Influence of eight ABCB1 polymorphisms on antidepressant response in a prospective cohort of treatment-free Russian patients with moderate or severe depression: An explorative psychopharmacological study with naturalistic design.

BACKGROUND: Many antidepressants are substrates of P-glycoprotein, an efflux transporter in the blood-brain-barrier encoded by the ABCB1 gene. Genetic variations might influence the transport rate of antidepressants and hence their pharmacological effects. This study investigates the influence of eight polymorphisms in the ABCB1 gene on antidepressant treatment response. METHOD: 152 patients were included from psychiatric departments of the Mental Health Research Institute in Tomsk. The difference in Hamilton-Depression-Rating-Scale (HAMD-17)-scores between baseline and week two, week two and four, and baseline and week four was used to estimate timing of improvement of depression. Associations between the ABCB1 gene-polymorphisms and reduction in HAMD-17 score were assessed using independent t-test and multiple linear regression. RESULTS: Tricyclic antidepressants were associated with a higher reduction of HAMD-17 score when compared to SSRIs. The SNP rs2235040 A-allele had a significant positive influence on the ΔHAMD-17(0→2W) score but a significant negative influence on the ΔHAMD-17(2→4W) score. The rs4148739 G-allele had a significant negative influence on the ΔHAMD-17(0→2W) score but a significant positive influence on the ΔHAMD-17(2→4W) score. The SNP rs2235015 T-allele is significant negatively related to the ΔHAMD-17(2→4W) score. CONCLUSION: ABCB1 Genetic variations appear to affect speed but not magnitude of antidepressant drug response.

Can we predict unresponsiveness to methotrexate in rheumatoid arthritis? A pharmacogenetic study.

OBJECTIVE: Methotrexate (MTX) is the anchor drug in the treatment of rheumatoid arthritis (RA) and the therapeutic response to MTX has been observed to vary widely among these patients. The aim of this study was to investigate ABCB1 gene (the multidrug resistant 1 gene; MDR1 gene) polymorphism in patients with RA and to evaluate the relation between MTX unresponsiveness and this polymorphism. METHODS: Forty-five patients with RA administered MTX were included in this pharmacogenetic cross-sectional study. The gender, age, body mass index (BMI), rheumatoid factor (RF) positivity, anti-cyclic citrullinated peptide (anti-CCP) positivity, doses of MTX and glucocorticoids were recorded. In addition, initial and third month disease activity (DAS28, Simplified and Clinical Disease Activity Index; SDAI and CDAI) scores were evaluated. We also examined frequencies of two single-nucleotide polymorphisms (SNPs), G2677T and C3435T, within the gene encoding ABCB1. RESULTS: 22 patient's responsive and 20 patients unresponsive to MTX were enrolled. Initial demographic and disease related factors were similar between patients responsive or nonresponsive to MTX. In the third month evaluation, disease activity scores were significantly higher in patients unresponsive to MTX (p < 0.05). In addition, almost all patients unresponsive to MTX (19 of the 20 patients) presented heterozygosity in C3435T (p < 0.000). CONCLUSION: We determined heterozygosity in C3435T SNP of ABCB1 gene (multidrug resistant 1 gene) in almost all patients with RA who were non-responders to MTX. This result may contribute to predict unresponsiveness to MTX in RA. Individualized treatment strategies based on the pharmacogenetic characteristics of MTX may lead to optimization of the treatment.

Association between 8 P-glycoprotein (MDR1/ABCB1) gene polymorphisms and antipsychotic drug-induced hyperprolactinaemia.

