SLC4A3-related SQTS resulted from experimental models showing that the membrane anion exchange (bicarbonate vs. chloride) protein showed a reduced membrane localization of the mutant protein (harboring an amino acid exchange) leading to a loss-of-function by intracellular alcalinization and shortening of the cardiomyocyte action potential duration. This evidence concerns the gene SLC4A3 and Familial short QT syndrome.