Polymorphisms of the MDR1 and MIF genes in children with nephrotic syndrome

Association of ABCB1(Rs10276036, C/T) Gene, IL-18, and TNFα as Risk Factors for Nephrotic Syndrome Incidence

Background

The most common cause of Nephrotic Syndrome (NS) in children is idiopathic NS, also called nephrosis. The most prominent clinical signs are hyperlipidemia, severe proteinuria, edema, swelling of body tissues, and an increased risk of infection. The object of this study was to examine the correlation of the ABCB1 gene (rs10276036, C > T), IL-18, and TNFα to the prevalence of NS among Egyptian children having NS.

Methods

This study included 100 participants with NS and 100 healthy controls. To analyze the ABCB1 gene (rs10276036 C >T) variant PCR technique was used. IL-18 and TNF levels were estimated using Enzyme-Linked Immunosorbent Assay (ELISA).

Results

Increased frequency of CT and TT genotypes of the ABCB1 gene (rs10276036 C / T) in NS patients compared to controls, with p-value = 0.001, OR = 2.270, CI = (1.550-3.327) for CT genotype and p-value = 0.001, OR = 5.070, CI = (2.463-10.438) for TT genotype. The frequencies of ABCB1 (rs10276036 C >T) genotypes were statistically significant in the dominant model (OR 2.560; p< 0.001) and in the recessive model OR, 3.231; p= 0.001). Significantly high levels of both IL-18 and TNFα were found in NS patients compared to controls.

Conclusions

The ABCB1gene (rs10276036 C/T), IL-18, and TNFα are associated with the prevalence of NS in Egyptian children and might be considered as independent risk factors for its incidence.

Assessment of the Link of ABCB1 and NR3C1 gene polymorphisms with the prednisolone resistance in pediatric nephrotic syndrome patients of Bangladesh: A genotype and haplotype approach

Introduction

Nephrotic syndrome is a common pediatric kidney disease. Investigations on several genetic polymorphisms revealed an inconsistent influence on the resistance of patients to steroids.

Objectives

This study aimed to identify the association of ABCB1 (1236C > T, 2677G > T, 3435C > T), NR3C1 (rs10482634, rs6877893), and CYP3A5 (CYP3A5*3) gene polymorphism as well as sociodemographic and clinicopathological parameters with the risk of developing prednisolone resistance in pediatric patients with nephrotic syndrome.

Methods

A case-control analysis was performed on 180 nephrotic syndrome patients. Among them, 30 patients were classified as prednisolone resistant group, and 150 were classified as prednisolone sensitive group. Genotyping was performed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

Results

No significant association of 1236C > T polymorphism with the risk of prednisolone resistance (p > 0.05) was found. The GT heterozygous of 2677G > T was found to be significantly associated with the development of prednisolone resistance (OR = 3.9, p = 0.034). In the case of 3435C > T, a statistically significant association was observed in TC heterozygous and TT mutant homozygous genotypes (OR = 0.38, p = 0.047; OR = 3.06, p = 0.038, respectively) with prednisolone resistance. For rs10482634 polymorphism, the AG heterozygous and AG+GG genotypes were significantly linked with prednisolone resistance (OR = 2.40, p = 0.033; OR = 2.36, p = 0.034, respectively). We found no association with the risk of prednisolone resistance with rs6877893 and CYP3A5*3 polymorphism (p > 0.05). CTC and TGT haplotypes of ABCB1 and GA haplotype of NR3C1 were also associated with the increased risk of pediatric prednisolone resistance (OR = 4.47, p = 0.0003; OR = 2.71, p = 0.03; and OR = 4.22, p = 0.022, consecutively). We also observed the correlation of different sociodemographic and clinicopathological factors with prednisolone resistance in pediatric nephrotic syndrome.

Conclusion

Our findings showed a significant association of ABCB1 and NR3C1 gene polymorphisms with prednisolone resistant pediatric nephrotic syndrome.

Steroid-resistant Nephrotic Syndrome in Children: A Mini-review on Genetic Mechanisms, Predictive Biomarkers and Pharmacotherapy Strategies

Steroid-resistant nephrotic syndrome (SRNS) constitutes the second most frequent cause of chronic kidney disease in childhood. The etiology of SRNS remains largely unknown and no standardized treatment exists. Recent advances in genomics have helped to build understanding of the molecular mechanisms and pathogenesis of the disease. The genetic polymorphisms in genes encoding proteins which are involved in the pharmacokinetics and pharmacodynamics of glucocorticoids (GCs) partially account for the different responses between patients with nephrotic syndrome. More importantly, single-gene causation in podocytes-associated proteins was found in approximately 30% of SRNS patients. Some potential biomarkers have been tested for their abilities to discriminate against pediatric patients who are sensitive to GCs treatment and patients who are resistant to the same therapy. This article reviews the recent findings on genetic mechanisms, predictive biomarkers and current therapies for SRNS with the goal to improve the management of children with this syndrome.

