In the most recent evaluation by an expert consensus, only three of these genes were considered to have adequate evidence to be classified as definitive for typical LQTS (KCNQ1, KCNH2, SCN5A) and four genes for LQTS with atypical features (CALM1, CALM2, CALM3, TRDN). This evidence concerns the gene SCN5A and familial long QT syndrome.