XQ duplication syndrome, specifically the int22h1/int22h2-mediated Xq28 duplication syndrome, is an X-linked intellectual disability syndrome. According to available information, it is characterized by a range of features that vary in severity, most notably:
- Cognitive impairment, which is typically more pronounced in males.
- A wide range of neurobehavioral abnormalities.
- Variable facial dysmorphic features.