Several studies including FCD type I (35 patients in total) were unable to find somatic mutations in mTOR pathway-related genes (Jansen et al., 2015; Nakashima et al., 2015; Moller et al., 2016; Sim et al., 2016) and N-glycosylation pathway-associated SLC35A2 gene (Baldassari et al., 2019b; Sim et al., 2019). This evidence concerns the gene SLC35A2 and isolated focal cortical dysplasia type I.