A Japanese case of oculopharyngeal muscular dystrophy (OPMD) with PABPN1 c.35G\u2009>\u2009C; p.Gly12Ala point mutation

Yo-Suke Nishii,Takamasa Kitaoji,Shinji Ashida,Eijirou Tanaka,Yu-Ichi Noto,Rei Yasuda,Toshiki Mizuno,Ichizo Nishino,Narihiro Minami

doi:10.1186/s12883-021-02300-x

Yo-Suke Nishii, Takamasa Kitaoji + Show 7 more

Open Access

https://doi.org/10.1186/s12883-021-02300-x

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Abstract

BackgroundOculopharyngeal 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 presentationA 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.ConclusionWe 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.

Highlights

We describe the first reported Japanese case of Oculopharyngeal muscular dystrophy (OPMD) with Poly(a) binding protein nuclear 1 (PABPN1) point mutation, suggesting that this mutation is causative in Asians as well as in Europeans, in whom it was originally reported
Oculopharyngeal muscular dystrophy (OPMD) is a late-onset muscular dystrophy characterised by slowly progressive ptosis, dysphagia, and proximal limb muscle weakness
The G → C substitution changes a glycine GGG codon, located immediately 3’ to the normal 10 alanine codon repeat sequence, to an alanine GCG codon. This change causes an increase in the number of contiguous polyalanine codons from 10 to 13 alanines without gene expansion ((GCG)6(GCA)3(GCG)2(GCT)1(GCG)1), which has the same effect as the common triplet repeat expansion mutation in OPMD [8]

Summary

Conclusion

We 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.

Background

Discussion and conclusions