INTRODUCTION: Hyperprolactinaemia, a common adverse effect of antipsychotic drugs, is primarily linked to blockade of dopamine D2 receptors in the pituitary gland. Certain antipsychotic drugs, such as, for example risperidone and paliperidone, are more likely to induce hyperprolactinaemia compared to others. This effect is probably caused by a relatively high blood/brain concentration ratio, a consequence of being a substrate of P-glycoprotein. Genetic variants of P-glycoprotein with changed functional activity might influence the potential of risperidone and paliperidone to cause hyperprolactinaemia as the altered blood/brain concentration ratio would lead to a reduced therapeutic drug level within essential brain areas making dose adaptations necessary. This increases exposure of dopamine D2 receptors within the pituitary gland. AIMS: To investigate possible associations between MDR1/ABCB1 gene polymorphisms and antipsychotic drug-induced hyperprolactinaemia in Russian patients with schizophrenia and to determine possible differences between risperidone/paliperidone and other antipsychotics. METHODS: In total, 446 patients with schizophrenia were included from 3 psychiatric hospitals in Siberia. Blood samples were obtained in a cross-sectional study design for DNA extraction and prolactin measurement. Associations between hyperprolactinaemia and 8 MDR1/ABCB1 gene-polymorphisms were assessed using logistic regression analysis accounting for covariates. The analysis was repeated in a patient subgroup using risperidone or paliperidone. RESULTS: We did not observe an association between any of the 8 single nucleotide polymorphisms and the prevalence of antipsychotic-induced hyperprolactinaemia in the total patient population. However, in the risperidone/paliperidone subgroup, the single nucleotide polymorphism rs2032582 (G2677T) was found to be negatively associated with risperidone/paliperidone-induced hyperprolactinaemia. CONCLUSION: This study revealed a significant association between the ABCB1 gene polymorphism rs2032582 (G2677T) and risperidone/paliperidone-induced hyperprolactinaemia.

Association of ABCB1 gene polymorphism (C1236T and C3435T) with refractory epilepsy in Iraqi patients.

The mechanisms of refractory epilepsy (RE) are most likely multifactorial, involving environmental, genetic, as well as disease- and drug-related factors. We aimed to study is to investigate the possible association of two ABCB1 gene polymorphism (C3435T and C1236T) with the development of RE in Iraqi patients. One hundred patients with either generalized tonic-clonic seizures, myoclonic epilepsy, or absence epilepsy comprised of 60 patients responsive to AEDs and 40 patients who were refractory to treatment who used multi AEDs for at least one month were studied. Fifty family-unrelated age- and sex-matched healthy subjects represent the control group. ABCB1 gene fragments corresponding to two targeted polymorphisms were amplified with conventional polymerase chain reaction using specific sets of primers. Genotyping was performed by restriction fragment length polymorphism (RFLP) technique. Epileptic patients refractory to AEDs showed a significantly higher frequency of CC genotypes of C3435T polymorphism than controls. Allele C was significantly higher in patients than controls and far more frequent among patients with RE. C1235T polymorphism had no significant role neither in the incidence of epilepsy nor in the AEDs resistance. The CT haplotype was more frequent among patients refractory to AEDs. In contrast, the haplotype block TT was more frequent among responsive (41.3%) than refractory patients (28.7%) (p = 0.068). The CC genotype and C allele of the C3435T polymorphism can increase the risk of RE. The haplotype block CT of C3435T and C1236T can predispose for epilepsy as well as the drug resistance.

Influence of Potential Gene Polymorphisms on Propofol Dosage Regimen in Patients Undergoing Abdominal Hysterectomy.

Propofol (2,6-diisopropylphenol) is the most common intravenous anesthetic used in modern medicine. It is postulated that individual differences in genetic factors [polymorphism of single nucleotide polymorphisms (SNPs)] in the genes encoding metabolic enzymes, molecular targets and molecular binding sites of propofol can be responsible for susceptibility to propofol effects. The aim of our study was to investigate the influence of the cytochrome P450 2B6 isozyme CYP2B6 (rs3745274), γ-aminobutyric acid type A (GABAA) receptor α1 subunit GABRA1 (rs2279020) and ATP-binding cassette subfamily B member 1 ABCB1 (rs1045642) gene polymorphisms on propofol therapeutic outcomes in the patients undergoing abdominal hysterectomy. Ninety patients aged 29-74 years, with different ethnicities were included in this study. The presence of polymorphisms was analyzed using TaqMan SNP genotype analysis on Stratagene MxPro 3005P real-time polymerase chain reaction (qPCR). The distribution of all three genetic variants was within the Hardy-Weinberg equilibrium. There was no significant difference (p >0.05) in the allelic frequencies of polymorphic variants and genotype distributions between adult and older patients and between patients of different ethnicities. Our study did not detect a statistically significant influence of the CYP2B6 (c.516G>A), GABRA1 (c.1059+15G>A) and ABCB1 (c.3435T>C) variants on the variability of clinical parameters (doses for induction in anesthesia, additional doses, induction time and wake time after anesthesia and side effects of propofol). However, the observed trend on the possible influence of the CYP2B6 (c.516G>A) and GABRA1 (c.1059+15G>A) variants warrant an extension of these studies on a larger number of patients.

