Alcohol dehydrogenase 2 genotype and allelic variants are not associated with the risk for essential tremor

OBJECTIVE: To investigate the possible association between alcohol dehydrogenase 1B, beta-polypeptide (ADH2) genotype and allelic variants and the risk for developing essential tremor (ET). METHODS: Leukocytary DNA from 204 ET patients and 200 healthy controls was studied for the genotype ADH2 and the occurrence of ADH2 allelic variants using allele-specific polymerase chain reaction amplification and MslI-restriction fragment length polymorphism's analyses. RESULTS: The frequencies of the ADH2*1/ADH2*2 genotype and of the allelic variant ADH2*2 did not differ significantly in ET patients when compared with those of the controls. The mean age at onset of ET did not differ significantly between patients with genotypes ADH2*1/ADH2*2 and ADH2*1/ADH2*1. The frequencies of the genotype ADH2*1/ADH2*2 and of the allelic variant ADH2*2 in patients with voice, tongue, and chin tremors did not differ from those of the controls, whereas patients with voice tremor showed lower frequencies of mutated genotypes and ADH2*2 alleles. The frequencies of ADH2 genotypes and ADH2 alleles did not differ significantly between patients who did not drink ethanol and those who reported improvement, no improvement, or unknown response of tremor to ethanol. CONCLUSIONS: These results suggest that ADH2 genotype and allelic variants are not associated with the risk for ET in white Spanish people.     

Paraoxonase 1 (PON1) polymorphisms and risk for essential tremor

Background: The polymorphic enzyme human serum paraoxonase 1 (PON1), encoded by the gene PON1 (chromosome 7q21.3), plays a major role in the metabolism of organophosphorus compounds. We investigated the possible association between the PON1 genotype and allelic variants of the polymorphisms Leu55Met and Glu192Arg, and the risk for essential tremor (ET). Methods: We studied the frequency of the PON1 genotypes and allelic variants in 201 patients with ET and 220 healthy controls using a PCR‐RLFP method. Results: The frequencies of the PON1 genotypes and allelic variants of the polymorphisms Leu55Met and Gln192Arg did not differ significantly between patients with ET and controls. These polymorphisms were unrelated with the age of onset of ET. Conclusions: PON1 polymorphisms are not related with the risk for ET.     

Environmental risk factors for essential tremor

We conducted a case-control study searching for a possible role of environment in the risk of essential tremor (ET). We interviewed 142 ET patients and 284 age- and sex-matched controls about a family history of ET, exposure to environmental products containing lead, mercury, manganese, solvents and beta-carbolines, and exposure to agricultural work, well water, pesticides, and cigarette smoking and alcohol drinking habits. In a univariate study, reported family history of ET and exposure to agricultural work, pesticides, smelting, frosted glass, paintings, wheat, corn, and barley were more frequent in the ET patient group. With a multivariate study, only reported family history of ET and exposure to agricultural work and frosted glass remained significant. Time of exposure to agricultural work, wheat and barley was significantly higher in ET patients. Age at onset of ET was significantly lower in patients with a family history of tremor and higher in patients exposed to iron-manganese alloys and alcohol. Time of exposure, but not total consumption of alcohol and cigarettes, was correlated with age at onset of ET. In conclusion, our study shows that the association between ET and reported family history of ET was robust, and that there were also associations between ET and exposure to some environmental factors (agricultural work and frosted glass).     

