Focal seizures often secondarily generalize but the reverse is much less frequently documented. The idiopathic generalized epilepsies have the EEG signature of generalized, or bilaterally synchronous spike wave activity and although focal features can be seen, seizures are usually generalized once they commence. Although focal seizures can be seen in some syndromes, it is not well recognized that generalized seizures can become focal during the attack. Here we describe two cases of idiopathic epilepsy with a genetic basis; both cases falling within the spectrum of generalized epilepsy with febrile seizures plus (GEFS+). One patient has a family history consistent with the family epilepsy syndrome diagnosis of GEFS+, whilst the second has a de novo SCN1A mutation in the setting of "severe" Febrile Seizures. In both patients, seizures began with generalized spike wave activity and then a focal ictal rhythm emerged. This is a further example of the increasingly blurred distinction between generalized and focal categories of specific genetically determined epilepsies. [Published with video sequences].