Joubert syndrome: large clinical variability and a unique neuroimaging aspect.

Joubert syndrome (JS) is an autosomal recessive inherited disorder characterized by hypotonia, cerebellar vermis hypoplasia, ocular abnormalities (e.g, pigmentary retinopathy, oculomotor apraxia and nystagmus), renal cysts and hepatic fibrosis. Respiratory abnormalities, as apnea and hyperpnea, may be present, as well as mental retardation. At least seven JS loci have been determined and five genes identified. Herein, we report five children, belonging to independent families, with JS: they shared the same typical MRI abnormality, known as molar tooth sign, but had an otherwise quite variable phenotype, regarding mostly their cognitive performance, visual abilities and extra-neurological compromise.