General hypotonia with developmental delay and progressive microcephaly are evident in the first 6-12 months of life. Seizures may be present at birth or within the first month of life. Edema of the feet, hands, and face are also present at birth. Cognitive deficits and motor delays are usually evident during infancy. The central hypotonia may be accompanied by peripheral spasticity. Kyphoscoliosis often develops. Other dysmorphic features include micrognathia, narrow forehead, short nose, and open mouth.
Brain imaging reveals coarse pachygyria, polymicrogyria, and dilated ventricles with hypoplastic corpus callosum and pons. Cerebellar hypoplasia was found in one child.