A case report: autosomal recessive Myotonia congenita caused by a novel splice mutation (c.1401\u2009+\u20091G\u2009>\u2009A) in CLCN1 gene of a Chinese Han patient

Jing Miao,Xiao-Jing Wei,Xue-Fan Yu,Zhi-Xia Kang,Xue-Mei Liu,Yan-Lu Gao

doi:10.1186/s12883-018-1153-x

Abstract

BackgroundAutosomal recessive Myotonia congenita (Becker’s disease) is caused by mutations in the CLCN1 gene. The condition is characterized by muscle stiffness during sustained muscle contraction and variable degree of muscle weakness that tends to improve with repeated contractions.Case presentationA 21-year-old man presented with transient muscle stiffness since the last 10 years. He had difficulty in initiating movement and experienced muscle weakness after rest, which typically improved after repeated contraction (warm-up phenomenon). There was no significant family history. Medical examination showed generalized muscle hypertrophy. Serum creatine kinase level was 2-fold higher than the normal value. Electromyogram showed myotonic discharges. DNA sequence analysis identified a novel splice mutation (c.1401 + 1G > A) and a known mutation (c.1657A > T,p.Ile553Phe). He rapidly responded to treatment with mexiletine 100 mg three times a day for 6 months.ConclusionsThis case report of autosomal recessive Myotonia congenita caused by a novel compound heterozygous mutation expands the genotypic spectrum of CLCN1 gene.

Highlights

Autosomal recessive Myotonia congenita (Becker’s disease) is caused by mutations in the CLCN1 gene
This case report of autosomal recessive Myotonia congenita caused by a novel compound heterozygous mutation expands the genotypic spectrum of CLCN1 gene
Autosomal recessive Myotonia congenita (Becker’s disease) is caused by mutations in CLCN1 gene, which is located on the 7q35 chromosomal region and contains 23 coding exons

Summary

Introduction

Autosomal recessive Myotonia congenita (Becker’s disease) is caused by mutations in the CLCN1 gene. Background Autosomal recessive Myotonia congenita (Becker’s disease) is caused by mutations in CLCN1 gene, which is located on the 7q35 chromosomal region and contains 23 coding exons. * Correspondence: dr_yuxuefan@126.com Department of Neurology and Neuroscience Center, the First Affiliated Hospital of Jilin University, Changchun 130021, Jilin, People’s Republic of China our knowledge, only a few splicing mutations of the CLCN1 gene have been reported. These mutations may induce depolarisation of the skeletal muscle cell membrane which leads to hyperexcitablity (myotonia), which may improve on treatment with sodium (Na+) blocking agents such as mexiletine [1,2,3,4,5].

Results

Conclusion