Klinefelter syndrome

Variations in the number of copies of the X chromosome do occur in Klinefelter syndrome, and sometimes all the cells do not have an extra X chromosome. The most common mosaic pattern in Klinefelter syndrome is 46,XY/47, XXY and this indicates that some cells in the male body have the normal XY chromosome count while other cells have an additional X chromosome. Because of this mosaic pattern, there may be enough normally functioning cells to be able to have children. Often, men with less XXY cells and more cells with only XY will have less severe symptoms. Mosaicism is very complicated, and it is challenging to predict how a man will be affected. Medical geneticists and genetic counselors can help interpret confusing results in these situations.

Other individuals or families with Klinefelter syndrome can most often be found through online support groups (listed below). In-person support groups may also and your genetic counselor may be able to recommend or locate one in your area.

The Association for X and Y Chromosome Variations offers helpful information for healthcare professionals and materials for them to provide to patients. The American Association for Klinefelter Syndrome Information and Support also offers brochures targeted to healthcare providers as well as families and patients.

Men with Klinefelter syndrome are often recommended to have androgen replacement therapy to increase their testosterone levels. Treatment begins around the age of puberty (generally near 12 years old). Testosterone can help with many symptoms relating to Klinefelter syndrome, like behavior, and it may decrease the risk for breast cancer, osteoporosis, and autoimmune disorders. Unfortunately, testosterone therapy cannot treat or cure infertility. For more information on testosterone therapy, please see an endocrinologist. An endocrinologist can be found by talking to your doctor or by using the “Find a Endocrinologist” function at the American Association of Clinical Endocrinologists.

Males with Klinefelter syndrome should see a geneticist or a genetic counselor. A genetic counselor can help to further explain Klinefelter syndrome and answer any questions you have. Genetics professional can also help you make the appropriate next referrals. Through the National Society of Genetic Counselors (NSGC) website, you can find a genetic counselor in your area. Other necessary specialists will be dependent on what symptoms a child has, but may include a multidisciplinary team composed of endocrinologists, behavioral therapists, and speech therapists.

Besides an increased risk of breast cancer, men with Klinefelter syndrome also have a greater chance to develop an endocrine disorder than men in the general population. Endocrine disorders include diabetes, hypo/hyperthyroidism, and autoimmune disorders, such as lupus and rheumatoid arthritis. Treatment with testosterone may decrease the risk for developing an autoimmune disease though and your doctor may refer you to an endocrinologist for further care. An endocrinologist can be found by talking to the patient’s main doctor or by looking at the endocrinologist finder on the American Association of Clinical Endocrinologists site.

Men with Klinefelter syndrome are expected to have a normal life expectancy. Some studies have shown that the average life span may be about 2 years shorter than the average life span of men in the general population.

Both males with Klinefelter syndrome and women with Triple X syndrome have an extra X chromosome; however women with Triple X syndrome do not also have a "Y" chromosome. Both conditions can cause some behavioral concerns, learning difficulties, and taller stature. Both conditions also affect people differently and symptoms can vary from person to person. Women with Triple X syndrome are generally able to have children naturally though, unlike men with Klinefelter syndrome. There are other differences in how the two conditions can affect people.

Both Klinefelter syndrome and Triple X syndrome are both caused by nondisjunction, or when the chromosomes do not properly separate. Nondisjunction can occur in a parent’s egg or sperm or can occur very early in embryonic development. The risk of nondisjunction and thus the chance to have a child with extra chromosomes does increase as a woman ages.

To learn more about Triple X syndrome, please visit http://ghr.nlm.nih.gov/condition/triple-x-syndrome. This site was created by the National Institutes of Health and details the condition, symptoms, and treatment available.

