Fragile X syndrome is an inherited condition caused by a defect on the X chromosome that results in intellectual disabilities ranging from mild to severe. It is characterized by symptoms such as intellectual disabilities, attention issues, anxiety, autism-like behaviors, sensory issues, speech delays, seizures, and in males large testes after puberty. The condition is caused by a DNA mutation that results in the FMR1 gene being switched off and the FMRP protein not being produced, preventing normal brain development. While there is no cure, treatments can help minimize symptoms and include education, medications, and therapy.