In HEK293 cells, P2006A displayed biophysical defects typically associated with long QT syndrome by increasing persistent sodium current, producing a depolarizing shift in voltage dependence of inactivation, and hastening recovery from inactivation.
Five variants (S216L, T1304M, F1486L, F2004L, and P2006A) exhibited significantly increased persistent sodium currents (range, 0.5% to 1.7% of peak current) typical of SCN5A mutations associated with long-QT syndrome.