Gamma-aminobutyric acid (GABA) receptor rho (GABRR) polymorphisms and risk for essential tremor

Some clinical and experimental data suggest a possible role of gamma-aminobutyrate (GABA)-ergic mechanisms in the pathophysiology of essential tremor (ET), such as the improvement of ET with some GABAergic drugs and the development of an experimental model of ET in GABA A receptor alpha-1 knockout mice (postural and kinetic tremor and motor incoordination similar to human ET). To investigate the possible association between the GABA receptor subtype rho1, rho2, and rho3 (GABRR1, GABRR2, and GABRR3) genotypes and allelic variants of the single nucleotide polymorphisms GABRR1-M26V (Met26Val, rs12200969), GABRR1-H27R (His26Arg, rs1186902), GABRR2-T455M (Thr55Met, rs282129), and GABRR3-Y205X (Tyr205X, rs832032), and the risk for ET, we studied the frequency of the previously mentioned GABRR genotypes and allelic variants in 200 patients with ET and 250 healthy controls using TaqMan genotyping. The frequencies of the GABBR1 genotypes and allelic variants of the studied polymorphisms did not differ significantly between patients with ET and controls, and were unrelated with the age at onset of tremor, gender, localization of tremor, and response of tremor to ethanol. These data suggest that the single nucleotide polymorphisms studied in the GABBR genes are not related to the risk for ET.     

CYP2C19 polymorphism and risk for essential tremor

Many patients with essential tremor (ET) develop acute adverse effects to primidone. We investigated the association between CYP2C19 polymorphism (possibly related to primidone metabolism) and the risk for developing essential ET and acute adverse effects to primidone. Leukocytary DNA from 200 ET patients and 300 healthy controls was studied for the genotype CYP2C19 and the occurrence of CYP2C19 allelic variants by using allele-specific PCR amplification and Sma I and BamH I RFLP analyses. The frequencies of the genotype CYP2C19*1/CYP2C19*2 and of the allelic variant CYP2C19*2 were significantly higher in ET patients than in controls. The mean age at onset of ET did not differ significantly between patients with genotypes CYP2C19*1/CYP2C19*2andCYP2C19*1/CYP2C19*1. The frequencies of the genotype CYP2C19*1/CYP2C19*2 and the allelic variant CYP2C19*2 were similar in ET patients who developed acute adverse effects to primidone, in those who tolerated primidone and in controls; the frequencies were also similar in patients with head, voice, tongue and chin tremor compared with controls. These results suggest that heterozygosis CYP2C19*1/CYP2C19*2 is associated with the risk for ET, but not with the age at onset of ET, the presentation of acute side effects of primidone, or the existence of head, voice, tongue or chin tremor.     

MDR1 variants and risk of Parkinson disease

The multidrug resistance protein 1 (MDR1 or ABCB1) gene encodes a P-glycoprotein that protects the brain against neurotoxicants. Certain MDR1 genetic variants are known to compromise the function of this transporter and may thus be associated with Parkinson disease (PD). We therefore conducted a large case-control study investigating the potential relationship between MDR1 variants and PD. We determined the frequency of three MDR1 variants in 599 European PD patients and controls and further stratified the population by ethnicity, age at onset, and exposure to pesticides. We detected no relevant association in either the entire sample, or when separately investigating by ethnic origin or age at onset. However, the distribution of c.3435C/T differed significantly between PD patients exposed to pesticides compared to those non-exposed (odds ratio = 4.74; confidence interval = [1.009; 22.306]); p = 0.047), suggesting that common MDR1 variants might influence the risk to develop PD in conjunction with exposure to pesticides.     

Paraoxonase 1 Polymorphisms Are Not Related with the Risk for Multiple Sclerosis

It has been suggested a possible role of oxidative stress and lipid peroxidation in the inflammatory processes and in the pathogenesis of multiple sclerosis. Human serum paraoxonase 1 is a polymorphic enzyme encoded by the gene PON1, located in chromosome 7q21.3, that plays a major role in the metabolism of organophosporus compounds, and in the protection against oxidative stress. Paraoxonase-1 activity has been found decreased in the plasma of multiple sclerosis patients. An association between PON1 polymorphism and the risk of multiple sclerosis has been described in Italians. To investigate the possible association between the PON1 genotype and allelic variants of the polymorphisms L55M and Q192R and the risk for multiple sclerosis in the Spanish Caucasian population; we studied the frequency of the PON1 genotypes and allelic variants in 228 patients with multiple sclerosis and 220 healthy controls using a PCR-RLFP method. The frequencies of the PON1 genotypes and allelic variants did not differ significantly between patients and controls, and were unrelated with gender, age of onset, and course of the disease. The OR (95% confidence intervals) for the variant alleles PON1-55L and PON1-192R were 0.96 (0.73–1.26) and 1.01 (0.76–1.35), respectively. The results of the present study suggest that PON1 polymorphism is not related with the risk for multiple sclerosis in our population.     

