Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant disorder characterized by slow progressive bilateral ptosis, dysphagia, dysarthria, and proximal limb weakness. The symptoms of OPMD usually manifest in the fifth or sixth decade of life. Early symptoms are ptosis and dysphagia, followed by other signs that are observed as the disease progresses, such as proximal upper and lower extremity weakness, wet voice due to pooling of saliva, dysarthria, dysphonia, facial muscle weakness and limitation of upward gaze. Diagnosis of OPMD is based on clinical presentation and genetic confirmation of a mutation in the first exon of the PABPN1 gene. There is no cure for OPMD, but surgical treatments are available to improve symptoms that result from ptosis and dysphagia.
Oculopharyngeal muscular dystrophy is inherited as an autosomal dominant trait, but a few autosomal recessive cases have also been reported. Expansion of the polyalanine tract in the PABPN1 gene (14q11.2), which encodes a protein that plays an important role in processing mRNAs, is the cause of oculopharyngeal muscular dystrophy. The extra alanine leads to overexpression of a mutant protein and accumulation of intranuclear inclusions within the muscles.
Oystreck et al. (2011) reported five Saudi patients with genetically and pathologically different ocular motility abnormalities, but share the phenotype of straight eyes. The first patient was a 47-year-old male with oculopharyngeal muscular dystrophy presented with complete bilateral ophthalmoparesis and ptosis covering the pupillary axis. He had substantial weakness and wasting of facial muscles, frontal balding, moderate proximal and distal muscle weakness, and nasal speech.