The role of ABCB1 polymorphism as a prognostic marker for primary central nervous system lymphoma.

To investigate the possible role of functional single nucleotide polymorphism (SNP) in circadian genes as prognostic markers of primary central nervous system lymphoma (PCNSL). We conducted a prospective study using data from Huashan Hospital 2006-2015 and followed up 91 PCNSL patients until June 30, 2016. The survival of patients with different prognostic factors was compared by log-rank test. Univariate and multivariate analyses were performed by Cox regression. During a long-term follow-up (6-110 months), overall survival (OS) was 32 months (95% CI, 13.3-91.1) and progression-free survival (PFS) was 23 months (95% CI, 9.0-41.0) for the entire cohort. Age (P = 0.046, P = 0.001) and performance status (PS) score (P = 0.013, P = 0.003) showed differences in OS and PFS. ABCB1 rs1045642 variant showed significant difference in PFS between patients with CC genotype and those with CT/TT genotypes (P = 0.020). In multivariate analysis, age (HR = 2.3; 95% CI, 1.2-4.2, P = 0.008), PS (HR = 2.4; 95% CI, 1.3-4.4, P = 0.007), and ABCB1 rs1045642 (HR = 1.9; 95% CI, 1.0-3.3, P = 0.036) were the independent risk factors for PFS. In our results, the most important prognostic factors associated with higher risk of progression were ABCB1 rs1045642 CC genotype, PS > 2, and older age.

Effects of ABCB1 gene polymorphisms on autonomic nervous system activity during atypical antipsychotic treatment in schizophrenia.

BACKGROUND: There are interindividual differences in the adverse effects of atypical antipsychotics, which include autonomic nervous system (ANS) dysfunction. Accordingly, to clarify the interindividual differences in the adverse effects of specific atypical antipsychotics in schizophrenia, we investigated the association between ANS dysfunction and ATP-binding cassette transport sub-family B member 1 (ABCB1) gene polymorphisms in patients with schizophrenia. METHODS: In total, 233 Japanese patients with schizophrenia participated in this study. All of the participants received an atypical antipsychotic as monotherapy: 89 participants received risperidone, 69 olanzapine, 48 aripiprazole, and 27 quetiapine. ANS activity was assessed by means of a power spectral analysis of heart rate variability. Four single nucleotide polymorphisms (SNPs) in ABCB1 (rs1045642, rs1128503, rs2032582, and rs2235048) were genotyped using the TaqMan method. RESULTS: For aripiprazole, sympathetic and total autonomic nervous activities were significantly lower in the rs1045642 T allele carrier-rs2235048 C allele carrier group than in the rs1045642 non-T allele carrier-rs2235048 non-C allele carrier group. In addition, in the aripiprazole group, the T-C-T-A haplotype (rs1045642-rs2235048-rs1128503-rs2032582) was associated with decreased ANS activity. However, there were no significant associations between ANS activity and ABCB1 gene polymorphisms in the risperidone, olanzapine, and quetiapine groups. Multiple regression analysis revealed that sympathetic and total nervous activities were significantly associated with the ABCB1 rs1045642-rs2235048 genotype and the T-C-T-A haplotype (rs1045642-rs2235048-rs1128503-rs2032582). CONCLUSION: We suggest that ABCB1 genetic polymorphisms affect aripiprazole-related ANS dysfunction but do not affect risperidone-, olanzapine-, or quetiapine-related ANS dysfunction.

