Triple X syndrome is an abnormality of the chromosomes that affects about 1 in 1,000 females. Females normally have two X chromosomes, one from each parent. In triple X syndrome, a female has three X chromosomes — hence, the name.
Triple X syndrome usually results from an error in the formation of a mother's egg cell or a father's sperm cell. Sometimes, triple X syndrome occurs as a result of an error early in the embryo's development.
Many girls and women with triple X syndrome have no symptoms or only mild symptoms. In other cases, symptoms may be more pronounced — possibly including developmental delays.
Treatment for triple X syndrome depends on which symptoms, if any, your daughter exhibits and their severity.