The majority of girls with fragile X syndrome show learning problems and a short attention span along with shyness, social anxiety, and moodiness. The majority of males with fragile X syndrome are mentally retarded, meaning that their IQs are below 70. Children with fragile X are usually extra sensitive to stimuli in their environment, such as noises or changes in their routine. They are usually anxious and have frequent tantrums. For most boys and some girls with fragile X, the activity level is high and the attention span is short.
Language development is especially slow.
Most boys do not talk much by age 3. Unusual behaviors, sometimes termed autisticlike behaviors, commonly develop by 3 years of age. Some of these behaviors are hand flapping, hand biting, poor eye contact, excessive chewing on clothes, and pulling away from touch. These children may ask questions over and over again even after hearing the answer. There is no cure for fragile X syndrome, but many treatments are available.