Bilateral temporal lobe dysplasia and seizure onset associated with biallelic CNTNAP2 variants.

Biallelic CNTNAP2 variants have been associated with Pitt-Hopkins like syndrome. We describe six novel and one previously reported patients from six independent families and review the literature including 64 patients carrying biallelic CNTNAP2 variants. Initial reports highlighted intractable focal seizures and the failure of epilepsy surgery in children, but subsequent reports did not expand on this aspect. In all our patients (n=7), brain MRI showed bilateral temporal grey/white matter blurring with white matter high signal intensity, more obvious in the T2-FLAIR sequences, consistent with bilateral temporal lobe dysplasia. All patients had focal seizures with temporal lobe onset and semiology, which were recorded in five, showing bilateral independent temporal onset in four. Epilepsy was responsive to anti-seizure medications in two patients (2/7, 28.5%), and pharmaco-resistant in five (5/7, 71.5%). Splice-site variants identified in five patients (5/7, 71.5%) were the most common mutational finding. Our observation expands the phenotypic and genetic spectrum of biallelic CNTNAP2 alterations focusing on the neuroimaging features and provides evidence for an elective bilateral anatomoelectroclinical involvement of the temporal lobes in the associated epilepsy with relevant implications on clinical management.