OBJECTIVES: Ritonavir-boosted atazanavir (atazanavir/ritonavir) is a widely used antiretroviral drug, though it can potentially cause nephrolithiasis. The aim of this study was to determine the relationship between polymorphisms in genes encoding proteins involved in metabolism and transportation of atazanavir, and atazanavir/ritonavir-induced nephrolithiasis in HIV-1-infected patients treated with atazanavir/ritonavir. METHODS: Nineteen SNPs in the ABCB1, NR1I2, UGT1A1, SLCO1B1 and CYP3A5 genes were examined in case patients with atazanavir/ritonavir-induced nephrolithiasis (n = 31) and controls (n = 47). Case patients were those with a clinical diagnosis of nephrolithiasis while on atazanavir/ritonavir, based on new-onset acute flank pain plus one of the following: (i) new-onset haematuria; (ii) documented presence of stones by either abdominal ultrasonography or CT; or (iii) confirmed stone passage. Control patients were consecutively enrolled among those with >2 years of atazanavir/ritonavir exposure free of nephrolithiasis. Genotyping was performed by allelic discrimination using TaqMan 5'-nuclease assays with standard protocols. Associations between alleles and atazanavir/ritonavir-induced nephrolithiasis were tested by univariate and multivariate logistic regression analyses. RESULTS: Multivariate analysis showed a significant association between atazanavir/ritonavir-induced nephrolithiasis and genotype T/C versus C/C at position c.211 (adjusted OR = 3.7; 95% CI, 1.13-11.9; P = 0.030), genotype G/C versus C/C at 339 (adjusted OR = 5.8; 95% CI, 1.56-21.3; P = 0.009) and genotype G/G or G/C versus C/C at 440 (adjusted OR = 5.8; 95% CI, 1.56-21.3; P = 0.009) of the UGT1A-3' untranslated region (UTR). CONCLUSIONS: This is the first known study to identify the association between SNPs in the UGT1A-3'-UTR and atazanavir-induced nephrolithiasis. Further studies are warranted to confirm this association and to elucidate how these SNPs might influence atazanavir exposure.
OBJECTIVES:Ritonavir-boosted atazanavir (atazanavir/ritonavir) is a widely used antiretroviral drug, though it can potentially cause nephrolithiasis. The aim of this study was to determine the relationship between polymorphisms in genes encoding proteins involved in metabolism and transportation of atazanavir, and atazanavir/ritonavir-induced nephrolithiasis in HIV-1-infectedpatients treated with atazanavir/ritonavir. METHODS: Nineteen SNPs in the ABCB1, NR1I2, UGT1A1, SLCO1B1 and CYP3A5 genes were examined in case patients with atazanavir/ritonavir-induced nephrolithiasis (n = 31) and controls (n = 47). Case patients were those with a clinical diagnosis of nephrolithiasis while on atazanavir/ritonavir, based on new-onset acute flank pain plus one of the following: (i) new-onset haematuria; (ii) documented presence of stones by either abdominal ultrasonography or CT; or (iii) confirmed stone passage. Control patients were consecutively enrolled among those with >2 years of atazanavir/ritonavir exposure free of nephrolithiasis. Genotyping was performed by allelic discrimination using TaqMan 5'-nuclease assays with standard protocols. Associations between alleles and atazanavir/ritonavir-induced nephrolithiasis were tested by univariate and multivariate logistic regression analyses. RESULTS: Multivariate analysis showed a significant association between atazanavir/ritonavir-induced nephrolithiasis and genotype T/C versus C/C at position c.211 (adjusted OR = 3.7; 95% CI, 1.13-11.9; P = 0.030), genotype G/C versus C/C at 339 (adjusted OR = 5.8; 95% CI, 1.56-21.3; P = 0.009) and genotype G/G or G/C versus C/C at 440 (adjusted OR = 5.8; 95% CI, 1.56-21.3; P = 0.009) of the UGT1A-3' untranslated region (UTR). CONCLUSIONS: This is the first known study to identify the association between SNPs in the UGT1A-3'-UTR and atazanavir-induced nephrolithiasis. Further studies are warranted to confirm this association and to elucidate how these SNPs might influence atazanavir exposure.