Review Question - QID 109449

A 6-year-old boy presents to the pediatrician with seizures. He has had 2 seizures lasting about 30 seconds each over the last 3 days. She reports that the patient has previously had seizures a few times per year since he was 12 months of age. The patient’s medical history is otherwise notable for intellectual disability. He rolled over at 14 months of age and walked at 24 months of age. The patient’s mother denies any family history of epilepsy or other neurologic diseases. The patient is in the 3rd percentile for height and the 15th percentile for weight. The patient’s temperature is 98.6°F (37°C), blood pressure is 111/67 mmHg, pulse is 93/min, and respirations are 19/min. On physical exam, he has a happy demeanor with frequent smiling. The patient has strabismus and an ataxic gait accompanied by flapping of the hands. He responds intermittently to questions with 1-word answers. This patient is most likely to have which of the following genetic abnormalities?