Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0030567 (Parkinson's disease)
 63,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Because drug transporters such as P-glycoprotein, the product of the multidrug resistance (MDR1 ) gene, contribute to the function of the blood-brain barrier, we hypothesized that differences in their expression could affect the uptake of neurotoxic xenobiotics, thereby modulating interindividual susceptibility for neurological disorders such as Parkinson's disease. In a pilot case-control study comprising 95 Parkinson's disease patients (25 early-onset patients with onset age < or = 45 years) and 106 controls we analysed the three common polymorphisms, 3435C >T in exon 26, 2677G > T,A in exon 21, and -129T > C in exon 1b. There were no statistically significant associations between any of these polymorphisms and Parkinson's disease. However, a distribution pattern consistent with our hypothesis was observed in that the frequency of the 3435T/T genotype, which had previously been associated with decreased P-glycoprotein expression and function, was highest in the early-onset Parkinson's disease group (36.0%), second-highest in the late-onset Parkinson's disease group (22.9%), and lowest in the control group (18.9%). Furthermore, we confirmed that the MDR1 exon 21 and exon 26 polymorphisms are in significant linkage disequilibrium since the [2677G, 3435C] and [2677T, 3435T] haplotypes were far more frequently observed than expected. In conclusion, MDR1 and other drug transporters represent plausible candidates as Parkinson's disease risk genes. Larger studies are required to confirm this role in the etiology of Parkinson's disease.
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PMID:Expression polymorphism of the blood-brain barrier component P-glycoprotein (MDR1) in relation to Parkinson's disease. 1236 Jan 3

P-glycoprotein is a membrane protein encoded by the MDR1 gene, which demonstrates functional polymorphism. It is present in endothelial cells of the blood-brain barrier, thus limiting accumulation of its substrates in the central nervous system. Many epidemiological studies suggest an association between pesticides, which are substrates for P-glycoprotein, and Parkinson's disease. It was hypothesized that polymorphism of the MDR1 gene could modulate interindividual susceptibility for the disease in subjects exposed to pesticides. In a pilot case-control study involving 107 Parkinson's disease patients (30 early onset and 77 late onset patients; 59 exposed to pesticides and 48 non-exposed) and 103 controls, C3435T polymorphism of the gene was analysed. No statistically significant correlation between MDR1 gene polymorphism and Parkinson's disease was found. The 3435TT genotype was noted more frequently, but not significantly, in patients with early onset compared to late onset disease (23.3% versus 10.4%, respectively). A significant association between patients with parkinsonism exposed to pesticides and C3435T polymorphism of the MDR1 gene was found. Comparing the exposed and non-exposed patients, a statistically higher frequency of heterozygous subjects was observed (72.9% versus 47.9%, respectively). This genotype was associated with a significant, almost three-fold increased risk of disease. Similarly, a higher frequency of 3435TT subjects was revealed in exposed subjects (15.5%) compared to non-exposed patients (12.5%). In exposed versus non-exposed subjects, patients carrying at least one 3435T allele (i.e. homozygous and heterozygous) had a significant, five-fold higher risk of Parkinson's disease. Thus, it appears that mutation of the MDR1 gene predisposes to damaging effects of pesticides, and possibly other toxic xenobiotics transported by P-glycoprotein, leading to Parkinson's disease.
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PMID:Polymorphism in the P-glycoprotein drug transporter MDR1 gene: a possible link between environmental and genetic factors in Parkinson's disease. 1272 17

The multi-drug resistant transporter MDR1/P-glycoprotein, the gene product of MDR1, is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette (ABC) superfamily of membrane transporters. MDR1 was originally isolated from resistant tumor cells as part of the mechanism of multi-drug resistance, but over the last decade, it has been elucidated that human MDR1 is also expressed throughout the body to confer intrinsic resistance to the tissues by exporting unnecessary or toxic exogeneous substances or metabolites. A number of various types of structurally unrelated drugs are substrates for MDR1, and MDR1 and other transporters are recognized as an important class of proteins for regulating pharmacokinetics and pharmacodynamics. In 2000, Hoffmeyer et al. performed a systemic screening for MDR1 polymorphisms and indicated that a single nucleotide polymorphism (SNP), C3435T in exon 26, which caused no amino acid change, was associated with the duodenal expression of MDR1 and thereby the plasma concentrations of digoxin after oral administration. Interethnic differences in genotype frequencies of C3435T have been clarified, and, at present, a total of 28 SNPs have been found at 27 positions on the MDR1 gene. Clinical studies on the effects of C3435T on MDR1 expression and function in the tissues, and also on the pharmacokinetics and pharmacodynamics have been performed around the world; however, there are still discrepancies in the results, suggesting that the haplotype analysis of the gene should be included instead of SNP detection, and the design of clinical trials must be carefully planned to avoid misinterpretations. A polymorphism of C3435T is also reported to be a risk factor for a certain class of diseases such as the inflammatory bowel diseases, Parkinson's disease and renal epithelial tumor, and this might also be explained by the effects on MDR1 expression and function. In this review, the latest reports are summarized for the future individualization of pharmacotherapy based on MDR1 genotyping.
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PMID:Pharmacogenetics of MDR1 and its impact on the pharmacokinetics and pharmacodynamics of drugs. 1283 20

