KCNH2 and familial long QT syndrome: For LQTS, based on Jiang et al’s6 method we subdivided it into two classification tasks: the prediction of LQTS, defined as ECGs from individuals with a pathogenic or likely pathogenic variant in the KCNQ1 or KCNH2 genes, and the subtask of LQTS subtype distinction, distinguishing between KCNQ1- and KCNH2-based types.