All individuals were born after uneventful pregnancies and deliveries, with normal head circumference at birth that remained within the normal range during follow-up. Seizure onset occurred in late neonatal life or early infancy (median 10 weeks), typically presenting as focal seizures that were often prolonged or occurred in clusters. After this early severe phase, seizure frequency decreased, and one individual was seizure-free at last follow-up. EEG showed age-appropriate background activity, with focal epileptiform discharges in only one case. All individuals exhibited developmental delay ranging from mild to moderate, with more pronounced impairment of speech than motor development. Autism spectrum disorder was diagnosed in three individuals. No systemic involvement was observed. Brain MRI was normal in three individuals, while one showed mild cortical atrophy.
GAD2