MedGen

CHD2-related neurodevelopmental disorders are characterized by early-onset epileptic encephalopathy (i.e., refractory seizures and cognitive slowing or regression associated with frequent ongoing epileptiform activity). Seizure onset is typically between ages six months and four years. Seizure types typically include drop attacks, myoclonus, and rapid onset of multiple seizure types associated with generalized spike-wave on EEG, atonic-myoclonic-absence seizures, and clinical photosensitivity. Intellectual disability and/or autism spectrum disorders are common. [from GeneReviews]

Neuronal ceroid lipofuscinosis-11 is an autosomal recessive neurologic disorder characterized by rapidly progressive visual loss due to retinal dystrophy, seizures, cerebellar ataxia, and cerebellar atrophy. Cognitive decline may also occur (summary by Smith et al., 2012). For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730). [from OMIM]

EEG with repetitive generalized sharp transient waves of a duration less than 80 msec. [from HPO]