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<p><b>New page</b></p><div>'''SCN3A''' is a gene that encodes the alpha subunit of the [[voltage-gated sodium channel]] Nav1.3. This channel is primarily expressed in the [[central nervous system]] and plays a crucial role in the initiation and propagation of [[action potentials]] in neurons. Mutations in the SCN3A gene have been associated with a variety of neurological disorders, including [[epilepsy]], [[migraine]], and [[autism spectrum disorder]].<br />
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== Structure ==<br />
The SCN3A gene is located on the short arm of [[chromosome 2]] (2q24.3) and spans approximately 200 kilobases. It consists of 26 exons that encode a protein of 2000 amino acids. The Nav1.3 channel is composed of four homologous domains (I-IV), each containing six transmembrane segments (S1-S6). The S4 segment in each domain acts as the voltage sensor, while the pore-forming loop between S5 and S6 is responsible for sodium ion selectivity and conductance.<br />
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== Function ==<br />
The Nav1.3 channel is a critical component of the [[neuronal excitability]] machinery. It is responsible for the rapid influx of sodium ions into the neuron, which depolarizes the membrane and initiates the action potential. The channel is also involved in the regulation of [[neurotransmitter]] release and synaptic plasticity.<br />
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== Clinical significance ==<br />
Mutations in the SCN3A gene can lead to a variety of neurological disorders. For example, gain-of-function mutations can cause familial hemiplegic migraine type 3 (FHM3), a severe form of [[migraine]] characterized by hemiplegia (paralysis on one side of the body) during the aura phase. Loss-of-function mutations, on the other hand, can result in [[epilepsy]] and [[autism spectrum disorder]]. In addition, recent studies have suggested a potential role of SCN3A in the pathogenesis of [[Alzheimer's disease]].<br />
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== See also ==<br />
* [[Voltage-gated sodium channel]]<br />
* [[Neuronal excitability]]<br />
* [[Action potential]]<br />
* [[Epilepsy]]<br />
* [[Migraine]]<br />
* [[Autism spectrum disorder]]<br />
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== References ==<br />
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{{medicine-stub}}<br />
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[[Category:Genes]]<br />
[[Category:Neurology]]<br />
[[Category:Medical genetics]]</div>Prab