NPHS2 mutations in children with steroid-resistant nephrotic syndrome.

Introduction: Congenital nephrotic syndrome may be caused by mutations in NPHS1 and NPHS2, which encode nephrin and podocin, respectively. Since the identification of the NPHS2 gene, various investigators have demonstrated that its mutation is an important cause of steroid-resistant nephrotic syndrome. We aimed to evaluate frequency and spectrum of podocin mutations in the Iranian children with steroid-resistant nephritic syndrome.

Materials And Methods: We examined 20 children with steroid-resistant nephritic syndrome referred to Ali Asghar Children's Hospital, in Tehran, Iran. Mutations in the 5th and 7th exons of NPHS2 were assessed. The mutational analysis of NPHS2 was performed by DNA sequencing.

Results: The mean age at the onset of proteinuria was 6.4 +/- 3.6 years. None of the children had mutations in the exons 5 or 7.

Conclusions: Our study suggests that NPHS2 mutations in exons 5 and 7 are not seen in our children. Therefore, we cannot recommend NPHS2 (exons 5 and 7) mutation for screening in Iranian children with steroid-resistant nephritic syndrome. Other exons of podocin or other podocyte proteins in Iranian children may play a role in pathogenesis of steroid-resistant nephritic syndrome.