Landau–Kleffner syndrome (LKS), is a rare, poorly‐understood epileptic encephalopathy with spike–wave activation in sleep associated with mutations in GRIN2A, encoding the N‐Methyl‐D‐Aspartate receptor (NMDAR) GluN2A subunit. The gene discussed is GRIN2A; the disease is Epileptic encephalopathy.