DIAGNOSIS OF SPORADIC HUNTINGTONS-DISEASE

The diagnosis of Huntington's disease (HD) in patients with progressiv e chorea and mental impairment, but without similarly affected relativ es, remains uncertain and impedes genetic counseling. Twenty patients with suspected HD, but with no family history of the disease underwent molecular analysis of the CAG repeat in the IT15 gene for HD. Eightee n patients displayed the HD expanded allele and two had CAG repeats in the normal range. Neuropsychological tests could be performed in 12 o f the 20 patients. Of these 10 with the expanded allele presented the deficits typical of HD, but not the two patients without the HD mutati on. This study shows that a neuropsychological pattern is specific to patients with the expanded CAG and that most isolated patients with su spected HD are in fact affected.