BackgroundIn addition to HLA genetic incompatibility, non-HLA difference between donor and recipients of transplantation leading to allograft rejection are now becoming evident. We aimed to create a unique genome-wide platform to facilitate genomic research studies in transplant-related studies. We designed a genome-wide genotyping tool based on the most recent human genomic reference datasets, and included customization for known and potentially relevant metabolic and pharmacological loci relevant to transplantation.MethodsWe describe here the design and implementation of a customized genome-wide genotyping array, the ‘TxArray’, comprising approximately 782,000 markers with tailored content for deeper capture of variants across HLA, KIR, pharmacogenomic, and metabolic loci important in transplantation. To test concordance and genotyping quality, we genotyped 85 HapMap samples on the array, including eight trios.ResultsWe show low Mendelian error rates and high concordance rates for HapMap samples (average parent-parent-child heritability of 0.997, and concordance of 0.996). We performed genotype imputation across autosomal regions, masking directly genotyped SNPs to assess imputation accuracy and report an accuracy of >0.962 for directly genotyped SNPs. We demonstrate much higher capture of the natural killer cell immunoglobulin-like receptor (KIR) region versus comparable platforms. Overall, we show that the genotyping quality and coverage of the TxArray is very high when compared to reference samples and to other genome-wide genotyping platforms.ConclusionsWe have designed a comprehensive genome-wide genotyping tool which enables accurate association testing and imputation of ungenotyped SNPs, facilitating powerful and cost-effective large-scale genotyping of transplant-related studies.Electronic supplementary materialThe online version of this article (doi:10.1186/s13073-015-0211-x) contains supplementary material, which is available to authorized users.

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Background: The osteocyte-derived hormone, fibroblast growth factor 23 (FGF23), regulates the phosphorus metabolism and suppresses 1,25-dihydroxyvitamin D production, thereby mitigating hyperphosphatemia in patients with renal disorders. An elevated FGF23 level is suggested to be an early biomarker of altered phosphorus metabolism in the initial stages of chronic kidney disease (CKD) and acts as a strong predictor of mortality in dialysis patients. In the Saudi population, there is no report on the FGF23 level in CKD patients to date. This study aims to estimate the plasma FGF23 levels in the Saudi population and to correlate it with its clinical manifestations in order to ascertain its role in the pathogenesis of CKD patients. Methods: The FGF23 level in the plasma samples was determined using ELISA in a diverse cohort of 89 cases with stage 3-5 CKD and 100 healthy subjects. The plasma FGF23 level was correlated with other biochemical parameters. Results: The results revealed that the FGF23 level was markedly elevated among CKD patients compared to the control group, and a significant inverse correlation was observed between the FGF23 level and glomerular filtration rate. FGF23 elevation was approximately 40-fold among stage 5 patients compared to the control, while the elevation of phosphate, parathyroid hormone (PTH) and alkaline phosphatase was 2-, 3- and 8-fold in this stage, respectively. Conclusion: Elevated FGF23 levels may have a strong correlation with the disease pathogenesis. In addition, FGF23 might be a future therapeutic target to intervene against the progression of CKD as well as to increase patient survivability.

BackgroundGenome wide association studies of patients with European descent have identified common variants associated with risk of reduced estimated glomerular filtration rate (eGFR). A panel of eight variants were selected to evaluate their association and prevalence in a Saudi Arabian patient cohort with chronic kidney disease (CKD).MethodsEight genetic variants in four genes (SHROOM3, MYH9, SLC7A9, and CST3) were genotyped in 160 CKD patients and 189 ethnicity-matched healthy controls. Genetic variants were tested for association with the development of CKD (eGFR < 60 ml/min/1.73m2) and effects were compared with results obtained from 133,413 participants in the CKD genetics consortium. Multivariable regression was used to evaluate the role of these eight variants in improving prediction of CKD development.ResultsAll eight variants were present in Saudi populations with minor allele frequency ranging from 16 to 46%. The risk variant in all four genes demonstrated the same direction of effect as observed in European populations. One variant, rs4821480, in MYH9 was significantly associated with increased risk of development of CKD (OR = 1.69, 95% CI 1.22–2.36, P = 0.002), but the additional variants were not statistically significant given our modest sample size.ConclusionsCKD risk variants identified in European populations are present in Saudis. We did not find evidence to suggest heterogeneity of effect size compared to previously published estimates in European populations. Multivariable logistic regression analysis showed a statistically significant improvement in predicting the CKD using models with either FGF23 and vitamin D or FGF23, vitamin D level, and MYH9 genotypes (AUC = 0.93, 95% CI 0.90–0.95, P <  0.0001).Electronic supplementary materialThe online version of this article (10.1186/s12882-018-0890-9) contains supplementary material, which is available to authorized users.