A Systematic Review and Meta-Analysis of Pharmacogenetic Studies in Patients with Chronic Kidney Disease

Chronic kidney disease (CKD) is an important global public health problem due to its high prevalence and morbidity. Although the treatment of nephrology patients has changed considerably, ineffectiveness and side effects of medications represent a major issue. In an effort to elucidate the contribution of genetic variants located in several genes in the response to treatment of patients with CKD, we performed a systematic review and meta-analysis of all available pharmacogenetics studies. The association between genotype distribution and response to medication was examined using the dominant, recessive, and additive inheritance models. Subgroup analysis based on ethnicity was also performed. In total, 29 studies were included in the meta-analysis, which examined the association of 11 genes (16 polymorphisms) with the response to treatment regarding CKD. Among the 29 studies, 18 studies included patients with renal transplantation, 8 involved patients with nephrotic syndrome, and 3 studies included patients with lupus nephritis. The present meta-analysis provides strong evidence for the contribution of variants harbored in the ABCB1, IL-10, ITPA, MIF, and TNF genes that creates some genetic predisposition that reduces effectiveness or is associated with adverse events of medications used in CKD.

Association Between Macrophage Migration Inhibitory Factor -173 G>C Gene Polymorphism and Childhood Idiopathic Nephrotic Syndrome: A Meta-Analysis

Background: Studies have identified that MIF -173 G>C gene polymorphism is associated with idiopathic nephrotic syndrome (INS) susceptibility and steroid resistance, but the results remain inconclusive. Methods: We searched PubMed, Embase, and Web of Science for relevant studies published before 31 March 2021. Pooled data were reported as odds ratio (OR) with 95% confidence interval (CI). Noteworthiness of significant OR was estimated by the false positive report probability (FPRP) test. Trial sequential analysis (TSA) was used to control type I and type II errors. Results: We selected seven case-control studies that included 1,026 INS children (362 were steroid-resistant NS and 564 were steroid-sensitive NS) and 870 controls. The results showed that MIF -173 G>C polymorphism was significantly associated with INS susceptibility in allelic, heterozygous and dominant genetic models (C vs. G: OR = 1.325, 95% CI: 1.011-1.738; GC vs. GG: OR = 1.540, 95% CI: 1.249-1.899; CC + GC vs. GG: OR = 1.507, 95% CI: 1.231-1.845), and FPRP test and TSA indicated that the associations were true in heterozygous and dominant models. The pooled results also revealed that MIF -173 G>C polymorphism was significantly associated with steroid resistance in allelic, homozygous and recessive models (C vs. G: OR = 1.707, 95% CI: 1.013-2.876; CC vs. GG: OR = 4.789, 95% CI: 2.109-10.877; CC vs. GC + GG: OR = 4.188, 95% CI: 1.831-9.578), but FPRP test indicated that all these associations were not noteworthy. Furthermore, TSA revealed that the non-significant associations between MIF -173 G>C polymorphism and steroid resistance in heterozygous and dominant models were potential false negative. Conclusions: This meta-analysis could draw a firm conclusion that MIF -173 G>C polymorphism was significantly associated with increased INS risk in heterozygous and dominant genetic models. MIF -173 G>C polymorphism was not likely to affect steroid responsiveness, but more studies were needed to confirm.

Correlations of MIF polymorphism and serum levels of MIF with glucocorticoid sensitivity of sudden sensorineural hearing loss

Objective

This study explored the relationship between macrophage migration inhibitory factor (MIF) gene polymorphism (−173G/C) and glucocorticoid sensitivity in sudden sensorineural hearing loss (SSNHL).

Methods

A total of 120 patients with SSNHL were divided into a glucocorticoid-sensitive group and a glucocorticoid-resistant group. A group of 93 healthy individuals served as the control group. Serum MIF levels of the participants were measured and MIF genotyping was performed.

Results

The frequency of the MIF −173C allele was significantly higher in glucocorticoid-sensitive patients than in glucocorticoid-resistant patients. Serum MIF levels were significantly higher in SSNHL patients than in healthy controls, and higher in the glucocorticoid-sensitive group than in the glucocorticoid-resistant group of SSNHL patients, which was unexpected. Compared with patients with the GG genotype, patients with the −173C allele (GC and CC genotypes) had significantly higher levels of serum MIF and superoxide dismutase activity and lower levels of tumor necrosis factor-α and malondialdehyde.

Conclusion

The MIF −173G/C polymorphism is associated with glucocorticoid sensitivity in SSNHL patients. The C allele can result in higher MIF production, reduced oxidative stress, and greater glucocorticoid sensitivity.

