Genetic Loci of the Renin-Angiotensin System and IgA Nephropathy

Background: IgA nephropathy (IgAN) is the most common primary glomerular disease. The renin-angiotensin system (RAS) plays an important role in the development of IgAN. Polymorphisms in genetic loci coding for the RAS may be associated with IgAN progression. Methods: We analyzed the M235T, A1166C, and A1675G polymorphisms in 297 IgAN patients, and analyzed their associations with clinical manifestations, pathological damage, effects of RAS-inhibitor treatment, and IgAN patient prognosis. Results: In patients with the A1675G polymorphism, creatinine levels were significantly lower in those with the AG genotype than in those with the AA genotype (p = 0.023). However, this difference was not significant when creatinine levels were analyzed according to sex. Patients with endocapillary proliferation according to the Oxford Classification of IgAN were less likely to have the AG genotype than the AA genotype (p = 0.025). In IgAN patients treated with angiotensin-II-receptor blockers, 24-h urine protein levels were lower in patients with the AC genotype of A1166C than in those with the AA genotype at baseline and follow-up (Base p = 0.013, 1 month p = 0.0035, 3 months p = 0.009). Cox regression analysis implied that the three gene polymorphisms were not independent risk factors for the prognosis of IgAN. Conclusion: The AG genotype of A1675G may confer protection against the development of IgAN, with a stronger protective effect observed in females. M235T, A1166C, and A1675G do not appear to be independent risk factors for IgAN.