Histamine‐N‐methyl transferase polymorphism and risk for multiple sclerosis

Background: Histamine N‐methyltransferase (HNMT) is the main metabolizing enzyme of histamine (a mediator of inflammation implicated in the pathogenesis of multiple sclerosis‐MS) in the CNS. We have investigated the possible association between a single nucleotide polymorphism of the HNMT (chromosome 2q22.1), that causes the amino acid substitution Thr105Ile (decreasing enzyme activity) and the risk for MS. Methods: We studied the frequency of the HNMT genotypes and allelic variants in 228 MS patients and 295 healthy controls using a PCR‐RLFP method. Results: The frequencies of the HNMT genotypes and allelic variants did not differ significantly between MS patients and controls, and were unrelated with the age of onset of MS, gender, and course of MS. Conclusion: The HNMT polymorphism is not related with the risk for MS.     

Paraoxonase 1 (PON1) polymorphisms and risk for migraine

The polymorphic enzyme human serum paraoxonase 1 (PON1), encoded by the gene PON1 (chromosome 7q21.3) plays a role as an antioxidant molecule through several mechanisms. Because oxidative stress has been implicated in the pathogenesis of migraine, we have investigated the possible association between the nonsynonymous polymorphisms 55LM and 192QR in the PON1 and the risk for migraine. We studied the frequency of the PON1 genotypes and allelic variants in 197 patients with migraine and 220 healthy controls using a TaqMan single nucleotide polymorphism analysis. The frequencies of the PON1 genotypes and PON1 allelic variants did not differ significantly between patients with migraine and controls, and were unrelated with gender, family history of migraine, and presence or absence of aura. The frequencies of the genotype PON1 192QQ and the allelic variant PON1 192Q were significantly higher in patients with earlier onset of migraine. The results of the present study suggest that PON1 polymorphisms are not related with the risk for migraine in Caucasian Spanish people, although PON1 192Q/Q genotype and PON1 192Q allelic variant should be related with an earlier onset of migraine.     

Dopamine receptor 3(DRD3) polymorphism and risk for migraine

Background/objectives: Dopamine has been implicated in the pathogenesis of migraine. We investigated the possible association between the polymorphism 312G>A (rs6280) in the DRD3 gene(essential tremor 1‐ETM1‐ locus, chromosome 3q13) and the risk for migraine and for triggering migraine attacks by alcohol. Methods: We studied the frequency of the DRD3 genotypes and allelic variants in 197 patients with migraine and 282 healthy controls using a polymerase chain reaction and MlsI‐restriction fragment length polymorphisms method. Results: The frequencies of the DRD3 genotypes and DRD3Gly9 were similar in patients with migraine and controls and were unrelated to the age of onset of migraine, gender, family history of migraine and triggering of migraine attacks by alcohol. The frequency of the genotype DRD3Gly9Gly9 was significantly higher in patients with migraine with aura when compared with patients with migraine without aura, but not with controls. Conclusion: DRD3 genotype and allelic variants were not related to the risk for migraine in Caucasian Spanish people.     

