Trisomy x

Because trisomy X does not run in families, if one family member has been diagnosed with trisomy X, it is not recommended that other family members be tested for this condition.

There are several ways to find other girls and women with trisomy X. Support groups are an excellent way to connect individuals with trisomy X to one another. There are various groups that support individuals and families of girls and women with trisomy X. The Association for X and Y Chromosome Variations has a list of support groups on their Local Support Groups page. They also have a list of International Support Groups.

Alternatively, you can ask your doctor if he or she knows of other patients with a diagnosis of trisomy X. This might help connect you to someone local who has the same diagnosis.

Most of the medical care females with trisomy X will need throughout their lifetime can be performed by general medical practitioners, given that most girls and women with this condition are healthy and without major medical problems. Nonetheless, consultation by certain specialists can help these individuals obtain the highest quality care as well as up-to-date information about the condition. In particular, seeking consultation with a medical geneticist and/or genetic counselor can be helpful. 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.

Additional specialists needed will depend on the affected person’s individual medical issues, but may include mental health professionals, developmental specialists, speech and other supportive therapists, and neurologists.

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.

Trisomy X is a chromosome disorder. 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.

Almost all cases of trisomy X occur spontaneously, most often due to an error in the production of an egg cell leading to it containing two copies, instead of the usual one, of the X chromosome. When an egg cell containing two X chromosomes is fertilized by a sperm cell containing one X chromosome, the baby ends up with three copies of that chromosome. This error in chromosome packaging is known as "nondisjunction" and does happen more frequently as women age. Therefore, the chance of having a baby with trisomy X does increase with a woman’s age.

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.

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.

What to do after a diagnosis of trisomy X depends on the timing at which this diagnosis is made. It is also important to be sure that the testing was diagnostic and was not a screening test. Pregnant women sometimes pursue a non-invasive prenatal screening blood test known as cell-free fetal DNA testing or non-invasive prenatal testing ("NIPT") which can indicate a high probability of trisomy X in a fetus. It is essential to be aware that an abnormal NIPT does not diagnose the baby with trisomy X, only suggests an increased chance. Trisomy X can only be diagnosed or ruled out with certainty through chromosome analysis. This chromosome analysis can be performed after birth on a sample of blood, or prenatally on placental tissue ("chorionic villus sampling" or "CVS") or on amniotic fluid ("amniocentesis"). If a baby has been found to have trisomy X on CVS or amniocentesis, consultation with a genetic counselor is essential. The genetic counselor can help explain what trisomy X is and help the family plan and make decisions about their pregnancy. To find a local genetic counselor, use the Find a Genetic Counselor search tool on the National Society of Genetic Counselors’ website. While there is no prenatal treatment or therapy for babies with trisomy X, early intervention after birth is the best method by which to maximize that child’s potential and developmental outcome.

Most often, females with trisomy X are diagnosed during childhood, after they have shown some signs of developmental delays or other concerns. The pediatrician or medical geneticist may order a chromosome analysis such as a karyotype to determine the cause of these delays and ultimately make the diagnosis of trisomy X. When a family learns that their daughter has trisomy X, they may feel confused or overwhelmed. To get up-to-date information about trisomy X, it is essential that they meet with a medical geneticist and/or a 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.

It is important to realize that nothing immediate must be done for someone who has been diagnosed with trisomy X. The condition is not life-threatening and the diagnosis will not significantly change how the child is cared for on a day-to-day basis. Nonetheless, because of the increased incidence of developmental delays and behavioral/psychiatric issues in females with trisomy X, consultation with specialists and close developmental monitoring is recommended. Early and ongoing interventions and therapies such as speech therapy are the best tools by which to help a child with trisomy X achieve her maximum potential.

Trisomy X is not an inherited condition. Although it is caused by a difference in the amount of genetic information a person has, specifically by an extra copy of the X chromosome, this extra chromosome is almost never inherited from either parent. Instead, this extra chromosome is present due to a random occurrence. Most often it is due to an error in the production of an egg cell leading to it containing two copies, instead of the usual one, of the X chromosome, although it can be caused by the same spontaneous error in a sperm cell. When an egg cell containing two X chromosomes is fertilized by a sperm cell containing one X chromosome, or when a sperm cell containing two X chromosomes fertilizes an egg cell containing one X chromosome, the baby ends up with three copies of the X chromosome. This error in chromosome packaging is known as "nondisjunction" and does happen more frequently in the eggs of women as they age. Therefore, the chance of having a baby with trisomy X does increase with a woman’s age. When a couple has had a daughter with trisomy X, it is considered unlikely for them to have another affected daughter.