Drug transporters are increasingly recognized to be important to drug disposition and response. P-glycoprotein, the encoded product of the human MDR1 (ABCB1) gene, is of particular clinical relevance in that this transporter has broad substrate specificity, including a variety of structurally divergent drugs in clinical use today. Moreover, expression of this efflux transporter in certain tissue compartments such as the gastrointestinal tract and brain capillary endothelial cells limits oral absorption and central nervous system entry of many drugs. Recently, a number of single-nucleotide polymorphisms (SNPs) in MDR1 have been identified. An increasing number of studies have also implicated certain commonly occurring SNPs in MDR1 in problems including altered drug levels and host susceptibility to diseases such as Parkinson's disease, inflammatory bowel disease, refractory seizures, and CD4 cell recovery during human immunodeficiency virus therapy. However, in many such cases, the reported effects of MDR1 SNPs have been inconsistent and, in some cases, conflicting. In this review SNPs in MDR1 in relation to population frequencies, drug levels, and phenotypes are outlined. In addition, issues relating to MDR1 haplotypes, environmental factors, and study design, as potential confounding factors of the observed MDR1 polymorphism effect in vivo, are also discussed.
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PMID:Polymorphisms in human MDR1 (P-glycoprotein): recent advances and clinical relevance. 1474 89

Most drug responses are determined by the interplay of several gene products that influence pharmacokinetics and pharmacodynamics, i.e., drug metabolizing enzymes, drug transporters, and drug targets. With the sequencing of the human genome, it has been estimated that approximately 500-1200 genes code for drug transporters. Concerning the effects of genetic polymorphisms on pharmacotherapy, the best characterized drug transporter is the multidrug resistant transporter P-glycoprotein/MDR1, the gene product of MDR1. Little such information is available on other drug transporters. MDR1 is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette superfamily, and is expressed mainly in intestines, liver, kidneys and brain. A number of various types of structurally unrelated drugs are substrates for MDR1, and their intestinal absorption, hepatobiliary secretion, renal secretion and brain transport are regulated by MDR1. The first investigation on the effects of MDR1 genotypes on pharmacotherapy was reported in 2000: a silent single nucleotide polymorphism (SNP), C3435T in exon 26, was found to be associated with the duodenal expression of MDR1, and thereby the plasma concentration of digoxin after oral administration. At present, a total of 28 SNPs have been found at 27 positions on the MDR1 gene. Clinical investigations on the association of MDR1 genotypes with the expression and function of MDR1 in tissues, and with pharmacokinetics and pharmacodynamics have mainly focused on C3435T; however, there are still discrepancies in the results, suggesting that the haplotype of the gene should be analyzed instead of a SNP. C3435T is also reported to be a risk factor for a certain class of diseases including the inflammatory bowel diseases, Parkinson's disease and renal epithelial tumor, and this also might be explained by the effects on MDR1 expression and function. In this review, the latest reports on the effects of genetic polymorphisms of MDR1 on pharmacotherapy are summarized, and the pharmacogenetics of other transporters is briefly introduced.
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PMID:Pharmacogenetics of drug transporters and its impact on the pharmacotherapy. 1537 52

Drug transporters significantly influence drug pharmacokinetics and pharmacodynamics. P-glycoprotein (P-gp), the product of the MDR1 (ABCB1) gene, is among the most well-characterized drug transporters, particularly in veterinary medicine. A number of clinically relevant, structurally and functionally unrelated drugs are substrates for P-gp. P-gp is expressed by a variety of normal tissues including the intestines, renal tubular cells, brain capillary endothelial cells, biliary canalicular cells, and others, where it functions to actively extrude substrate drugs. In this capacity, P-gp limits oral absorption and central nervous system entry of many substrate drugs. A number of MDR1 polymorphisms have been described in human patients, some of which result in altered drug pharmacokinetics and susceptibility to diseases such as Parkinson's disease, inflammatory bowel disease, refractory seizures, and others. An MDR1 polymorphism in herding breed dogs, including collies and Australian shepherds, has been demonstrated to be the cause of ivermectin sensitivity in these breeds. Recent evidence suggests that this polymorphism, a 4-bp deletion mutation, results in increased susceptibility to the toxicity of several drugs in addition to ivermectin. Furthermore, data in rodent models suggest that P-gp may play an important role in regulating the hypothalamic-pituitary-adrenal axis.
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PMID:Therapeutic implications of the MDR-1 gene. 1550 May 62

