In addition, disease-causing MECP2 mutations and genomic abnormalities have been reported in a wide range of disorders such as autism (4–6), schizophrenia (7–9), intellectual disability (10–12), developmental delay, obsessive compulsive disorder, attention deficit-hyperactivity disorder (13), and MECP2 duplication syndrome (14–16), and have also been reported in individuals with mild cognitive and behavioural impairments (17–24). Here, MECP2 is linked to attention deficit-hyperactivity disorder.