Ассоциация полиморфных вариантов гена мозгового нейротрофического фактора (BDNF rs6265) и гена переносчика глутамата второго типа (SLC1A2 rs4354668) с течением рассеянного склероза у пациентов, проживающих в Томской области

Background: Multiple sclerosis (MS) is an autoimmune disease of the central nervous system that affects people of working age and ultimately leads to disability. This disease is of polygenic origin. The role of factors related to the pathogenesis of the disease and affecting both neuroinflammation and remyelination is studied. Aims: Our goal was to investigate the association of single nucleotide polymorphisms BDNF rs6265 and SLC1A2 rs4354668 with the risk of occurrence, clinical manifestations and the course of MS.Materials and methods: The study included 302 patients with MS, 268 healthy volunteers were enrolled in a control group. The obtained blood was used for DNA extraction by standard phenol-chloroform method. The identification of allelic variants of genes SLC1A2 (rs4354668) and BDNF (rs6265) was performed by polymerase chain reaction.Results: When comparing the frequencies of genotypes and alleles of polymorphic variants of BDNF and SLC1A2 genes between the groups of MS patients and the control group, no statistically significant differences were revealed. Comparison of genotype and allele frequencies of patients depending on sex, age of onset of the disease also did not reveal statistically significant differences. The study of the association of polymorphic variant of the gene BDNF (rs6265) with clinical manifestations of the disease revealed the association of genotype CC with oculomotor and trigeminal disorders at the onset of the disease (F=7, p=0.017). The study of the polymorphic variant rs4354668 of the glutamate transporter gene SLC1A2 revealed the association of allele G with an earlier (within 5 years from the moment of debut) transition of the disease to the stage of secondary progression, despite the therapy with DMT (χ2=5.940; p=0.010; OR 1.58; 95% CI 1.09−2.29). Homozygous genotype of TT (χ2=6.393; p=0.041; OR 0.50; 95% CI 0.28−0.88) and allele T (χ2=5.940; p=0.010; OR 0.63; 95% CI 0.44−0.92) of the polymorphism rs4354668 of the glutamate transporter gene SLC1A2 are significantly more common in the group of patients with late transition (15 years or more from the moment of debut) to the secondary progressive course.Conclusions: In our study we revealed the relationship of the studied polymorphic variants of genes with clinical signs at the onset of the disease and with the clinical manifestations of MS in patients living in the Tomsk region.Обоснование. Рассеянный склероз ― аутоиммунное заболевание нервной системы, поражающее людей трудоспособного возраста и приводящее в конечном итоге к инвалидизации. В последние годы наблюдается рост числа больных, связанный как с истинным увеличением заболеваемости, так и с качеством диагностики.Цель исследования ― оценка ассоциации однонуклеотидных полиморфных вариантов генов BDNF rs6265 и SLC1A2 rs4354668 с риском возникновения, клиническими проявлениями и течением рассеянного склероза.Методы. В исследование было включено 302 пациента с рассеянным склерозом, 268 здоровых добровольцев составили группу контроля. Пациенты находились на лечении в неврологической клинике Сибирского государственного медицинского университета. Определение аллельных вариантов генов SLC1A2 (rs4354668) и BDNF (rs6265) проводили методом полимеразной цепной реакции. Амплификацию и анализ результатов осуществляли с помощью приборов StepOnePlus и Quant Studio 5 (Applied Biosystems, США).Результаты. При сравнении частоты генотипов и аллелей полиморфных вариантов генов BDNF и SLC1A2 между группами пациентов с рассеянным склерозом и группой контроля статистически значимых различий не выявлено. Сравнение частоты генотипов и аллелей пациентов в зависимости от пола, возраста начала заболевания также статистически значимых различий не выявило. При исследовании связи полиморфного варианта гена BDNF (rs6265) с клиническими проявлениями болезни найдена ассоциация генотипа СС с глазодвигательными и тригеминальными расстройствами в дебюте заболевания (F=7; p=0,017). При исследовании полиморфного варианта rs4354668 гена глутаматного транспортера SLC1A2 выявлена ассоциация аллеля G с более ранним (в течение 5 лет от момента дебюта) переходом заболевания в стадию вторичного прогрессирования, несмотря на терапию препаратами, изменяющими течение рассеянного склероза (χ2=5,940; р=0,010; OR 1,58; 95% CI 1,09−2,29). Гомозиготный генотип ТТ (χ2=6,393; р=0,041; OR 0,50; 95% CI 0,28−0,88) и аллель Т (χ2=5,940; р=0,010; OR 0,63; 95% CI 0,44−0,92) полиморфизма rs4354668 гена глутаматного транспортера SLC1A2 статистически значимо чаще встречаются в группе пациентов с поздним переходом (через 15 и более лет от момента дебюта) во вторично-прогрессирующее течение.Заключение. В нашем исследовании выявлена связь изучаемых полиморфных вариантов генов с клиническими признаками в дебюте заболевания и с особенностью течения заболевания у пациентов, проживающих на территории Томской области

