PDE6D and Joubert syndrome: In this context, it is notable that mutations in the genes of all the components involved in the ciliary targeting of INPP5E are known to cause JBTS, namely, INPP5E/JBTS1, ARL13B/JBTS8, PDE6D/JBTS22, and ARL3/JBTS35 [Parisi and Glass, 2003 (updated 2017)].