Association of A313 G polymorphism (GSTP1*B) in the glutathione-S-transferase P1 gene with sporadic Parkinson's disease

Genetic predisposition, environmental toxins and aging contribute to Parkinson's disease (PD) multifactorial etiology. Weak environmental neurotoxic factors may accumulate over time increasing the disease risk in genetically predisposed subjects. Polymorphic genes encoding drug-metabolizing-enzymes (DMEs) are considered to account for PD susceptibility by determining individual toxic response variability. In this work, the allelic distributions and genotype associations of three major brain-expressed DMEs were characterized, in sporadic PD cases and controls. No significant association was found between CYP2D6 genotype and PD, but subjects with extensive metabolizer (EM) CYP2D6 phenotype, and the variant GSTP1 *B genotype were at significantly higher PD risk than the corresponding poor or intermediary metabolizers ( CYP2D6 poor metabolizer phenotype+intermediary metabolizers). A significant association was observed between the GSTP1*B allele and zygosity with PD ( GSTP1*A/*B – 51.58%/34.37%, odds ratio (OR) = 2.29; 95% confidence interval (95% CI) = 1.25–4.18; * B /* B – 6.32%/1.05%, OR = 10.67; 95% CI = 1.19–94.79). This association was particularly strong in the elder patients group (≥69 year) who showed double PD risk for GSTP1*B heterozygous, whilst GSTP1*B/*B homozygous were exclusively found amongst patients. An interaction between GSTM1 and GSTP1 was observed in this late onset PD group. The present results suggest that native GSTP1 encoding the fully active transferase variant should play a relevant role in dopaminergic neuroprotection.     

A family study of DRD3 rs6280, SLC1A2 rs3794087 and MAPT rs1052553 variants in essential tremor

Background/Objective: Despite many data suggesting a role of genetic factors in the risk for essential tremor (ET), the responsible genes have not been identified. We analyzed in ET Spanish families three single nucleotide polymorphisms (SNPs): DRD3 rs6280, SLC1A2 rs3794087, and MAPT rs1052553) previously related to an increased risk for developing the disease.

Methods: We recruited 45 subjects with ET and 13 subjects without tremor belonging to 11 families who were evaluated because of familial tremor. Diagnosis of probable or definite ET was done according to TRIG criteria. Genotyping of the 3 SNPs was done using TaqMan-based qPCR assays. Data were compared with those of healthy controls of our laboratory. Family-based association testing for disease traits was performed as well.

Results: rs6280 and rs3794087 genotype and allelic frequencies did not differ significantly between subjects with ET and healthy controls. However, rs1052553AA genotype and the allele rs1052553A allele were significantly more frequent among ET patients. rs1052553A allele was non-significantly overrepresented in ET patients compared with controls when considering only the more severely affected member of each ET family. Family-based association test for disease traits showed lack of association between ET and the three SNPs studied.

Conclusions: Our results showed a lack of association between rs6280 and rs3794087 with the risk for ET, though a marginal increased risk for ET was observed among the rs1052553A allele carriers, which was not confirmed with a family-based association study.     

Dissociating medial temporal and basal ganglia memory systems with a latent learning task

The medial temporal (MT) lobes and basal ganglia have both been implicated as brain substrates of associative learning. Here, we show a dissociation between medial temporal and basal ganglia damage using a latent learning task, in which prior exposure to cues, uncorrelated with each other, slows subsequent learning of an association between them. Consistent with prior work, we found a robust exposure effect in healthy controls, with exposed controls learning more slowly than non-exposed controls. This effect was abolished in medial temporal amnesia: both exposed and non-exposed amnesic patients learned at the same speed. A group of patients with basal ganglia damage due to Parkinson’s disease showed a reversal of the effect: exposed subjects learned faster than non-exposed subjects. Our findings point to distinct and dissociable contributions of medial temporal lobe and basal ganglia structures to learning and memory.     

