The most significant predictor of kidney failure in our cohort was moderate to severe interstitial fibrosis, which was similar to findings in the French Nationwide Study in IRGN patients with IgA deposits.13 Tubulointerstitial fibrosis is mediated by interstitial myofibroblasts which are alpha-smooth muscle actin (α-SMA) positive cells. The gene discussed is ACTA1; the disease is kidney failure.