Christianson Syndrome, also known as X-linked intellectual disability 21 (XLID 21), is a genetic disorder characterized by developmental delay, intellectual disability, and speech and language difficulties. It is caused by mutations in the SLC9A6 gene, which plays a crucial role in brain function. Individuals with Christianson Syndrome may also exhibit behaviors such as autistic features, epilepsy, and difficulties with coordination and balance. The condition primarily affects males, although some females can be carriers. Early intervention, specialized therapies, and a supportive environment can significantly improve the quality of life for individuals with Christianson Syndrome.