Ann Clin Neurophysiol.  2024 Apr;26(1):22-25. 10.14253/acn.23008.

A recurrent case of SCN4A related Paramyotonia congenita in two Korean brothers: a case report

• Kang M
• Kim S
• Hah H
• Seok HY
• Park JS

• KMID: 2554850
• DOI: http://doi.org/10.14253/acn.23008

Abstract

Paramyotonia congenita (PMC) is characterized by nondystrophic myotonia aggravated by exercise and cold exposure. SCN4A mutations manifest as various phenotypes of channelopathy, including PMC, myotonia congenita, and periodic paralysis. SCN4A-related channelopathy is characterized by autosomal dominant inheritance. Parental gonadal mosaicism is suspected in cases of recurrent de novo mutation in an autosomal dominantly inherited disease. We report a case of two Korean brothers presenting with PMC due to same de novo SCN4A point mutation, probably due to parental gonadal mosaicism.

Keyword

Paramyotonia congenita; Phenotype; Paramyotonia congenita; Phenotype

Figure

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  Fig. 1. (A) The pedigree of recurrent de novo paramyotonia congenita in our case. (B) The two siblings with clinical paramyotonia harbored a heterozygous pathogenic variant in SCN4A (c.3877G>A), but neither parent carried any SCN4A variant. (C) Muscle magnetic resonance imaging (MRI) of the proband. (D) Muscle MRI of the proband’s brother. MRI revealed mild diffuse muscle hypertrophy in both siblings.

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