We compared the positions of the 11 polymicrogyria-associated GRIN1 mutations with 16 different heterozygous proven (or likely) de novo GRIN1 mutations previously reported in 23 patients with non-syndromic intellectual disability and epileptic encephalopathy (Fig. 2) (Lemke et al., 2016). The gene discussed is GRIN1; the disease is Epileptic encephalopathy.