[Unilateral multifocal uveal melanoma (a clinical and genetic study)]. / Monolateral'naia mul'tifokal'naia uveal'naia melanoma (kliniko-geneticheskoe issledovanie).

The study presents clinical and genetic analysis of a case of unilateral multifocal uveal choroidal melanoma in a patient of 67 years. Results of ophthalmoscopy, echography, fluorescent angiography, optical coherence tomography are described. Molecular genetic testing of peripheral blood samples was performed, including detection of the occurrences of CC genotype in C3435T polymorphism of the gene ABCB1/MDR1 associated with unfavorable vital prognosis. Analysis of the genes GNAQ and GNA11 revealed two mutually exclusive mutations in the genes GNAQG183A and GNAQA209C showing genetic heterogeneity of the two tumor lesions. Organ preservation treatment of unilateral multifocal uveal melanoma was proven possible with brachytherapy method. Uveal melanoma with multicentric growth is of interest to ophthalmologists because it requires differential diagnostics from a variety of diseases including metastases in the choroid, such as metastases of uveal melanoma and skin melanoma, as well as other intraocular neoplasms.

Parallel loss of introns in the ABCB1 gene in angiosperms.

BACKGROUND: The presence of non-coding introns is a characteristic feature of most eukaryotic genes. While the size of the introns, number of introns per gene and the number of intron-containing genes can vary greatly between sequenced eukaryotic genomes, the structure of a gene with reference to intron presence and positions is typically conserved in closely related species. Unexpectedly, the ABCB1 (ATP-Binding Cassette Subfamily B Member 1) gene which encodes a P-glycoprotein and underlies dwarfing traits in maize (br2), sorghum (dw3) and pearl millet (d2) displayed considerable variation in intron composition. RESULTS: An analysis of the ABCB1 gene structure in 80 angiosperms revealed that the number of introns ranged from one to nine. All introns in ABCB1 underwent either a one-time loss (single loss in one lineage/species) or multiple independent losses (parallel loss in two or more lineages/species) with the majority of losses occurring within the grass family. In contrast, the structure of the closest homolog to ABCB1, ABCB19, remained constant in the majority of angiosperms analyzed. Using known phylogenetic relationships within the grasses, we determined the ancestral branch-points where the losses occurred. Intron 7, the longest intron, was lost in only a single species, Mimulus guttatus, following duplication of ABCB1. Semiquantitative PCR showed that the M. guttatus ABCB1 gene copy without intron 7 had significantly lower transcript levels than the gene copy with intron 7. We further demonstrated that intron 7 carried two motifs that were highly conserved across the monocot-dicot divide. CONCLUSIONS: The ABCB1 gene structure is highly dynamic, while the structure of ABCB19 remained largely conserved through evolution. Precise removal of introns, preferential removal of smaller introns and presence of at least 2 bp of microhomology flanking most introns indicated that intron loss may have predominantly occurred through non-homologous end-joining (NHEJ) repair of double strand breaks. Lack of microhomology in the exon upstream of lost phase I introns was likely due to release of the selective constraint on the penultimate base (3rd base in codon) of the terminal codon by the splicing machinery. In addition to size, the presence of regulatory motifs will make introns recalcitrant to loss.

ABCB1 polymorphisms and steroid treatment in children with idiopathic nephrotic syndrome.

