P1.52 Infantile facioscapulohumeral muscular dystrophy with a very short 4q35 fragment: additional features

Oculopharyngeal muscular dystrophy (OPMD; MIM 164300) is a hereditary myopathy, caused by abnormal (GCG) expansions or (GCA) insertions in exon 1 of the polyadenylate binding protein nuclear 1 gene (PABPN1) on chromosome14q11.2–q13.Wedescribed 23 OPMD patients in five Chinese Han families. The age of onset ranged from 30 to 70 years. The initial symptoms consisted of dysphagia in 14patients, ptosis infivepatients, lower limbweakness in1 patient, and both dysphagia and ptosis in two patients. Muscle biopsise of five index patients revealed only mild changes with a few of rimmed vacuoles.Ultrastructural examination showed typicalOPMD intranuclear inclusions. Molecular analysis found (GCG)9 expansions of the PABPN1 gene in two OPMD families, while (GCG)6(GCA)(GCG)3, (GCG)10, and (GCG)8 were identified in one family respectively. The two families with (GCG)9 expansion shared a common rs2239579(C)-(GCG)9-SNP2622(C) haplotype, which is different from other ethnic patients with same genotype. This study suggested that dysphagiamay be the common initial symptom in ChineseHanOPMD patients. Both (GCG) expansions and (GCA) insertion of the PABPN1 gene could be detected in Chinese patients. Different families with same (GCG)9 expansions probably arose from a common ancestor.