Gabriela Klodowska-Duda

The effect of monoamine oxidase B (MAOB) and catechol-O-methyltransferase (COMT) polymorphisms on levodopa therapy in patients with sporadic Parkinson's disease

Objectives –  The etiology of sporadic idiopathic Parkinsons disease (PD) is considered multifactorial with both genetic and environmental factors modifying the disease expression. Recent studies suggest that polymorphism in monoamine oxidase B (MAOB) and catechol‐O‐methyltransferase (COMT) might influence the risk and treatment of PD. The aim of the study was to evaluate the effect of MAOB and COMT genetic polymorphism on effective daily dose of levodopa applied during the first 5 years of treatment, and to find out if a relationship exists between MAOB and COMT haplotypes and motor disturbances onset in PD patients treated with levodopa preparations.

Interleukin-10 (IL10) and tumor necrosis factor α (TNF) gene polymorphisms in Parkinson's disease patients

Recent studies revealed that inflammatory processes might play an important role in the pathogenesis of Parkinsons disease (PD). We hypothesized that genetically determined differences in the immune response, especially in anti- and pro-inflammatory cytokines production might influence the risk for the development and/or onset of sporadic PD. In the present study, we investigated the genetic polymorphisms of the IL10 (-1082 and -519) and TNF (-308) genes in relation to the risk of PD, and their associations with age of PD onset in a group of 316 patients, divided into two subgroups: Group 1: patients with early onset PD (EOPD), i.e. before 50 years of age (102 patients), and group 2: patients with onset of PD after 50 years of age comprising 214 subjects. Control samples were obtained from 300 randomly selected healthy individuals from the same geographical region with no signs of Parkinsonism as evaluated by a neurologist. PCR-RFLP methods were used for genotyping. No statistically significant differences between PD patients and controls were found in the frequency of a single locus of IL10 promoter. We found TNF -308A allele significantly more frequent in EOPD patients compared to the controls (p=0.007). The overrepresentation of the A allele was reflected by a significant increase in AA homozygous individuals in EOPD patients compared to the controls (p=0.0021). The results from our study revealed that the TNF -308AA genotype might increase the risk of early onset of PD.

CARD15 variants in patients with sporadic Parkinson's disease

Recent reports have proven the importance of genetic factors and inflammation in the pathogenesis of sporadic Parkinsons disease (PD). In the current study, the frequency of CARD15/NOD2 gene variants (R702W, G908R, L1007fs), previously associated with Crohns disease--a common inflammatory bowel disease, have been examined in a group of 308 sporadic PD patients and 220 healthy controls. Significantly higher frequency of total CARD15 variant alleles in PD patients (13.0%) compared to the controls (8.0%, p<0.02) was observed. 24.0% of PD patients carried at least one CARD15 variant allele compared to 15.5% of healthy controls (p<0.02, OR=1.73). The results of the study suggest, that the polymorphism in CARD15/NOD2 gene may be a risk factor for sporadic PD development, and support the concept of inflammatory pathogenesis of PD.

Analysis of LRRK2 G2019S and I2020T mutations in Parkinson's disease

Mutations in the leucine-rich repeat kinase 2 (LRRK2), encoding dardarin protein, have been demonstrated to be linked to autosomal dominant Parkinsons disease (PD). In the present study the entire exon 41 of LRRK2 gene was evaluated in a series of 174 PD patients recruited from Polish population, aged at the time of diagnosis 54.0 ± 39.1 years, 21 of them had positive family history of PD with mean onset of the disease of 51.9 ± 11.7 years as well as in 190 healthy controls aged 73.7 ± 6.0 years. The mutations were evaluated by direct sequencing for mutations in exon 41 of LRRK2 gene. In the studied patients no known mutations in exon 41 of LRRK2 gene, including G2019S and I2020T were found, both in PD patients as well as in the controls. It can be concluded that the G2019S and I2020T mutations in exon 41 of LRRK2 gene are rare causes of Parkinson disease in a Polish population.

