| Disease with characteristics of early-onset of cerebellar signs with eye movement abnormalities and a very slow disease progression.Three families have been reported to date. Clinical manifestations include cerebellar signs (ataxia, dysarthria, and intention tremor) and eye movement abnormalities such as gaze-evoked nystagmus, down beat nystagmus, and impaired smooth pursuit. Occasionally defects of the visual field and horizontal gaze palsy can be also present. Non-cerebellar signs such as facial myokymia, resting tremor, writer's cramp, impaired vibration sense and brisk deep tendon reflexes have been reported in some patients. Caused by mutations in the SPTBN2 gene (11q13.2) encoding beta-III spectrin, a protein essential for the correct functioning and development of Purkinje cells. Inherited autosomal dominantly. |
