| Main clinical features
|
neurodevelopmental disorder characterized by severely delayed psychomotor development apparent soon after birth or in infancy, profound intellectual disability, poor or absent speech, and seizures, muscle weakness, absent visual tracking, and postnatal microcephaly, with flat and expressionless faces, downturned corners of the mouth, and open mouths
most patients are never able to walk due to hypotonia or spasticity
brain imaging shows cerebral and cerebellar atrophy, thin corpus callosum, and secondary hypomyelination associated to microcephaly, consistent with a neurodegenerative process |