ADNP and autism spectrum disorder: Pathogenic variants of the ADNP gene (MIM 611386) cause Helsmoortel–Van der Aa syndrome (MIM 615873), an autosomal dominant neurodevelopmental disorder characterised by intellectual disability, motor delay (ID/DD), autism spectrum disorder (ASD), hypotonia, speech delay and variable other features, such as congenital heart defects, distinctive facial appearance, urogenital anomalies, ophthalmological, gastrointestinal and behavioural problems [1].