Severe neonatal episodic laryngospasm due to de novo SCN4A mutations: a new treatable disorder.
BACKGROUND
Myotonia is unusual in infants, and not well-known.


METHODS
We describe neonatal life-threatening features of myotonia caused by de novo mutations in the muscle sodium channel gene SCN4A.


RESULTS
Three male neonates initially displayed episodic laryngospasms, with face and limb myotonia appearing later. We found SCN4A de novo mutations in these neonates: p.Gly1306Glu in 2 unrelated cases and a novel mutation p.Ala799Ser in the third. Two patients survived their respiratory attacks and were efficiently treated by sodium channel blockers (mexiletine, carbamazepine) following diagnosis of myotonia.


CONCLUSIONS
Severe neonatal episodic laryngospasm is a new phenotype caused by a sodium channelopathy, which can be alleviated by channel blockers.
Lion-Francois
L
L
Hôpital Femme Mère Enfant, 59, boulevard Pinel, 69 677 Bron Cedex, France. laurence.francois@chu-lyon.fr
Mignot
C
C
Vicart
S
S
Manel
V
V
Sternberg
D
D
Landrieu
P
P
Lesca
G
G
Broussolle
E
E
Billette de Villemeur
T
T
Napuri
S
S
des Portes
V
V
Fontaine
B
B
D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007826:Laryngismus / Q000235:genetics*; D018895:Microsatellite Repeats / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D062553:NAV1.4 Voltage-Gated Sodium Channel; D015222:Sodium Channels / Q000235:genetics*
D062553:NAV1.4 Voltage-Gated Sodium Channel; C106251:SCN4A protein, human; D015222:Sodium Channels