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Trisomy X Syndrome

Last updated Jan. 6, 2019

Approved by: Maulik P. Purohit MD, MPH


Image of variable facial features in girls with trisomy X. (a) Epicanthal folds and hypertelorism in 2 year old girl, (b) Hypertelorism in 9 year old girl, (c) Lack of dysmorphic features in a 19 year old girl with trisomy X.

What are the other Names for this Condition? (Also known as/Synonyms)

  • 47, XXX Aneuploidy Syndrome
  • Karyotype 47, XXX Syndrome
  • Super Female Syndrome

What is Trisomy X Syndrome? (Definition/Background Information)

  • Trisomy X Syndrome, also known as Triple XXX Syndrome, is characterized by the presence of an additional X chromosome, in some female individuals
  • In normal cases, there are two X chromosomes (which are the sex chromosomes) found in a female. However, individuals with this syndrome are affected by a chromosomal aberration, and each cell might contain an additional X chromosome
  • The severity of the condition is based on the proportion of normal cells (with XX chromosomes) to abnormal cells (with XXX chromosomes) occurring in the body. In a majority of the cases, there is no apparent visual difference between women, who suffer from this condition and those who do not

Who gets Trisomy X Syndrome? (Age and Sex Distribution)

  • Trisomy X Syndrome is exclusively seen in females; the incidence rate is about 1 in 1000 live births
  • All races and ethnic groups may be affected by this syndrome

What are the Risk Factors for Trisomy X Syndrome? (Predisposing Factors)

There are no established risk factors for Trisomy X Syndrome.

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Trisomy X Syndrome? (Etiology)

  • Normally, the female sex has XX chromosome, with a single X chromosome being obtained from each parent. However, if either the sperm cell (obtained from the father) or egg cell (obtained from the mother) had an extra X chromosome, due to a genetic defect; then, after fertilization and formation of the fetus, this extra X chromosome is incorporated into the cell
  • The origin of Trisomy X Syndrome is due to a genetic process that is caused by a defective egg or sperm cell. The condition does not run in the families
  • Since, in some cases, not all the cells contain an additional X chromosome, the proportion of such abnormal cells to normal cells, creates a mosaic pattern, where only a certain percentage of cells are affected. The severity of the disorder is based on this proportion. The greater the proportion of abnormal cells to normal cells, the more severe is the signs and symptoms

What are the Signs and Symptoms of Trisomy X Syndrome?

The signs and symptoms of Trisomy X Syndrome include:

  • Size of the head is not proportional to body size
  • The individual is tall for one’s age
  • Epicanthal (skin) folds may be observed at the eye corners
  • Delayed development causing learning, speech disabilities
  • Weakness of muscles, weak motor skills

How is Trisomy X Syndrome Diagnosed?

A diagnosis of Trisomy X Syndrome may involve:

  • Physical exam and medical history evaluation
  • A blood test for chromosomal analysis helps detect Trisomy X
  • In certain high-risk pregnancy cases, sometimes prenatal genetic testing is performed. This may establish any chromosomal anomalies, at an early stage
  • A majority of the cases go undetected

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Trisomy X Syndrome?

Some of the possible complications of Trisomy X Syndrome are:

  • Delays in development could in later life, lead to social problems, poor performance at schools due to learning disabilities, stress, and isolation
  • In rare occasions, abnormalities of the ovaries (malformation) and kidneys may occur
  • Sometimes, seizures are observed

How is Trisomy X Syndrome Treated?

Symptomatic treatment is provided, once Trisomy X Syndrome is confirmed. There is no cure for the condition, since it is a genetic disorder. Any developmental progress concerns or any delayed development as the girl child grows, have to be addressed. The treatment options include:

  • Periodic check-ups are recommended to assess the child’s developmental progress
  • Psychological counseling and providing strategies to cope with learning disabilities may be helpful
  • A supporting environment with encouragement and positivity can help cope with stress and social problems  

How can Trisomy X Syndrome be Prevented?

  • Currently, there are no specific methods or guidelines to prevent Trisomy X Syndrome genetic condition
  • If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
  • Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

What is the Prognosis of Trisomy X Syndrome? (Outcomes/Resolutions)

  • In a majority of Trisomy X Syndrome cases, the girl child can have a normal quality of life at school, home, and at play
  • Individuals, who are severely affected by the syndrome have to be provided suitable help and support, in order to lead a normal life

Additional and Relevant Useful Information for Trisomy X Syndrome:

There many organizations that provides assistance to women and girls, in order to address problems associated with Trisomy X Syndrome, thus helping them lead a normal life.

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: June 4, 2014
Last updated: Jan. 6, 2019