The SCN5A gene is a phenotype severity predictor in Brugada syndrome - a comprehensive literature review

Objective: The purpose of this review is to ascertain whether patients with Brugada syndrome (BrS) having SCN5A mutations have a more severe clinical phenotype and prognosis than do patients without SCN5A mutations. Methods: A comprehensive Scopus database search was conducted; studies were selected by using Brugada syndrome and SCN5A as keywords for the main query. Results: The available literature consistently shows greater electrophysiological abnormalities in patients with Brugada syndrome having SCN5A-related etiology. These include conduction disorder evidenced by longer QRS, PQ and His-ventricular interval duration. Novel lines of evidence suggest that SCN5A mutations are predictors of malignant arrhythmic events. In addition, SCN5A-positive patients and their carrier relatives frequently suffer from various abnormal cardiac phenotypes such as sick sinus syndrome and progressive conduction disorder. Rare variants have also been shown to play a role in cases of epilepsy, hyperthyroidism, irritable bowel syndrome and malignancy. Conclusion: In this review, we show how the SCN5A mutation status predicts phenotypic characteristics and prognosis in patients with BrS. We conclude that SCN5A mutations weakly predict greater malignant arrhythmic event risk in BrS patients. However, SCN5A mutations do not show robust enough associations with severity indicators to be an independent part of current risk stratification strategies. With advancing knowledge of BrS genetics, the integration of data on rare variants of SCN5A and polygenic risk scores could make an impact on clinical decision making.