Background：Congenital myasthenic syndromes are a group orrare disorders that are clinically and genetically heterogeneous and caused by mutations in the genes encoding proteins of the neuromuscular junction.Here,we d...Background：Congenital myasthenic syndromes are a group orrare disorders that are clinically and genetically heterogeneous and caused by mutations in the genes encoding proteins of the neuromuscular junction.Here,we described a Chinese family that presented with phenotypes of classic slow-channel congenital myasthenic syndrome （SCCMS）.Methods：Clinical characteristics and electrophysiological features of three patients from a Chinese family were examined,and next-generation sequencing followed by direct sequencing was carried out.Results：The patients revealed variability in clinical and electrophysiological features.However,weakness,scoliosis,and repetitive-compound muscle action potential were found in all affected members in the family.A heterozygous C〉T missense mutation at nucleotide 865 in acetylcholine receptor epsilon-subunit （CHRNE） gene that causes a leucine-to-phenylalanine substitution at position 289 （L289F） was found.Conclusions：We reported a SCCMS family of Chinese origin.In the family,classical clinical phenotype with phenotypic variability among different members was found.Genetic testing could help diagnose this rare disease.展开更多
Background： Congenital myasthenic syndromes （CMSs） are a group of clinically and genetically heterogeneous disorders caused by impaired neuromuscular transmission. The defect of AGRN was one of the causes of CMS th...Background： Congenital myasthenic syndromes （CMSs） are a group of clinically and genetically heterogeneous disorders caused by impaired neuromuscular transmission. The defect of AGRN was one of the causes of CMS through influencing the development and maintenance of neuromuscular transmission. However, CMS reports about this gene mutation were rare. Here, we report a novel homozygous missense mutation （c.5302G〉C） of AGRN in a Chinese CMS pedigree. Methods： We performed a detailed clinical assessment of a Chinese family with three affected members. We screened for pathogenic mutations using a disease-related gene panel containing 519 genes associated with genetic myopathy （including 17 CMS genes）. Results： In the family, the proband showed limb-girdle pattern of weakness with sparing of ocular, facial, bulbar, and respiratory muscles. Repetitive nerve stimulation showed a clear decrement of the compound muscle action potentials at 3 Hz only. Pathological analysis of the left tibialis anterior muscle showed predominance of type I fiber and the presence of scattered small angular fibers. The proband＇s two elder sisters shared a similar but more severe phenotype. By gene analysis, the same novel homozygous mutation （c.5302G〉C, p.A1768P） of AGRN was identified in all three affected members, whereas the same heterozygous mutation was found in both parents, revealing an autosomal recessive transmission pattern. All patients showed beneficial responses to adrenergic agonists. Conclusions： This study reports a Chinese pedigree in which all three children carried the same novel AGRN mutation have CMS only affecting limb-girdle muscle. These findings might expand the spectrum of mutation in AGRN and enrich the phenotype of CMS.展开更多
文摘Background：Congenital myasthenic syndromes are a group orrare disorders that are clinically and genetically heterogeneous and caused by mutations in the genes encoding proteins of the neuromuscular junction.Here,we described a Chinese family that presented with phenotypes of classic slow-channel congenital myasthenic syndrome （SCCMS）.Methods：Clinical characteristics and electrophysiological features of three patients from a Chinese family were examined,and next-generation sequencing followed by direct sequencing was carried out.Results：The patients revealed variability in clinical and electrophysiological features.However,weakness,scoliosis,and repetitive-compound muscle action potential were found in all affected members in the family.A heterozygous C〉T missense mutation at nucleotide 865 in acetylcholine receptor epsilon-subunit （CHRNE） gene that causes a leucine-to-phenylalanine substitution at position 289 （L289F） was found.Conclusions：We reported a SCCMS family of Chinese origin.In the family,classical clinical phenotype with phenotypic variability among different members was found.Genetic testing could help diagnose this rare disease.
文摘Background： Congenital myasthenic syndromes （CMSs） are a group of clinically and genetically heterogeneous disorders caused by impaired neuromuscular transmission. The defect of AGRN was one of the causes of CMS through influencing the development and maintenance of neuromuscular transmission. However, CMS reports about this gene mutation were rare. Here, we report a novel homozygous missense mutation （c.5302G〉C） of AGRN in a Chinese CMS pedigree. Methods： We performed a detailed clinical assessment of a Chinese family with three affected members. We screened for pathogenic mutations using a disease-related gene panel containing 519 genes associated with genetic myopathy （including 17 CMS genes）. Results： In the family, the proband showed limb-girdle pattern of weakness with sparing of ocular, facial, bulbar, and respiratory muscles. Repetitive nerve stimulation showed a clear decrement of the compound muscle action potentials at 3 Hz only. Pathological analysis of the left tibialis anterior muscle showed predominance of type I fiber and the presence of scattered small angular fibers. The proband＇s two elder sisters shared a similar but more severe phenotype. By gene analysis, the same novel homozygous mutation （c.5302G〉C, p.A1768P） of AGRN was identified in all three affected members, whereas the same heterozygous mutation was found in both parents, revealing an autosomal recessive transmission pattern. All patients showed beneficial responses to adrenergic agonists. Conclusions： This study reports a Chinese pedigree in which all three children carried the same novel AGRN mutation have CMS only affecting limb-girdle muscle. These findings might expand the spectrum of mutation in AGRN and enrich the phenotype of CMS.