A diagnosis of Klinefelter syndrome most often implies that a male has two X chromosomes and one Y chromosome. However, males with Klinefelter syndrome can often have more than one extra X chromosome. Some men with Klinefelter syndrome may 3, 4, or even more X chromosomes. Typically, the greater number of extra X chromosomes that an individual has, the more serious symptoms may be. These individuals can have seizures, crossed eyes, constipation, and recurrent ear infections in childhood. They might also show slight differences in other physical features as well as have lower intelligence levels. To learn more about these variations, please visit the the link for Klinefelter syndrome through the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

The chance to have a second baby with Klinefelter syndrome is typically below 1%, though not 0%. Though the condition is not inherited, having one child with Klinefelter syndrome does slightly increase the risk in comparison to a family who has not had a child with Klinefelter syndrome. Additionally, the chance in general to have a child with extra or missing chromosomes, such as Klinefelter syndrome, does increase as women age. Prenatal genetic counseling and testing can be offered to parents who would like to know their personalized risk assessment and ways to determine if a pregnancy could have Klinefelter syndrome.

Klinefelter syndrome is a chromosome condition that can affect a male’s physical appearance, fertility, and cognitive development. Most individuals have two sex chromosomes in each cell that contain some of the instructions for growth and development of the body. Females will have two X chromosomes (46, XX) and males will have one X and one Y chromosome (46, XY). In Klinefelter syndrome, males most often have an extra copy of the X chromosome in each cell (47, XXY). It’s the extra X chromosome that interferes with male sexual development and causes the features of Klinefelter syndrome. It’s important to note that not all individuals affected with Klinefelter syndrome have the same degree of signs and symptoms.

Males with Klinefelter syndrome typically have small testes, which do not produce as much testosterone as usual. Testosterone is the hormone that directs male sexual development before birth and during puberty. When testosterone is lacking, this can lead to delayed or incomplete puberty, breast enlargement (gynecomastia), reduced facial and body hair, and fertility problems. Some males with Klinefelter syndrome have undescended testes (cryptorchidism), the opening of the urethra on the underside of the penis (hypospadias), or an unusually small penis (micropenis).

Children with Klinefelter syndrome can have delayed speech and language development, as well as learning disabilities. Children affected with Klinefelter syndrome are typically quiet, sensitive, and unassertive, but these characteristics vary among affected individuals.

When males with Klinefelter syndrome enter into adulthood, they tend to be taller than their peers. These males have an increased risk of developing breast cancer and systemic lupus erythematosus (SLE), a chronic inflammatory disease. The chance of an individual with Klinefelter syndrome developing these disorders is similar to that of women in the general population.

To learn more about Klinefelter syndrome, please talk to your genetic counselor or look on a reliable website such as Genetics Home Reference.

Klinefelter syndrome is typically caused by an extra X chromosome. Humans generally have 46 chromosomes (23 pairs) in every cell in their body. We label them chromosome 1, 2, 3, all the way to 22. The last pair of chromosomes are sex chromosomes. Females will have two X chromosomes (46, XX) and males will have one X and one Y chromosome (46, XY). Males with Klinefelter syndrome have at least one extra X chromosome (47, XXY). Most often, all the cells of an individual will have that extra copy of the X chromosome and that is what interferes with male sexual development and causes the features of Klinefelter syndrome. It’s important to note that not all individuals affected with Klinefelter syndrome have the same degree of signs and symptoms.

Sometimes not all of an individual’s cells will have the same number of chromosomes. This is called mosaicism. Some individuals with Klinefelter syndrome are considered mosaic as some cells in the male body have an additional X chromosome and the rest of the cells have the normal XY chromosome count (46,XY/47,XXY). Because of this mosaic pattern, the signs and symptoms may be more variable. For example, some individuals with mosaic Klinefelter syndrome do not have concerns with infertility.

There’s also the possibility that some individuals with Klinefelter syndrome have the addition of more than one extra sex chromosome in all their cells (e.g. 48,XXXY or 49, XXXXY). When these variations occur, they tend to have more serious signs and symptoms than the classic form of Klinefelter syndrome. To learn more about variations in sex chromosomes please visit AXYS.

Chromosomes are made up of genes, and genes act as instructions for the body. Extra or duplicated genetic information can lead to health concerns, because the body now has changed instructions. Adding another whole X chromosome to a male, in the case of Klinefelter syndrome, can cause infertility and behavioral problems. For males with Klinefelter syndrome who have more than one extra X chromosome, they are at an increased risk for other concerns including distinctive facial features, learning disabilities, and skeletal problems.