MIF plasma level as a possible tool to predict steroid responsiveness in children with idiopathic nephrotic syndrome

PURPOSE

Idiopathic nephrotic syndrome (INS) is the most frequent form of childhood nephrotic syndrome. Steroids represent the best therapeutic option; however, inter-individual differences in their efficacy and side effects have been reported. To date, there is no way to predict patients' resistance and/or dependence. Alterations in the cytokine profile of INS patients might contribute to proteinuria and glomerular damage and affect drug sensitivity.

METHODS

The cytokine plasma levels were measured in 21 INS children at diagnosis to investigate the association among cytokines pattern and clinical response. Patients were selected on the basis of their clinical response: 7 steroid sensitive (SS), 7 dependent (SD), and 7 resistant (SR). Significant results were then analyzed in 41 additional pediatric INS patients.

RESULTS

Within the 48 cytokines analyzed, macrophage migration inhibitory factor (MIF) was a good predictor of steroid response. Indeed, SR patients showed significantly higher MIF plasma levels compared with all others (p = 0.022; OR = 4.3, 95%CI = 1.2-25.4): a cutoff concentration of MIF > 501 pg/ml significantly discriminated SR patients (sensitivity = 85.7%, specificity = 71.4%). On the contrary, SD patients showed lower MIF plasma levels compared with others (p = 0.010; OR = 0.12, 95%CI = 9.2 × 10-3-6.7 × 10-1). Significant results were confirmed in the entire cohort.

CONCLUSIONS

Our comprehensive cytokine analysis indicates that assessing MIF plasma levels at diagnosis could predict response to glucocorticoids in children with INS.

Crosstalk Between Lipids and Mitochondria in Diabetic Kidney Disease

PURPOSE OF REVIEW

The goal of this review is to review the role that renal parenchymal lipid accumulation plays in contributing to diabetic kidney disease (DKD), specifically contributing to the mitochondrial dysfunction observed in glomerular renal cells in the context of DKD development and progression.

RECENT FINDINGS

Mitochondrial dysfunction has been observed in experimental and clinical DKD. Recently, Ayanga et al. demonstrate that podocyte-specific deletion of a protein involved in mitochondrial dynamics protects from DKD progression. Furthermore, our group has recently shown that ATP-binding cassette A1 (a protein involved in cholesterol and phospholipid efflux) is significantly reduced in clinical and experimental DKD and that genetic or pharmacological induction of ABCA1 is sufficient to protect from DKD. ABCA1 deficiency in podocytes leads to mitochondrial dysfunction observed with alterations of mitochondrial lipids, in particular, cardiolipin (a mitochondrial-specific phospholipid). However, through pharmacological reduction of cardiolipin peroxidation DKD progression is reverted. Lipid metabolism is significantly altered in the diabetic kidney and renders cellular components, such as the podocyte, susceptible to injury leading to worsened DKD progression. Dysfunction of the lipid metabolism pathway can also lead to mitochondrial dysfunction and mitochondrial lipid alteration. Future research aimed at targeting mitochondrial lipids content and function could prove to be beneficial for the treatment of DKD.

Pharmacology and pharmacogenetics of prednisone and prednisolone in patients with nephrotic syndrome

Nephrotic syndrome is one of the most common glomerular disorders in childhood. Glucocorticoids have been the cornerstone of the treatment of childhood nephrotic syndrome for several decades, as the majority of children achieves complete remission after prednisone or prednisolone treatment. Currently, treatment guidelines for the first manifestation and relapse of nephrotic syndrome are mostly standardized, while large inter-individual variation is present in the clinical course of disease and side effects of glucocorticoid treatment. This review describes the mechanisms of glucocorticoid action and clinical pharmacokinetics and pharmacodynamics of prednisone and prednisolone in nephrotic syndrome patients. However, these mechanisms do not account for the large inter-individual variability in the response to glucocorticoid treatment. Previous research has shown that genetic factors can have a major influence on the pharmacokinetic and dynamic profile of the individual patient. Therefore, pharmacogenetics may have a promising role in personalized medicine for patients with nephrotic syndrome. Currently, little is known about the impact of genetic polymorphisms on glucocorticoid response and steroid-related toxicities in children with nephrotic syndrome. Although the evidence is limited, the data summarized in this study do suggest a role for pharmacogenetics to improve individualization of glucocorticoid therapy. Therefore, studies in larger cohorts with nephrotic syndrome patients are necessary to draw final conclusions about the influence of genetic polymorphisms on the glucocorticoid response and steroid-related toxicities to ultimately implement pharmacogenetics in clinical practice.

