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SCN1A

Domain

The sequence contains 4 internal repeats, each with 5 hydrophobic segments (S1, S2, S3, S5, S6) and one positively charged segment (S4). Segments S4 are probably the voltage-sensors and are characterized by a series of positively charged amino acids at every third position.

The S3b-S4 and S1-S2 loops of repeat IV are targeted by H.maculata toxins Hm1a and Hm1b, leading to inhibit fast inactivation of Nav1.1/SCN1A. Selectivity for H.maculata toxins Hm1a and Hm1b depends on S1-S2 loops of repeat IV.

Function

Pore-forming subunit of Nav1.1, a voltage-gated sodium (Nav) channel that directly mediates the depolarizing phase of action potentials in excitable membranes. Navs, also called VGSCs (voltage-gated sodium channels) or VDSCs (voltage-dependent sodium channels), operate by switching between closed and open conformations depending on the voltage difference across the membrane. In the open conformation they allow Na(+) ions to selectively pass through the pore, along their electrochemical gradient. The influx of Na(+) ions provokes membrane depolarization, initiating the propagation of electrical signals throughout cells and tissues (PubMed:14672992). By regulating the excitability of neurons, ensures that they respond appropriately to synaptic inputs, maintaining the balance between excitation and inhibition in brain neural circuits (By similarity). Nav1.1 plays a role in controlling the excitability and action potential propagation from somatosensory neurons, thereby contributing to the sensory perception of mechanically-induced pain (By similarity).

Involvement in disease

Generalized epilepsy with febrile seizures plus 2

GEFSP2

A rare autosomal dominant, familial condition with incomplete penetrance and large intrafamilial variability. Patients display febrile seizures persisting sometimes beyond the age of 6 years and/or a variety of afebrile seizure types. This disease combines febrile seizures, generalized seizures often precipitated by fever at age 6 years or more, and partial seizures, with a variable degree of severity.

None

The disease is caused by variants affecting the gene represented in this entry.

Dravet syndrome

DRVT

A severe form of epileptic encephalopathy characterized by generalized tonic, clonic, and tonic-clonic seizures that are initially induced by fever and begin during the first year of life. Later, patients also manifest other seizure types, including absence, myoclonic, and simple and complex partial seizures. Psychomotor development delay is observed around the second year of life. Some patients manifest a borderline disease phenotype and do not necessarily fulfill all diagnostic criteria for core DRVT. DRVT is considered to be the most severe phenotype within the spectrum of generalized epilepsies with febrile seizures-plus.

None

The disease is caused by variants affecting the gene represented in this entry.

Intractable childhood epilepsy with generalized tonic-clonic seizures

ICEGTC

A disorder characterized by generalized tonic-clonic seizures beginning usually in infancy and induced by fever. Seizures are associated with subsequent mental decline, as well as ataxia or hypotonia. ICEGTC is similar to SMEI, except for the absence of myoclonic seizures.

None

The disease is caused by variants affecting the gene represented in this entry.

Migraine, familial hemiplegic, 3

FHM3

A subtype of migraine associated with transient blindness in some families. Migraine is a disabling symptom complex of periodic headaches, usually temporal and unilateral. Headaches are often accompanied by irritability, nausea, vomiting and photophobia, preceded by constriction of the cranial arteries. The two major subtypes are common migraine (migraine without aura) and classic migraine (migraine with aura). Classic migraine is characterized by recurrent attacks of reversible neurological symptoms (aura) that precede or accompany the headache. Aura may include a combination of sensory disturbances, such as blurred vision, hallucinations, vertigo, numbness and difficulty in concentrating and speaking.

None

The disease is caused by variants affecting the gene represented in this entry.

Febrile seizures, familial, 3A

FEB3A

Seizures associated with febrile episodes in childhood without any evidence of intracranial infection or defined pathologic or traumatic cause. It is a common condition, affecting 2-5% of children aged 3 months to 5 years. The majority are simple febrile seizures (generally defined as generalized onset, single seizures with a duration of less than 30 minutes). Complex febrile seizures are characterized by focal onset, duration greater than 30 minutes, and/or more than one seizure in a 24 hour period. The likelihood of developing epilepsy following simple febrile seizures is low. Complex febrile seizures are associated with a moderately increased incidence of epilepsy.

None

The disease is caused by variants affecting the gene represented in this entry.

Developmental and epileptic encephalopathy 6B

DEE6B

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE6B is an autosomal dominant condition characterized by onset of seizures in early infancy, profoundly impaired intellectual development, and a hyperkinetic movement disorder.

None

The disease is caused by variants affecting the gene represented in this entry.

SCN1A mutations may be involved in Panayiotopoulos syndrome, a benign age-related focal seizure disorder occurring in early and mid-childhood. It is characterized by seizures, often prolonged, with predominantly autonomic symptoms, and by an electroencephalogram that shows shifting and/or multiple foci, often with occipital predominance. Autonomic seizures in Panayiotopoulos syndrome consist of episodes of disturbed autonomic function with emesis as the predominant symptom. Cardiorespiratory arrest is exceptional.

Post-translational modifications

Phosphorylation at Ser-1516 by PKC in a highly conserved cytoplasmic loop slows inactivation of the sodium channel and reduces peak sodium currents.

Sequence Similarities

Belongs to the sodium channel (TC 1.A.1.10) family. Nav1.1/SCN1A subfamily.

Cellular localization

Alternative names

NAC1, SCN1, SCN1A, Sodium channel protein type 1 subunit alpha, Sodium channel protein brain I subunit alpha, Sodium channel protein type I subunit alpha, Voltage-gated sodium channel subunit alpha Nav1.1

swissprot:P35498 swissprot:Q9UI33 entrezGene:6331 entrezGene:6323 swissprot:Q9UQD0 swissprot:Q9Y5Y9 swissprot:Q9NY46 swissprot:Q99250 swissprot:Q14524 swissprot:Q15858 swissprot:P35499 omim:600163 omim:182389