Klinefelter syndrome is a variable condition and the type and severity of symptoms may be different from individual to individual. Many men with the condition are actually not diagnosed with or even suspected to have Klinefelter syndrome until they have a delayed start to puberty. Most men with Klinefelter syndrome are also have concerns with infertility, and are typically not able to have children naturally. Physical symptoms can include tall height, small testes size (hypogonadism), or slight breast development (gynecomastia). Some men with Klinefelter syndrome may also have delayed speech development, need extra help in school, or have difficulty socializing with peers. In order to learn whether you or a loved one are having symptoms related to Klinefelter syndrome or not, people can ask their genetic counselor or medical geneticist who best understands their health issues.

There is variable expression among males with Klinefelter syndrome. Some people may never know that they have Klinefelter syndrome, while others may be more severely affected. Whether or not a male with Klinefelter has visible symptoms depends on many factors, including how much testosterone his body makes and the number of cells with the extra X chromosome. To learn more about specific symptoms, people can talk their healthcare provider, medical geneticist, or genetic counselor.

As of January 2016, Klinefelter syndrome is not on the Recommended Uniform Screen Panel (RUSP). The Health Resources and Services Administration create the RUSP, and states use this list to guide what conditions they screen for on newborn screening. If you have received prenatal screening results concerning for Klinefelter syndrome and wish to pursue diagnostic testing at delivery, please make sure to inform your delivery team and genetic counselor so that such testing can be arranged ahead of time.

There are a few types of genetic tests that can diagnose Klinefelter syndrome. Most often, it will be done by chromosomal analysis or karyotype, which looks at the number, size, and arrangement of an individual’s chromosomes. After birth, chromosomal analysis is performed most often on blood. Samples can also be collected during the prenatal period through procedures called a chorionic villus sampling (CVS) or amniocentesis. These procedures remove either a small piece of the placenta or amniotic fluid for testing from and allow parents and healthcare providers to learn about a baby’s chromosomes prior to delivery. To learn more about prenatal testing for Klinefelter syndrome, please talk to a genetic counselor. A genetic counselor in the area can be found on the National Society of Genetic Counselor’s “Find a Genetic Counselor” page.

There is research being conducted on Klinefelter syndrome, particularly on the effects of testosterone replace therapy. For information on clinical trials available, ClinicalTrials.gov can provide up-to-date information on research being conducted. The Association for X and Y Chromosome Variations details different research that is currently being conducted (http://www.genetic.org/Action/CurrrentResearch.aspx).

There is no treatment that can cure Klinefelter syndrome as we cannot remove the extra X chromosome. Certain symptoms do have treatments available. Your healthcare provider can help you find services to improve your hormone balance. Other supportive services and therapies, like speech therapy, may be helpful to some children. The treatment plan for Klinefelter syndrome is different from case to case and depends on the individual symptoms and concerns of each child. Please talk to your genetic counselor or medical geneticist on the types of care recommended.

Prenatal testing is available for Klinefelter syndrome. With prenatal diagnosis, genetic information from the pregnancy is tested during the pregnancy to determine whether the baby has Klinefelter syndrome. This can be done through chorionic villus sampling (CVS) or amniocentesis and both procedure have benefits, risks, and limitations. Further discussion with a prenatal genetic counselor can further explain these procedures as well as discuss if one or none may be better suited to your family. A genetic counselor in the area can be found on the National Society of Genetic Counselor’s “Find a Genetic Counselor” page.

Preimplantation genetic screening (PGS) is available for Klinefelter syndrome. PGS allows for parents to only implant embryos into the mother’s uterus that do not have extra or missing chromosomes. PGS is an option when families are going through in vitro fertilization (IVF). PGS typically has a detection rate of 90-95%, but is not considered diagnostic and does not replace prenatal diagnosis. Additionally, PGS and IVF can be costly to families and are not guaranteed to lead to a pregnancy. Talking to a preconception or prenatal genetic counselor can be beneficial to further discuss how these tests are done and their benefits and limitations. A genetic counselor in the area can be found on the National Society of Genetic Counselor’s “Find a Genetic Counselor” page.

