Joubert syndrome (JS) is an inherited multi-visceral disorder caused by aberrant primary cilia formation and function. JS is characterized by the Molar Tooth Sign (MTS), a mid-hindbrain malformation easily identifiable through an axial brain MRI scan. Neurological features include hypotonia, ataxia, and cognitive impairment. The clinical phenotype additionally includes retinal, renal, hepatic -and more rarely- orofacial, skeletal, cardiac, genital, and endocrinal defects. JS is thought to affect 1 in 100,000 births; however the incidence in consanguineous populations is thought to be much higher (e.g. ~1 in 5000 for UAE).
JS16 (JBTS16) is a subtype of JS very similar to JBTS2, involving characteristic neurological features with mainly ocular involvement; renal, skeletal (polydactyly), and genital (cryptorchidism) defects are additional albeit relatively rarely reported features. The ocular phenotype involves retinal dystrophy, oculomotor apraxia, reduced visual acuity, as well as chorioretinal and optic nerve coloboma. Renal involvement include cystic kidneys, nephronophthisis and nephrocalcinosis.