GATAD2B-related developmental and epileptic encephalopathy (DEE): Extending the epilepsy phenotype and a literature appraisal.

Heterozygous pathogenic variants in GATAD2B gene have been related to the GATAD2B-associated neurodevelopmental disorders (GAND) characterized by neurodevelopmental delay with predominant language impairment, infantile hypotonia, macrocephaly, ophthalmological abnormalities, and dysmorphic facial features with nonspecific findings on brain magnetic resonance imaging (MRI). Occasionally, affected individuals exhibit drug responsive epilepsy, psychiatric disorders, and other extra-neurological comorbidities. We report a patient carrying a de novo heterozygous missense variant in GATAD2B gene. She presents a developmental and epileptic encephalopathy (DEE) with drug-resistant atypical absences. An extensive review of the literature did not show any similar phenotype. Our report broadens the electroclinical spectrum related to GATAD2B pathogenic variants and supports the inclusion of this monogenic etiology among the genetic causes of epilepsy with drug-resistant atypical absences, a group with few known genetic etiologies. PLAIN LANGUAGE SUMMARY: We describe a patient with drug-resistant atypical absences caused by a pathogenic variant in the GATAD2B gene. Mutations in the GATAD2B gene should be considered among the rare monogenic causes of atypical absences.