Renal cystic diseases are a leading cause of renal failure. Mutations associated with renal
cystic diseases reside in genes encoding proteins that localize to primary cilia. These
cystoproteins can disrupt ciliary structure or cilia-mediated signaling, although molecular
mechanisms connecting cilia function to renal cystogenesis remain unclear. The ciliary
gene, Thm1 (Ttc21b), negatively regulates Hedgehog signaling and is most commonly
mutated in ciliopathies. We report that loss of murine Thm1 causes cystic kidney disease …