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November 1996

Limits of Clinical Assessment in the Accurate Diagnosis of Machado-Joseph Disease

Author Affiliations

From the Centre for Research in Neuroscience, The Montreal General Hospital Research Institute, McGill University, Montreal, Quebec (Drs Lopes-Cendes, Silveira, and Rouleau and Mss Maciel and Gaspar); UnIGENe, IBMC, and Laboratório de Genética Médica, ICBAS and Universidade do Porto, Porto, Portugal (Drs Silveira and Sequeiros and Mss Maciel and Gaspar); Neurologia, Hospital Albert Einstein, Sao Paulo, Brazil (Dr Radvany); Division of Clinical Genetics, Hospital for Sick Children, Toronto, Ontario (Dr Chitayat and Ms Babul); Montreal Neurological Institute and Hospital, McGill University, Montreal (Dr Stewart); Department of Genetics, Kaiser Hospital, Sacramento, Calif (Ms Dolliver); and University of Montreal, Montreal (Dr Robitaille).

Arch Neurol. 1996;53(11):1168-1174. doi:10.1001/archneur.1996.00550110120020

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.

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