AUTOSOMAL-DOMINANT CEREBELLAR ATAXIAS IN THE KINKI AREA OF JAPAN

The autosomal dominant cerebellar ataxias are a heterogeneous group of neurodegenerative disorders characterized by slowly progressive cereb ellar ataxia; Recently, among the ataxias, spinocerebellar ataxia type 1 (SCA1), Machado-Joseph disease (MJD) and dentatorubral-pallidoluysi an atrophy have been found to be caused by expansion of a CAG trinucle otide repeat in the coding region of the disease genes. We have analyz ed the CAG repeats of 67 patients from 47 families with dominantly inh erited ataxia who lived in the Kinki area of Japan. The following resu lts were obtained, First, 31 patients from 22 families were found to b e positive for the MJD repeat expansion, indicating that MJD is the mo st common dominantly inherited ataxia in the Kinki area of Japan. Seco nd, no SCA1 repeat expansion was found among the families studied. Thi s presents a striking contrast to the fact that there are many familie s with SCA1 in Hokkaido and the Tohoku area of Japan. These findings s uggest geographic variation in autosomal dominant cerebellar ataxias i n Japan.