A Japanese family with Machado-Joseph disease characterized by initial emaciation and myoclonus

We describe a Japanese family with hereditary spinocerebellar ataxia characterized by initial emaciation and myoclonus. The proband first noted truncal ataxia, myoclonus in the shoulder and general emaciation at age 24. The other affected members of the family also had such emaciation in the early stage of the disease. The DNA analyses of the family revealed that the patients of the family are associated with the expansions of CAG repeats for Machado-Joseph disease (MJD) on the long arm of chromosome 14. Although the clinical features of MJD are very variable, general emaciation in an early stage of the disease and systemic myoclonus have not been documented. Because it is sometimes difficult to distinguish among hereditary spinocerebellar ataxias such as spinocerebellar ataxia type 1 (SCA1) or dentatorubropallidoluysian atrophy (DRPLA) by clinical features, a genetic examination provides better understanding of such a rare and ambiguous type of hereditary spinocerebellar ataxia.