Triple X syndrome

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.

Symptoms Causes Complications

Triple X syndrome may not cause any signs or symptoms. If symptoms do appear, they may include:

  • Tall stature
  • Vertical skinfolds that may cover the inner corners of the eyes (epicanthal folds)
  • Delayed development of speech and language skills
  • Weak muscle tone (hypotonia)
  • Curved pinky fingers (clinodactyly)
  • Behavior and mental health problems
  • Premature ovarian failure or ovary abnormalities
  • Constipation or abdominal pains

When to see a doctor

See your daughter's doctor if you have any concerns about your daughter's developmental progress. Your doctor can help determine what may be the cause and suggest appropriate action.

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