ERRFI1 and developmental and/or epileptic encephalopathy with spike-wave activation in sleep: Last, new potentially pathogenic variants in GABBR2, SCN1A, TRPC1, ERRFI1, CTXN3, IRX6, and IQCA1 have been identified in GRIN2A‐negative individuals, emphasizing the underlying genetic heterogeneity of LKS.