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    Trisomy X (Triple X syndrome)


    Definition of Trisomy X (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 of Trisomy X (Triple X syndrome)

    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.


    Most people have 46 chromosomes occurring in 22 pairs, plus two sex chromosomes, one maternal and one paternal. These chromosomes contain genes, which carry instructions that determine everything from your height to your eye color.

    One of these chromosome pairs determines your sex. You receive one sex chromosome from your mother and another from your father. Your mother can give you only an X chromosome, but your father can pass on an X or a Y chromosome. If you receive an X chromosome from your father, the XX pair makes you genetically a female. If you receive a Y chromosome from your father, then your XY pair means you’re genetically a male.

    Females with triple X syndrome have a third X chromosome. Although this condition is genetic, it’s typically not inherited. Instead, what usually happens is that either the mother’s egg cell or the father’s sperm cell has not formed correctly, resulting in an extra X chromosome. This random error in egg or sperm cell division is called nondisjunction.

    When the cause is a malformed egg cell or sperm cell, as is usually the case, all the cells in the offspring’s body have the extra chromosome. Occasionally, the extra chromosome doesn’t appear until early in the development of the embryo. If this is the case, then the female is said to have a mosaic form of triple X syndrome.

    In the mosaic form, only some of the body’s cells have the third X chromosome. Because only some cells contain the extra X chromosome, females with the mosaic form of triple X syndrome may have less severe symptoms.

    Triple X syndrome is also called trisomy X, triplo X syndrome and XXX syndrome. It’s also referred to as 47,XXX syndrome because of the existence of a 47th chromosome, which is the extra X chromosome.

    Complications of Trisomy X (Triple X syndrome)

    Triple X syndrome can cause developmental delays or learning disabilities, and it’s possible that learning disabilities or delayed development could eventually lead to a variety of other issues, including academic problems, stress and poor socialization skills that cause social isolation.

    Other possible, though much rarer, complications that may occur include:

    • Premature ovarian failure or ovary abnormalities. When the ovaries stop working before the expected age of menopause, there’s a decline in the production of certain hormones and eggs are no longer released by the ovaries each month. This can cause infertility. Additionally, girls and women with triple X syndrome may have malformed ovaries.
    • Seizures. Girls and women with triple X syndrome may develop a seizure disorder.
    • Kidney abnormalities. Females born with triple X syndrome may also have abnormally developed kidneys or may have only one kidney.

    Preparing for your appointment

    If you’re concerned about your daughter’s development, make an appointment to talk about it with your family doctor or pediatrician.

    Because appointments can be brief, and there’s often a lot of ground to cover, it’s a good idea to arrive well prepared. Here’s some information to help you get ready for your appointment, and what you might expect from your doctor.

    What you can do

    • Write down any symptoms you’ve noticed in your daughter, including any that may seem unrelated to the reason for which you scheduled the appointment.
    • Write down key personal information, including any significant illnesses you may have experienced during pregnancy or any medications that you may have used during pregnancy. Also, try to recall when your daughter met developmental milestones, such as learning to say her first word or learning to walk.
    • Write down questions to ask your child’s doctor.

    Your time with your daughter’s doctor may be limited, so preparing a list of questions can help you make the most of your time together. For triple X syndrome, some basic questions you might want to ask include:

    • What’s the most likely cause of my daughter’s symptoms?
    • What kinds of tests does she need? Do these tests require any special preparation?
    • How might this condition affect her?
    • What treatments are available, and which do you recommend?
    • My daughter has other health conditions. How can we best manage these conditions together?
    • What services are available to help my daughter with developmental delays or learning disabilities?
    • Are there any brochures or other printed material that I can take with me? What websites do you recommend visiting?

    In addition to the questions that you’ve prepared in advance, don’t hesitate to ask questions you may think of during your appointment.

    What to expect from your doctor

    Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over points you want to spend more time on. Your doctor may ask:

    • When did you first notice your daughter’s symptoms?
    • Does anything seem to improve your daughter’s symptoms?
    • What, if anything, appears to worsen the symptoms?
    • Did your daughter achieve developmental milestones on time, such as learning to talk or walk?

    Tests and diagnosis

    Because many girls with triple X syndrome are healthy and have a normal appearance, they may remain undiagnosed all their lives, or the diagnosis may be discovered while investigating for other reasons.

    Prenatal genetic testing, such as amniocentesis or chorionic villus sampling, can provide a diagnosis of triple X syndrome before birth.

    After birth, triple X syndrome can be diagnosed by performing a chromosome analysis on a blood sample taken from your daughter.

    Before genetic testing, it’s important to receive genetic counseling to provide you with all the information about triple X syndrome.

    Treatments and drugs

    If your daughter has triple X syndrome, treatment is based on her symptoms, if any are present. For instance, if she has a learning disability from the triple X, she would require the same counseling as anyone else with that learning disability. This counseling usually involves teaching new techniques and strategies for learning, as well as providing motivation and help with using these tips in daily life.

    If your daughter has been diagnosed with triple X syndrome, her doctor may recommend periodic screenings throughout childhood. This would help ensure that any developmental delays or learning disabilities that may occur receive prompt treatment.

    Because girls with triple X syndrome may be more susceptible to stress, it’s important to make sure your daughter has a supportive environment as well. Psychological counseling may help, both by teaching you and your family useful methods of demonstrating love and encouragement, and by discouraging behaviors that you might not realize are negative.

    The chromosome change that causes triple X syndrome cannot be repaired, so the syndrome itself has no cure. However, given the treatable nature of most symptoms and how frequently no symptoms appear at all, it’s quite possible to lead a full and normal life with this syndrome.

    Coping and support

    A number of groups can provide help and support for people with triple X syndrome and their families. They include Knowledge Support & Action, which offers information and advice on coping with the syndrome, as well as ways to meet and talk with others in similar situations. The phone number is 888-999-9428. In addition, your daughter’s doctor may be able to recommend a local support group.

    If learning disabilities appear, the National Center for Learning Disabilities is a good resource as well. It can be reached at 888-575-7373 or through its website.

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