This is an early-onset disorder with global developmental delays and seizures. It is the result of a change (mutation) in a specific gene.
Seizures of various types have their onset from birth to several years of age. They may not respond to the usual treatments for epilepsy. Normal developmental milestones are delayed and some patients are unable to walk or speak. Most patients have subnormal vision. The head may be small. Muscle tone may be decreased or increased and there are often purposeless movements such as tremors while gait, if present, is unsteady. No diagnostic tests are available and even brain MRIs may be normal.
A specific gene mutation has been identified in a configuration expected to follow an autosomal dominant pattern of transmission. However, the severity of the neurological disease is incompatible with reproduction and the mutation seems to occur de novo.
Pediatricians and neurologists may collaborate in the identification and care of children with this condition. The small head seen in some infants may be noted at birth but this is not diagnostic. Seizures occurring at birth or during the neonatal period likewise are nondiagnostic. An encephalogram (EEG) may show evidence of the seizures. The delayed development soon becomes apparent and is often associated with abnormal movements in the limbs. Vision is considered abnormal when infants or young children do not follow targets with their eyes.
No effective general treatment has been reported. Physical therapy and special education might be of benefit if applied early. Nothing is known regarding longevity.