Brugada Syndrome Caused by Sodium Channel Dysfunction Associated with a SCN1B Variant A197V.

Objective: We aimed to identify and characterize a SCN1B variant, A197V, associated with Brugada Syndrome (BrS).

Methods: Whole-exome sequencing was employed to explore the potential causative genes in 8 unrelated clinically diagnosed BrS patients. A197V variant was only detected in exon 4 of SCN1B in a 46 year old patient, who was admitted due to syncope. Wild type (WT) and mutant (A197V) genes were co-expressed with SCN5A in human embryonic kidney cells (HEK293 cells) and studied using whole-cell patch clamp and immunodetection techniques.

Results: Coexpression of 5A/WT + 1B/A197V resulted in a marked decrease in current density compared to 5A/WT + 1B/WT. The activation velocity was decelerated by A197V mutation. No significant changes were observed in recovery from inactivation parameters. Cell surface protein analyses confirmed that Na1.5 channel membrane distribution was affected by A197V mutation.

Conclusions: The current study is the first to report the functional analysis of SCN1B/ A197V, serving as a substrate responsible for BrS.