Distinctive features of degenerating P urkinje cells in spinocerebellar ataxia type 31

Spinocerebellar ataxia type 31 ( SCA 31) is an autosomal dominant form of pure cerebellar ataxia that is caused by a disease‐specific insertion containing penta‐nucleotide repeats ( TGGAA ) n . N europathologically, cerebellar P urkinje cells are preferentially affected and reduced in number in SCA 31, and they are often surrounded by halo‐like amorphous materials. In the present study, we performed neuropathological analyses on two SCA 31 brains, and discussed the serial morphological changes of Purkinje cells in SCA 31.We found that bent, elongated, often folded nuclei were observed frequently in degenerating P urkinje cells with the halo‐like structure. Conversely, P urkinje cells without this structure developed marked atrophy with severely slender and condensed nuclei. On the basis of these pathological findings, we propose two different processes for Purkinje cell degeneration in SCA 31, namely, shrinkage of P urkinje cells with or without the halo‐like amorphous materials. The former, but not the latter, was considered to be specific to SCA 31. Correspondingly, fragmentation of the G olgi apparatus was observed more frequently in Purkinje cells with the halo‐like structure than in those without this structure. We consider that the profound nuclear deformity and fragmentation of the G olgi apparatus are closely linked with the formation of the halo‐like structure in SCA 31.