Brugada syndrome masked by complete left bundle branch block. A clinical
and functional study of its association with the p.1449Y>H
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 a 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.