In the study of Olsen et al.18, they identified pathogenic variants in 61% of patients excluding those with cortical malformations, and the most commonly identified gene was KCNQ2. In our study, after excluding the nine patients with hemimegalencephaly or focal cortical dysplasia, the percentage of patients with genetic disorders was further up to 69.6% (16/23). Here, KCNQ2 is linked to hemimegalencephaly.