The MDR1 multidrug transporter is important in regulating environmental xenobiotics and hence may play a causative role in Parkinson's disease (PD). MDR1 haplotype comprising 2677 G > T/A and 3435 C > T may be protective against PD. Using a case control methodology, we investigated the association of MDR1 haplotypes (single nucleotide polymorphisms (SNPs) 2677 G > T/A and 3435 C > T) in a Polish PD population. Seven SNPs, extending from the promoter to exon 28 of the MDR1 gene in 158 PD patients and 139 healthy controls were evaluated. Specifically we examined the association of haplotypes containing SNPs 2677 G > T/A and 3435 C > T and risk of PD. The multivariate logistic regression model was used to evaluate the effects of the covariates on the phenotypes. Haplotypes' frequencies were estimated using the Expectation-Maximization algorithm. The frequency of each individual SNPs; -41 A > G (intron -1), -145 C > G (exon 1), -129 T > C (exon 1), 1236 T > C (exon 12), 2677 G > T/A (exon 21), 3435 C > T (exon 26), and 4036 A > G (exon 28) did not differ between PD and controls. However, there was a trend towards significance in PD patients having the haplotype 2677G-3435C (p < 0.09, chi-square 2.85, odds ratio 0.25, 95% CI 0.06-1.08). Haplotype constructs of the other loci did not differ significantly between the two groups. There was a weak protective effect of the haplotype 2677G-3435C in our white population. However, the MDR1 haplotypes did not generally modulate the risk of PD.
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PMID:Analysis of MDR1 haplotypes in Parkinson's disease in a white population. 1554 48

The cause of Parkinson's disease (PD) is unknown. Genetic susceptibility and exposure to environmental toxins contribute to specific neuronal loss in PD. Decreased blood-brain barrier (BBB) P-glycoprotein (P-gp) efflux function has been proposed as a possible causative link between toxin exposure and PD neurodegeneration. In the present study BBB P-gp function was investigated in vivo in 10 early stage PD patients and 8 healthy control subjects using (R)-[(11)C]-verapamil and PET. Cerebral volume of distribution (V(d)) of verapamil was used as measure of P-gp function. Both region of interest (ROI) analysis and voxel analysis using statistical parametric mapping (SPM) were performed to assess regional brain P-gp function. In addition, MDR1 genetic polymorphism was assessed. In the present study, a larger variation in V(d) of (R)-[(11)C]-verapamil was seen in the PD group as compared to the control group. However, decreased BBB P-gp function in early stage PD patients could not be confirmed.
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PMID:Blood-brain barrier P-glycoprotein function is not impaired in early Parkinson's disease. 1832 22

The membrane transporter multi-drug resistance 1 (MDR1, P-gp) regulates the bioavailability of endogenous and exogenous compounds and has been implicated in disorders such as Parkinson's disease, cancer, epilepsy, human immunodeficiency virus disease, and inflammatory bowel disease. To promote further understanding of the role of MDR1 in disease, we have characterized cellular MDR1 mRNA expression in post-mortem human and fresh-frozen Sprague-Dawley rat tissues by using radioactive oligonucleotide probe in situ hybridization. We report MDR1 mRNA in human and rat endothelial cells of small vessels in the brain and pia mater. Mdr1 mRNA is also expressed in the blood vessel walls of rat sensory dorsal root and sympathetic ganglia. In peripheral tissues, we have observed MDR1 mRNA in human and rat liver and renal tubules and in human adrenal cortex and the epithelial lining of rat intestine. In female and male reproductive tissues of rat, strong gene activity has been found in steroid-hormone-synthesizing cells. Quantification of MDR1 mRNA in human striatum has revealed reduced levels in Parkinson patients compared with control individuals. The high expression of MDR1 mRNA in blood vessels of the nervous system, in tissues involved in absorption and excretion, and in tissues forming barriers to the environment support the physiological role of MDR1 as a regulator of intracellular levels of endogenous and exogenous compounds.
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PMID:Expression of multi-drug resistance 1 mRNA in human and rodent tissues: reduced levels in Parkinson patients. 1885 17

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.
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PMID:MDR1 variants and risk of Parkinson disease. Association with pesticide exposure? 1918 62


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