TTC21B and Hydrocephalus: For example, defaults in centrosomal protein Cep290 or intraflagellar transport (IFT) components such as Kinesin family member 3a (Kif3a), Ift188 and Ttc21b, impair primary cilia formation/signaling in turn disrupting ependymal cilia and leading to hydrocephalus in mice [88–90].