AIM AND PATIENTS: To analyse 38 patients with Huntington's disease from 27 families.
Results: The CAG repeat at the huntingtin gene was expanded between 40 and 72 times. The size in normal chromosomes varied from 12 to 30 repeats. We found a significantly negative correlation between the number of CAG-repeats and the age of clinical manifestations. However, age and clinical characteristics of the first symptoms were highly variable between patients with a similar size of the expanded allele. Patients who inherited the disease from their fathers showed a higher number of repeats than those who received the disease from their mothers. However, in one case of father to son transmission we observed a reduction of the number of CAG repeats.
Conclusions: These data make it difficult to use the molecular analysis for the presymptomatic diagnosis of clinical course in individuals carrying the expansion.