Abstract
Studies on spinocerebellar ataxias (SCA) have been hampered by a lack of disease
markers. Clinical and pathological heterogeneity also made the classification
unreliable. Linkage studies established that there are multiple subtypes of SCA.
Five types are found to have unstable CAG expansion; the diagnosis can be
established by molecular genetic study. Therefore, we systemically screened
degenerative ataxia patients for these five SCA types, and identified eight
patients with SCA2 (seven from six families and one sporadic case). This paper
presents the clinical information on the seven patients, whose clinical
information was available in detail. CAG repeat expansion in the patients ranged
from 38 to 47 (normal control, 19 to 27). The onset ages ranged from 16 to 41
with 27.1 years as the mean, which correlated inversely with repeat lengths. All
patients presented dysarthria and gait ataxia. Upper limb dysmetria or
dysdiadochokinesia appeared later but progressed, causing severe disability.
Slow saccade (4 patients in 7) and decreased DTR (4 in 7) were common. MRIs
showed severe atrophy of the brainstem and cerebellum in all patients. We
conclude that SCA2 is the most frequent type in Korea and carries rather pure
cerebellar syndrome, slow saccade, and hyporeflexia.