Glutathione S-transferase polymorphisms in MS: their relationship to disability

BACKGROUND: Oxidative stress has been implicated in inflammatory demyelination. The glutathione S-transferase (GST) supergene family encodes isoenzymes that appear to be critical in protection against oxidative stress. Certain GST loci are polymorphic, demonstrating alleles that are null (GSTM1/GSTT1), encode low activity variants (GSTP1), or are associated with variable inducibility (GSTM3). OBJECTIVES: To investigate the association between clinical outcome in MS and allelic variants of GSTM1, GSTM3, GSTT1, and GSTP1. METHODS: Four hundred patients with clinically definite MS were studied. Disability was measured using the Kurtzke Expanded Disability Status Scale (EDSS). Disability was graded as mild (EDSS 0-4), moderate (4.5-5.5), or severe (EDSS 6-10). PCR-based genotyping was performed using DNA extracted from lymphocytes. Significant associations between GST genotypes and clinical outcome were corrected for gender, onset age, and disease duration using logistic regression. Results: We found that the GSTM3 AA genotype was associated with severe disability in patients with a disease duration of more than 10 years (p = 0.027, n = 177, OR = 2.4, 95% CI = 1.1-5.0). Homozygosity for both GSTM1*0 and GSTP1*Ile105 containing allele was associated with severe disability in patients with a disease duration greater than 10 years (p = 0.022, n = 179, OR = 5.0, 95% CI = 1.3-19.8). CONCLUSIONS: Our results suggest that long-term prognosis in MS is influenced by a genetically determined ability to remove the toxic products of oxidative stress.     

Lack of association of LINGO1 rs9652490 and rs11856808 SNPs with familial essential tremor

Background: Essential tremor (ET) is a frequent movement disorder with a substantial family aggregation. A genome‐wide association study has recently shown that LINGO1 gene variants are associated with increased risk of ET. Methods: We intended to replicate these findings by genotyping rs9652490 and rs11856808 in a series of 226 familial ET subjects and 1117 healthy controls from referral movement disorder clinics in Spain. Results: We were unable to replicate the association between LINGO1 variants and familial ET. Conclusions: Our results indicate that the LINGO1 variants analyzed are not a major risk factor for developing familial ET in our population, which suggests the existence of other unknown genetic risk factors responsible for familial ET in the Spanish population.     

对氧磷酶-2（PON2）基因内含子单核苷酸多态性与脑梗死的相关性研究

目的探讨对氧磷酶-2（PON2）基因内含子单核苷酸多态性（SNP）与脑梗死（cerebral infarction,CI）的关系。方法检测108例健康体检者（对照组）和128例脑梗死患者（病例组）PON2基因内含子的两个位点（intron1,rs2299267和intron4,rs17166875）的基因多态性,分析其在正常人群及脑梗死患者中的频率分布特点。结果rs2299267 A/G及rs17166875 C/T的基因型和等位基因频率在脑梗死组和对照组之间的差异无显著性意义（P〉0.05）。经性别分层分析后,脑梗死组女性的rs2299267 G等位基因频率为37.8%,对照组为21.3%,差异有统计学意义（P=0.024）;脑梗死组女性G等位基因（AG＋GG）携带者为56.1%,对照组为35.1%,其差异接近有显著性（P=0.064）,提示该多态性与女性脑梗死有相关倾向,女性G等位基因携带者发生脑梗死的风险是AA基因型的2.36倍（OR：2.36,95%,CI：0.95～5.9）。结论本研究发现,PON2基因内含子1的rs2299267 G等位基因与中国汉族人女性的脑梗死发病有关,内含子4的rs17166875位点的单核苷酸多态性与脑梗死无关。因此,PON2参与脑梗死的发病的具体机制还需要进一步研究。基金项目：2006湛江市科技招标项目（卒中单元的建设和推广项目号ZZ060T）资助作者单位：524001广东医学院附属医院神经内科作者简介：冼文川（1979一）,男,硕士,住院医师。研究方向：脑血管疾病。     

Risk-factors for Parkinson's disease: case-control study in the province of Cáceres, Spain

This case-control study, performed in a mixed rural and urban province, of 74 patients with Parkinson's disease (PD) and 148 unselected age and sex-matched controls, attempted to look possible risk factors for PD. Rural living, well-water drinking, positive family history for PD and postural tremor, were associated to an increased risk for PD, with results regarding exposure to pesticides near to statistical significance. Alcohol-drinking habit in males were associated to a decreased risk for PD, with results regarding cigarette-smoking habit in males near to statistical significance. We did not find association between the risk for PD and the following variables: 1) exposure to industrial toxins; 2) agricultural work; 3) cranial trauma; 4) previous common illnesses including some infections, arterial hypertension, diabetes mellitus, coronary heart disease and thyroid disease; 5) coffee and tea drinking habits.     