Genetics of Childhood Steroid Sensitive Nephrotic Syndrome: An Update

Advances in genome science in the last 20 years have led to the discovery of over 50 single gene causes and genetic risk loci for steroid resistant nephrotic syndrome (SRNS). Despite these advances, the genetic architecture of childhood steroid sensitive nephrotic syndrome (SSNS) remains poorly understood due in large part to the varying clinical course of SSNS over time. Recent exome and genome wide association studies from well-defined cohorts of children with SSNS identified variants in multiple MHC class II molecules such as HLA-DQA1 and HLA-DQB1 as risk factors for SSNS, thus stressing the central role of adaptive immunity in the pathogenesis of SSNS. However, evidence suggests that unknown second hit risk loci outside of the MHC locus and environmental factors also make significant contributions to disease. In this review, we examine what is currently known about the genetics of SSNS, the implications of recent findings on our understanding of pathogenesis of SSNS, and how we can utilize these results and findings from future studies to improve the management of children with nephrotic syndrome.

Causes and Consequences of Variability in Drug Transporter Activity in Pediatric Drug Therapy

Drug transporters play a key role in mediating the uptake of endo- and exogenous substances into cells as well as their efflux. Therefore, variability in drug transporter activity can influence pharmaco- and toxicokinetics and be a determinant of drug safety and efficacy. In children, particularly in neonates and young infants, the contribution of tissue-specific drug transporters to drug absorption, distribution, and excretion may differ from that in adults. In this review 5 major factors and their interdependence that may influence drug transporter activity in children are discussed: developmental differences, genetic polymorphisms, pediatric comorbidities, interacting comedication, and environmental factors. Even if data are sparse, altered drug transporter activity due to those factors have been associated with clinically relevant differences in drug disposition, efficacy, and safety in pediatric patients. Single nucleotide polymorphisms in drug transporter-encoding genes were the most studied source of drug transporter variability in children. However, in the age group where drug transporter activity has been reported to differ from that in adults, namely neonates and young infants, hardly any studies have been performed. Longitudinal studies in this young population are required to investigate the age- and disease-dependent genotype-phenotype relationships and relevance of drug transporter drug-drug interactions. Physiologically based pharmacokinetic modeling approaches can integrate drug- and patient-specific parameters, including drug transporter ontogeny, and may further improve in silico predictions of pediatric-specific pharmacokinetics.

A PRISMA-compliant meta-analysis of MDR1 polymorphisms and idiopathic nephrotic syndrome: Susceptibility and steroid responsiveness

BACKGROUND

Studies have investigated rs1128503, rs1045642, and rs2032582 in multidrug resistance protein 1 (MDR1) for association with susceptibility to idiopathic nephrotic syndrome (INS) and steroid resistance. However, because these findings were inconsistent, we performed a meta-analysis to determine whether there was evidence of a role of these MDR1 variants in INS.

METHODS

The PubMed, Embase, and Web of Science databases were systematically searched to identify studies that examined MDR1 polymorphisms with susceptibility to INS and/or to steroid resistance. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by a fixed-effects or random-effects model based on heterogeneity.

RESULTS

We selected 9 case-control studies that included 928 patients with INS, of which steroid resistance data were available for 724 (236 were steroid resistant and 488 were steroid sensitive), and 879 healthy controls. All subjects were children. No significant relationships between these polymorphisms and INS susceptibility were identified. Significantly increased risk of steroid resistance was observed with rs1128503 allelic (OR = 1.49, 95% CI = 1.20-1.86) and genotypic (OR = 1.97, 95% CI = 1.18-3.30; OR = 2.03, 95% CI = 1.43-2.88) comparisons, and with allelic (OR = 1.56, 95% CI = 1.05-2.31) and genotypic (OR = 2.85, 95% CI = 1.15-7.07; OR = 2.21, 95% CI = 1.01-4.8) comparisons to rs2032582 in Caucasian populations. However, this association between rs2032582 and steroid resistance was not robust enough to withstand corrections for multiple comparisons. Similarly, we found that the rs1128503T-rs2032582G-rs1045642C (T-G-C) haplotype was associated with an increased risk of steroid resistance (OR = 2.02, 95% CI = 1.13-3.59), while the wild-type C-G-C haplotype was associated with a decreased risk (OR = 0.32, 95% CI = 0.12-0.88) in Caucasians; however, these findings were not significant following adjustments for multiple comparisons.

CONCLUSIONS

MDR1 rs1128503, rs1045642, and rs2032582 polymorphisms are not associated with INS susceptibility; however, there is evidence of an association between rs1128503 and increased risk of steroid resistance in children with INS, which indicates MDR1 may play a role in steroid resistance found in children with INS.

