Electrical myotonia in heterozygous carriers of recessive myotonia congenita

Muscle Nerve. 1999 Jan;22(1):123-5. doi: 10.1002/(sici)1097-4598(199901)22:1<123::aid-mus20>3.0.co;2-y.


We investigated electrophysiologically the unaffected parents of patients with recessive myotonia congenita. We studied 18 families, in nine of which the diagnosis was confirmed by molecular genetics. Brief myotonic discharges were present in at least one parent in 67% of the families. Fathers were more likely than mothers to show these discharges. The difficulty in distinguishing very mildly affected parents with dominant myotonia congenita from the heterozygous carriers of recessive myotonia congenita is stressed.

MeSH terms

  • Action Potentials
  • Chloride Channels / genetics
  • Electromyography
  • Fathers
  • Female
  • Genes, Recessive*
  • Heterozygote*
  • Humans
  • Male
  • Mothers
  • Muscle, Skeletal / physiopathology
  • Mutation
  • Myotonia Congenita / diagnosis
  • Myotonia Congenita / genetics*
  • Myotonia Congenita / physiopathology*


  • Chloride Channels