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Triple X syndrome | What we need to know

Triple X syndrome (trisomy X) is a rare disease in which female babies are born with three X chromosomes. Girls with triple X syndrome have slightly lower intelligence and special problems with verbal skills. Sometimes the syndrome causes menstrual irregularities and infertility, although some women with triple X syndrome can give birth to an anatomically healthy baby with normal chromosomes.

It is very rare to identify cases where babies have four or five X chromosomes. The more X chromosomes a girl has, the greater the risk of mental retardation/intellectual disability and physical abnormalities.


Females with triple X syndrome have a third X chromosome as a result of random incorrect cell division. This can occur before conception or early in embryonic development, although triple X syndrome is genetic, it is not usually inherited – it is a random genetic abnormality that can cause the following forms of triple X syndrome:

1. Non-disjunction – in most cases, the mother's egg or father's sperm divide incorrectly, which causes an extra X chromosome in the child. This random error is called nondisjunction ( ).

2. Mosaicism – Sometimes, extra chromosomes are formed by accidental cell division early in embryonic development. If this is the case, the child has a mosaic form of triple X syndrome, and only some cells have the extra X chromosome, not all. Women with a mosaic form may have less pronounced symptoms.


Some girls and women with triple X syndrome have no symptoms at all, which is why the disease is often overlooked. In some cases, pronounced symptoms in physical and behavioral characteristics may also be detected.

These symptoms include:

  • head shape anomaly;
  • above average height (especially with long legs);
  • delayed development of speech and language skills;
  • behavioral problems such as: attention deficit/hyperactivity disorder (ADHD) or symptoms of autism spectrum disorder;
  • psychological problems such as anxiety and depression;
  • Information processing problems.

Other symptoms:

  • Vertical skin folds that cover the inner corners of the eyes (epicanthal folds);
  • eyes wide apart;
  • curved pinky fingers;
  • flat feet
  • Convulsions;
  • Kidney problems.


There are two main types of tests available to prevent fetal syndromes during pregnancy (prenatal period): screening tests and diagnostic tests. Screening and diagnostic tests determine whether a fetus has a low or high chance of developing various syndromes. If screening tests show that you have a high risk of having a baby with triple X syndrome, it is recommended that you also have a diagnostic test to determine whether the fetus has the genetic disorder.

1. Screening Tests – A prenatal screening test can determine if your baby is more or less likely to have birth defects, many of which are genetic disorders. These tests include blood tests, specific ultrasounds, and prenatal cell-free DNA screening.

2. Diagnostic tests – after the screening test, the final answer is given by the diagnostic test, which checks the genetic material of the fetus and therefore can also find out whether the fetus has a genetic disorder. Invasive and non-invasive prenatal diagnostic tests ((NIPT) Verasity, Veragen) are the only, safe and effective way to confirm the diagnostics.

Be aware that some diagnostic tests, such as chorionic villus sampling and amniocentesis, carry a small risk of miscarriage.

Learn more about prenatal diagnostics → (

Complications and solution

While some women may have mild or no symptoms associated with triple X syndrome, others may have severe developmental, psychological, and behavioral problems that can also lead to a number of other problems, including:

  • social relationship problems;
  • poor self-esteem;
  • needing additional support or assistance in learning, daily activities, school or work;
  • lock-in
  • Aggressiveness.

There is no cure for triple X syndrome. Treatment includes supporting girls and women to cope with symptoms.

  • Developmental delay responds well to speech and physical therapy.
  • Learning problems can be solved with educational plans.
  • Behavioral problems can be managed through counseling as well as psychological and family support.




For prenatal screening of triple X syndrome, "Synevo" laboratory offers the following tests:

Name of the test Category Price CODE Response time (working day) ** Location of the analysis **** Buyhf: categories

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