Genetic variation in the glucocorticoid pathway involved in interindividual differences in the glucocorticoid treatment

Glucocorticoids (GCs) are widely used for treating asthma, rheumatoid arthritis, nephrotic syndrome, acute lymphoblastic leukemia and other autoimmune diseases. However, in a subgroup of patients, failure to respond to GCs is known as GC resistance or GC insensitivity. This represents an important barrier to effective treatment and a clinical problem requiring an urgent solution. Genetic variation in the GC pathway is a significant factor in interindividual differences in GC treatment. This article reviews the pharmacogenetics of GCs in diverse diseases based on the GC pathway.

Functional dyspepsia susceptibility is related to CD14, GNB3, MIF, and TRPV1 gene polymorphisms in the Greek population

BACKGROUND

Functional dyspepsia (FD) susceptibility might be influenced by polymorphisms of genes related to inflammation (CD14, macrophage migration inhibitory factor [MIF]), motor (GNB3), and sensory dysfunction (GNB3, TRPV1). We examined the association between CD14 rs2569190, GNB3 rs5443, MIF rs222747, and TRPV1 rs755622 gene polymorphisms with FD (Rome III criteria) in the Greek population.

METHODS

We genotyped 174 dyspeptics (115 with epigastric pain syndrome; 41% Helicobacter pylori positive) and 181 controls using polymerase chain reaction-based methods and we measured disease symptoms' burden with a modified Gastrointestinal Symptoms Related Scale.

KEY RESULTS

Homozygous for the TT genotype and the T allele of the CD14 gene were significantly associated (OR [95% CI]) with FD (2.65 [1.42-4.94] and 1.67 [1.23-2.26], respectively). The CT, TT genotypes, and T allele frequencies of GNB3 showed also significant association with FD (2.18 [1.35-3.54], 3.46 [1.30-9.23], and 2.18 [1.48-3.19]). While heterozygous GC MIF genotype was more common in dyspeptics (1.67 [1.07-2.60]), homozygous CC genotype and the C allele of TRPV1 gene were more prevalent in controls (0.47 [0.25-0.87] and 0.69 [0.51-0.92], respectively). None of the gene polymorphism was related either to dyspepsia clinical syndrome type or to the H. pylori infection. Among dyspeptics, CD14 TT genotype was related to lower epigastric pain burden score (p<.011); CD14 CT genotype was related to higher epigastric burning and nausea burden scores (p<.04) while belching score was lower (p=.027) in MIF CG dyspeptics.

CONCLUSION & INFERENCES

Functional dyspepsia susceptibility is related to CD14, GNB3, MIF, and TRPV1 gene polymorphisms, while CD14 and MIF gene variants are also associated with dyspepsia symptoms burden.

Association between MDR1 gene polymorphisms and the risk of Crohn's disease in a cohort of Algerian pediatric patients

BACKGROUND

The multi-drug resistance gene (MDR1) has raised increasing interest as a susceptibility gene for Crohn's disease (CD). The role of MDR1 single-nucleotide polymorphisms (SNPs) in the predisposition and behavior of CD in the pediatric population is still elusive. Here, we investigated whether SNPs in MDR1 are associated with CD in Algerian pediatric patients.

METHODS

A case-control study was conducted enrolling 47 pediatric CD patients and 100 controls. All subjects were genotyped for the most common MDR1 SNPs (C3434T, C1236T, and G2677A/T) using PCR-RFLP method. We also explored the association between polymorphisms and clinical sub-phenotypes.

RESULTS

We have detected no significant association of C3435T SNP and pediatric CD. However, we observed a significantly higher frequency of the risk alleles, 1236T and 2677T/A among the CD patients compared to controls. Moreover, the risk allele 1236T was associated to a higher risk for resective surgery.

CONCLUSION

Our data suggest that the C1236T and G2677A/T SNPs in the MDR1 gene are associated with CD and the C1236T risk allele with a more severe course of disease in Algerian pediatric patients. Further analysis using larger patients group and functional studies would be interesting to elucidate the role of MDR1 gene in pediatric CD.Pediatric Research (2016); doi:10.1038/pr.2016.163.

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.

Differential effects of hydrocortisone, prednisone, and dexamethasone on hormonal and pharmacokinetic profiles: a pilot study in children with congenital adrenal hyperplasia

Background

Little is known about the comparative effects of different glucocorticoids on the adrenal and growth hormone (GH) axes in children with congenital adrenal hyperplasia (CAH). We sought to compare the effects of hydrocortisone (HC), prednisone (PDN), and dexamethasone (DEX) in children with classic CAH and to investigate a potential role of pharmacogenetics.

Methods

Subjects were randomly assigned to three sequential 6-week courses of HC, PDN, and DEX, each followed by evaluation of adrenal hormones, IGF-1, GH, and body mass index (BMI). Single nucleotide polymorphism (SNP) analysis of genes in the glucocorticoid pathway was also performed.

