The fact that LQTS-linked KCNQ1 LOF is commonly caused by reduced surface channel levels led us to hypothesize that known human disease mutations resulting in aberrant gain of KCNQ1 function might in some cases result from an increase in its cell surface level arising from elevated overall expression, decreased channel degradation, and/or enhanced surface-trafficking efficiency. Here, KCNQ1 is linked to familial long QT syndrome.