<unk>  is a rare, childhood neurological syndrome characterized by the sudden or gradual development of aphasia (the inability to understand or express language) and an abnormal electroencephalogram (EEG).<unk> <unk>  affects the parts of the brain that control comprehension and speech. Typically, children with<unk>  develop normally but then lose their language skills.  While many of the affected individuals have clinical seizures, some only have electrographic seizures, including electrographic status epilepticus of sleep (ESES). 
Approximately 80 percent of the children with<unk>  have one or more epileptic seizures that usually occur at night. Behavioral disorders such as hyperactivity, aggressiveness and depression can also accompany this disorder.
Landau-Kleffner syndrome
Smith-Lemli-Opitz syndrome
Singleton-Merten syndrome
Smith–Lemli–Opitz syndrome
Smith-Magenis syndrome
Cruveilhier-Baumgarten syndrome
Sturge-Weber syndrome
Turcot syndrome