Genetic testing in steroid-resistant nephrotic syndrome: why, who, when and how?

Steroid-resistant nephrotic syndrome (SRNS) is a common cause of chronic kidney disease in childhood and has a significant risk of rapid progression to end-stage renal disease. The identification of over 50 monogenic causes of SRNS has revealed dysfunction in podocyte-associated proteins in the pathogenesis of proteinuria, highlighting their essential role in glomerular function. Recent technological advances in high-throughput sequencing has enabled indication-driven genetic panel testing for patients with SRNS. The availability of genetic testing combined with the significant phenotypic variability of monogenic SRNS, poses unique challenges for clinicians when directing genetic testing. This highlights the need for clear clinical guidelines providing a systematic approach for mutational screening in SRNS. The likelihood of identifying a causative mutation is inversely related to age of disease-onset and is increased with a positive family history or the presence of extra-renal manifestations. An unequivocal molecular diagnosis could allow for a personalized treatment approach with weaning of immunosuppressive therapy, avoidance of renal biopsy and in the provision of accurate, well-informed genetic counselling. Identification of novel causative mutations will continue to unravel the pathogenic mechanisms of glomerular disease and provide new insights into podocyte biology and glomerular function.