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

• Main Authors: Ji-Yeon Han (Author), June-Bum Kim (Author)
• Format: Book
• Published: Korean Pediatric Society, 2011-11-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 1738-1061; 2092-7258; 10.3345/kjp.2011.54.11.470
• Keywords: Hyperkalemic periodic paralysis; Mutation; Pediatrics; RJ1-570
• Source: Korean Journal of Pediatrics, Vol 54, Iss 11, Pp 470-472 (2011)

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.