It is characterized by neonatal-onset myolconic seizures with also other seizure types such as symmetric or asymmetric tonic spasms which may occur singly or in clusters. The symptoms may start appearing as<unk>  as a few hours after birth and up to three months of age. Around three-fourths of affected children present with neonatal seizure. The distinctive feature of the phenotypes is severe progressive encephalopathy which develops a few hours to a few days after birth. It is also associated with clonic seizures, jerks, hiccups and vomiting. Sometimes neonates with apnea require ventilator support. Abnormal neurological behavior could be observed before the seizure onst in some patients. Head circumference is usually normal at onset but microcephaly may develop over time.
Early myoclonic encephalopathy
Wernicke encephalopathy
Post-encephalitic parkinsonism
Powassan encephalitis
Ethylmalonic encephalopathy
Camel spongiform encephalopathy
Glycine encephalopathy
Autoimmune encephalitis