We report a cluster of patients from a Karaite Jew community with a movement 
disorder suggestive of Huntington disease (HD), in some cases associated with 
repeat lengths below the edge of 36 CAG repeats. The study describes the 
clinical and genetic features of four patients who were followed over several 
years. Patients belonged to an inbred family in whom progressive chorea, 
manifesting predominantly with dystonia and cerebellar features, developed 
during middle age. Although severe psychiatric symptoms ultimately developed in 
two of the four patients, cognitive function remained reasonably well preserved 
in all of them even after several disease years. Moderate cognitive deficits 
were limited to the visuomotor organization and abstract thinking subtests in 
three of the four patients. Qualitative brain imaging showed atrophy of brain 
predominantly involving cortex and cerebellum. Genetic testing revealed a 
variable mutation penetrance among family members, some affected members showing 
an upper allele size ranging from 34 to 49, whereas others remained unaffected 
despite the presence of the full mutation beyond 40 CAG repeats. Co-morbidity 
with recessive hereditary inclusion body myopathy was found in two subjects from 
one family. Although the main diagnosis of HD remains to be confirmed by further 
neuropathological studies, these cases may suggest that HD could manifest with 
as few as 34 CAG repeats, in some geographic areas, the disease phenotype most 
probably being influenced by additional, as yet unidentified, genes.