In 1990, we launched a major study to ascertain the clinical picture of OPMD in Québec and to identify large families for linkage analysis. In 14 patients, the chromosomes were karyotyped to eliminate any deletion or translocation. Relevant family information and clinical data were computerized and correlations were sought for the age of onset, the identification of the first symptom and the distribution of weakness. A simple test to detect dysphagia was validated. Twenty-one families have taken part in the study, which led to our localization of the gene in 1995 [Brais B, Xie Y-G, Sanson M, et al. Hum Mol Genet 1995; 4:429-434]. At least one case in each family underwent muscle biopsy to confirm the presence of the typical nuclear filaments found in OPMD. Electrodiagnostic and pathologic studies were also conducted to better understand the disease process. An illustrative case is presented.