Oculopharyngeal muscular dystrophy

Oculopharyngeal muscular dystrophy (OPMD) is a late onset myopathy with autosomal dominant inheritance. Clinical symptoms are eyelid drooping (ptosis), swallowing difficulties (dysphagia), and proximal limb weakness. Autosomal dominant OPMD is caused by an increased number of alanine coding trinukleotids in the PABPN1 gene leading to the expansion of a polyalanine stretch from 10 to 12-17 alanins in the N-terminal region of PABPN1. The expanded protein tends to form aggregates which ore detectable as intranuclear filaments by electron microscopy. The definite pathogenetic mechanism leading to the selective damage of skeletal muscle cells and to the characteristic phenotype is presently unknown.