In 2012, one study showed that urinary miR-21, miR-29b, miR-29c, and miR-93 are involved in the transforming growth factor (TGF)- β1/mothers against decapentaplegic homolog 3 (SMAD3) pathway, and that miR-93 is associated with pathological glomerular scarring; these miRNAs may contribute to renal fibrosis within IgAN (17). Here, SMAD3 is linked to renal fibrosis.