RT Journal Article T1 Brugada syndrome masked by complete left bundle branch block: A clinical and functional study of its association with the p.1449Y>H SCN5A variant. A1 Arana-Rueda, Eduardo A1 Pezzotti, María R A1 Pedrote, Alonso A1 Acosta, Juan A1 Frutos-López, Manuel A1 Varela, Lourdes-María A1 García-Fernández, Noelia A1 Castellano, Antonio K1 Brugada syndrome K1 SCN5A K1 left bundle branch block K1 loss of function K1 patch clamp AB SCN5A gene variants are associated with both Brugada syndrome and conduction disturbances, sometimes expressing an overlapping phenotype. Functional consequences of SCN5A variants assessed by patch-clamp electrophysiology are particularly beneficial for correct pathogenic classification and are related to disease penetrance and severity. Here, we identify a novel SCN5A loss of function variant, p.1449Y>H, which presented with high penetrance and complete left bundle branch block, totally masking the typical findings on the electrocardiogram. We highlight the possibility of this overlap combination that makes impossible an electrocardiographic diagnosis and, through a functional analysis, associate the p.1449Y>H variant to SCN5A pathogenicity. YR 2021 FD 2021-09-01 LK http://hdl.handle.net/10668/18395 UL http://hdl.handle.net/10668/18395 LA en DS RISalud RD May 9, 2025