CNTNAP2 deficiency due to biallelic variants leads to a distinct neurodevelopmental disorder typically characterized by:
• Developmental delay
• Seizure onset within the first 2 years followed by developmental regression (suggesting a developmental epileptic encephalopathy)
• Moderate to severe intellectual disability
• Variable occurrence of autism spectrum disorder and behavioral abnormalities
Other features:
• Hypotonia
• Hyporeflexia
• Non-specifc facial dysmorphisms
• Feeding difficulties
• Failure to thrive
• Unilateral or bilateral anterior temporal lobe T2 hyperintensities consistent with focal cortical dysplasia (malformation of cortical development due to CNTNAP2-deficiency)
• Brain MRI non-specific dysmorphisms such as inferior cerebellar vermis hypoplasia, abnormalities of the corpus callosum, superior cerebellar vermis atrophy (less frequent), mild white matter volume reduction with ventricular enlargement (rare), cerebellar dentate nuclei signal alterations (rare), and mild cerebral atrophy (rare)
• Ataxia (less frequent)
CNTNAP2