MOLECULAR ANALYSIS OF THE IT15 GENE IN PATIENTS WITH APPARENTLY SPORADIC HUNTINGTONS-DISEASE

The diagnosis of Huntington's disease (HD) may be uncertain in patient s without a positive family history, particularly when atypical clinic al features are present. We examined the expanded trinucleotide (GAG) repeat sequence in the IT15 gene of 27 'sporadic' cases, classified as having clinically probable or clinically doubtful HD. An abnormal num ber of CAG repeats (42-85) were found in 14 patients. Mutation analysi s confirmed the diagnosis in 63.6% of patients with clinically probabl e HD and in 43.7% of patients with clinically doubtful HD. DNA analysi s allows an accurate diagnosis of apparently 'sporadic' HD patients an d has important implications for genetic counselling.