CEP290 activates ATF4 mediated transcription and is required for the correct localization of ciliary and phototransduction proteins in retinal photoreceptor cells; may play a role in ciliary transport processes. CEP290 is ubiquitously expressed; strongly in placenta and weakly in brain. There are two named isoforms. Defects in CEP290 are a cause of Joubert syndrome type 5 (JBTS5), Senior-Loken syndrome type 6 (SLSN6) [MIM:610189], Leber congenital amaurosis type 10 (LCA10) and Meckel syndrome type 4 (MKS4) [MIM:611134]. Antibodies against CEP290 are present in sera from patients with cutaneous T cell lymphomas, but not in the healthy control population.