If you or someone in your family has trisomy X and you are concerned about risks for this or other chromosome disorders in your offspring, talk to your doctor or make an appointment with a genetic counselor. To find a local genetic counselor, use the Find a Genetic Counselor search tool on the National Society of Genetic Counselors’ website.

As of October 2016, Down syndrome is not on the Recommended Uniform Screen Panel (RUSP). The RUSP is created by the Health Resources and Services Administration, and states use this list to guide what conditions they screen for on newborn screening. It should be noted that babies with trisomy X are expected to be healthy newborns and not require any immediate medical intervention.

There is more than one test for trisomy X, but medical experts agree that a diagnosis should be confirmed by a test known as a karyotype. A karyotype is essentially an organized image of the chromosomes within a cell obtained by microscopic evaluation. It is very important to remember that a prenatal screening performed on maternal blood known as a non-invasive prenatal testing ("NIPT") or cell-free fetal DNA screening test are not diagnostic. Therefore, a pregnancy which has been considered high risk or at increased risk for trisomy X by these screens needs confirmatory testing by karyotype before the diagnosis can be made. It is also important to know that there are other chromosome tests such as chromosomal microarray and fluorescent in situ hybridization (FISH) that can diagnose trisomy X. A chromosomal microarray gives much more detail about an individual’s chromosome makeup, but is not more sensitive at diagnosing or ruling out trisomy X and is a more expensive test than karyotyping. Furthermore, while microarray and FISH can diagnose or rule out trisomy X, they often cannot determine if mosaicism is present. Only a karyotype can determine this important piece of information.

There are several researchers interested in studying trisomy X. As of October 2016, there are a handful of studies listed at www.clinicaltrials.gov in regards to trisomy X. Many are focused on the psychiatric basis of the condition, and others are seeking to develop or improve prenatal screening for this and other chromosome disorders. To find current studies on trisomy X that are recruiting subjects, go to www.clinicaltrials.gov and type "trisomy X" in the search box.

The Focus Foundation is an organization that is dedicated to research and advocacy to help families of children with X and Y chromosome variations, including children with trisomy X. Their research studies web page lists current, ongoing research that supports their mission. At this time, they have a study listed through the National Institute of Mental Health (NIHM) studying the effects of sex chromosomes on brain development. For more information about this study, see the study home page at the NIHM website, which can be found here.

As of October 2016, there is no targeted treatment for trisomy X, nor is there a cure. Current treatment methods focus on the specific symptoms that each person with trisomy X has. Most often this includes supportive therapies such as speech therapy, which can be essential to allowing all individuals with trisomy X to meet their maximum developmental potential.

Researchers are still working to understand how an extra copy of the X chromosome causes the features associated with trisomy X. The extra X chromosome will remain in a woman’s cells throughout her life. The only way to treat trisomy X right now is to provide early intervention services, educational opportunities, and quality health care. Additionally, future research through clinical trials may identify new therapies or treatments effective for women with trisomy X. If you are interested in learning more about clinical trials on trisomy X, please visit www.clinicaltrials.gov for up-to-date information on what these trials are studying and where they are being conducted.

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.

The issues associated with trisomy X are caused by the extra X chromosome, which is present from the moment the egg and sperm cell come together. In most females, there are two X chromosomes and one of them is inactivated or "turned off" in each cell. This is because most genes on the X chromosome need only one copy to be turned on and explains why the genes on the X chromosome function normally in both females, who typically have two copies of each of these genes, and males, who typically have only one X chromosome and therefore one copy of each of these genes. In females with trisomy X, however, if one copy of the X chromosome is inactivated, that leaves two copies turned on. This overexpression of genes on the X chromosome is thought to be the cause of the symptoms of trisomy X; however, the exact mechanism of this is not well understood.

Deciding how and when to tell your daughter that she has been diagnosed with trisomy X can be difficult. The eXtraordinarY Kids Clinic at Children’s Hospital Colorado has developed a brochure to help parents with this task. The brochure can be downloaded for free from their website.

