Background and purpose: Oculopharyngeal muscular dystrophy (OPMD) is mostly an autosomal dominant myopathic disorder, characterized by progressive bilateral ptosis, dysphagia and proximal muscle weakness, appearing usually in the fifth to sixth decade of life. The underlying cause of OPMD is an expanded GCG repeat in the first exon of the gene encoding poly (A)-binding protein nuclear 1 (PABPN1) localized on chromosome 14.q11.2-q13. The number of GCG expansion ranges from 8 to 13 repeats. PABPN1 is a nuclear multifunctional protein which is involved in transcription regulation and post-transcriptional processes.
Material and methods: We report on clinical characteristics in 9 Polish patients with genetically confirmed OPMD.
Results: The expanded repeat ranged from (GCG)8 to (GCG)11. Ptosis and dysphagia were present in all examined cases. In 4 patients weakness of extraocular muscle was found and two of them experienced transient diplopia. Mild limb-girdle weakness was observed in 6 patients. Muscle biopsy performed in all cases showed myopathic changes with rare rimmed vacuoles. Strikingly, despite thorough examination on electron microscopy, intranuclear inclusions typical for OPMD were found only in one patient.
Conclusions: Genetic testing is necessary to confirm the diagnosis of OPMD, especially in cases with ptosis and external ophthalmoparesis, which may be initially diagnosed as mitochondrial myopathy.