A synergistic association of ACE I/D and eNOS G894T gene variants with the progression of immunoglobulin A nephropathy - A pilot study

Abstract

Background: Individual variability in the natural history and response to therapy of immunoglobulin A nephropathy (IgAN) suggests a complex multifactorial pathogenesis. We investigated whether single nucleotide polymorphisms (SNPs) involved in the non-immunologic progression of renal disease are related with disease progression. Methods: This is a pilot historic cohort study of 64 Caucasian patients with biopsy-proven IgAN and a median follow-up of 70 months. Three SNPs of the renin-angiotensin system genes (angiotensin I converting enzyme insertion/deletion (ACE I/D), angiotensinogen (AGT) M235T, and angiotensin II type 1 receptor (AT 1 R) 1166A/C), 2 of the endothelial nitric oxide synthase (eNOS), 4a/b and G894T, and 1 of the bradykinin 1 receptor, G-699C, were genotyped. The primary outcome was 'kidney survival' defined as a 30% decrease of baseline creatinine clearance; annualized decrease of glomerular filtration rate was also calculated. Results: Proteinuria, histological lesions, and mean arterial pressure were related to an unfavorable outcome. The simultaneous presence of the DD and GG variants of the ACE and eNOS genes was related to an unfavorable outcome as compared with other combinations [hazard ratio ranging from 4.7 (95% CI 1.52-14.33) to 8.4 (95% CI 2.45-29.10)] after controlling for proteinuria, mean arterial pressure and baseline histological lesions. Conclusion: This study suggests that in our population with IgAN, an interaction between ACE and eNOS polymorphisms may be a prognostic factor for renal function deterioration.