A Korean family with Arg1448Cys mutation of SCN4A channel causing paramyotonia congenita: electrophysiologic, histopathologic, and molecular genetic studies.
A family with paramyotonia congenita (PC) is presented. At least 10 family members were affected in an autosomal dominant inheritance pattern. The proband had cold-sensitive muscle stiffness, paradoxical myotonia, and intermittent muscle weakness since childhood. The serum level of creatine kinase was mildly elevated and short exercise test with cooling revealed a drastic reduction of compound muscle action potentials with repetitive discharges. Muscle biopsy revealed marked variation in the fiber size and increased internal nuclei. The molecular biological study revealed a common missense mutation (Arg1448Cys) at the voltage-gated sodium channel gene (SCN4A). The repetitive CMAP discharges during short exercise test with cooling observed in the proband has not been reported previously. This observation needs to be confirmed among PC patients with different mutations. This is the first report on a PC family confirmed by the molecular biological technique in Korea.
Kim
Dae-Seong
DS
Department of Neurology, College of Medicine, Pusan National University, Busan, Korea. kimcm@hyowon.cc.pusan.ac.kr
Kim
Eun-Joo
EJ
Jung
Dae-Soo
DS
Park
Kyu-Hyun
KH
Kim
In-Joo
IJ
Kwak
Ki-Young
KY
Kim
Cheol-Min
CM
Ko
Hyun-Yoon
HY
D000328:Adult; D001120:Arginine / Q000737:chemistry*; D002467:Cell Nucleus / Q000378:metabolism; D003402:Creatine Kinase / Q000097:blood; D003545:Cysteine / Q000737:chemistry*; D004252:DNA Mutational Analysis; D015444:Exercise; D005260:Female; D006801:Humans; D007723:Korea; D008297:Male; D020125:Mutation, Missense; D020967:Myotonic Disorders / Q000235:genetics*; D062553:NAV1.4 Voltage-Gated Sodium Channel; D010375:Pedigree; D010641:Phenotype; D015222:Sodium Channels / Q000235:genetics* / Q000378:metabolism
D062553:NAV1.4 Voltage-Gated Sodium Channel; C106251:SCN4A protein, human; D015222:Sodium Channels; D001120:Arginine; D003402:Creatine Kinase; D003545:Cysteine