CYP2D6 and catechol-O-methyltransferase gene polymorphisms in Parkinson patients with levodopa-induced dyskinesias

Parkinson's disease (PD), a common neurodegenerative disorder caused by the loss of the dopaminergic input to the basal ganglia, is commonly treated with levodopa (L-DOPA). Use of this drug, however, is severely limited by the development of side effect. Levodopa-induced dyskinesias (LID) are involuntary muscle movements that occur as a consequence of chronic levodopa (L-DOPA) treatment. LID are a substantial barrier to effective symptomatic management of Parkinson's disease (PD), up to 45% of L-DOPA users develop LID within 5 years [1]. Clinical heterogeneity of LID suggests a significant role of endogenous factors in determining their prevalence. Some evidence suggest a relationship between LID and specific genetic changes, such as changes in the genes controlling enzymes responsible for drug and monoamine metabolism, neurotransmitter receptors and proteins involved in oxidative stress or antioxidant function [2-4]. Objective: To investigate contribution of polymorphic variants of CYP2D6 and COMT genes in the development of LID in PD patients. Methods: 212 patients with Parkinson's disease on levodopa therapy were investigated. Dyskinesias were estimated with use of Abnormal Involuntary Movement Scale (AIMS). DNA extraction and fluorogenic 5'-exonuclease TaqMan genotyping assays were conducted according to standard protocols and blind to the clinical status of the subjects. Genotyping was carried out on 2 SNPs of CYP2D6 (CYP2D6∗3, rs35742686; CYP2D6∗4, rs3892097) and 7 SNPs of COMT genes (rs4680, rs6269, rs4633, rs4818, rs769224, rs165774, rs174696). The SPSS software was used for statistical analysis. Results: Patients in our cohort demonstrated typical PD demographics, with a mean age of onset of 60.04±9.46 years, a mean disease duration of 9.79±5.57 years. Dyskinesias were reported in 57 (26.9%) patients. The distribution of genotypes of studied genes corresponded to the Hardy-Weinberg equilibrium. Association of polymorphisms in CYP2D6 gene with side effects was not revealed. We found that rs4680 polymorphism in COMT gene is significantly associated with LID (χ2 = 6.048, p = 0.049). Odds ratio for carriers of the genotype AA is 2.14 [95% CI: 1.11- 4.11], which indicates the predisposing effect of this genotype on the development of dyskinesias. Rs4680 is a functional SNP in genes encoding the catechol-O-methyltransferase enzyme, which catabolizes dopamine. A valine to methionine substitution at codon 158 of the COMT gene produces a Met variant that catabolizes dopamine up to four times slower than its Val counterpart. Conclusions: Polymorphisms in the COMT gene play significant role in the therapy response to L-DOPA as well as in various adverse effects. COMT is an extracellular enzyme which inactive variants increase the extracellular concentration of dopamine. This may increase the uptake of dopamine by indirect pathway MSN and therefore increase oxidative stress. We hypothesized that functional single nucleotide polymorphism rs4680 in COMT gene may result in a clinical phenotype contributing to an increased risk of LID. Thus, the polymorphism of gene possessing predisposing effects in development of levodopa induced dyskinesia in PD has been revealed that would allow predicting risk of development of movement disorders

