In jaundiced patients with cirrhosis, van Slambrouck et al. described bile casts in distal nephron segments and hypothesized that the formation of bile casts contributes to kidney injury by direct toxicity of bilirubin and bile itself, as well as by tubular obstruction, with a pathogenetic mechanism similar to that of myeloma or myoglobin cast nephropathy [38]. The gene discussed is MB; the disease is plasma cell myeloma.