Cardiac conduction disease
Gene: SCN5A
(Likely) pathogenic gain of function variants in SCN5A are associated with Multifocal Ectopic Purkinje-related Premature Contractions (MEPPC) syndrome, characterised by a high burden of premature ventricular contractions (PVCs) originating from multiple foci along the fascicular Purkinje system, and featuring a narrow QRS complex.
MEPPC syndrome was initially described in three Dutch families by Laurent et al. in 2012 (PMID: 22766342). As summarised in a systematic review of n=115 patients affected with MEPPC syndrome by Basile et al., 2025 (PMID: 41159261), MEPPC is typically diagnosed in young patients, with no reported cases with an age of onset >50 years. Common clinical manifestations include palpitations, dyspnea and syncope. Several reported cases are affected with, or have a family history of, dilated cardiomyopathy, sudden death, and/or other hereditary cardiovascular disorders.
The high degree of expressive variability of SCN5A (likely) pathogenic variants and/or simultaneous gain- and loss- of function conferred by these variants, have led to the recognition of "overlap syndrome" - wherein MEPPC syndrome may be associated with other hereditary cardiovascular disorders including long QT syndrome, Brugada syndrome, cardiac conduction disorders and/or dilated cardiomyopathy (PMID: 41159261).Created: 18 Jun 2026, 12:01 p.m. | Last Modified: 18 Jun 2026, 12:01 p.m.
Panel Version: 2.0
Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Phenotypes
Multifocal ectopic Purkinje-related premature contractions (MEPPC) syndrome; SCN5A-related cardiac rhythm disorder MONDO:1010181
Publications
ClinGen have lumped atrial conduction disease, atrioventricular block, Brugada syndrome, familial atrial fibrillation, familial sick sinus syndrome, long QT syndrome 3, progressive familial heart block, and ventricular fibrillation, paroxysmal familial, type 1 under 1 term
SCN5A-related cardiac rhythm disorder MONDO:1010181Created: 19 Feb 2026, 1:35 p.m.
Phenotypes
SCN5A-related cardiac rhythm disorder MONDO:1010181
Pathogenic SCN5A variants have been associated with cardiac conduction disease alone or in pleiotropic/overlapping cardiac syndromes. In a large study of SCN5A PV carriers 3.5% (6/170) had isolated progressive cardiac conduction disease.
Sources: NHS GMSCreated: 5 Feb 2025, 1:53 p.m.
Mode of inheritance
BOTH monoallelic and biallelic (but BIALLELIC mutations cause a more SEVERE disease form), autosomal or pseudoautosomal
Phenotypes
progressive familial heart block MONDO:0019490
Publications
Variants in this GENE are reported as part of current diagnostic practice
At least three unrelated families reported.Created: 1 Aug 2021, 3:55 p.m.
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Sick sinus syndrome 1, MIM# 608567
Publications
Gene: scn5a has been classified as Green List (High Evidence).
Phenotypes for gene: SCN5A were changed from progressive familial heart block MONDO:0019490; SCN5A-related cardiac rhythm disorder MONDO:1010181 to progressive familial heart block MONDO:0019490; SCN5A-related cardiac rhythm disorder MONDO:1010181; Multifocal ectopic Purkinje-related premature contractions (MEPPC) syndrome
Publications for gene: SCN5A were set to 39134129; 11804990; 16643399; 15466643
Phenotypes for gene: SCN5A were changed from progressive familial heart block MONDO:0019490 to progressive familial heart block MONDO:0019490; SCN5A-related cardiac rhythm disorder MONDO:1010181
Mode of inheritance for gene: SCN5A was changed from MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted to BOTH monoallelic and biallelic (but BIALLELIC mutations cause a more SEVERE disease form), autosomal or pseudoautosomal
Gene: scn5a has been classified as Green List (High Evidence).
gene: SCN5A was added gene: SCN5A was added to Cardiac conduction disease. Sources: NHS GMS Mode of inheritance for gene: SCN5A was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: SCN5A were set to 39134129; 11804990; 16643399; 15466643 Phenotypes for gene: SCN5A were set to progressive familial heart block MONDO:0019490 Review for gene: SCN5A was set to GREEN gene: SCN5A was marked as current diagnostic