Mitochondrial transcription factor A variants and the risk of Parkinson's disease.

The mitochondrial transcription factor A (TFAM) has been recently shown to decrease reactive oxygen species (ROS) generation. It is also known that mitochondrial DNA (mtDNA) haplogroups might confer different coupling properties, resulting in different ROS levels. We hypothesized that potentially functional TFAM variants could influence PD risk depending on haplogroup background. To test this we assessed the role of six TFAM variants on PD risk in 326 PD patients and 316 controls, and correlated it with mtDNA haplogroup clusters (HV, JTKU and a putative functionally different group U4U5a1KJ1cJ2, connected previously with partial uncoupling of oxidative phosphorylation). Both genotype and haplotype analysis showed that intronic variant rs2306604 modifies PD risk. Multivariate logistic regression analysis confirmed that rs2306604 G/G genotype is an independent risk factor for PD (OR 1.789, 95% CI 1.162-2.755, p=0.008). There was a borderline interaction between G/G genotype and HV haplogroup (p=0.075). Haplotype analysis showed that all three haplotypes containing rs2306604 allele A occurred at higher frequencies in controls, but only one of them reached statistical significance (chi(2) 4.523, p=0.0334). Conversely, four of five haplotypes containing allele G had higher frequencies in PD group, with no statistical significance.

Polymorphism in semaphorin 5A (Sema5A) gene is not a marker of Parkinson's disease risk

A SNP rs7702187 within the semaphorin 5A gene (Sema5A) has been recently associated with sporadic Parkinsons disease (PD) risk in American Caucasians. In the present study frequencies of rs7702187 was determined in two independent populations involving 427 sporadic PD patients (235 Polish Caucasians and 192 Asians from Singapore) and 412 healthy controls (220 Caucasians and 192 Asians), with the use of PCR-RFLP assay. The frequencies of the minor allele were found to be very similar in PD patients and healthy controls in both populations studied: 0.147 versus 0.143 in Caucasian, and 0.224 versus 0.221 in Asian, respectively. Our research does not confirm the previous observation, as no relationship was found between polymorphism within Sema5A gene and the risk of PD. It can be concluded that rs7702187 SNP in Sema5a gene is not a marker of PD risk in the studied populations.

PARK2 variability in Polish Parkinson’s disease patients - interaction with mitochondrial haplogroups

AIMS AND OBJECTIVES A new pathomechanism of Parkinsons disease (PD) involving regulation of mitochondrial functions was recently proposed. Parkin complexed with mitochondrial transcription factor A (TFAM) binds mtDNA and promotes mitochondrial biogenesis, which is abolished by PARK2 gene mutations. We have previously shown that mitochondrial haplogroups/clusters and TFAM common variation influenced PD risk. We investigate the role of PARK2 polymorphisms on PD risk and their interactions with mitochondrial haplogroups/clusters as well as with TFAM variability. METHODS 104 early-onset PD patients (EOPD, age at onset ≤ 50 years) were screened for PARK2 coding sequence changes including gene dosage alterations. Three selected PARK2 polymorphisms (S167N, V380L, D394N) were genotyped in 326 PD patients and 315 controls using TaqMan allelic discrimination assay. RESULTS PARK2 screen revealed two heterozygous changes in two EOPD patients: exon 2 deletion and one novel synonymous variation (c.999C > A, P333P). In association study no differences in genotype/allele frequencies of S167N, V380L, D394N were found between analyzed groups. Stratification by mitochondrial clusters revealed higher frequency of V380L G/G genotype and allele G in PD patients, within HV cluster (p = 0.040; p = 0.022, respectively). Moreover, interaction between genotypes G/G V380L of PARK2 and G/G rs2306604 of TFAM, within HV cluster was significant (OR 2.05; CI 1.04-4.04; p = 0.038). CONCLUSIONS Our results indicate that co-occurrence of G/G V380L PARK2 and G/G rs2306604 TFAM on the prooxidative HV cluster background can contribute to PD risk. We confirm low PARK2 mutation frequency in Polish EOPD patients.