Genetic testing in LQTS index patients has a yield of about 75 % – with 90 % of genotype-positive cases harboring variants in one of the three “classical” LQTS genes – KCNQ1,KCNH2 and SCN5A [3], the only genes for which precision therapy approaches have thus far been studied. The gene discussed is KCNQ1; the disease is familial long QT syndrome.