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. CONCLUSION: Severe neonatal episodic laryngospasm is a new phenotype caused by a sodium channelopathy, which can be alleviated by channel blockers.
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. CONCLUSION:Severe neonatal episodic laryngospasm is a new phenotype caused by a sodium channelopathy, which can be alleviated by channel blockers.
Authors: Alberto Bergareche; Marcin Bednarz; Elena Sánchez; Catharine E Krebs; Javier Ruiz-Martinez; Patricia De La Riva; Vladimir Makarov; Ana Gorostidi; Karin Jurkat-Rott; Jose Felix Marti-Masso; Coro Paisán-Ruiz Journal: Hum Mol Genet Date: 2015-10-01 Impact factor: 6.150