Results

Nine prepubertal subjects aged 8.1 ± 2.3 years completed the study. Mean ACTH, androstenedione, and 17-hydroxyprogesterone (17-OHP) values were lower following the DEX arm of the study than after subjects received HC (p ≤ 0.016) or PDN (p ≤ 0.002). 17-OHP was also lower after HC than PDN (p < 0.001). There was no difference in IGF-1, GH, or change in BMI. SNP analysis revealed significant associations between hormone concentrations, pharmacokinetic parameters, and variants in several glucocorticoid pathway genes (ABCB1, NR3C1, IP013, GLCCI1).

Conclusions

DEX resulted in marked adrenal suppression suggesting that its potency relative to hydrocortisone and prednisone was underestimated. SNPs conferred significant differences in responses between subjects. Although preliminary, these pilot data suggest that incorporating pharmacogenetics has the potential to eventually lead to targeted therapy in children with CAH.

Single Nucleotide Polymorphisms in Pediatric Idiopathic Nephrotic Syndrome

Polymorphic variants in several molecules involved in the glomerular function and drug metabolism have been implicated in the pathophysiology of pediatric idiopathic nephrotic syndrome (INS), but the results remain inconsistent. We analyzed the association of eleven allelic variants in eight genes (angiopoietin-like 4 (ANGPTL4), glypican 5 (GPC5), interleukin-13 (IL-13), macrophage migration inhibitory factor (MIF), neural nitric oxide synthetase (nNOS), multidrug resistance-1 (MDR1), glucocorticoid-induced transcript-1 (GLCCI1), and nuclear receptor subfamily-3 (NR3C1)) in 100 INS patients followed up till adulthood. We genotyped variants using PCR and direct sequencing and evaluated estimated haplotypes of MDR1 variants. The analysis revealed few differences in SNP genotype frequencies between patients and controls, or in clinical parameters among the patients. Genotype distribution of MDR1 SNPs rs1236, rs2677, and rs3435 showed significant (p < 0.05) association with different medication regimes (glucocorticoids only versus glucocorticoids plus additional immunosuppressives). Some marginal association was detected between ANGPTL4, GPC5, GLCCI1, and NR3C1 variants and different medication regimes, number of relapses, and age of onset. Conclusion. While MDR1 variant genotype distribution associated with different medication regimes, the other analyzed gene variants showed only little or marginal clinical relevance in INS.

Association between Macrophage Migration Inhibitory Factor Gene Variation and Response to Glucocorticoid Treatment in Sudden Sensorineural Hearing Loss

Several lines of evidence suggest the role of the immune system in the pathogenesis of sudden sensorineural hearing loss (SSNHL). Macrophage migration inhibitory factor (MIF) mediates its role in various immune and inflammatory conditions by the regulation of immune reactions. Several studies have confirmed an association between MIF gene polymorphisms and susceptibility to various inflammatory and autoimmune disorders. The aim of this study was to explore the association between the MIF (-173 G/C) polymorphism (rs755622) and SSNHL in an Iranian population. In this case-control association study, SSNHL cases (n = 77) were included. Normal healthy subjects (n = 100) were also recruited from the same region. Genotyping for MIF (-173 G/C) polymorphism was carried out using the polymerase chain reaction-restriction fragment length polymorphism technique. The frequency of the MIF -173 C allele carriers (GC + CC genotype) was significantly elevated in SSNHL patients who responded to glucocorticoid treatment compared with the patients with no response to treatment. These results suggest that the MIF gene polymorphism is associated with a response to glucocorticoid treatment in patients with SSNHL.

Glucocorticoid pharmacogenetics in pediatric idiopathic nephrotic syndrome

Idiopathic nephrotic syndrome represents the most common type of primary glomerular disease in children: glucocorticoids (GCs) are the first-line therapy, even if considerable interindividual differences in their efficacy and side effects have been reported. Immunosuppressive and anti-inflammatory effects of these drugs are mainly due to the GC-mediated transcription regulation of pro- and anti-inflammatory genes. This mechanism of action is the result of a complex multistep pathway that involves the glucocorticoid receptor and several other proteins, encoded by polymorphic genes. Aim of this review is to highlight the current knowledge on genetic variants that could affect GC response, particularly focusing on children with idiopathic nephrotic syndrome.

A Study of Human Killer Cell Immunoglobulin-Like Receptor and Multidrug Resistance Gene Polymorphisms in Children With Immune Thrombocytopenia

THE OBJECTIVE

This study was undertaken to detect characterization of the different gene polymorphisms in Human killer cell immunoglobulin-like receptor (KIR2) gene and multi-drug resistance (MDR1) gene, among childhood ITP Egyptian patients. In addition to assess the potential role of these polymorphisms in relation to types of ITP and response to different treatment modalities.

