PodoNet

Steroid-resistant nephrotic syndrome (SRNS) is a rare but important clinical condition. While in up to 50% of patients intensified immunosuppression can eventually induce disease rem-ission and prevent long-term sequelae, a major subset of cases appears to be caused by genetic abnormalities of genes encoding for proteins specifically expressed in podocytes, the visceral epithelial cells forming the glomerular filtration barrier. The hereditary forms of SRNS typically do not respond to any immunosuppressive medication and progress rapidly to end-stage renal failure. To date, up to 10 genes involved in non-immunological SRNS have been identified which altogether explain less than half of the SRNS cases which remain unrespon-sive to intensified immunosuppression. The PodoNet collaboration aims to establish a trinat-ional SRNS registry to explore the demographics of immunological and genetic forms of ped-iatric and adult-onset SRNS, establish significant genotype-phenotype correlations, provide essential diagnostic and therapeutic guidelines to clinicians and collect the critical mass of cases and families, which will be utilized to search for new genetic entities of SRNS. More-over, we will explore innovative pharmacological treatment strategies for the most frequent genetic cause of autosomal recessive SRNS, a mutation causing defective intracellular traff-icking of the podocyte membrane protein podocin. The latter objective will be approached by novel high-throughput screening techniques for small molecules enhancing the trafficking of mutated podocin (‘chaperones’) in a cell-based assay system, and by testing the efficacy of established antiproteinuric drugs as well as candidate chaperone molecules in a recently de-veloped inducible mouse model of the podocin mutation-related SRNS. Hence, PodoNet will be a paradigmatic transnational collaboration to explore the genetic and molecular causes, improve clinical management and develop novel treatment strategies for an important group of rare genetic diseases that up to now inevitably lead to irreversible loss of kidney function.