Evidence of neurotoxicity in working children in Lebanon

The potential for exposure to neurotoxicants in Lebanon is high, especially in the absence of strict control and regulatory measures in workplaces. Children working in mechanical and other trade workshops are at significant risk of exposure to organic solvents and as a result at significant risk to develop clinical and subclinical signs of neurotoxicity. This study investigated the association between exposure to solvents and neurobehavioral performance of 10-17 years old working children in comparison to groups of non-exposed working children and non-exposed children at school. A convenience cross-sectional sample of 100 working children (10-17 years) exposed to organic solvents at work, a positive control of 100 non-solvent exposed working children, and a negative control of 100 non-working, non-exposed school children were recruited to the study. The exposed and non-exposed groups were, as far as possible, frequency matched on geographic location of residence and on age. Neurotoxic effects were assessed through a questionnaire and the child's performance on a battery of neurobehavioral tests, which were specifically selected for a non-English speaking population and were tailored to assess the specific modalities of the central nervous system commonly known to be affected by the neurotoxicants identified. Children in the non-exposed groups (working and non-working) performed better than the working exposed group on reaction speed for the choice reaction time, symbol-digit and dual task tracking tests, but accuracy of performance was not affected on these tests. Children in the working exposed group also complained of more headaches, loss of concentration, memory deficits and higher irritability. This study identifies an association between exposure to solvents and lower neurobehavioral performance. Response speed appears to be particularly affected in solvent exposed working children.     

Lack of association of hormone receptor polymorphisms with migraine

Background and purpose:  Previous studies concerning the role of hormone receptor genetic variants in migraine have provided conflicting results. The aim of this study was to investigate the role of common polymorphisms in the estrogen receptor gene ( ESR1 ) and the progesterone receptor gene ( PGR ) in the risk for migraine in a Spanish population.
Methods:  In a case–control study, including 210 Caucasoid migraine patients and 210 controls, we examined association between three single nucleotide polymorphisms in the coding region of ESR1 , rs2077642, rs1801132, and rs2228480, and an Alu insertion in PGR , and migraine, migraine without aura or migraine with aura. Genotypic, allelic and reconstructed haplotype distributions were compared.
Results:  We found no significant differences between cases and controls in the distribution of genotypes or alleles for either polymorphism. No haplotype was over-represented in patients.
Conclusions:  Our study does not support a major contribution of ESR1 and PGR to the pathogenesis of migraine.     

Environmental exposure to pesticides and Amyotrophic Lateral Sclerosis in the South of Spain

ObjectiveTo determine if there is a relationship between environmental exposure to pesticides and the prevalence of Amyotrophic Lateral Sclerosis (ALS) in Andalusia.MethodWe carried out a case–control study using the logistic regression method to verify the relationship between the prevalence of ALS in the area exposed to pesticides versus the unexposed area, through the Odds Ratio statistical test.ResultsThe study population consisted of 519 individuals diagnosed with ALS between January 2016 and December 2018 according to the CMBD (Minimum Basic Data Set) as cases. In the control group, we have 8,384,083 individuals obtained from data from the National Institute of Statistics (INE). The Odds Ratio (OR) was used as a measure of association between cases and controls, obtaining an OR between 0.76 and 1.08 for the confidence interval of the CI (95%).ConclusionsDespite the existence of various studies that suggest a possible association between environmental exposure to pesticides and the risk of Amyotrophic Lateral Sclerosis, our analysis of the Andalusian population did not find significant evidence of this association.