Molecular and clinical analyses of spinocerebellar ataxia type 8 in Japan

Abstract

The CTG repeat expansions in the SCA8 alleles were much greater than the range of repeats in normal elderly subjects. The SCA8 phenotype manifested by cerebellar symptoms and atrophy corresponded to features of the autosomal dominant cerebellar ataxia type III (ADCA III).

Incoordinated thought and emotion in spinocerebellar ataxia type 8

“…Ataxic dysarthria with limb and gait ataxia are the usual neurological findings but spasticity and diminished vibration perception have also been recorded. Neuropsychological or psychiatric deficits were not noted in the first two reports [1,2], but mild to moderate memory impairment was present in two of the seven patients reported by Silveira et al [3]. The paediatric patient had mental retardation.…”

“…Sirs: A new form of autosomal dominant spinocerebellar ataxia (SCA8) with incomplete penetrance due to a non-coding expansion of CTG repeats on chromosome 13q21 has been described in seven kindreds in the United States [1], in a series of six patients from Japan [2] and seven from Portugal [3]. Further studies have reported a number of healthy controls and elderly unaffected family members who do not have ataxia but nevertheless have large expansions at the gene locus [3][4][5][6][7].…”

“…SCA8 has thus far been described in three clinical reports [1][2][3]. The mean reported age at onset ranges from 20-31 years [3] to 54±20 years [2].…”

“…The mean reported age at onset ranges from 20-31 years [3] to 54±20 years [2]. Silveira et al [3] have reported a possible case with onset in the first year of life.…”

“…Three studies have reported unaffected 'carriers', in ataxia families [1,3,7] with repeat sizes well over 100 some of whom are in their eighth decade [7]. In three studies the analysis of healthy control samples of 1200 [1], 1818 [3] and 110 [2] chromosomes failed to find a single non-pathogenic expanded allele greater than 100 repeats. However, four groups have now reported the discovery of expanded CTA/CTG repeats of over 100 in control patients without ataxia [4][5][6][7].…”