BACKGROUND: The most common cause of nephrotic syndrome (NS) is idiopathic nephrotic syndrome (INS), also called nephrosis. Although most patients respond to steroid therapy, there is unequal response to treatment suggesting the involvement of genetic factors. The current study was conducted to evaluate the influence of two single nucleotide polymorphisms (SNPs) in ABCB1 (C3435T and C1236T) on the steroid treatment response in INS children. MATERIALS AND METHODS: Genotyping of ABCB1 C3435T and C1236T polymorphisms by real time PCR were conducted on 120 INS children, 80 steroid sensitive (SS) and 40 steroid resistant (SR). RESULTS: A significant difference in the distribution of ABCB1 C3435T and C1236T genotypes was observed between SS and SR patients. C1236T polymorphism was associated with steroid resistance in INS children (odds ratio: 2.27, 95 % confidence interval: 1.2-4.4; P = 0.012). The frequency of the T allele was significantly higher in SR than in SS patients (81.2 vs. 65.6%, respectively). The odds ratio for the C3435T polymorphism in response to steroid treatment was smaller than that of the polymorphism C1236T, and did not reach statistical significance (odds ratio: 1.1, 95 % confidence interval: 0.6-1.9; P = 0.77). CONCLUSION: Our results suggested that C1236T polymorphism in ABCB1 gene was associated with steroid resistance. A higher proportion of SR children had C1236T TT genotype and T allele, these patients may require other therapeutic strategies.

[Genetic tests for controlling treatment with antidepressants]. / Genetische Tests zur Steuerung der Behandlung mit Antidepressiva.

In clinical practice, there is a need for a more individualized selection of antidepressants and adequate dosage. The investigation of pharmacokinetically relevant genes is a promising approach to assist this selection. In the past 2 years, two commercially available tests have been subject of advertisement, a test from Stada, which analyses variants of the cytochrome P450 isoenzymes CYP2D6 and CYP2C19 and a test from HMNC Brain Health, which analyses variants of the ABCB1 gene. The costs for both kits are not covered by the statutory health insurance and it is therefore proposed that the patients are invoiced directly in the form of individual healthcare payment. The companies claim that by applying the tests antidepressant treatment failure can be avoided and that patients will respond faster to the antidepressant used. These claims are not based on appropriate clinical trials, which are either lacking or reveal conflicting results. Hence, the routine use of these tests is not recommended. In accordance with the German S3 Guideline for unipolar depression, therapeutic drug monitoring (TDM) of serum levels should be carried out in cases of non-response to an antidepressant with adequate dosage and duration. As a rule the costs for TDM are covered by the statutory health insurance. Cytochrome P450 genotyping is only indicated when the serum level is not within the expected range and other reasons to explain this discrepancy are excluded. Many laboratories provide these analyses and in individual cases the costs are reimbursed by the statutory health insurance. Further research should be carried out to investigate the importance of the ABCB1 gene for the treatment with antidepressants.

ABCB1 polymorphism as prognostic factor in breast cancer patients treated with docetaxel and doxorubicin neoadjuvant chemotherapy.

Expression of the adenosine triphosphate-binding cassette B1 (ABCB1) transporter and P-glycoprotein are associated with resistance to anticancer drugs. The purpose of this study was to investigate the role of single nucleotide polymorphism in the ABCB1 and CYP3A genes in breast cancer patients who were treated with neoadjuvant chemotherapy. Stage II/III breast cancer patients were treated with three cycles of neoadjuvant, after which the patients received curative surgery and adjuvant chemotherapy. The polymorphisms of ABCB1 and CYP3A were genotyped. The correlation of polymorphism of ABCB1, CYP3A, and clinical outcomes was analyzed. Among the 216 patients, ABCB1 3435TT genotype had a longer overall survival (OS). than CC/CT. Multivariate analyses demonstrated that good PS, invasive ductal carcinoma, non-triple negative phenotype and initial operable stage were significantly associated with a lower death risk. ABCB1 3435TT genotype had a higher AUC than CC/CT for docetaxel. These higher AUCs in the C3435TT was associated with increased toxicities of neutropenia and diarrhea. This study showed that the genetic polymorphism of ABCB1 C3435T might be associated with a longer OS. Our results also suggest that the prediction of docetaxel toxicity might be possible for C3435T polymorphism. This study results provides valuable information on individualized therapy according to genotypes.

Higher frequency of C.3435 of the ABCB1 gene in patients with tramadol dependence disorder.

