Twala, Nomthandazo Athelia2023-02-012023-02-012022https://hdl.handle.net/10539/34372A dissertation submitted in fulfilment of the requirements for the degree of Master of Science in Medicine to the Faculty of Health Sciences, School of Clinical Medicine, University of the Witwatersrand, Johannesburg, 2022Background: Iatrogenic contrast-induced nephropathy (CIN) is the third leading cause of hospital-acquired acute kidney injury (AKI) in the world, and it remains a major cause of morbidity, increases overall mortality and is associated with prolonged hospital stay and higher medical costs. Despite the positive association of genetic polymorphisms in the ACE, IL-6, IL-8, VEGF and AGT genes with CIN seen in previous studies, the CIN genetic susceptibility in SubSaharan Africa is unknown. Thus, this study was conducted for the purpose of demonstrating genetic association of candidate gene (IL-6, IL-8, ACE, VEGF, and AGT) polymorphisms with increased CIN in the black population receiving contrast media. Methods: This retrospective study is based on black South African patients that had undergone enhanced computerized tomography (CT) and angiography procedures. CIN was defined as an increase in serum creatinine >25% or an absolute increase >44 µmol/l from baseline at 48-72 hours after exposure to contrast media. Genomic DNA was extracted from peripheral blood samples using the automated Maxwell® 16 DNA Purification Kit from Promega®. For the samples in which insufficient DNA was extracted, a standard salting out method was used. Single nucleotide polymorphisms (SNPs) in the IL-6 (rs1800796), IL-8 (rs4073), VEGF (rs3025039 and rs2010963) and AGT (rs699) genes were genotyped using a TaqMan® SNP genotyping assay to generate a fluorescent signal during Real-Time PCR. The ACE SNP (rs4646994) was genotyped using conventional PCR and the resulting PCR products resolved using agarose gel electrophoresis. Sequencing was performed to confirm the genotype results of IL-6, IL-8, VEGF, and AGT SNPs. Outcome variables were the occurrence of CIN and mortality rate. Results: 228 patients were included in the study, 30 (13%) of whom developed CIN. Statistical analysis using different genetic models (dominant, recessive, multiplicative and additive) indicated no association between IL-6, IL-8, ACE, VEGF, and AGT gene polymorphisms and the risk of CIN. The p-values of all the SNPs were above 0.05. The mortality rate was significantly increased in the CIN+ group compared to the CIN- group (24.1% versus 7.5%; p=0.007). Conclusion: This study proposes that there is no association between the polymorphisms assessed in the candidate genes and the risk of CIN in the black South African population. The most limiting factor of this study was sample size, since only 13% of the cohort developed CIN. Therefore, further research using a larger sample size is suggested which could provide useful information for the early detection of CIN and guiding directed therapy.enDissertation