A Form of Inherited Cerebellar Ataxia with Saccadic Intrusions, Increased Saccadic Speed, Sensory Neuropathy, and Myoclonus

Over the past five years, rapid progress has been made in genetically identifying dif-ferent forms of spinocerebellar atrophy (SCA), for which several characteristic dis-orders of eye movements have been reported.1,2 Nonetheless, the genetic disorder in some families has not yet been discovered, and this report concerns one such kin-ship. We studied a family of Slovenian descent in which 5 of 14 siblings presented with progressive ataxia. Two other siblings, who we did not study, may also show involvement, but neither parent and none of 27 children of the 14 siblings has been affected. We examined the five definitely affected patients several times over a 5-year period; electroencephalography, electromyography, and MRI brain imaging were performed. In Patient 5 (the proband), we carried out genetic screening (Athena Laboratories) for Friedreich’s ataxia, spinocerebellar ataxia (SCA) 1-3 and 6-8, and Unverricht-Lundborg progressive myoclonic epilepsy (EMP1). We compared results of eye movement studies with a group of 10 normal subjects (2 female; median age 40 years, range 23–60). We measured horizontal and vertical eye movements using the magnetic search coil technique. We tested fixation, horizontal and vertical sac