A neurodevelopmental disorder caused by variation in the TRA2B gene. This disorder is characterised by intellectual disability and/or developmental delay, with delayed or absent speech and delayed motor development. Most patients present axial or global hypotonia in the neonatal to infancy period, and brain MRI abnormalities. Other phenotypic features commonly reported include infantile spasms, microcephaly, variable behavioral abnormalities, feeding difficulties, and short stature.