Polymorphisms of DRD2, DRD3, DRD4 and HTR2C genes in levodopa-induced dyskinesias in Parkinson's disease

Levodopa-induced dyskinesias (LID) are involuntary muscle movements that occur as a consequence of chronic levodopa (L-DOPA) treatment. LID are a substantial barrier to effective symptomatic management of Parkinson's disease (PD), up to 45% of L-DOPA users develop LID within 5 years [1]. Clinical heterogeneity of LID suggests a significant role of endogenous factors in determining their prevalence. Some evidence suggest a relationship between LID and specific genetic changes, such as changes in the genes controlling enzymes responsible for drug metabolism, neurotransmitter receptors, as well as proteins involved in oxidative stress or antioxidant function [2]. Our previous results showed that the susceptibility to LID was associated with two NMDA receptor (GRIN2A) variants [3]. Objective: To investigate contribution of polymorphic variants of HTR2C serotonin receptor gene and DRD2, DRD3 and DRD4 dopamine receptors genes in the development of LID in PD patients. Methods: 143 patients with Parkinson's disease were examined. Dyskinesias were estimated with use of Abnormal Involuntary Movement Scale (AIMS). Orofaciolingual LID (LIDof) and limb-truncal LID (LIDlt) were assessed with AIMS items 1-4 and 5-7, respectively. DNA extraction and fluorogenic 5- exonuclease TaqMan genotyping assays were conducted according to standard protocols and blind to the clinical status of the subjects. Genotyping was carried out on 23 polymorphic variants of DRD2, DRD3, DRD4 and HTR2C genes (rs6275, rs1800497, rs1799732, rs71653615, rs11721264, rs167770, rs3773678, rs963468, rs7633291, rs2134655, rs9817063, rs324035, rs1800828, rs167771, rs3758653, rs6318, rs5946189, rs569959, rs17326429, rs4911871, rs3813929, rs1801412, rs12858300). The softwares “R” and SPSS were used for statistical analysis. The Hardy-Weinberg equilibrium (HWE) of genotypic frequencies was tested by the chi-square test. For the SNPs in the X-chromosomal HTR2C gene, deviation from HWE was not calculated. Results: Associations of 5 polymorphisms with levodopainduced dyskinesias in patients with PD were revealed. Polymorphisms associated with orofaciolingual LID virtually did not overlap with polymorphisms associated with limb-truncal LID, indicating the different genetic basis of these phenotypes. Moreover, LIDof and LIDlt are associated with different genes polymorphisms. LIDof is associated with DRD4 (rs3758653) and HTR2C (rs4911871, rs5946189) genes polymorphisms whereas LIDlt is associated with only one of studied polymorphism. Polymorphisms of DRD3 gene (rs2134655, rs963468) are associated with severity of dyskinesia: rs2134655 - with orofaciolingual LID; rs963468 - with limb-truncal LID, but not with the fact of the presence of dyskinesia itself. Conclusions: Polymorphisms in the genes coding for neurotransmitter receptors play significant roles in the therapy response to L-DOPA as well as in various adverse effects. We hypothesised that single nucleotide polymorphisms in specific genes, particularly those coding for dopamine and serotonin receptors, may result in a clinical phenotype contributing to an increased risk of LID. Thus, the polymorphisms of genes possessing protective or predisposing effects in development of levodopa induced dyskinesia in PD have been revealed that would allow predicting risk of development of movement disorders