What is trisomy X?
Trisomy X, which is also known as triple X syndrome or 47,XXX, is a chromosome disorder that occurs in females. Typically, individuals have 23 pairs, or 46 total chromosomes. The chromosome pairs are numbered 1-22, with the final pair being known as the sex chromosomes. Generally, males have one X and one Y chromosome, whereas females typically have two X chromosomes. When a female has trisomy X, however, she has an extra X chromosome, or three total X chromosomes. This means that she has 47 total chromosomes.
Most females with trisomy X are unaware of their different chromosome makeup. This is because the signs and symptoms of this condition are generally quite mild and therefore escape detection or diagnosis. There are some features that are seen more frequently in women with this condition, however. These features include: mild learning disabilities mainly affecting speech and reading, some delay in attaining motor skills, low muscle tone (hypotonia), taller than average height, and increased incidence of anxiety or other emotional disorders. Less frequently, kidney disorders, seizures, digestive issues and cardiac defects have been associated.
Overall, women with trisomy X are able to have relatively typical lives and their condition does not prevent them from attending regular school classes nor from pursuing the careers of their choosing. Females with trisomy X can benefit from early intervention and therapies, the benefit of which appears to bring their IQ closer to the average. Without this early intervention, women with this condition may have IQ's 10-15 points below expected; however, they still are not expected to fall into the category of intellectually disabled. Furthermore, this condition does not cause infertility, and women with this condition are expected to have healthy offspring.
For more information about trisomy X, see the informational brochure from Unique, the Rare Chromosome Disorder Support Group.
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Are there other names for trisomy X?
Trisomy X is also known as:
- Trisomy X syndrome
- Triple X
- Triple X syndrome
- XXX syndrome
- 47,XXX syndrome
- Tri-X syndrome
- Triplo-X syndrome
How common is trisomy X?
Trisomy X is thought to occur in about 1 in 1,000 females. This condition occurs equally across all races and individuals from all geographical regions.