| Main clinical features
|
neurodevelopmental disorder characterized by delayed psychomotor development apparent in infancy and resulting in severe to profound intellectual disability with poor or absent speech, and most patients never achieve independent walking; neurodevelopmental disorder characterized by delayed psychomotor development apparent in infancy and resulting in severe to profound intellectual disability with poor or absent speech; most patients never achieve independent walking; onset of refractory multifocal seizures between the first weeks and years of life, and some may show developmental regression
also hypotonia and spasticity; MRI was normal or with mild abnormalities |