New onset seizures in a patient with Long QT Syndrome (LQTS2) and a pathogenic carboxyl-terminus frameshift variant of the KCNH2 gene.

•Long QT Syndrome mutations in the potassium channel KCNH2 gene increase seizure risk.•A young man having recurrent syncope and seizures was found to have profound LQTS.•The cause was a carboxyl-terminus frameshifting/nonsense mutation of the KCNH2 gene.•This pathogenic mutation has never been reported in association with epilepsy.