BACKGROUND: Polymorphic variation at the ABCB1 gene has been shown to affect the pharmacodynamics and kinetics of various drugs. AIM: This study aimed to determine the frequency of occurrence of Single Nucleotide Polymorphism (SNP) in position A118G OPRM1 (rs1799971) gene and C.3435 (rs1045642) gene in tramadol users in comparison with normal controls. METHODS: This was a cross sectional case-control outpatient study. The study sample consisted of 127 subjects (74 tramadol-dependents and 50 healthy controls). All patients fulfilled the Diagnostic and Statistical Manual IV Criteria for substance dependence (on tramadol). Genotyping of the OPRM1 gene 118 SNP and ABCB1 genes C.3435 SNP was performed by PCR, followed by restriction fragment length polymorphism identification. RESULTS: A significant association was found between the ABCB1 gene T allele at the polymorphic site 3435 and tramadol dependence. No significant association was observed with the A118G OPRM1 gene. CONCLUSION: The high frequency of ABCB1 gene T allele present at the polymorphic site 3435 could provide a protective mechanism from tramadol dependence disorder. Further study, using a larger sample, would be useful in further evaluating the possible role of ABCB1 gene polymorphisms.

The Effect of Platelet Activity, ABCB1 Genetic Polymorphism, and Renal Function on the Development of Ticagrelor-Related Dyspnea in Patients with Acute Coronary Syndrome.

Purpose: The aim of this study was to determine the effect of ABCB1 genetic polymorphism and renal function on the occurrence of ticagrelor-related dyspnea. Patients and Methods: A total of 299 patients with acute with type 1, 2, or 3 myocardial infarction (with and without ST-segment elevation), who underwent coronary angiography and PTCA with stent implantation and were treated with antiplatelet drugs (ticagrelor and aspirin), were enrolled in this prospective study. For all enrolled patient's platelet aggregation (induction with high-sensitivity adenosine diphosphate, ADP HS) testing was performed using a MULTIPLATE® analyzer. Venous blood was also collected for genotyping. Results: Patients experiencing ticagrelor-related dyspnea had lower ADP HS value (ADP HS ≤ 19.5 U; OR = 2.254; P = 0.009), higher creatinine concentration (>90 µmol/l; OR = 3.414; P = 0.019), and lower GFR value (<60 mL/min/1.73 m2; OR = 2.211; P = 0.035). ABCB1 T allele was associated with ticagrelor-related dyspnea (OR = 2.550; P = 0.04). Conclusion: Ticagrelor-related dyspnea was found to be related to low platelet aggregation, increased plasma creatinine concentration, decreased GFR, and ABCB1 T allele. Carriers of the ABCB1 T allele had a higher plasma creatinine concentration that could be associated with an inhibitory effect of ticagrelor on P-glycoprotein function.

The Effect of the ABCB1(MDR-1) C3435T Polymorphism in Turkish Patients with Aspirin Resistance in Acute Ischemic Stroke.

Recurrence of thrombotic events during aspirin therapy is known as aspirin resistance (AR). This study aimed to investigate the rate of AR, the factors influencing AR in patients with acute ischemic stroke under regular aspirin use, and the relationship between AR and ABCB1 (MDR-1) C3435T (rs1045642) polymorphism. Throughout this multicenter prospective study, 174 patients with acute ischemic stroke who had been prescribed aspirin for at least one month due to the risk of vascular disease, along with 106 healthy volunteers, were included as part of the study group. The results of our study indicate that AR was detected in 21.3% of the patient group. According to the results of an analysis of the polymorphism of the ABCB1 C3435T in patients with AR compared to those with aspirin sensitivity, patients with AR possessed more heterozygous (CT) and homozygous genotypes (TT) than those with aspirin sensitivity (p = 0.001). Based on multivariate logistic regression analysis of factors affecting AR in acute ischemic stroke patients, hypertension (OR: 5.679; 95% CI: 1.144-28.19; p = 0.034), heterozygous (CT) genotype (OR: 2.557; 95% CI: 1.126-5.807; p = 0.025), increased platelet values (OR: 1.005; 95% CI: 1.001-1.009; p = 0.029), and CRP/albumin values (OR: 1.547; 95% CI: 1.005-2.382; p = 0.047) were found to be associated with a greater risk of AR. The presence of heterozygous (CT) genotype in the ABCB1 C3435T gene region in the Turkish population is associated with an increased risk of AR. When planning aspirin therapy, it is crucial to consider the ABCB1 (MDR-1) C3435T polymorphism.

