RESUMO
BACKGROUND: Oral steroid treatment is the first line of therapy for childhood nephrotic syndrome (NS). However, resistance to this treatment has been observed in some patients. Here, we investigated the association of two steroid metabolism-related genes with susceptibility to childhood NS and the steroid response. METHODS: We genotyped the single nucleotide polymorphisms (SNP) of MDR-1 [C1236T (rs1128503), G2677T/A (rs2032582), and C3435T (rs1045642)] and the CYP3A5 gene (A6986G) in 63 NS patients and 110 age and gender matched controls by PCR-RFLP. RESULTS: Based on multivariate logistic regression analysis carrying the G2677A A allele seemed to multiply both the risk of NS and the risk of developing glucocorticoid (GC) resistance by three-fold (OR = 3.50, [1.37 - 7.06] , p < 0.001, OR = 3.07, [1.06 - 26.10], p = 0.048, respectively). When combined into haplotype, the TAT (1236_T, 2677_A, and 3435_T) haplotype conferred a two-fold NS risk (OR = 2.26, [1.11 - 4.58], p = 0.023) and almost three-fold risk to develop resistance to GC (OR = 2.69, [1.12 - 8.79], p = 0.044). However, TAT carriers seemed to have less risk to develop NS at late age (OR = 0.34, [0.12 - 0.92], p = 0.037). The C1236T (MDR-1) and the A6986G (CYP3A5) polymorphisms showed a trend of association to GC resistance but these associations did not reach the statistical significance (OR = 2.83, [0.54 - 14.67], p = 0.294), (OR = 2.11, [0.53 - 8.38], p = 0.28), respectively. CONCLUSIONS: Here we report that only the G2677A polymorphism was associated to NS susceptibility and steroid resistance. The TAT haplotype was associated with NS susceptibility especially at an early age and with steroid resistance.
