AIM: We evaluated the influence of C-344T polymorphism of the aldosterone synthase gene, associated with aldosterone levels and the development of arterial hypertension, on focal segmental glomerulosclerosis (FSGS).METHODS: We studied 81 patients with primary FSGS followed up for 8.0 ± 12 years. Patients were classified according to their slope of reciprocal serum creatinine into group A (slow progressors, n = 57) and B (fast progressors, n = 24). One hundred healthy volunteers were analysed as controls. The biopsies of n = 50 patients were reviewed and analysed by the same pathologist. C-344T polymorphism was determined by polymerase chain reaction.RESULTS: The allele frequencies differed significantly between patients (C-allele: 0.55, T-allele: 0.45) and controls (C-allele: 0.45, T-allele: 0.55; P < 0.05). Patients carrying the C-allele tended to have a higher percentage of sclerosed glomeruli (41.8 ± 30% vs 31. 2 ± 19% in TT genotype, ns) and tubulointerstitial fibrosis (22.8 ± 18% vs 16.0 ± 5%, ns). The rate of deterioration of renal function was higher in the CC/CT genotypes (-0.216 ± 0.449 dL/mg per year) compared to the TT genotype (-0.030 ± 0.041 dL/mg per year, P = 0.002). Furthermore, 36.4% of the C-allele carriers and none of the patients with the TT genotype belonged to group B (P = 0.005). C-allele carriers also had a worse kidney survival in the Kaplan-Meier analysis (P = 0.027).CONCLUSION: Our results indicate that aldosterone synthase gene C-344T polymorphism not only acts as a risk factor for the development of FSGS, but also may influence its pathologic appearance and could serve as a marker of disease progression.