This is one of a large number of hereditary disorders of brain maldevelopment in which epilepsy is a prominent sign. This specific one is associated with severe delay in development and intellectual disability.
Infants have the onset of some type of seizures in the first few months of life. These may be intractable to treatment. Infants do no visually follow targets and the MRI of the brain may show underdevelopment of the optic nerve which connects the eye to the brain. They likely have decreased vision due to the abnormal optic nerve. Infants may also have seemingly random to-and-fro movements of the eyes (nystagmus).
The growth in head size is below normal. Muscle tone is decreased (hypotonia) but hyperactive reflexes and stiffness of the limbs are often present (spasticity). Brain MRIs may show delayed development. Feeding abnormalities are common and physical growth is slow. Severe intellectual disability is a common feature with absent speech and inability to walk. Patients may have behavioral features of autism.
A mutation in a specific mutation is responsible for this disorder and it would be reasonable to expect the disease-causing transmission to resemble an autosomal dominant pattern in which the condition can be passed directly from parent to child. However, the severe neurological defects preclude reproduction so all individuals have a de novo mutation which is not transmitted.
Some neurological signs such as 'floppiness' and poor feeding can be present at birth but these are nonspecific and nondiagnostic. Clinical evidence of epilepsy and the presence of seizure patterns on the electroencephalogram (EEG) can suggest the diagnosis to pediatricians and neurologists but because of the large number of similar conditions a gene test is necessary to determine the exact diagnosis.
No treatment for the general condition has been reported. Seizure medications for the epilepsy should be used but are often ineffective. Nutrition is a problem and placement of stomach tubes could be helpful. Total supportive care is often necessary. Nothing is known about longevity.