PMID 20301536


Spinocerebellar ataxia type 15 (SCA15) is characterized by slowly progressive gait and limb ataxia, often in combination with ataxic dysarthria, titubation, upper limb postural tremor, mild hyperreflexia, gaze-evoked nystagmus, and impaired vestibulo-ocular reflex gain. Onset is between ages seven and 72 years, usually with gait ataxia but sometimes with tremor. Affected individuals remain ambulatory for ten to 54 years after symptom onset. Mild dysphagia usually after two or more decades of symptoms has been observed in members of multiple affected families and movement-induced oscillopsia has been described in one member of an affected family. The diagnosis of SCA15 should be considered in individuals in whom the diagnoses of SCA5, SCA6, SCA8, SCA11, SCA12, SCA14, and SCA27 have been excluded by molecular genetic testing (if available) and who fulfill the clinical diagnostic criteria for SCA15. ITPR1 is the only gene known to be associated with SCA15. Neuroimaging reveals atrophy of the rostral and dorsal vermis of the cerebellum with mild atrophy of the cerebellar hemispheres. Treatment of manifestations: Physical and occupational therapy; management of neurogenic dysphagia, if it occurs. Prevention of secondary complications: Aids for walking and home modifications to help prevent falls; prevention/treatment of osteoporosis to reduce fracture risk. Surveillance: Follow up by a neurologist with consultation from physiatrists and physical and occupational therapists every two or three years. Agents/circumstances to avoid: Limit alcohol intake to lessen the risk of falls. SCA15 is inherited in an autosomal dominant manner. If a parent of the proband is affected, the risk to each sib is 50%. Prenatal testing for pregnancies at increased risk is possible through laboratories offering either testing for the gene of interest or custom testing.