MED13 mutation: A novel cause of developmental and epileptic encephalopathy with infantile spasms

Purpose: Mutations in the MED13 gene are reported in the literature in association with clinically variable, neurodevelopmental disorders, which are characterized by mild-to-severe intellectual disability, autism spectrum disorder, attention deficit/hyperactivity disorder, epilepsy, ocular or skeletal abnormalities, congenital cardiac defects, and facial dysmorphisms. Here, we report a patient with an epileptic phenotype carrying a novel missense mutation characterized by developmental and epileptic encephalopathy with infantile spasms.Methods: Through trio-based WES, we identified a novel de novo heterozygous missense variant c.2501A>G in the MED13 gene. We reviewed all medical charts of the present patient and reviewed all previously reported cases with pathogenic variants of MED13. Results: This study involves a 24-month-old boy with epilepsy onset at the age of 3 months with drug-resistant focal seizures followed by infantile spasms at the age of 10 months. He had a severe, developmental delay along with microcephaly and dysmorphic features. From a literature review, it emerged that epilepsy is described in only one out of nineteen of previously reported patients with a phenotype of generalized, drug-resistant epilepsy with myoclonic-atonic seizures. Microcephaly, developmental delay, hypotonia, corpus callosum abnormalities, deafness, and retinal atrophy were common features in the previously described cases.Conclusion: This case expands the genetic landscape of infantile spasms as well as the phenotype of MED13-related disorders adding the electroclinical features of early-onset developmental and epileptic encephalopathy with infantile spasms to the previously described, generalized epilepsy with myoclonic-atonic seizures.