Pharmacogenetic Study of Prednisolone Resistance in Childhood Nephrotic Syndrome Patients of Bangladesh

Abstract

Nephrotic syndrome is a common childhood kidney disease characterized by protein leakage from the blood to the urine through the glomeruli, resulting in proteinuria, hypoalbuminemia, generalized edema and hypercholesterolemia. The cause of nephrotic syndrome is still unknown. Till now no pharmacogenetic study of ABCB1, NR3C1 and CYP3A5 genes have been reported on the Bangladeshi pediatric prednisolone resistance nephrotic syndrome patients. Additionally, researchers studied several genetic polymorphisms of ABCB1, NR3C1 and CYP3A5 genes to explain their influence on different patients’ resistance to steroids; however, the results were inconsistent. Therefore, we aimed to investigate the association of ABCB1 gene polymorphisms 1236T>C (rs1128503), 2677G>T (rs2032582) and 3435T>C (rs1045642), NR3C1 gene polymorphisms rs10482634 and rs6877893 and CYP3A5*3 (rs776746) polymorphism of the CYP3A5 gene with the risk of developing prednisolone resistance in nephrotic syndrome in Bangladeshi population. A case-control study was carried out on 180 nephrotic syndrome patients and the patients were recruited from different hospitals of Bangladesh. Among them, 30 had prednisolone resistance nephrotic syndrome were considered as cases and 150 had prednisolone sensitive nephrotic syndrome were considered as controls. After isolation of genomic DNA, genotyping was done by polymerase chain reaction-restriction fragment length polymorphism method. The risk of prednisolone resistance nephrotic syndrome was estimated as an odds ratio (OR) with 95% confidence interval (CI) using unconditional logistic regression models. A significant association was found between 2677G>T, 3435T>C SNPs of the ABCB1 gene, rs10482634 SNP of the NR3C1 gene and the prednisolone resistance risk in nephrotic syndrome patients. From our present study, we found that the 1236T>C polymorphism of the ABCB1 gene was not significantly associated with prednisolone resistance risk in childhood nephrotic syndrome patients (p >0.05). The GT heterozygous of 2677G>T polymorphism was found significantly responsible for the development of prednisolone resistance nephrotic syndrome (OR = 3.9, 95% Cl = 1.11 to 13.70, p = 0.034) and it possesses 3.9 times higher risk compared to GG normal homozygous genotype. The TT mutant homozygous and combined heterozygous and mutant homozygous GT+TT genotypes were found to have 1.18 and 1.46 times more risk for the development of prednisolone resistance compared to GG normal homozygous genotype, respectively, but these results were not statistically significant. In case of 3435T>C SNP of the ABCB1 gene, TC heterozygous genotype was found to have 0.38 times lower risk of developing prednisolone resistance compared with TT homozygous wild-type and it was statistically significant (OR = 0.38, 95% CI = 0.15 to 0.99, p = 0.047). The CC mutant homozygous genotype was found to be significantly associated (OR = 3.06, 95% Cl = 1.06 to 8.79, p = 0.038, respectively) with 3.06 times elevated risk of prednisolone resistance nephrotic syndrome whereas the combined heterozygous and mutant homozygous TC+CC genotype shown a lower risk of developing prednisolone resistance nephrotic syndrome but this finding was not statistically significant (OR = 0.71, 95% Cl = 0.32 to 1.58, p = 0.408). In this present study, we also examined two polymorphisms of the NR3C1 gene. In case of rs10482634 polymorphism, the TC heterozygous and combined heterozygous and mutant homozygous TC+CC genotypes were significantly found to be responsible for the development of prednisolone resistance in childhood nephrotic syndrome (OR = 2.40, 95% Cl = 1.07 to 5.40, p = 0.033; OR = 2.36, 95% Cl = 1.06 to 5.21, p = 0.034, respectively) and they showed 2.40 and 2.36 times greater risk of developing prednisolone resistance compared to TT wild genotype, respectively. The CC mutant homozygous was not significantly associated with prednisolone resistance and it possesses 1.80 times higher risk for the development of prednisolone resistance nephrotic syndrome. For the rs6877893 SNP, we observed that there was no significant association between rs6877893 and the risk of prednisolone resistance in children with nephrotic syndrome (p >0.05). For CYP3A5*3 polymorphism of the CYP3A5 gene, we found no significant association between CYP3A5*3 polymorphism and prednisolone resistance risk in childhood nephrotic syndrome patients (p >0.05). This study demonstrates that the presence of GT heterozygous genotype of 2677G>T polymorphism, CC mutant homozygous genotype of 3435T>C polymorphism of ABCB1 gene as well as TC heterozygous and combined heterozygous and mutant homozygous TC+CC genotypes of rs10482634 polymorphism of the NR3C1 gene are associated with the risk of prednisolone resistance development in Bangladeshi nephrotic syndrome children.