Smith-Magneis syndrome: behavioural phenotype mimics ADHD.

A mentally retarded 7-year-old male child presented with inattention and hyperactivity which was initially diagnosed as attention deficit hyperactivity disorder (ADHD). However, a careful evaluation of symptomatology along with clues provided by specific features of facial dysmorphism in this case along with genetic testing clinched the diagnosis of Smith-Magneis syndrome the behavioural phenotype of which closely resembles ADHD.