We recently showed that a frameshifted mutant mucin 1 protein, the cause of ADTKD-MUC1 (phenotypically identical to ADTKD-UMOD), is trapped in transmembrane Emp24 protein transport domain–containing 9 (TMED9) cargo receptor–containing vesicles. This evidence concerns the gene MUC1 and autosomal dominant medullary cystic kidney disease with or without hyperuricemia.