EBF3-related HADDS is a recently recognized condition that is characterized by developmental delay, low muscle tone, imbalance and incoordination, decreased pain sensitivity, and reduced facial expressions. Cognition ranges from moderate intellectual disability to normal cognition. People with this disorder typically have a disposition that is described as sociable. However, also behavioral issues have been described including autism, autistic-like traits (impaired eye contact and repetitive behaviors), anxiety, and ADHD. Children have a low muscle tone (hypotonia) resulting in feeding problems, especially in the neonatal and early childhood periods. Speech and language development is delayed with oral-motor apraxia. Receptive language is often age appropriate. Some children with HADDS are born with structural malformations of the brain or urogenital tract. Moreover, some children with HADDS can have febrile seizures between 6 months to 6 years of life, and there is a mildly increased risk of unprovoked seizures that typically respond well to medical management.
An extensive description of the broad clinical spectrum of EBF3-related HADDS can be found in the section Professionals – Clinical Characteristics.