ADNP and autism spectrum disorder: Helsmoortel-van der Aa syndrome (MIM #615873), an autosomal dominant disorder characterized by impaired intellectual development, autism spectrum disorder, motor delay, hypotonia, visual difficulties, congenital heart disease, gastrointestinal phenotypes, and facial dysmorphisms, is caused by heterozygous variants in activity-dependent neuroprotective homeobox (ADNP; MIM #611386) [47].