Paralysis periodica paramyotonica caused by SCN4A Arg1448Cys mutation.
Paralysis periodica paramyotonica is an overlapping disease that shares the features of paramyotonia characteristic of paramyotonia congenita (PC) and periodic paralysis characteristic of hyperkalemic periodic paralysis. We report the case of a 23-year-old man with paralysis periodica paramyotonica. His father and a younger brother also exhibited a similar phenotype. A SCN4A Arg1448Cys mutation was detected in this family. The affected family members exhibited marked shifts in compound muscle action potential amplitudes on exercise test, and muscle weakness could be induced by potassium loading and cold exposure. This case demonstrates that SCN4A Arg1448Cys can produce paralysis periodica paramyotonica. Other genetic or environmental factors may modulate the manifestation of SCN4A Arg1448Cys mutation.
Hsu
Wei-Chih
WC
Department of Neurology, Shin-Kong WHS Memorial Hospital, Fu-Jen Catholic University, Taipei, Taiwan.
Huang
Yung-Chuan
YC
Wang
Chung-Wei
CW
Hsueh
Chia-Hsiang
CH
Lai
Ling-Ping
LP
Yeh
Jiann-Horng
JH
D000328:Adult; D006801:Humans; D008297:Male; D009154:Mutation; D009224:Myotonia Congenita / Q000235:genetics*; D062553:NAV1.4 Voltage-Gated Sodium Channel; D020513:Paralysis, Hyperkalemic Periodic / Q000235:genetics*; D010375:Pedigree; D015222:Sodium Channels / Q000235:genetics*
D062553:NAV1.4 Voltage-Gated Sodium Channel; C106251:SCN4A protein, human; D015222:Sodium Channels