In terms of manifestation of CVI-related features, JBTS can be classified into pure JBTS (JBTS8, JBTS13, JBTS15, JBTS22, JBTS25-27, JBTS30, JBTS32, JBTS33, and JBTS35-40), mixed JBTS with retinal diseases (JBTS1-5, JBTS7, JBTS9, JBTS14, JBTS16, JBTS20, JBTS28, and JBTS29), and mixed JBTS without retinal diseases (JBTS6, JBTS10, JBTS12, JBTS17-19, JBTS21, JBTS23, JBTS24, JBTS31, and JBTS34). Here, ARL13B is linked to Joubert syndrome.