Influence of CYP450 Enzymes and ABCB1 Polymorphisms on Clopidogrel Response in Moroccan Patients with Acute Coronary Syndromes.

Introduction: Clopidogrel is an antiplatelet prodrug primarily prescribed to prevent or treat acute coronary syndrome (ACS) or acute ischemic stroke (IS), polymorphisms of genes encoding cytochrome P-450 (CYP) and P-glycoprotein transporter, could affect the efficiency of clopidogrel absorption and biotransformation, especially during the first critical hours following its administration. Methods: The present study was designed to investigate the potential association of clopidogrel responsiveness and 14 polymorphisms in the genes encoding the CYPs (CYP2C9, 2C19, 3A4, 3A5, 1A2, and 2B6), the ATP binding cassette subfamily B member 1 (ABCB1). Platelet aggregation activity was measured after 8h of 300mg clopidogrel administration for fifty-five ACS patients. Results: There was no significant association between polymorphism of the studied CYPs and clopidogrel responsiveness (P>0.05). The frequency of the ABCB1 3435 T allele in clopidogrel non-responders was higher (78.9%) compared to responders (52.8%), but this difference was not significant (P=0.057). Demographic characteristics, comorbidities, concomitant treatments were not associated with clopidogrel response. Discussion: There was no effect of the studied genetic variations and demographic factors on the platelet activity of clopidogrel in Moroccan ACS patients.

An Improved Technique for Genotyping the ABCB1 Gene Variant of Exon 21.

The Multidrug Resistance protein (ABCB1, MDR1) is involved in the transport of xenobiotics and antiretroviral drugs. Some variants of the ABCB1 gene are of clinical importance; among them, exon 12 (c.1236C>T, rs1128503), 21 (c.2677G>T/A, rs2032582), and 26 (c.3435C>T, rs1045642) have a high incidence in Caucasians. Several protocols have been used for genotyping the exon 21 variants, such as allele-specific PCR-RFLP using adapted primer to generate a digestion site for several enzymes and automatic sequencing to detect the SNVs, TaqMan Allele Discrimination assay and High-Resolution Melter analysis (HRMA). The aim was to describe a new approach to genotype the three variants c.2677G>T/A for the exon 21 doing only one PCR with the corresponding primers and the digestion of the PCR product with two restriction enzymes: BrsI to identify A allele and BseYI to differentiate between G or T. An improvement of this methodology was also described. The proposal technique here described is demonstrated to be very efficient, easy, fast, reproducible, and cost-effective.

ABCB1 gene variants as risk factors and modulators of age of onset of demyelinating disease in Mexican patients.

INTRODUCTION: The C1236T, G2677T/A, and C3435T variants of the ABCB1 gene alter the functioning of P-glycoprotein and the transport of endogenous and exogenous substances across the blood-brain barrier, and act as risk factors for some neurodegenerative diseases. This study aimed to determine the association between demyelinating disease and the C1236T, G2677T/A, and C3435T variants of ABCB1 and its haplotypes and combinations of genotypes. METHODS: Polymerase chain reaction with restriction fragment length polymorphism analysis (PCR-RFLP) and Sanger sequencing were used to genotype 199 patients with demyelinating disease and 200 controls, all Mexicans of mixed race; frequencies of alleles, genotypes, haplotypes, and genotype combinations were compared between patients and controls. We conducted a logistic regression analysis and calculated chi-square values and 95% confidence intervals (CI); odds ratios (OR) were calculated to evaluate the association with demyelinating disease. RESULTS: The TTT and CGC haplotypes were most frequent in both patients and controls. The G2677 allele was associated with demyelinating disease (OR: 1.79; 95% CI, 1.12-2.86; P =  .015), as were the genotypes GG2677 (OR: 2.72; 95% CI, 1.11-6.68; P =  .025) and CC3435 (OR: 1.82; 95% CI, 1.15-2.90; P =  .010), the combination GG2677/CC3435 (OR: 2.02; 95% CI, 1.17-3.48; P =  .010), and the CAT haplotype (OR: 0.21; 95% CI, 0.05-0.66; P =  .001). TTTTTT carriers presented the earliest age of onset (23.0 ±â€¯7.7 years, vs 31.6 ±â€¯10.7; P =  .0001). CONCLUSIONS: The GG2677/CC3435 genotype combination is associated with demyelinating disease in this sample, particularly among men, who may present toxic accumulation of P-glycoprotein substrates. In our study, the G2677 allele of ABCB1 may differentially modulate age of onset of demyelinating disease in men and women.

