Tumor Necrosis Factor-α Gene G-308A Polymorphism Is a Risk Factor for the Development of Membranous Glomerulonephritis

Abstract

Background: Tumor necrosis factor-α (TNF-α) is a major pro-inflammatory cytokine. Recently, the G-308A polymorphism of the TNF-α gene has been associated with modified gene expression and increased TNF-α production in the -308A allele. We evaluated its influence on the incidence and clinical course of membranous glomerulonephritis. Methods: We studied 53 patients with biopsy-proven primary membranous glomerulonephritis followed up for 5.7 ± 4.9 years. 100 volunteers were analyzed as controls. According to the slope of the curve of reciprocal serum creatinine against time, group A (slow progressors, n = 35) and group B (fast progressors, n = 18) were defined. TNF-α G-308A polymorphism was determined by polymerase chain reaction amplification. Results: The frequency of the A-allele (associated with higher TNF-α levels) was significantly higher in patients than control subjects (patients: G-allele: 0.66, A-allele: 0.34; controls: G-allele 0.85, A-allele 0.15, p < 0.001). Similarly, the genotype distribution differed significantly between our study and control populations (patients: GG-genotype: 41.5%, GA: 49.1%, AA 9.4%; controls: GG: 71%, GA: 27%, AA 2%, p = 0.001). Age, renal function, proteinuria and blood pressure were similar at the time of renal biopsy between patients with different genotypes (NS). There was also a tendency towards an overpresentation of the A-allele in group B indicating a possible impact on the progression of membranous nephropathy, but a significance was not reached. Furthermore, no impact on renal survival in the Kaplan- Meier analysis was detected (NS). Conclusion: Our results suggest that TNF-α gene G-308A polymorphism is a risk factor for the development of membranous glomerulonephritis.