SCN5A-linked disease syndromes: complex monogenic disorders of cardiac rhythm

Significant advances in the field of molecular biology have enabled the identification of genes that confer susceptibility to disease. Inherited arrhythmia syndromes resulting from genetic alterations of various cardiac ion channels and proteins have been invaluable to further our understanding of the molecular basis of cardiac excitability. Mutations in SCN5A, the gene encoding the pore-forming subunit of the cardiac sodium channel, have been associated with distinct life-threatening cardiac rhythm syndromes. While electrophysiological characterization of mutant sodium channels in dissociated systems have revealed abnormalities in channel function, significant overlap between aberrant rhythm phenotypes suggests a complex relationship between mutations and disease phenotype. These new insights not only enhance our understanding of the structure--unction relationships of ion channels, but also highlight the complexities involved in linking single mutations, ion-channel behavior, and cardiac rhythm.