Finnish of nephrotic syndrome is caused by a defect in the following protein -

Ans. is 'a' i.e., Nephrin The glomerular capillary wall is a filtering membrane and consists of the following structuresEndothelial cellsGlomerular basement membraneVisceral epithelial cells (podocytes)Mesangial cellsThe visceral epithelial cell known as Podocyte is important for the maintenance of glomerular barrier function.They are structurally complex cells that possess interdigitating foot processes (pedicels).The adjacent foot processes are separated by 20-30 nm wide filtration slits.The filtration slit or slit diaphragm maintains glomerular barrier function.They present a size selective distal diffusion barrier to the filtration of proteins and it is the cell type that is largely responsible for the synthesis of GBM components.Proteins located in the slit diaphragm control glomerular permeability.Important proteins have been identified in this regardNephrinPodocinCD2 associated protein andActin cytoskeletonThe importance of these proteins in maintaining glomerular permeability is demonstrated by the observation that mutations in the gene encoding them give rise to nephrotic syndrome sclerosis.* The mutations in these genes commonly lead to focal segmental glomerulosclerosis.GeneChromosomeProtein encodedDiseaseNPHS119ql3NephrinCongenital nephrotic syndrome of the furnish typeNPHS2lq 25-31PodocinSteroid-resistant nephritic syndrome 30% cases* Mutations in the Podocyte action-binding protein a actinin 4 also produce FSGS