To date, epilepsy is the most recurrent disorder among the subjects carrying a KCNH1 mutation and, interestingly, 3 cases of somatic variants were reported in subjects with epilepsy, one detected in the resected brain tissue of a patient with focal cortical dysplasia [39] and in two subjects, mothers of children with TMBTS, who have epilepsy but are otherwise healthy [30]. This evidence concerns the gene KCNH1 and Focal cortical dysplasia.