Abstract

Mutations in SCN5A gene have been associated with different cardiac manifestations, so it is frequently tested in familial cardiovascular diseases. Our objective was to analyze the prevalence of pathogenic mutations (PM) in SCN5A in hereditary cardiovascular diseases and to describe the clinical characteristics of genetic carriers.

SCN5A gene (NM_198056.2) was sequenced by NGS in panels of genes directed to each cardiac phenotype. We studied 219 index cases with theses phenotypes: 144 dilated/arrhythmogenic cardiomyopathy (DCM), 34 Brugada syndrome (BS), 19 idiopathic ventricular fibrillation (IVF), 10 long QT syndrome (LQTS), 9 sudden death with nondiagnostic necropsy and 3 advanced conduction system abnormalities.

We identified 8 PM in 9 families, two of them have not been previously described: deletion of exons 1–16 of SCN5A and 15_27 in SCN10A and c.2665C>G. The prevalence of PM according to phenotypes was: 3 DCM (2%), 1 IVF (5%), 4 BS (12%) and 1 advanced conduction system abnormalities (33%). Additionally, we identified 4 variants of uncertain pathogenicity, two of them in the same patient with LQTS (compound heterozygosis). The index cases description is developed in Table 1.

In our cohort the prevalence of PM in SCN5A is similar to those described in literature. The majority are associated with a combined phenotype (overlap syndrome of cardiac sodium channelopathy) which is characterized by supraventricular and ventricular arrhythmias and conduction system abnormalities, and some of them with DCM. Patients with BS had no additional manifestations, apart from ventricular arrhythmias in follow up.

Family numberSCN5A MutationOther mutationsSex/Age at diagnosis of index case (years)Phenotype of index caseDevices (Age, years)Number of studied relatives (+ Genotype)Phenotypes in the family (Age, years)Family history
1Deletion in exons 1_16 of SCN5A, y 15_27 of SCN10ASCN5A:c.3068G>T (VUS)Female/38SCD due to nocturnal VF, Brugada syndromeSecondary prevention ICD (38)2 (0)SCD at paternal line
2c.2254G>ALMNA:c.986G>A (VUS)Female/64DCMPrimary prevention ICD (69)3 (1)Daughter PM (39) and atrial flutterSCD in first degree family members
3c.2665C>GMale/46AF (27), AVB (36), VF (46)PM (36), secondary prevention ICD (46)6 (3)Father PM (47) and atrial flutterPaternal grandfather SCD (53), cousin SCD (26)
4c.2665C>GSCN5A:c.4057G>A (VUS)Male/ 64DCM, VT, AF, atrial flutter (64)Secondary prevention (64), cardiac resynchronization therapy (68)15 (7)Sister PM (26)None
5c.3823G>AMale/48BSPrimary prevention ICD (48)0 (0)SCD. Cousin with BS and ICD. Maternal grandmother with pacemaker.
6c.4297G>TMale/42BSNO4 (2)Sister Type 2 BSNone
7c.4783G>AMale/14Bifascicular heart block (right bundle branch block and left anterior division block), VT, atrial flutter.Primary prevention ICD (15)3 (0)None (de novo mutation)
8c.4876C>TMYH7:c.4763G>A (VUS)Male/38DCM, AVB, VFSecondary prevention ICD (38)0 (0)SCD in sibling (39 years)
9c.4981G>AFemale/23BSPrimary prevention ICD (25), appropriate therapy in follow up3 (0)None (de novo mutation)
Family numberSCN5A MutationOther mutationsSex/Age at diagnosis of index case (years)Phenotype of index caseDevices (Age, years)Number of studied relatives (+ Genotype)Phenotypes in the family (Age, years)Family history
1Deletion in exons 1_16 of SCN5A, y 15_27 of SCN10ASCN5A:c.3068G>T (VUS)Female/38SCD due to nocturnal VF, Brugada syndromeSecondary prevention ICD (38)2 (0)SCD at paternal line
2c.2254G>ALMNA:c.986G>A (VUS)Female/64DCMPrimary prevention ICD (69)3 (1)Daughter PM (39) and atrial flutterSCD in first degree family members
3c.2665C>GMale/46AF (27), AVB (36), VF (46)PM (36), secondary prevention ICD (46)6 (3)Father PM (47) and atrial flutterPaternal grandfather SCD (53), cousin SCD (26)
4c.2665C>GSCN5A:c.4057G>A (VUS)Male/ 64DCM, VT, AF, atrial flutter (64)Secondary prevention (64), cardiac resynchronization therapy (68)15 (7)Sister PM (26)None
5c.3823G>AMale/48BSPrimary prevention ICD (48)0 (0)SCD. Cousin with BS and ICD. Maternal grandmother with pacemaker.
6c.4297G>TMale/42BSNO4 (2)Sister Type 2 BSNone
7c.4783G>AMale/14Bifascicular heart block (right bundle branch block and left anterior division block), VT, atrial flutter.Primary prevention ICD (15)3 (0)None (de novo mutation)
8c.4876C>TMYH7:c.4763G>A (VUS)Male/38DCM, AVB, VFSecondary prevention ICD (38)0 (0)SCD in sibling (39 years)
9c.4981G>AFemale/23BSPrimary prevention ICD (25), appropriate therapy in follow up3 (0)None (de novo mutation)

AF: atrial fibrillation; AVB: atrioventricular block; BS: Brugada syndrome; DCM: dilated cardiomyopathy; ICD: implantable cardioverter defibrillator; PM: pacemaker; SCD: sudden cardiac death; VF: ventricular fibrillation; VT: ventricular tachycardia; VUS: Variant of uncertain significance.

Funding Acknowledgement

Type of funding source: None

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