SCN4A

Highest pathogenic variant AF is 0.0005239833

Gene type

protein_coding

Transcript type

protein_coding

Transcript

ENST00000435607

Coding exons

24

Length

34365

Individuals with no LoFs

125436

Homozygous LoFs

0

Heterozygous LoFs

310

Defined

125746

p

0.00123

Function

FUNCTION: This protein mediates the voltage-dependent sodium ion permeability of excitable membranes. Assuming opened or closed conformations in response to the voltage difference across the membrane, the protein forms a sodium-selective channel through which Na(+) ions may pass in accordance with their electrochemical gradient. This sodium channel may be present in both denervated and innervated skeletal muscle. {ECO:0000269|PubMed:15318338, ECO:0000269|PubMed:16890191}.;

Disease

DISEASE: Paramyotonia congenita of von Eulenburg (PMC) [MIM:168300]: An autosomal dominant channelopathy characterized by myotonia, increased by exposure to cold, intermittent flaccid paresis, not necessarily dependent on cold or myotonia, lability of serum potassium, non-progressive nature and lack of atrophy or hypertrophy of muscles. In some patients, myotonia is not increased by cold exposure (paramyotonia without cold paralysis). Patients may have a combination phenotype of PMC and HYPP. {ECO:0000269|PubMed:10369308, ECO:0000269|PubMed:10727489, ECO:0000269|PubMed:1310898, ECO:0000269|PubMed:1316765, ECO:0000269|PubMed:1338909, ECO:0000269|PubMed:15318338, ECO:0000269|PubMed:15790667, ECO:0000269|PubMed:16786525, ECO:0000269|PubMed:18166706, ECO:0000269|PubMed:18690054, ECO:0000269|PubMed:19077043, ECO:0000269|PubMed:20076800, ECO:0000269|PubMed:8242056, ECO:0000269|PubMed:8308722, ECO:0000269|PubMed:8388676, ECO:0000269|PubMed:8580427}. Note=The disease is caused by mutations affecting the gene represented in this entry.; DISEASE: Periodic paralysis hypokalemic 2 (HOKPP2) [MIM:613345]: An autosomal dominant disorder manifested by episodic flaccid generalized muscle weakness associated with falls of serum potassium levels. {ECO:0000269|PubMed:10599760, ECO:0000269|PubMed:10851391, ECO:0000269|PubMed:10944223, ECO:0000269|PubMed:11558801, ECO:0000269|PubMed:11591859, ECO:0000269|PubMed:16890191, ECO:0000269|PubMed:17898326, ECO:0000269|PubMed:18162704, ECO:0000269|PubMed:19118277, ECO:0000269|PubMed:20522878, ECO:0000269|PubMed:21043388, ECO:0000269|PubMed:24549961}. Note=The disease is caused by mutations affecting the gene represented in this entry.; DISEASE: Periodic paralysis hyperkalemic (HYPP) [MIM:170500]: An autosomal dominant channelopathy characterized by episodic flaccid generalized muscle weakness associated with high levels of serum potassium. Concurrence of myotonia is found in HYPP patients. {ECO:0000269|PubMed:1659668, ECO:0000269|PubMed:1659948, ECO:0000269|PubMed:20076800}. Note=The disease is caused by mutations affecting the gene represented in this entry.; DISEASE: Periodic paralysis normokalemic (NKPP) [MIM:170500]: A disorder closely related to hyperkalemic periodic paralysis, but marked by a lack of alterations in potassium levels during attacks of muscle weakness. {ECO:0000269|PubMed:15596759, ECO:0000269|PubMed:18046642, ECO:0000269|PubMed:20522878}. Note=The disease is caused by mutations affecting the gene represented in this entry.; DISEASE: Myotonia SCN4A-related (MYOSCN4A) [MIM:608390]: A phenotypically highly variable myotonia aggravated by potassium loading, and sometimes by cold. Myotonia is characterized by sustained muscle tensing that prevents muscles from relaxing normally. It causes muscle stiffness that can interfere with movement. In some people the stiffness is very mild, while in other cases it may be severe enough to interfere with walking, running, and other activities of daily life. Myotonia SCN4A- related includes myotonia permanens and myotonia fluctuans. In myotonia permanens, the myotonia is generalized and there is a hypertrophy of the muscle, particularly in the neck and the shoulder. Attacks of severe muscle stiffness of the thoracic muscles may be life threatening due to impaired ventilation. In myotonia fluctuans, the muscle stiffness may fluctuate from day to day, provoked by exercise. {ECO:0000269|PubMed:10218481, ECO:0000269|PubMed:16786525, ECO:0000269|PubMed:16832098, ECO:0000269|PubMed:17212350, ECO:0000269|PubMed:17998485, ECO:0000269|PubMed:18203179, ECO:0000269|PubMed:18337100, ECO:0000269|PubMed:19015483, ECO:0000269|PubMed:19347921, ECO:0000269|PubMed:20076800, ECO:0000269|PubMed:27653901, ECO:0000269|PubMed:8058156, ECO:0000269|PubMed:9392583}. Note=The disease is caused by mutations affecting the gene represented in this entry.; DISEASE: Myasthenic syndrome, congenital, 16 (CMS16) [MIM:614198]: A form of congenital myasthenic syndrome, a group of disorders characterized by failure of neuromuscular transmission, including pre-synaptic, synaptic, and post-synaptic disorders that are not of autoimmune origin. Clinical features are easy fatigability and muscle weakness. CMS16 is characterized by fatigable generalized weakness and recurrent attacks of respiratory and bulbar paralysis since birth. The fatigable weakness involves lid-elevator, external ocular, facial, limb and truncal muscles and an decremental response of the compound muscle action potential on repetitive stimulation. {ECO:0000269|PubMed:12766226, ECO:0000269|PubMed:25707578, ECO:0000269|PubMed:26659129}. Note=The disease is caused by mutations affecting the gene represented in this entry.; DISEASE: Note=SCN4A mutations are the cause of an autosomal recessive neuromuscular disorder characterized by severe fetal hypokinesia, neonatal hypotonia and congenital myopathy of variable severity. The most severe clinical features include reduced or absent fetal movements, in-utero upper and lower limb contractures, talipes and hydrops, and intrauterine or early postnatal death. Mildly affected patients present with generalized hypotonia and weakness at birth or within the first few days of life, mild-to-moderate facial muscle weakness without ptosis, significant early respiratory and feeding difficulties, and skeletal abnormalities of the spine and palate. Symptoms improve over time in patients who survive infancy, resulting in gain of muscle strength and motor skills and concomitant resolution of early respiratory and feeding difficulties. In contrast to other SCN4A-related channelopathies, affected individuals manifest in- utero or neonatal onset of permanent muscle weakness, rather than later-onset episodic muscle weakness. {ECO:0000269|PubMed:26700687}.;