Oculopharyngeal muscular dystrophy - A genetically verified Taiwanese family

Background: Oculopharyngeal muscular dystrophy (OPMD) is a rare inherited muscular disorder, clinically characterized by late-onset, slowly progressive bilateral ptosis, dysphagia, and proximal limb weakness. A short polyalanine expansion in the polyadenylate binding-protein nuclear 1 (PABPN1) gene is a commonly reported mutation. Methods: We studied a large family with 12 affected members who inherited a dominant trait. Drooping of eye lids and dysphagia were characteristic phenotypes starting in the sixth decade. We collected blood samples from all available familial members and 30 control subjects. They were analyzed using modified polymerase chain reaction (PCR) amplification and direct sequence analysis. Results: The abnormally extended three GCG resulting in heterozygous (GCG)₉ of PABPN1 gene was identified in four affected and two asymptomatic carriers, but not in the 30 control individuals. The expansion of the PABPN1 polyalanine tract which resulted from 10 to 13 alanines was further confirmed by subcloning into TOPO cloning vectors. Conclusions: The phenotypic characteristics and genetic information confirmed our diagnosis of OPMD. We suggest that genetic intervention should be undertaken to understand the genetic epidemiology and provide counseling for carriers of OPMD in Taiwan.