If you would like to donate money to help advance research on trisomy X, there are a few options. The Focus Foundation is an organization that is dedicated to research and advocacy to help families of children with X and Y chromosome variations, including children with trisomy X. You can make donations and support this organization in other ways by visiting their "Get Involved" page on their website.

Unique Rare Chromosome Disorders Support Group is another organization that supports individuals and families with rare chromosome disorders such as trisomy X. To make a donation to Unique, check out their donation web page.

The Association for X and Y Chromosome Variations is another organization that seeks to meet the needs and improve the lives of individuals and families affected by X and Y chromosome aneuploidies including trisomy X. To donate to their cause, check out their donation web page.

Trisomy X can be diagnosed by chromosome analysis before a baby is born (prenatally) or after a baby is born (postnatally). The most common type of chromosome analysis used to diagnose trisomy X is known as a karyotype, which is essentially an organized image of the chromosomes within a cell obtained by microscopic evaluation.

A karyotype is most often obtained prenatally on a sample of cells from amniotic fluid (via a procedure known as amniocentesis) or placental tissue known as chorionic villi (via chorionic villus sampling). There is also noninvasive prenatal screening tests such as cell-free fetal DNA testing (a blood test performed on the mother during pregnancy) that can identify pregnancies at increased risk for trisomy X, but these are not diagnostic and should not be relied on as final test results.

If a karyotype is performed on an individual postnatally, it is most often done on a blood sample.

If you wish to obtain more information about the specific testing used to diagnose trisomy X, consider making an appointment with a genetic counselor. To find a local genetic counselor, use the Find a Genetic Counselor search tool on the National Society of Genetic Counselors’ website.

The Association for X and Y Chromosome Variations has a clinic and research consortium which lists clinics nationwide that specialize in treating individuals with sex chromosome abnormalities such as trisomy X. The list of clinics can be found here.

Alternatively or in addition to those clinics, seeking consultation with a medical geneticist and/or genetic counselor can be helpful in attaining the best possible care for, as well as up-to-date information about, trisomy X. 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.

To find current studies on trisomy X that are recruiting subjects, go to www.clinicaltrials.gov and type "trisomy X" in the search box.

The Focus Foundation is an organization that is dedicated to research and advocacy to help families of children with X and Y chromosome variations, including children with trisomy X. Their research studies web page lists current, ongoing research that supports their mission.

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.

There is nothing known to make the symptoms of trisomy X worse.

Trisomy X is almost never associated with life-threatening medical complications or major birth defects, and affected girls and women typically experience normal health throughout their lives. For this reason, the life span of women with trisomy X is not shorter than average.

There are some noninvasive blood tests that pregnant women can have to help detect trisomy X and other fetal chromosome disorders. These tests have several names including non-invasive prenatal testing ("NIPT") or cell-free fetal DNA (cfDNA). It is very important to remember that NIPT/cfDNA are not diagnostic tests. Therefore, a pregnancy which has been considered high risk or at increased risk for trisomy X by these screens needs confirmatory testing by karyotype before the diagnosis can be made. To better understand the chance to have a baby with trisomy X as well as what screening or diagnostic testing is available for trisomy X, consultation with a genetic counselor is recommended. To find a local genetic counselor, use the Find a Genetic Counselor search tool on the National Society of Genetic Counselors’ website.

Women with trisomy X have normal fertility and can have healthy pregnancies. Because most women with this condition are never diagnosed, there is not good data to determine if the offspring of women with trisomy X are at increased risk for trisomy X, other sex chromosome disorders, or other chromosome disorders such as Down syndrome. If there is an additional risk, however, it appears likely to be small. To better understand the chance to have a baby with a chromosome abnormality as well as what screening or diagnostic testing is available for a pregnant woman with trisomy X, she should seek consultation with a genetic counselor. To find a local genetic counselor, use the Find a Genetic Counselor search tool on the National Society of Genetic Counselors’ website.

Trisomy X is also known as:

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.

There are various groups that support individuals and families of girls and women with trisomy X. The Association for X and Y Chromosome Variations has a list of support groups on their Local Support Groups page. They also have a list of International Support Groups.

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.