GRIN2B and infantile spasms: Among the 357 patients of Cohort A, we identified 2 individuals with West syndrome (Patients 1and 2) carrying novel heterozygous de novo mutations in GRIN2B (2 of 91 EE cases,2.2%) affecting key amino acids (p.Val618Gly and p.Asn615Ile) within the NR2B ionchannel-forming re-entrant loop, as well as a patient with ID and childhood onset focal epilepsy(Patient 3) carrying a novel heterozygous de novo mutation (p.Arg540His) within the NR2Bglutamate-binding domain (see Table, Fig 1).