using R (v-3.6) software. 5 genetic models have been used in the present study: Allele model (A vs. G), Dominant model (AA+AG vs. GG), Homozygote model (AA vs. GG), Co-dominant/heterozygote model (AG vs. GG), and Recessive model (AA vs. AG + GG).

RESULTS

The results indicated a significant association between COMT rs4680 (Val158Met) polymorphism and LID risk. The genotype AA of COMT rs4680 is a risk factor for LID in PD patients under the recessive model (AA vs GG+AG) in the random-effect model. Analysis based on ethnicity showed that COMT rs4680 SNP allele A is a risk factor for LID development in Asian PD patients, while GG genotype is a risk factor for LID development in non-Asian PD patients using different genetic models.

CONCLUSION

The results of the present meta-analysis support that the COMT Val158Met polymorphism is a risk factor for the development of LID in PD patients having ethnic variations.

Genetic variations in catechol-O-methyltransferase gene are associated with levodopa response variability in Chinese patients with Parkinson's disease

Catechol-O-methyltransferase (COMT) is one of the main enzymes in dopamine metabolism and is reported to be associated with susceptibility to Parkinson’s disease (PD) and pharmacotherapy. However, researchers mostly focus on the most common polymorphism, rs4680. In this case-control study, we investigated the association of SNPs other than rs4680 with the levodopa (L-dopa) response and other clinical features in Chinese PD patients. Eleven single nucleotide polymorphisms (SNPs) in the COMT gene were genotyped, and clinical data were collected. Patients with the TT genotype of rs165728 or rs174699 had larger daily levodopa equivalent doses (LEDs) than the patients with CC and CT genotypes under the dominant model (p = 0.01421 for rs165728 and p = 0.02302 for rs174699). Under the dominant model, the patients with GG at rs4680 G > A had a lower occurrence of dyskinesia than those with AA and AG (p = 0.0196). Patients with CC at rs4633 had a lower occurrence of dyskinesia than those with TT and TC (p = 0.0429) under the dominant model. The frequencies of the rs174675 T and rs933271 C alleles were higher in PD patients than in the controls (p < 0.05). Our primary results showed the possible association of SNPs other than the most common functional rs4680 in COMT with interindividual variance in the L-dopa daily dose and susceptibility to dyskinesia in Chinese patients, although this was an exploratory study based on a small sample size. Larger and more randomized samples are necessary for further investigation.

Gene polymorphisms and motor levodopa-induced complications in Parkinson's disease

OBJECTIVE

The aim of the study was to evaluate the association of individual and combined single-nucleotide polymorphisms in brain-derived neurotrophic factor (BDNF), dopamine transporter (DAT), and catechol-O-methyltransferase (COMT) genes with the occurrence of motor levodopa-induced complications (MLIC) in Parkinson's disease (PD).

MATERIALS AND METHODS

We studied 76 patients with PD (MLIC occurred in 56.6%) and 60 controls. Allelic discrimination of rs6265 BDNF (Val66Met), rs397595 DAT (SLC6A3), and rs4680 COMT (Val158Met) genes were genotyped. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using multinominal logistic regression. Orthogonal partial least squares (OPLS) analysis and OPLS discriminant analysis (OPLS-DA) were used to analyze qualitative genetic data.

RESULTS

The risk of PD in subjects with the AG BDNF genotype was increased sixfold (OR = 6.12, 95% CI = 2.88-13.02, p < .0001), and AG BDNF and AG DAT genotypes were correlated with PD in OPLS-DA (VIP > 1). There were no differences in distributions of BDNF, DAT and COMT genotypes between PD groups with and without MLIC, while OPLS model showed that genotype combination of AG BDNF, AG DAT, and GG COMT was correlated with MLIC and genotypes combination of GG BDNF, AA DAT, and AA COMT with lack of MLIC in PD patients (VIP > 1).

CONCLUSIONS

Our results confirmed the association of rs6265 BDNF (Val66Met) with the risk of PD and suggest a synergic effect of rs6265 BDNF (Val66Met), rs397595 DAT (SLC6A3), and rs4680 COMT (Val158Met) polymorphisms on the occurrence of MLIC.

NAT2 Gene Polymorphisms in Turkish Patients with Psoriasis Vulgaris

Psoriasis is a common, chronic, and autoimmune skin disease. Factors that play a role in etiopathogenesis of psoriasis include internal factors such as genetic susceptibility and immunological factors and external factors such as stress, infection, trauma, drug, and environmental compounds. N-acetyltransferase 2 (NAT2) is a xenobiotic enzyme that is involved in the metabolism of drugs, environmental toxins, and carcinogens. In this study, we aimed to demonstrate whether the variations in the NAT2 gene lead to a predisposition to psoriasis by affecting the enzyme's ability to metabolize drugs and environmental components or not. Three polymorphisms (rs1799929, rs1799930, and rs1799931) in NAT2 gene were genotyped and compared by real-time PCR method in 260 psoriasis vulgaris patients and 200 healthy controls. There was no difference in the genotype distributions and allele frequencies of polymorphisms between psoriasis vulgaris patients and controls. When the effects of polymorphisms on the clinical features of the disease, such as onset age and severity, are assessed, it has been found that rs1799930 and rs1799929 are, respectively, associated with early onset age and severity of the disease. In conclusion, rs1799929, rs1799930, and rs1799931 polymorphisms of the NAT-2 gene do not appear to be a risk factor for the development of psoriasis. Conversely, they may have an effect on either more severe or early onset cases of the disease.

Roles of functional catechol-O-methyltransferase genotypes in Chinese patients with Parkinson's disease

Background

Recent studies have found that the functional catechol-O-methyltransferase (COMT) gene may be associated with the susceptibility to and pharmacotherapy of Parkinson’s disease (PD). In this case–control study, we investigated the most common functional COMT gene haplotypes that had been shown to influence COMT enzymatic activity and the association of the single and combined COMT haplotypes with clinical symptoms and pharmacotherapy in Chinese patients with PD.

Methods

One hundred forty-three patients with idiopathic PD and 157 healthy individuals were enrolled in this study. Four single nucleotide polymorphisms (SNPs) in the COMT gene (formed by SNPs) were genotyped in each participant: rs6269 A > G; rs4633 C > T; rs4818 C > G; and rs4680 G > A.

Results

The frequencies of rs4633 T carriers, rs4680 A carriers and the two linked rs4633-rs4680 T/A carriers were significantly higher in the early onset PD group than in the healthy controls (all P < 0.05). Homozygosity for rs4633 (TT), rs4680 (AA) and of the two linked rs4633-rs4680 (TT/AA) was significantly more frequent in patients who exhibited the “wearing-off” phenomenon, longer disease duration, higher levodopa equivalent doses (LED) and higher Unified Parkinson’s Disease Rating Scale (UPDRS) scores (P < 0.05). No significant differences were observed in the clinical features of patients who carried individual rs6269 and rs4818, the two linked rs6269-rs4818 and the four combined COMT SNPs.

Conclusions

The results showed a possible association of combined functional COMT SNPs with PD risk, disease duration, the “wearing-off” phenomenon, daily LEDs and higher UPDRS scores, which may be useful in instituting individualized therapy for patients with PD.

Electronic supplementary material

The online version of this article (doi:10.1186/s40035-017-0081-9) contains supplementary material, which is available to authorized users.