Trisomy x

Symptoms

What are the signs and symptoms of trisomy X?

Trisomy X is a relatively mild condition, with up to 90% of females remaining undiagnosed due to the subtlety of their symptoms. Nonetheless, there are a few features associated with the condition. Babies with trisomy X are more likely to have poor muscle tone ("hypotonia") which may lead to some delays in attaining motor skills such as walking. As they grow up, this hypotonia may contribute to their increased incidence of clumsiness. Females with trisomy X tend to be taller than average, with earlier growth spurts. Learning disorders are more common, typically those involving language such as speech and reading; however, average IQs typically do not fall into the category of true cognitive disability. Behavioral and social issues are more common in women with trisomy X, in particular anxiety disorders and trouble making friends and maintaining relationships during the school years. These problems may actually be secondary to the speech and other learning delays seen in females with this condition. Women with trisomy X appear to have improved social abilities after leaving school. Finally, in adulthood, an increased incidence of psychiatric disorders such as anxiety and impulse-control issues have been observed.

There are also some findings that have been very rarely associated with trisomy X. These include: kidney disorders such as absence of one kidney ("unilateral renal agenesis"), seizures, digestive problems such as constipation, and congenital heart defects. It should be noted, however, that many of the studies have been biased towards studying individuals who have more significant learning and/or physical issues. Historically, these individuals were the ones who were more likely to get chromosome testing and be diagnosed in the first place. As time goes on and increased prenatal diagnostic and screening tests for chromosome disorders becomes more common, and more females with trisomy X are discovered prenatally, the true scope of this condition, and the incidence of the associated symptoms, may become more clear.

A good review of the signs and symptoms of trisomy X can be found in this brochure from the Unique Rare Chromosome Disorders Support Group. To learn more about the symptoms of trisomy X, talk with your doctor or consult with a medical geneticist and/or genetic counselor. To find a local geneticist, use the Find Genetic Services search tool on the American College of Medical Genetics website. To find a local genetic counselor, use the Find a Genetic Counselor search tool on the National Society of Genetic Counselors' website.

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If you have trisomy X will you always show symptoms?

Are there different types of trisomy X?

What health problems should I look for in trisomy X?

Are there other diseases that look like trisomy X?

If you have trisomy X will you always show symptoms?

It is not known if all women with trisomy X show signs, because up to 90% of females with this chromosome disorder are undiagnosed. The reason for this is that the signs of the condition are often so subtle that they fail to indicate to families or physicians that genetic testing should be performed. In fact, the individuals who are most likely to be diagnosed are those with the most significant symptoms. Therefore, it appears likely that many women have little to no signs of trisomy X, despite the fact that if they had genetic testing, it would show that they do have the condition.

If you think you or your loved one may have trisomy X and wish to have a formal evaluation, or if you or your loved one have been found to have the chromosome disorder but wish to be evaluated for the associated symptoms, you should consult with a medical geneticist. To find a local geneticist, use the Find Genetic Services search tool on the American College of Medical Genetics website.

Are there different types of trisomy X?

Almost all females with trisomy X have the same chromosome findings, where they have three total copies of the X chromosome in all the cells of their body. This chromosome makeup is written as 47,XXX. There are a small number of individuals who are mosaic for trisomy X. Mosaicism means that there is a mixture of cells, some with trisomy X and some with another chromosome makeup. The percentage of the cells that are trisomy X, and depending on whether the other cells have normal chromosome makeups (two X chromosomes) or a different chromosome disorder (such as four X chromosomes, also known as tetrasomy X), will determine the symptoms and severity of complications a female displays.

For further information about the symptoms of trisomy X, talk with your doctor or consult with a medical geneticist and/or genetic counselor. To find a local geneticist, use the Find Genetic Services search tool on the American College of Medical Genetics website. To find a local genetic counselor, use the Find a Genetic Counselor search tool on the National Society of Genetic Counselors' website.

What health problems should I look for in trisomy X?

In general, trisomy X is not thought to be associated with an increased probability of physical health problems. Rarely, the condition has been associated with kidney problems, heart defects, constipation or seizure disorders. It should be noted that all of these associations are considered very rare. Talk with your doctor if you are concerned about any of these rare associations in yourself or a loved one who has been diagnosed with trisomy X.

Trisomy X is associated with an increased probability of learning disorders and psychiatric issues. Therefore, any female diagnosed with trisomy X should have developmental assessments performed periodically during childhood and throughout the school years. Additionally, any female with trisomy X should be monitored for signs of behavioral or psychiatric problems so that appropriate therapies or treatments can be initiated.

References
Are there other diseases that look like trisomy X?

In general, the symptoms of trisomy X are mild and non-specific. Therefore, there are many conditions whose features overlap with trisomy X. Nonetheless, the conditions which are more similar to trisomy X are other disorders which are caused by an abnormal number of X chromosomes. These include tetrasomy X, which happens when a woman has two extra or four total copies of the X chromosome, or pentasomy X, which happens when a woman has three extra or five total copies of the X chromosome. Tetrasomy X and pentasomy X are more rare than trisomy X and are typically associated with more severe findings than are seen in women with trisomy X. Trisomy X can be easily differentiated from tetrasomy X and pentasomy X by routine chromosome testing known as a karyotype.

References

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