[A case report of late-onset Huntington disease without family history and caudate atrophy who has diagnosed clinicopathologically and genetically].

We report a 66-year-old male with typical symptoms of Huntington's disease (HD), but without family history or atrophy of caudate nucleus on brain CT. The diagnosis of HD was confirmed in this apparently sporadic case by neuropathological findings as loss of small-sized neuron with gliosis in the striatum, and molecular testing of CAG repeat of the gene for HD using post mortem tissue. The DNA analysis showed that he had a mildly expanded allele with 45 repeat units, in the size range seen in HD chromosomes. The result suggests that there are some correlations between the repeat length and the clinicopathological findings such as late onset, lack of family history and insusceptible caudate atrophy.