Limits of clinical assessment in the accurate diagnosis of Machado-Joseph disease
I. Lopes-Cendes, I. Silveira, P. Maciel, C. Gaspar, J. Radvany, D. Chitayat, R. Babul, J. Stewart, M. Dolliver, Y. Robitaille, G. A. Rouleau and J. Sequeiros
Centre for Research in Neuroscience, Montreal General Hospital Research Institute, McGill University, Quebec.
BACKGROUND: Machado-Joseph disease (MJD) is a type of autosomal dominant
spinocerebellar ataxia for which molecular diagnosis is available. We
identified 4 families segregating the MJD mutation in which no unequivocal
clinical diagnosis could be established prior to molecular testing. Ethnic
background, clinical, and molecular characteristics of 19 individuals
carrying the MJD mutation in these 4 families were compared with a group of
32 Portuguese families who were clinically diagnosed as having MJD and were
found to carry the MJD mutation. RESULTS: Several factors seemed to have an
impact in the accuracy of the clinical diagnosis, such as ethnic origin;
the number of affected individuals available for examination in each
family; the absence of patients showing specific clinical features, such as
extrapyramidal signs; and the size of the expanded CAG repeat in the MJD
gene. CONCLUSION: Since the recognition of MJD based solely on clinical
grounds might sometimes be misleading, a search for the MJD mutation should
be performed in patients with a clinical diagnosis of spinocerebellar
degeneration.