Regional differences in genetic subgroup frequency in hereditary cerebellar ataxia, and a morphometrical study of brain MR images in SCA1, MJD and SCA6

Molecular genetic assessments of 69 individuals in 44 families with heredit ary cerebellar ataxia (HCA) were made to determine the relative frequencies of subtypes of HCA in Yamagata, Japan. Fifteen families (34%) had SCA1, no ne had SCA2, nine (20%) had MJD, five (11%) had SCA6 and nine (20%) had DRP LA. These findings differ markedly from those in other regions of Japan and the rest of the world. A morphometrical study of the brain MR images also was made on 38 individuals with SCA1 (n=14), MJD (n=8) or SCAG (n=16). In S CA1, the ventral pens was atrophic in proportion to the amount of cerebella r atrophy. In MJD, both the pens and the cerebellum were atrophic, cerebell ar atrophy being less pronounced than that in SCA1 and SCA6. While both the major and minor axes of the ventral pens were proportionally decreased in SCA1, the minor axis was more decreased than the major axis in MJD. In SCA6 , a mild reduction in the ratio of the ventral pontine area to the posterio r fossa area (Pv/PF) was observed as well as obvious cerebellar atrophy. Th ese findings indicate that in MR images SCA1, MJD and SCA6 show different a trophic features of the cerebellum and brainstem. (C) 1999 Elsevier Science B.V. All rights reserved.