CROCC and Usher syndrome: Ciliary rootlets are composed of rootletin fibers, encoded by the CROCC gene, which polymerize into thick filaments that are attached to the basal body by CEP250, mutations of which have been associated with Usher syndrome (USH) and retinitis pigmentosa (RP) (Yang et al., 2002, 2006; Khateb et al., 2014; De Castro-Miró et al., 2016).