Cilia are specialized organelles found in most species, wheretheyservediverseroles1. Inmammals, ciliary dysfunction has been linked to a numberof phenotypes, frommotileciliadefects inKartagenersyndrome, toleft-rightaxisspecification defects and polycystic kidney disease. Recently, the impact of ciliary dysfunction was expanded with the demonstration that defects in the cilium and its anchoring structure, the basal body, are also associated with pleiotropic phenotypes such as the Bardet-Biedl, Alstrom and Meckel-Gruber syndromes2, 3. These observations have highlighted the existence of the ciliopathies, an expanding group of overlapping clinical entities, and have suggested that an improved understanding of the cilium has the potentialtoinformthegeneticandcellularbasis of such phenotypes.