Molecular diagnostic analysis for Huntington's disease: a prospective evaluation.

The availability of mutation analysis for the CAG repeat expansion associated with Huntington's disease has prompted clinicians in various specialties to request testing of samples from patients displaying clinical features that might be attributable to Huntington's disease. A series of 38 cases presenting with clinical features thought possibly to be due to Huntington's disease were analysed prospectively. In 53% of such cases presenting initially with chorea and 62.5% with psychiatric symptoms an expansion was identified, a considerable lower proportion than found in previous series where the diagnosis was considered definite on clinical and genetic grounds. Mutation analysis is likely to be of considerable value in the diagnosis of Huntington's disease, especially where the family history in previous generations is inadequate or apparently negative.