Oculopharyngeal muscular dystrophy in Hispanic new Mexicans

Context Oculopharyngeal muscular dystrophy (OPMD) is a rare myopathy caused by polyalanine triplet repeat expansion in the gene for poly(A) binding pr otein 2 (PABP2) and is found in isolated cohorts throughout the world. We h ave observed numerous cases of OPMD in New Mexico. Objective To characterize the clinical, genetic, and demographic features o f the OPMD population in New Mexico. Design, Setting, and Participants Cohort study with analysis of outpatient clinic medical records from 1965 to 2001 at the University of New Mexico Ho spital and the New Mexico VA Health Care System in Albuquerque, which serve the entire state. Main Outcome Measures Clinical phenotype, supplemented with genetic confirm ation (n=10 patients) and in-depth clinical evaluations (n=49 patients). Results We identified 216 cases of OPMD (99 women and 117 men) from 39 kind reds of New Mexicans spanning up to 4 generations. All patients were Hispan ic, and the majority of probands came from northern New Mexico. In patients who had both ocular and pharyngeal muscle weakness, ptosis was just as lik ely to occur before or concurrent with dysphagia. Proximal limb muscle weak ness and gait abnormalities were common and occurred later than ocular or p haryngeal weakness. The clinical expression of OPMD caused marked debility, although life-table analysis showed no decrease in life expectancy compare d with unaffected family members (P=.81). Ten individuals from different ki ndreds were found to have an identical polyalanine triplet repeat expansion ([GCG](9)) in the PABP2 gene. Conclusions Individuals in this cohort had clinical and genetic characteris tics of classic OPMD. Longevity was not affected, but patients experienced considerable morbidity. The origin of the PABP2 mutation in New Mexican OPM D patients is unclear, although the geographic and genetic isolation of nor thern New Mexicans with a long ancestry in this region may have contributed to the development of this cohort. This disease cohort represents a large and previously unrecognized health care issue in the state of New Mexico an d should serve to raise the awareness of this disorder among clinicians who treat Hispanics in the Southwest and throughout the United States.