NPHS2 R229Q polymorphism in steroid resistant nephrotic syndrome: is it responsive to immunosuppressive therapy?

Steroid-resistant nephrotic syndrome (SRNS) patients with NPHS2 gene mutations have been reported as non-responsive to immunosuppressive therapy. Inter-ethnic differences can have influence over the frequency of mutations. The present study was undertaken to find out the incidence and treatment response. Mutational analysis of NPHS2 gene was performed in 20 sporadic idiopathic SRNS, 90 steroid-sensitive nephrotic syndrome (SSNS) and 50 normal controls. NPHS2 gene analysis showed R229Q polymorphism in six SRNS (30%), four SSNS (4.4%) and 13 controls (26%). The polymorphism (G→A) showed Hardy-Weinberg distribution and risk allele (G) had strong association with the disease (odds ratio 3.14, 95% CI 1.33-7.43) than controls. Five cases of SRNS having polymorphism showed partial remission to cyclosporine and prednisolone. Overall, partial remission was achieved in 14(70%), complete remission in four (20%), one(5%) patient had no response and one(5%) died. Thus, NPHS2 gene showed R229Q polymorphism and patients achieved partial remission to therapy.