A genetically heterogeneous autosomal recessive disorder presenting with psychomotor delay, decreased muscle tone, ataxia, oculomotor apraxia, and malformation of the midbrain–hindbrain junction. Joubert's syndrome type 3 (JBTS3) is caused by mutation in jouberin, JBTS4 by mutation in nephrocystin 1. The phenotype in JBTS5 overlaps that of Senior–Loken syndrome and both syndromes are caused by mutations in proteins of the centrosome or primary cilium (nephrocystin 6, 290-kDa centrosomal protein). JBTS6 is caused by mutation in the meckelin gene, JBTS7 by mutation in the RPGRIP1L gene that encodes a protein (1315 aa) having strong similarity to RPGRIP1, a protein present at the photoreceptor connecting cilium and mutated in Leber congenital amaurosis type VI.
Subjects: Medicine and Health.