Table 1.

Main classes of Nav1.4 skeletal muscle channelopathies (Trip et al., 2009; Raja Rayan and Hanna, 2010).

	Clinical manifestations	Triggers	Paraclinics	EMG canonical pattern	First intention treatment	Most frequently mutated residues	References
PC	Stiffness followed by weakness Paradoxical myotonia	Cold		Myotonia Type I (repeated short effort test)	Mexiletine	T1313 (ID III-IV), R1448 (DIV S4)	McClatchey et al., 1992b; Ptácek et al., 1992; Hayward et al., 1996; Featherstone et al., 1998; Bouhours et al., 2004
SCM	Stiffness at exertion (most often), permanently at rest (myotonia permanens), or acetazolamide-responsive myotonia	Exertion Acetazolamide		Myotonia Type III (repeated short effort test)	Mexiletine	G1306 (ID III-IV), G1306A/V: myotonia fluctuans G1306E: myotonia permanens	Lerche et al., 1993; Rüdel et al., 1993; Ricker et al., 1994; Hayward et al., 1996
HyperPP	Short episodes (minutes)	Fasting	Normal or high potassium level during episodes	Some myotonia Type IV (long effort test)	Acetazolamide	T704 (DIIS5), M1592 (DIV S6)	Ptácek et al., 1991; Rojas et al., 1991; Yang et al., 1994; Iaizzo et al., 1995
HypoPP	Long-lasting episodes (hours, days)	Glucide-rich meals Rest after exercise Prolonged rest	Markedly low potassium levels during episodes	No myotonia Type V (long effort test)	Acetazolamide	R669, R672 (DII S4)	Bulman et al., 1999; Jurkat-Rott et al., 2000; Bendahhou et al., 2001; Sternberg et al., 2001

PC, Paramyotonia Congenita; SCM, Sodium channel Myotonia; Hypo, Normo, Hyper PP, Hypo, Normo, Hyper-kalemic Periodic Paralysis.