Pharmacogenetic Study of the Impact of ABCB1 Single Nucleotide Polymorphisms on the Response to Cyclosporine in Psoriasis Patients.

Psoriasis is a chronic, T cell-mediated skin disease affecting 2-3% of the Caucasian population. Cyclosporine A is a calcineurin inhibitor that acts selectively on T cells. The cyclosporine A treatment response has been suggested to be modulated by single-nucleotide polymorphisms (SNPs) in the ABCB1 gene. The aim of this research was to evaluate the effect of ABCB1 genetic variants that could affect the response to a cyclosporine treatment in Russian psoriasis patients with the ABCB1 genotype status. The ABCB1 T-129C, G1199A, C1236T, G2677T/A and C3435T SNPs in the 168 patients with psoriasis were genotyped by PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) and TaqMan SNP genotyping assays. The ABCB1 C1236T, G2677T/A and C3435T SNPs were significantly associated with a negative response to cyclosporine therapy. A very strong association was evident for the C3435T SNP in the ABCB1 gene in the allele, dominant and recessive models (OR = 2.58, OR = 4.01, OR = 2.50, respectively). ABCB1 C1236T and G2677T/A polymorphisms were significantly associated with a negative response to the cyclosporine therapy in the codominant, dominant and recessive models (p ˂ 0.05). Additionally, the haplotype analysis identified that the TGC haplotype is significantly associated with a negative response to cyclosporine therapy in psoriasis patients (p ˂ 0.05). The current study to the best of our knowledge is the first of its kind to be performed in the Russian population. In conclusion, the present results suggest an association between the ABCB1 genetic variants and unresponsiveness to cyclosporine in the Russian population. Further, larger studies are necessary to confirm our findings and replicate them in various ethnic populations before its implementation in the clinical practice.

Association between G2677T/A polymorphism in ABCB1 gene and the risk of drug resistance epilepsy: An updated systematic review and meta-analysis.

PURPOSE: Epilepsy is a common serious brain condition characterized by the abnormal electrical activity of neurons. In most cases, epileptic patients respond to antiepileptic drugs. Approximately, one-third of patients prove medically intractable. The ABCB1 gene is a superfamily of ATP-binding cassette (ABC) transporters that encode a drug-transport protein, lead to cells and organs protects and eliminates toxic agents. We performed this meta-analysis to assess the association between G2677T/A in the ABCB1 gene and the risk of drug resistance in epileptic patients. METHODS: Two online libraries (PubMed and Scopus) were used to identify studies that report the relationship between G2677T/A polymorphism in the MDR1 gene and the risk of antiepileptic drug resistance. The meta-analysis was performed using Review Manager 5.3 software. The pooled odds ratios and 95 % confidence intervals (CIs) were calculated using a random or fixed effects model according to the heterogeneity between studies. RESULTS: A total of 33 eligible studies were included in this meta-analysis which 4192 patients were drug-resistant and 5079 patients were drug-responsive. As a result, a significant association was observed in overall population for the genetic model GG+GA vs AA (OR with 95 % CI = 0,56 [0.34,0.93]; P = 0.02). The subgroup ethnicity analysis showed a significant decrease in the risk of AEDs resistance in the Caucasian population. CONCLUSION: In conclusion, our analysis demonstrates that G2677T/A polymorphism in the ABCB1 gene decreases the risk of drug resistance. More studies are needed in the different ethnic groups to clarify the role of polymorphism in AEDs resistance.