Frequency of spinocerebellar ataxia mutations in the Kinki district of Japan.

OBJECTIVES

To determine the frequencies of spinocerebellar ataxias (SCAs) in the Kinki district, the western part of the main island of Japan.

MATERIAL AND

METHODS

One hundred and forty-three families with dominantly inherited ataxia and 220 patients with apparently sporadic cerebellar ataxia were examined for the SCA1, SCA2, SCA3/Machado-Joseph disease (MJD), SCA6, SCA7, SCA8, SCA12 and dentatorubral-pallidoluysian atrophy (DRPLA) mutations.

RESULTS

Among the dominant families, SCA1 accounted for 3%, SCA2 for 4%, SCA3/MJD for 24%, SCA6 for 31% and DRPLA for 12%. Neither SCA7 nor SCA12 mutations were detected. Among the apparently sporadic patients, 15% were found to have expanded triplet repeats. Of these, the SCA6 mutation was most frequently detected.

CONCLUSION

SCA6 is the most common SCA in the Kinki district of Japan. Comparison of our results with those from other regions of Japan and different countries shows geographic and ethnic variation in the frequency of SCAs.