In humans, single amino acid substitutions of OGT are associated with X-linked intellectual disability (XLID; OMIM #300997), a neurodevelopmental syndrome with heterogeneous symptoms that includes decreased intellectual ability (IQ<<70), low birth weight, short stature, drooling, compromised language skills and often anatomical brain and body anomalies [35]. This evidence concerns the gene OGT and cask-related x-linked intellectual disability.