Summary
Familial idiopathic steroid-resistant nephrotic syndrome is characterized by a nephrotic syndrome with often early onset. Prevalence in the general population is unknown. The nephrotic syndrome is defined by severe proteinuria with low serum albumin and possible edemas. This disease is rare but severe as it usually progresses to end-stage renal failure. Several causative mutations have recently been identified. Among these, mutations in the NPHS2 gene (chromosome 1q25-q31 and encoding podocine) have been found to be involved in autosomal recessive forms of the disease. Mutations in the podocine gene have also been detected in later-onset forms and in apparently sporadic forms (10 to 30% of the cases depending on the series). However, the other genes responsible for autosomal recessive forms of the disease remain to be identified. Mutations in the ACTN4 gene, coding for alpha-actinine 4, have been reported in autosomal dominant forms. Mutations are mainly observed in exon 8. An autosomal dominant form has also been described in patients carrying mutations in the TRPC6 gene, located on chromosome 11 and coding for a calcium channel. Familial forms of idiopathic steroid-resistant nephrotic syndrome do not respond to any treatment with steroids or immunosuppressive drugs and the disease progress to terminal renal failure. Recurrence of the disease in the grafted kidney after renal transplantation is exceptional. *Author: Prof. P. Niaudet (February 2007)*.
