A case report: autosomal recessive Myotonia congenita caused by a novel splice mutation (c.1401 + 1G > A) in CLCN1 gene of a Chinese Han patient

BMC Neurol. 2018 Sep 22;18(1):154. doi: 10.1186/s12883-018-1153-x.

Abstract

Background: Autosomal 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 presentation: A 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.

Conclusions: This case report of autosomal recessive Myotonia congenita caused by a novel compound heterozygous mutation expands the genotypic spectrum of CLCN1 gene.

Keywords: Autosomal recessive; CLCN1 gene; Case report; Myotonia congenita.

Publication types

  • Case Reports

MeSH terms

  • Asian People / genetics
  • Chloride Channels / genetics*
  • Genotype
  • Humans
  • Male
  • Mutation
  • Myotonia Congenita / genetics*
  • Young Adult

Substances

  • CLC-1 channel
  • Chloride Channels