Also called Fragile X syndrome (FXS), and is a hereditary disorder of the X chromosome. Symptoms vary and tend to be less severe in females. They can range from learning disabilities to retardation. Behavioral symptoms may include anxiety, ADHD, aggressiveness, outbursts, and/or extreme shyness. Physical symptoms may include seizures, large ears, long face with an extended jaw, and/or a high-pitched voice. Diagnosis can be confirmed by a DNA blood test.