MDR-1 gene polymorphisms and clinical course of steroid-responsive nephrotic syndrome in children

The study was aimed at investigating the association between MDR-1 genetic polymorphisms [C1236T, G2677T(A), C3435T] and parameters describing the clinical course and treatment response of childhood steroid-responsive nephrotic syndrome (SRNS). Three MDR-1 genetic markers were analyzed in 108 children diagnosed with SRNS and in 135 healthy controls with neither allergic nor renal disease. All subjects were genotyped by PCR-restriction fragment length polymorphism (RFLP) analysis, and an EM algorithm-based analysis was utilized to estimate haplotype frequencies. As expected, there was no difference in genotypic and allelic distribution between and among SRNS patients and healthy children. However, all individual polymorphisms were strongly associated with time to response to initial prednisone therapy. The frequencies of the mutated alleles were higher in late responders (time to remission: >7 days) to oral prednisone (0.53, 0.52,0.66) than in early responders (time to remission