Compared with normal mice, after intraperitoneal injection of AA for 6 weeks, Smad7 WT mice developed chronic AAN as evidenced by severe tubulointerstitial fibrosis accompanied by dilated tubular lumens with bared tubular basement membrane and an increase in 24h proteinuria and serum creatinine (Fig. 1). The gene discussed is SMAD7; the disease is Balkan nephropathy.