A Japanese case of oculopharyngeal muscular dystrophy (OPMD) with PABPN1 c.35G > C; p.Gly12Ala point mutation

BACKGROUND: Oculopharyngeal muscular dystrophy (OPMD) is a late-onset muscular dystrophy characterised by slowly progressive ptosis, dysphagia, and proximal limb muscle weakness. A common cause of OPMD is the short expansion of a GCG or GCA trinucleotide repeat in PABPN1 gene. CASE PRESENTATION: A 78-year-old woman presented with ptosis and gradually progressive dysphagia. Her son had the same symptoms. A physical examination and muscle imaging (MRI and ultrasound) showed impairment of the tongue, proximal muscles of the upper limbs, and flexor muscles of the lower limbs. Needle-electromyography (EMG) of bulbar and facial muscles revealed a myopathic pattern. Based on the characteristic muscle involvement pattern and needle-EMG findings, we suspected that the patient had OPMD. Gene analysis revealed PABPN1 c.35G > C point mutation, which mimicked the effect of a common causative repeat expansion mutation of OPMD. CONCLUSION: We herein describe the first reported Japanese case of OPMD with PABPN1 point mutation, suggesting that this mutation is causative in Asians as well as in Europeans, in whom it was originally reported.