Probable sporadic Creutzfeldt-Jakob disease with valine homozygosity at codon 129 and bilateral middle cerebellar peduncle lesions.

We describe a 67-year-old Japanese man with probable sporadic Creutzfeldt-Jakob disease (CJD) who had valine homozygosity at codon 129, a rarity in the Japanese. T2-weighted magnetic resonance imaging (MRI) detected high-intensity lesions in the bilateral middle cerebellar peduncles and basal ganglia as well as cerebellar and cortical atrophy. He developed cerebellar ataxia and subsequent mental deterioration, myoclonus, and periodic synchronous discharge as shown in an electroencephalogram. Cerebrospinal fluid examination showed a high level of neuron-specific enolase and a positive immunoassay for the 14-3-3 protein. He died of pneumonia 10 months after the initial symptoms appeared. Whether or not the genetic polymorphism increased his susceptibility to sporadic CJD is not clear because valine homozygosity at codon 129 is less than 1% in the normal Japanese population. Although there is no convincing evidence in the present case, the MRI findings of cerebellar peduncle changes, which are rare in CJD, suggest a kind of degeneration, demyelination, or both.