This is a rare and genetic neurodevelopmental disorder that affects brain development. It is characterized by global developmental delay, severe intellectual disability, and an absence of expressive language. Many people with this condition also experience muscular hypotonia, seizures, and autistic behaviors which can include repetitive or stereotypic movements. While the condition is complex and affects multiple aspects of development and behavior, information provided here is based on a brief definition from trusted sources. Details about additional features such as motor stereotypies, chronic constipation, and sleep-wake cycle disturbances appear in the disease name, but further clarification is limited from the current evidence.

Common symptoms include global developmental delay, severe intellectual disability, and a lack of expressive language. Other signs that have been reported are muscular hypotonia, seizures, autistic behaviors, and stereotypic movements. These symptoms can vary in severity from person to person.

This condition is genetic in nature. However, more details about the exact genetic cause, such as the role of the NRXN1 gene mentioned in the condition name, are currently limited. Information provided so far is based on the general definition of the disorder.