CAG repeat expansions in patients with sporadic cerebellar ataxia.
CAG repeat expansions cause spinocerebellar ataxia type 1 (SCA1), SCA2, SCA3, SCA6 and dentatorubral-pallidoluysian atrophy (DRPLA). So far these expansions have been examined mainly in ataxia patients with a family history. However, some sporadic cases with SCA have recently been reported. To elucidate the frequency and characteristics of sporadic SCAs, we screened 85 Japanese ataxia patients without a family history for the SCA1, SCA2, SCA3, SCA6 and DRPLA mutations. As a result, 19 patients (22%) were found to have expanded CAG repeats. Among sporadic SCAs, the SCA6 mutation was most frequently observed. The sporadic SCA6 patients had smaller CAG repeats and a later age of onset than SCA6 patients with an established family history. We also identified one father-child pair in which intermediate sized CAG repeats expanded into the SCA2 disease range during transmission. These findings suggest that patients with ataxia even without a family history should be examined for a CAG repeat expansion.
Department of Neurology, Nara Medical University, Kashihara, Japan.
N
N
Futamura
R
R
Matsumura
Y
Y
Fujimoto
H
H
Horikawa
A
A
Suzumura
T
T
Takayanagi
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D004252:DNA Mutational Analysis; D005260:Female; D005787:Gene Frequency / Q000235:genetics; D006580:Genetic Carrier Screening; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D013132:Spinocerebellar Degenerations / Q000175:diagnosis / Q000235:genetics*; D018911:Trinucleotide Repeats / Q000235:genetics*