HNRNPU-Related Neurodevelopmental Disorder (HNRNPU-RNDD, MIM#617391) is a rare neurodevelopmental disorder characterized by:
• Mild to severe developmental delay/intellectual disability
• Epilepsy and seizures, which may be refractory
• Speech and motor skills delay
• Behavioral differences such as autism spectrum disorder
• hypotonia (low muscle tone)
• Subtle but distinctive facial features, including widely spaced teeth, a thin upper lip, hypertelorism (increased space between the eyes), up or down slanted palpebral fissures, and prominent and/or arched eyebrows
• Strabismus
• Structural brain differences identified by brain imaging
• Growth delay/short stature
• Congenital heart defects
HNRNPU