Although Klinefelter syndrome is a genetic condition, it is not typically inherited or passed down in families. It most often occurs randomly during egg and sperm creation in a parent or early on in embryonic development in a fetus. For more information on sporadic conditions can occur in a family, please talk to your genetic counselor.

Klinefelter syndrome most often occurs randomly as sperm and eggs are created, most commonly due to a process called nondisjunction. Humans generally have 46 chromosomes (23 pairs) in every cell in their body. When a woman’s eggs are made, each egg generally has one copy of each of the 23 chromosomes. The same is true for sperm. The 23 copies from the sperm and the 23 copies from the egg then combine to create a person with 46 chromosomes (23 pairs). When nondisjunction occurs, an egg or a sperm is created with 2 or 0 copies of a chromosome instead of the usual one. If an egg with two X chromosomes combines with a sperm with one Y chromosome, the baby will have Klinefelter syndrome.

It is recommended for men with a clinical suspicion of Klinefelter syndrome to receive diagnostic testing via a blood sample. Laboratories can run a chromosome analysis, or karyotype, on the blood sample to assess the number and structure of each chromosome. For individuals with Klinefelter syndrome, we would expect to see 47 chromosomes, specifically an extra X chromosome (47, XXY). This type of testing can usually be coordinated through a medical geneticist or genetic counselor. A genetic counselor in the area can be found on the National Society of Genetic Counselor’s[link url=" http://nsgc.org/p/cm/ld/fid=164″ target=”_blank”> “Find a Genetic Counselor” page.

The Association for X and Y Chromosome Variations offers helpful tips about how to discuss a diagnosis of Klinefelter syndrome with a child. The eXtraordinarY Kids Clinic in Denver, Colorado created this brochure and surveyed both parents and their children to determine what information would be useful.

There are multiple ways to help the Klinefelter syndrome community through financial contribution. You can donate to a support group, like the American Association for Klinefelter Syndrome Information and Support, The Focus Foundation, Association for X and Y Chromosome Variations, Klinefelter Syndrome Information and Support. Support groups will use their funds differently with some focused on helping to raise awareness, assisting people with Klinefelter syndrome and contributing to needed resources, or donating to medical research.

The Association for X and Y Chromosome Variations offers information on which clinics specialize in Klinefelter syndrome. Through the National Society of Genetic Counselors (NSGC) website, you can also find a genetic counselor in your area. A genetic counselor or medical geneticist can help to further explain Klinefelter syndrome and answer any questions you have as well as help make referrals to the appropriate specialists.

ClinicalTrials.gov can provide up-to-date information on research being conducted on many conditions including Klinefelter sydnerome. The Association for X and Y Chromosome Variations details different research currently being conducted (http://www.genetic.org/Action/CurrrentResearch.aspx). Your medical geneticist or genetic counselor may also be able to provide additional information on current and future clinical trials focused on Klinefelter syndrome.

Around 1 in 500 to 1 in 1,000 male babies are born with Klinefelter syndrome. However, studies believe that this may be an underestimate as many individuals with mild symptoms may not be diagnosed and the features of Klinefelter syndrome can overlap with other genetic conditions.

Most males with Klinefelter syndrome have normal intelligence levels. They can typically complete all levels of education and pursue any type of career. Between 25% and 85% of all males with Klinefelter have some kind of learning or language-related problem, though the severity can be variable. Males with Klinefelter syndrome may be more likely to need extra help in school to avoid lagging period their peers. To help determine if therapies such as speech, occupational, and physical therapies may be beneficial, please talk to your healthcare provider.