To evaluate the use of rituximab in the treatment of severe glomerulonephritis (GN) in order to prevent progression of kidney disease toward the end stage, we designed a multicenter, retrospective study in Saudi Arabia about the efficacy and safety of the use of "off label" rituximab in a variety of severe refractory GN to conventional treatment and the progression of kidney disease for at least one year of follow-up. All the patients had kidney biopsies before treatment with rituximab, and proteinuria and glomerular filtration rate (GFR) were followed-up for the period of the study. The immediate side-effect at the time of administration of rituximab included itching in three patients, hypotension in one patient and anaphylaxis in one patient (dropped out from the study). After the administration of rituximab in 42 patients and during the first six months of therapy, 16 (38%) patients had complete remission (CR), 13 (31%) patients had partial remission (PR) and 13 (31%) patients had no remission. The mean follow-up period for the patients was 19.0 ± 6.97 months (median 18.0 months). The long-term follow-up during the study period disclosed a good hospitalization record for almost all of the patients. Membranous GN (MGN) was the largest group in the cohort (58% of the patients), and we observed CR and PR in 40% and 28% of them, respectively, which was comparable with the previous experience with rituximab in MGN patients with more CR than PR in our cohort. We conclude that our study suggests the safety and efficacy of the use of rituximab in patients with refractory GN and that larger and long-term prospective studies are required to define the role of rituximab in the different categories of these diseases.

Background:Hemodialysis (HD) patients are at an increased risk of acquiring hepatitis B virus (HBV) infection. Active HBV immunization in these patients is recommended. A response rate in HD patients is variable but generally lower than healthy individuals.Objective:The aim of this study is to assess the response of HD patients to the HBV vaccine and correlate response and long-term immunity to various clinical and biomedical factors.Patients and Methods:One hundred and one patients, with a mean age 48.7 ± 18.5 years, received 40 μg of HBV vaccine administered intramuscularly in the deltoid region at 0, 1, 2 and 6 months. The patients' responses to the vaccine were determined by measuring hepatitis B surface antibody (HBsAb) 6 weeks after the last injection and monitored thereafter at 3-month intervals.Results:Seventy-one patients (70.3%) mounted a response with HBsAb >10 mIU/ml 6 weeks following the fourth dose of vaccine, and thus were considered considered as adequate responders. Forty-nine (48.5%) patients mounted an excellent response with HBsAb >100 mIU/ml 6 weeks after the fourth dose. Thirty patients (29.7%) were nonresponders. Responders were significantly younger than nonresponders (P = 0.01). Gender, hemoglobin level, serum albumin, ferritin, parathyroid hormone level and hepatitis C virus infection had no effect on the response to the vaccine. Similarly, there was no difference in diabetic state and adequacy of HD between the two groups. Fifty-nine patients (88%) had persistent protective antibodies at 1 year, while eight (12%) lost such protection. Predictors of persistent immunity at 1 year were high HBsAb level at the completion of the vaccination regime and, to a lesser extent, young age.Conclusion:A 70% response rate to HBV vaccine was observed in the cohort of this study. Young age predicts a favorable response to HBV vaccine in HD patients. High (>100 mIU/ml) HBsAb levels achieved at vaccine completion predict persistent immunity at 1 year.

Renal dysfunction is encountered in 20-25% of patients with multiple myeloma (MM) at the time of diagnosis. There is often a precipitating event. Several biochemical and clinical correlations with renal failure in MM have been reported. Renal failure in MM is associated with worse outcome of the disease. We retrospectively analyzed the medical records of 64 patients with MM admitted to our institution during the period January 1992 to December 2012. Abnormal renal function was observed in 24 (37.5%) patients and 17 (26.6%) of them had renal failure; 14 of the 17 (82.4%) of patients with renal failure had Stage III MM. Urine Bence- Jones protein was positive in ten (58.8%) patients with renal failure versus ten (21.3%) patients without renal failure (P = 0.004). Potential precipitating factors of renal failure were determined in nine patients. Renal function normalized in 11 patients with simple measures, while six patients required hemodialysis; one remained dialysis dependent till time of death. Early mortality occurred in five (29.4%) patients with renal failure as compared with two (4.3%) patients in the group without renal failure (P = 0.005). In conclusion, renal failure is associated with a higher tumor burden and Bence-Jones proteinuria in patients with MM. It is reversible in the majority of patients; however, early mortality tends to be higher in patients with persistent renal failure.

Background. End-stage renal disease (ESRD) is the result of hypertensive nephrosclerosis and chronic glomerular diseases and is associated with high morbidity and mortality. There are strong heritable components in the manifestation of the disease with a genetic predisposition to renal disorders, including focal segmental glomerulosclerosis and arterionephrosclerosis. Recent studies in genetics have examined modifiable risk factors that contribute to renal disease, and this has provided a deep insight into progressive kidney disease. Single-nucleotide polymorphisms at the proximity of SHROOM3, CST3, SLC7A9, and MYH9 genes have been associated with an increased risk of developing CKD and ESRD. Methods. A total of 160 CKD patients and 189 control subjects of Saudi origin participated in the study. Eight polymorphisms (SHROOM3-rs9992101, rs17319721; SLC7A9-rs4805834; MYH9-rs4821480, rs4821481, rs2032487, rs3752462; CST3-rs13038305) were genotyped using TaqMan assay, and the haplotype analysis was done using the HaploView 4.2 software. Results. Haplotype analysis revealed a novel haplotype “E6”-GTTT to be associated significantly with an increased risk for ESRD (p=0.0001) and CKD (p=0.03). Conclusion. CKD is often silent until symptomatic uremia during the advanced stages of the disease. The newly identified haplotype will help recognize patients at risk for a rapid progression of CKD to ESRD. Accurate detection and mapping of the genetic variants facilitates improved risk stratification and development of improved and targeted therapeutic management for CKD.