What is Trisomy X?

Trisomy X, also called Triple X syndrome, is caused by the presence of an extra 'X' chromosome, one of the sex chromosomes, in the body's cells. Individuals with trisomy X will present as typical females. Signs and symptoms vary between individuals, but are usually mild, if present. Because the symptoms are so mild, only about 10% of individuals with trisomy X will be diagnosed. Individuals with trisomy X may have tall stature, developmental delay, and learning disabilities. Other symptoms may include distinct facial features, low muscle tone (hypotonia), heart defects, and seizures. Some individuals with the condition experience psychiatric problems. Individuals with trisomy X may experience fertility issues.

How common is Trisomy X?

The condition occurs in about one in every 1,000 female births. There is usually no family history of the condition.

How is Trisomy X treated?

Treatment depends on what needs the individual has. Individuals with trisomy X may need to be seen by physical, developmental, occupational, or speech therapists if they have developmental or speech problems. Additionally, a pediatric psychologist or group therapy may be helpful if they have social difficulties.

Because many individuals with trisomy X are healthy and have a normal appearance, they may remain undiagnosed all their lives, or the diagnosis may be discovered while investigating other medical issues.

What is the prognosis for an individual with Trisomy X?

Most individuals with trisomy X live a normal life without support.

Other names for
Trisomy X

  • Triple X syndrome


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