PATIENTS AND METHODS

A total of 48 pediatric patients with immune thrombocytopenia (ITP; 24 newly diagnosed and 24 chronic) and 35 healthy controls were investigated via polymerase chain reaction-restriction fragment length polymorphism analysis for multidrug resistance (MDR) 1 and killer cell immunoglobulin-like receptor (KIR) 2 genes.

RESULTS

The frequency of MDR1 gene in patients and control was not significant (P = .090). The CT genotype was the highest distribution among all ITP cases (62.50%, n = 30) and control (48.60%, n = 17). There was a significant difference in age at diagnosis of MDR1 gene with the CC genotype had the eldest age and lowest initial platelets count (P = .029 and P = .004). The distribution of KIR2 gene among all patients with ITP and controls was significant (P = .026) with (KIRDL2-/KIRDS2-) genotype was the most prevalent among patients.

CONCLUSION

The frequency of MDR1 polymorphisms was not associated with susceptibility to the development and clinical progression of the disease. However, KIR2 gene polymorphisms were independently associated with childhood ITP in Egyptian patients with highest prevalence among (KIRDL2-/KIRDS2-) genotypes.

MDR1 polymorphisms and idiopathic nephrotic syndrome in Slovak children: preliminary results

Background

The role of the multidrug resistance-1 (MDR1 or ABCB1) gene polymorphisms 1236T>C, 2677T>G, and 3435T>C was studied in relation to susceptibility, demographics, and pathological characteristics, as well as their role in the therapeutic response (TR) to prednisone treatment in children with idiopathic nephrotic syndrome (INS).

Material/Methods

The polymorphisms were analyzed using the polymerase chain reaction-restriction fragment length polymorphism method in 46 children with INS and in 100 healthy controls. Different genetic models (codominant, dominant, recessive, and overdominant) were used for testing of associations between polymorphisms and phenotypes.

Results

Statistical analysis showed a significantly increased chance of TR in children carrying 3435TC genotype (OR=5.13, 95% CI=1.18–22.25; overdominant model). Moreover, INS patients under 6 years of age had significantly decreased frequencies of MDR1 1236CC (7.7% vs. 35%, p=0.029) or 2677GG (3.8% vs. 30.0%, p=0.033) genotypes. We also observed that patients with minimal change in disease and patients under 6 years of age at the onset of INS were initial responders more frequently when compared with children with focal segmental glomerulosclerosis and patients ≥6 years old at the onset (p=0.0001, p=0.027, respectively).

Conclusions

These data suggest that prednisone TR may be influenced by histology, age at the onset of INS, and MDR1 3435T>C polymorphism. The MDR1 1236T>C and 2677T>G polymorphisms were significantly associated with age at onset. Larger multicenter studies and studies across other ethnic groups are needed to elucidate the contradictory implications of MDR1 polymorphisms with INS in children.

Multi-drug resistance-1 gene polymorphisms in nephrotic syndrome: impact on susceptibility and response to steroids

BACKGROUND

Role of multidrug resistance-1 (MDR-1) gene polymorphisms has not been clarified in nephrotic syndrome (NS). Additionally, researchers studied several genetic polymorphisms to explain their influence on different patients' responses to steroid; however the data were inconsistent. Therefore, we aimed to investigate the association of MDR-1 gene polymorphisms [C1236T, G2677T/A, C3435T] and haplotypes with susceptibility to childhood nephrotic syndrome, and whether they influence steroid response.

METHODS

We detected MDR-1 gene polymorphisms using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) in 138 NS patients and 140 age and sex matched healthy children.

RESULTS

The frequencies of MDR1 G2677T/A GT, GA, TT+AA genotypes or T allele, MDR1 C3435T TT genotype, and T allele genotype frequencies were significantly increased in NS group. While no significant differences were observed in distributions of C1236T genotypes or allele between NS patients and healthy children. Moreover, steroid non-responder NS patients had significantly higher frequencies of MDR1 G2677T/A GT, GA, and TT+AA genotypes than steroid responsive NS patients. We observed also that NS patients with age less than 6 years old had increased frequencies of MDR1 G2677T/A GT, GA, TT+AA genotypes or T allele MDR1 C3435T CT, TT genotypes and T allele. Interestingly the frequency of the TGC haplotype of MDR1 was lower in the initial steroid responders than in non-responders NS patients. On the contrary, there were no any association between the MDR1 haplotypes with NS susceptibility and they did not influence renal pathological findings.

CONCLUSION

Our data suggested that MDR1 C3435T or G2677T/A gene polymorphisms are risk factors of increased susceptibility, earlier onset of NS, and steroid resistance.

