MicroRNAs in Idiopathic Childhood Nephrotic Syndrome

Childhood nephrotic syndrome (NS)3 is associated with an increase in the permeability across the glomerular filtration barrier due to processes that affect the dynamics and permselectivity of the glomerular filtration barrier. This increased permeability leads to an inability to restrict the loss of protein to 50 mg/kg per day), hypoalbuminemia (<3 g/dL), edema, and hyperlipidemia (1). Severe complications include bacterial infections due to immunoglobulin losses and thromboembolisms related to a relative increase in the hematocrit (1).Children with NS have been classified into different categories. Patients with primary NS, in which a systemic disease cannot be identified, include children with idiopathic NS (absence of glomerular inflammation on renal biopsy) and children with primary glomerulonephritis. Secondary NS is related to a systemic disease. Less commonly, NS is caused by an inherited renal disease (congenital or infantile NS). This form occurs in children younger than 1 year and is associated with a poor outcome (2).Primary idiopathic NS may be associated with at least 3 different histologic abnormalities: minimal-change disease (MCD), focal segmental glomerulosclerosis (FSGS), and membranous nephropathy (1). Pathogenetically, MCD and FSGS have long been considered to be caused by a circulating permeability factor (3). Recently, circulating soluble urokinase plasminogen activator receptor has been shown to cause FSGS (4). Congenital or infantile NS is caused by mutations in podocyte or slit diaphragm proteins \[e.g., CD2AP (CD2-associated protein), podocin, the Wilms tumor-suppressor gene, and nephrin\] (1).Idiopathic NS has been identified as …