ATN1-related neurodevelopmental disorder (ATN1-NDD) is characterized by developmental delay / intellectual disability. Other neurologic findings can include infantile hypotonia, brain malformations, epilepsy, cortical visual impairment, and hearing loss. Feeding difficulties, present in some individuals, may require gastrostomy support when severe; similarly, respiratory issues, present in some, may require respiratory support after the neonatal period. Distinctive facial features and hand and foot differences are common. Other variable findings can include cardiac malformations and congenital anomalies of the kidney and urinary tract (CAKUT). To date, 18 individuals with ATN1-NDD have been identified.