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Dravet Syndrome and SCN1A gene mutations: a review


Journal of Neurology & Stroke
Letícia Ferreira Marques da Silva,1,2 Gabriela Siqueira Turolla,1 Manoela Marques Ortega,2 Paulo Henrique Pires de Aguiar2–6

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Abstract

1.1.  Introduction: Dravet’s Syndrome (DS) is epilepsy syndrome that strikes individuals in early childhood, also known as Severe Myoclonic Epilepsy of Infancy (SMEI). DS clinical presentation involves normal psychomotor development during the first month of life; premature convulsive conditions, beginning mainly during the first year of life; deceleration of psychomotor development later and other neurological deficits, similar to cerebellar ataxia, which ultimately results in a condition of severe disability and therefore individuals unable to live independently. The types of seizures are various and include clonic and tonic seizures, generalized or unilateral; myoclonic seizures and of absences.

1.2.  Objective:Knowing that DS has as important etiology genetic disorders, this review aims to shed light on the main mutations that occur in the SCN1A gene, which considered the main gene related to SMEI and thus to correlate with its phenotype.

1.3.  Methods:The databases PubMed, Scielo, Medscape and Google Scholar helped searching articles in both Portuguese and English.

1.4.  Discussion:The SCN1A gene has 26 coding exons and translates the subunit 1 of the voltage-dependent neuronal sodium channel protein (Nav1.1). This protein consists of four domains (DI-IV), containing six transmembrane segments each. The subunit of the sodium channel is responsible for the formation of the transmembrane pore that allows the entry of sodium ions into the intracellular medium of the neurons. It is known that there are more than 500 distinct mutations at SCN1A gene associated with the DS.

1.5.  Conclusion:Due to the impact of this syndrome on affected individuals and relatives lives, it is important to study the disease etiology. Therefore, this study is a review of several scientific publications encompassing mutations in the SCN1A gene. In conclusion, the main kind of SCN1A gene mutations consist of missense and truncating mutations.

Keywords

dravet’s syndrome, myoclonic epilepsy, SCN1A gene, subunit 1 of the voltage-dependent neuronal sodium channel protein (Nav1.1)

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