Oculopharyngeal Muscular Dystrophy: Phenotypic and Genotypic Studies in a Chinese Population

Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant late-onset neuromuscular degenerative disease characterized by ptosis, dysphagia, and proximal muscle weakness. The genetic basis has been identified as an abnormal (GCN) expansion encoding the polyalanine tract in exon 1 of the polyadenylate-binding protein nuclear 1 gene (PABPN1). OPMD is worldwide distributed, but has rarely been reported in East Asians. In this study, we summarized the clinical and genetic characteristics of 34 individuals from 13 unrelated families in Chinese population. In our cohort, the mean age at onset was 47.2 years. Dysphagia, rather than ptosis, was the most common initial symptom. Genetically, we identified seven genotypes in our patients, including one compound heterozygote of (GCN)₁₁/(GCN)₁₂. The genetic heterogeneity implies that there is no single founder effect in Chinese population, and our data also support that the (GCN)₁₁ polymorphism may have a disease-modifying effect. Additionally, the clinical features showed homogeneity within families, which suggests that other genetic factors apart from the already known genotype also play a role in modifying the phenotype.