This gene encodes a novel, evolutionarily conserved, ciliary protein. In human hTERT-RPE1 cells, the protein is found at the base of cilia, decorating the ciliary axoneme, and enriched at the ciliary tip. The protein binds to microtubules in vitro and regulates their stability when it is overexpressed. A null mutation in this gene has been associated with Joubert syndrome, a recessive disorder that is characterized by a distinctive mid-hindbrain and cerebellar malformation and is also often associated with wider ciliopathy symptoms. Consistently, in a serum-starvation ciliogenesis assay, human fibroblast cells derived from patients with the mutation display a reduced number of ciliated cells with abnormally long cilia.