Korean J Pediatr.  2011 Nov;54(11):470-472. 10.3345/kjp.2011.54.11.470.

Familial hyperkalemic periodic paralysis caused by a de novo mutation in the sodium channel gene SCN4A

• Han JY
• Kim JB

• KMID: 1506498
• DOI: http://doi.org/10.3345/kjp.2011.54.11.470

Abstract

Familial hyperkalemic periodic paralysis (HYPP) is an autosomaldominant channelopathy characterized by transient and recurrent episodes of paralysis with concomitant hyperkalemia. Mutations in the skeletal muscle voltage-gated sodium channel gene SCN4A have been reported to be responsible for this disease. Here, we report the case of a 16-year-old girl with HYPP whose mutational analysis revealed a heterozygous c.2111C>T substitution in the SCN4A gene leading to a Thr704Met mutation in the protein sequence. The parents were clinically unaffected and did not have a mutation in the SCN4A gene. A de novo SCN4A mutation for familial HYPP has not previously been reported. The patient did not respond to acetazolamide, but showed a marked improvement in paralytic symptoms upon treatment with hydrochlorothiazide. The findings in this case indicate that a de novo mutation needs to be considered when an isolated family member is found to have a HYPP phenotype.

Keyword

Hyperkalemic periodic paralysis; Mutation; SCN4A

MeSH Terms

Acetazolamide
Adolescent
Channelopathies
Humans
Hydrochlorothiazide
Hyperkalemia
Muscle, Skeletal
Paralysis
Paralysis, Hyperkalemic Periodic
Parents
Phenotype
Sodium
Sodium Channels
Acetazolamide
Hydrochlorothiazide
Sodium
Sodium Channels