Macrophage migration inhibitory factor gene polymorphisms and plasma levels in children with obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is associated with increased risk for cardiovascular and metabolic dysfunction in both adults and children. In adults with OSA, serum levels of macrophage migration inhibitory factor (MIF) are elevated. Therefore, we assessed plasma MIF levels and MIF allelic variant frequencies in children with and without OSA (NOSA).

METHODS

A total of 614 consecutive children ages 5-8 years were recruited. Children were divided into those with OSA and NOSA based on the apnea-hypopnea index (AHI). In addition to lipid profile, hsCRP, and fasting insulin and glucose levels, plasma MIF levels were assayed using ELISA, and 28 single nucleotide polymorphisms (SNPs) covering the region were genotyped. Linkage disequilibrium and haplotype blocks were analyzed using Haploview version 4.2 software.

RESULTS

Morning plasma MIF levels were increased in children with OSA. Of the 28 SNPs tested, the frequency of rs10433310 minor allele was significantly decreased in OSA. This SNP was also associated with reduced fasting insulin and hsCRP levels in OSA. The minor allele frequency of all other 27 SNPs was similar in OSA and NOSA groups.

CONCLUSIONS

Childhood OSA is associated with higher plasma MIF, hsCRP, and fasting insulin levels that promote cardiometabolic risk, and the MIF gene SNP rs10433310 may account for some of the variance in such risk.

Regulatory pathways for ATP-binding cassette transport proteins in kidney proximal tubules

The ATP-binding cassette transport proteins (ABC transporters) represent important determinants of drug excretion. Protective or excretory tissues where these transporters mediate substrate efflux include the kidney proximal tubule. Regulation of the transport proteins in this tissue requires elaborate signaling pathways, including genetic, epigenetic, nuclear receptor mediated, posttranscriptional gene regulation involving microRNAs, and non-genomic (kinases) pathways triggered by hormones and/or growth factors. This review discusses current knowledge on regulatory pathways for ABC transporters in kidney proximal tubules, with a main focus on P-glycoprotein, multidrug resistance proteins 2 and 4, and breast cancer resistance protein. Insight in these processes is of importance because variations in transporter activity due to certain (disease) conditions could lead to significant changes in drug efficacy or toxicity.

GLCCI1 single nucleotide polymorphisms in pediatric nephrotic syndrome

BACKGROUND

Empiric steroid therapy is the first-line therapy for pediatric nephrotic syndrome, but treatment response is variable. There are few predictors of steroid-responsiveness, although evidence for genetic factors does exist. Single nucleotide polymorphisms (SNPs) have been recently identified in the promoter region of glucocorticoid-induced transcript 1 gene (GLCCI1) which affect steroid-responsiveness in asthmatic patients. Independently, GLCCI1 was identified as a podocyte protein, the loss of which disrupts the function of the glomerular filtration barrier. We therefore examined whether SNPs associated with the steroid-responsive expression of GLCCI1 might predict steroid-responsiveness in nephrotic syndrome.

CASE-DIAGNOSIS/TREATMENT

A cohort of 211 pediatric patients with nephrotic syndrome and 102 controls were genotyped; among the cases, 117 were initial steroid responders, while 94 did not respond to oral steroids. No statistically significant differences were noted among the groups, although there was a trend based on the comparison of the small subgroups of steroid-responsive and non-responsive patients with biopsy-proven minimal change disease.

CONCLUSIONS

While larger cohorts are needed to ascertain the possibility of a small effect of GLCCI1 SNPs on the steroid-responsiveness of nephrotic syndrome, the GLCCI1 SNPs associated with steroid-responsiveness in asthmatic patients are unlikely to have a clinically actionable impact in pediatric nephrotic syndrome.

The influence of DNA polymorphism of multidrug resistant 1 (MDR1) on the effect of midazolam pretreatment in children

Background

Patients showed a different response following intravenous midazolam injection. Some children showed irritability or were not sedated by midazolam. We hypothesized that there may be genetic variations of the MDR1 gene, based on the response to midazolam.

Methods

One hundred and ninety-three pediatric patients were recruited in this study. Midazolam (0.1 mg/kg) was injected intravenously before surgery. Anxiety score (activity, vocalizations, emotional expressivity, state of apparent arousal) was checked before and 5 minutes after midazolam injection. In addition, other manifestations after midazolam injection were recorded. After anesthesia, 2 ml of blood was sampled. Children were genotyped MDR1. Haplotype was analyzed using the software package PHASE, version 2.0.

Results

The observed frequencies of MDR1 haplotype of TTT, TGC, CAC, CGC were 0.334, 0.205, 0.182 and 0.225, respectively. There was no significant correlation between the response of midazolam and the MDR1 haplotype of TTT, TGC, CAC or CGC (P = 0.98).

Conclusions

Genotyping of MDR1 may not be related to the response of midazolam in children.