Noninvasive prenatal testing (NIPT) is often able to screen for Klinefelter syndrome. NIPT is a screening option for pregnant women and looks at the amount of genetic information coming from the pregnancy. As it is still a screening test, it cannot provide a yes or no answer and more research needs to be conducted to better understand and improve the accuracy of this test. . Parents are recommended not to make decisions about the pregnancy solely based off of NIPT results. Diagnostic testing like chorionic villus sampling (CVS) or amniocentesis can confirm or rule out a screening result. A prenatal genetic counselor will be able to explain screening results and their implications as well what additional tests are available based on how far along a woman is in a pregnancy. A genetic counselor in the area can be found on the National Society of Genetic Counselor’s “Find a Genetic Counselor” page.

Most men with Klinefelter syndrome are not able to have biological children due to a very low amount or lack of working sperm. Some men that have mosaic Klinefelter syndrome may be able to produce working sperm and therefore have biological children. Meeting with a reproductive specialist or genetic counselor can help you learn more about your options. One option for some men is a new technology called intracytoplasmic sperm injection (ICSI) that is used as part of invitro fertilization (IVF). By injecting sperm directly into an egg, this technology can increase the odds of pregnancy. If a man does not have working sperm and/or does not wish to pursue ICSI, options to have a child may include adoption or use of a sperm donor. A consult with a preconception genetic counselor or reproductive endocrinologist and infertility specialist may be recommended to further discuss these options and what may be available to you and your family.

Most individuals have two sex chromosomes in each cell. Females will have two X chromosomes (46, XX) and males will have one X and one Y chromosome (46, XY). In Klinefelter syndrome, there is typically an extra copy of the X chromosome is found in each cell (47, XXY). Sometimes however, variations in the number of copies of the X chromosome do occur, and the most common cause of this is mosaicism, or when all the cells do not have the same number of chromosomes. In Klinefelter syndrome, some males have a mixture of cells that are 47, XXY and cells that are 46, XY. This would indicate that some cells in the male body have an additional X chromosome and the rest of the cells have the normal XY chromosome count. The percentage of normal or extra genetic information are different from case to case. Because of this mosaic pattern, signs and symptoms can vary and there may be enough normally functioning cells to be able to have children.

Other times some individuals with a diagnosis of Klinefelter syndrome have the addition of more than one extra sex chromosome in all their cells (e.g. 48,XXXY or 49, XXXXY). When these variations occur, they tend to have more serious signs and symptoms than the classic form of Klinefelter syndrome. These additional symptoms can include skeletal concerns, severe speech delay, and distinctive facial features. As the number of extra X increases, so does the concern for additional health issues.

To learn more about if you or a loved one could have mosaic Klinefelter syndrome, please review any genetic testing results with your genetic counselor or medical geneticist.

Klinefelter syndrome is frequently called XXY syndrome. It is sometimes referred to XXY trisomy as well.

There are several support groups options for individuals with Klinefelter syndrome and their loved ones. Listed below are a few of the ones available.

There are not different ages of onset for Klinefelter syndrome, but different health problems may be noticed or start at different times. Sometimes it may be apparent early on that a child may have Klinefelter syndrome from a genital anomaly, like hypospadias or small testes size. Other people though may not have symptoms that appear until early adolescence or adulthood. Whether or not a male with Klinefelter syndrome has visible symptoms can depend on many factors, including how much testosterone his body makes and the number of cells with the extra X chromosome.

Compared to men in the general population, men with Klinefelter syndrome do have some increased risk for breast cancer. This increased risk stems from increased amounts of estrogen (female hormones) in males with Klinefelter syndrome that lead them to have larger breast growth. One study of men with Klinefelter syndrome found that the risk of getting breast cancer was about 1% (1 in 100). However, research in this area is quite limited and the number may be an underestimate or overestimate. Regardless treatment with testosterone may decrease the risk of breast cancer in males with Klinefelter syndrome. Males interested in testosterone therapy should discuss the option with their main healthcare provider or geneticist.

Klinefelter syndrome may be confused with the genetic condition Kallmann syndrome. This possibility occurs as males with Klinefelter syndrome and Kallmann syndrome can have delayed or absent puberty and infertility concerns. However, genetic testing can easily distinguish between these two conditions as individuals with Kallman syndrome do not have an extra X chromosome.