CORRELATIONS BETWEEN TRIPLET REPEAT EXPANSION AND CLINICAL-FEATURES IN HUNTINGTONS-DISEASE

Objective: To investigate possible correlations between the length of the (GAG), trinucleotide repeat in Huntington's disease gene IT15 and clinical features (age at onset, symptoms at onset, and mode of progre ssion) in Huntington's disease. Design: In 59 patients with Huntington 's disease, the expansion of the (GAG), trinucleotide repeat was deter mined and clinical data were obtained retrospectively. Setting: The Ce nter for Human Genetics, affiliated with a university hospital.Patient s: All patients belonged to an initial group of 248 individuals tested in an indirect predictive testing procedure. Results: A good correlat ion was found between the expansion of the (GAG), trinucleotide repeat and the age at onset (r=-.71). No correlation was found between the r epeat length of the normal allele and the age at onset. No correlation s were found between repeat expansion and other clinical features, suc h as the nature of the symptoms at onset (neurologic, psychiatric/cogn itive, or both) and the mode of progression. Conclusion: Factors that determine the nature of symptoms at onset and the mode of progression of Huntington's disease seem to be operating independently of the (GAG ), trinucleotide repeat in gene IT15.