Triple X Syndrome

What is Triple X Syndrome?

Triple X syndrome, also known as trisomy X, is a rare genetic disorder that causes some females to be born with an extra X chromosome in all of their cells. Normally, females have two X chromosomes, one from each parent.

However, in triple X syndrome, the child is born with three. It usually happens when a sperm or egg cell is malformed prior to conception, but it can also occur as a result of an early error during embryo development.

Despite being a genetic condition, triple X syndrome is not typically inherited. Most of the time, it is due to nothing more than a random error in genetic development. For most women, the disorder does not cause any problems throughout their lives. However, for some, they may develop a variety of issues.

Some of the more common complications include poor self-esteem, difficulties at work or school, relationship problems, and anxiety or other emotional difficulties like ADHD and autism-like symptoms.

What are the Symptoms of Triple X Syndrome?

Many women with triple X syndrome do not always exhibit symptoms.

Symptoms include:

  • Learning disabilities
  • Speech delay
  • Tall stature
  • Long legs
  • Abnormally curved pinky fingers
  • Weak muscle tone
  • Widely spaced eyes
  • Delayed physical development
  • Emotional and behavioral problems
  • Difficulties with gross and fine motor skills
  • Problems with judgment, memory, and information processing

Less commonly, triple X syndrome can also be associated with:

  • Early or delayed puberty
  • Infertility
  • Menstrual irregularities
  • Constipation
  • Premature ovarian failure
  • Ovary, kidney, or heart abnormalities
  • Seizures
  • Flat feet
  • Frequent urinary tract infections
  • Abnormally shaped breastbone

Triple X Syndrome Causes

In most cases, Triple X Syndrome is not inherited. Instead, it’s a random chromosomal change that happens when the reproductive cells are forming in a fetus. Nondisjunction is the error that causes Triple X Syndrome, and it results in reproductive cells with a third chromosome. It happens only in female fetuses.

Although it is a genetic disorder, Triple X is not inherited because it occurs as a random error in reproductive cells. Typically, both men and women have 46 chromosomes per cell, grouped in 23 pairs, and including two sex chromosomes, one from each parent. These chromosomes pass on genes that determine all the physical and physiological traits of the child including things like height and eye color.

The pair of sex chromosomes will include a combination of XX or XY, and this determines whether the child is a boy or girl. A mother always passes on an X chromosome, but the father can pass an X or a Y. So an X chromosome from dad results in a female, with the sex chromosomes passing along an XX combination. Meanwhile, a Y chromosome from the father produces the XY combination needed for a boy.

Females with triple X syndrome contain a third X that derives from an error during cell division. This can occur early in the embryo’s development.

How is Triple X Syndrome Treated?

Most of the time, treatment is not required for patients with triple X syndrome, especially if they do not develop any symptoms.

Children who demonstrate learning disabilities or delays in their development may benefit from various therapies such as counseling, support groups, daily functioning support, and educational assistance.

Triple X Syndrome Prevention

The abnormal chromosome change that produces Triple X Syndrome can’t be fixed. Therefore, the syndrome doesn’t have a cure and is impossible to prevent. However, most symptoms are treatable and many never appear at all, making it possible to lead a normal life where you may never even know you have Triple X.

Additionally, the third X chromosome can occur in the egg even before conception, so you cannot predict it. This also makes genetic screening useless in preventing Triple X. However, all known results are low impact and treatable and focus should be placed on recognizing the syndrome and effectively treating the impacted girls and women when necessary.

Last Reviewed:
October 11, 2016
Last Updated:
September 10, 2017