The patient's sister, who had a milder phenotype consistent with absence epilepsy that was well-controlled with valproate, carried a combination of inherited heterozygous variants in genes encoding ion channels: SCN1A (maternal), CACNA1A (paternal), and SLC12A5. In individuals of French-Canadian origin, the SLC12A5 missense variants R952H and R1049C in heterozygosity have been shown to predispose carriers to generalized epilepsy (Kahle et al., 2014; Puskarjov et al., 2014). Here, SCN1A is linked to idiopathic generalized epilepsy.