On examination at nine years of age, the patient's occipitofrontal circumference, height and weight
were around average. There were no dysmorphic features. He was drooling excessively and had feeding
difficulties. He could only make a few steps unaided and his gait was unsteady. His deep tendon reflexes
were increased at the knees and he had right-sided clonus. He was excessively restless and became easily
agitated, upset and sometimes aggressive. Cardiovascular and the remainder of his examination were
unremarkable. In general, he enjoys good health with no extensive hospitalizations, although he seems to
be troubled by frequent upper respiratory tract infections. His sleep remains interrupted. He is on sodium
valproate and risperidone but with very little effect. He cannot speak and communication is very limited.
He attends a special educational needs school