Hyperkalemic periodic paralysis and paramyotonia congenita - A novel sodium channel mutation -

Novel mutations in human and mouse SCN4A implicate AMPK in myotonia and periodic paralysis

“…In a recent attempt to categorize patients with hyperkalaemic periodic paralysis, three clinical subgroups were proposed depending if patients presented without myotonia, with clinical or EMG myotonia or with paramyotonia congenita (Charles et al , 2013). In addition, the same SCN4A mutation can be found in patients with different clinical diagnosis (Sasaki et al , 1999; Okuda et al , 2001; Jurkat-Rott and Lehmann-Horn, 2007). Overall, there is little known about the consequences of SCN4A mutations in the muscle downstream of their impact on the electrophysiology of the Na v 1.4 channel.…”

Genotype-Phenotype Correlation and Therapeutic Rationale in Hyperkalemic Periodic Paralysis

“…In a Japanese family, the mutation M1370V resulted in PC in one family member and in hyperkalemic PP in others. 20 In typical hyperkalemic PP mutations such as T704M and M1592V, paramyotonic signs have been reported in single families. [31][32][33] The reason for the clinical variability is unknown.…”

Severe infantile hyperkalaemic periodic paralysis and paramyotonia congenita: broadening the clinical spectrum associated with the T704M mutation in SCN4A

“…2 HyperPP/PMC shows characteristics of both hyperPP and PMC with varying degrees of overlap and has been reported in association with eight mutations in SCN4A gene (I693T, T704M, A1156T, T1313M, M1360V, M1370V, R1448C, M1592V). [3][4][5][6][7][8][9] While T704M is an important cause of isolated hyperPP, this mutation has been only recently described in a single hyperPP/PMC family. As with other SCN4A mutations, there can be marked intrafamilial and interfamilial variability in paralytic attack frequency and severity in patients harbouring T704M.…”