Why is klinefelters syndrome a genetic disorder

Most commonly, affected individuals are taller than average are unable to father biological children infertile ; however the signs and symptoms of Klinefelter syndrome vary among boys and men with this condition. In some cases, the features of the condition are so mild that the condition is not diagnosed until puberty or adulthood, and researchers believe that up to 75 percent of affected men and boys are never diagnosed. Boys and men with Klinefelter syndrome typically have small testes that produce a reduced amount of testosterone primary testicular insufficiency.

Testosterone is the hormone that directs male sexual development before birth and during puberty. Without treatment, the shortage of testosterone can lead to delayed or incomplete puberty, breast enlargement gynecomastia , decreased muscle mass, decreased bone density, and a reduced amount of facial and body hair. As a result of the small testes and decreased hormone production, affected males are infertile but may benefit from assisted reproductive technologies.

Some affected individuals also have differences in their genitalia, including undescended testes cryptorchidism , the opening of the urethra on the underside of the penis hypospadias , or an unusually small penis micropenis.

Other physical changes associated with Klinefelter syndrome are usually subtle. Older children and adults with the condition tend to be somewhat taller than their peers. Other differences can include abnormal fusion of certain bones in the forearm radioulnar synostosis , curved pinky fingers fifth finger clinodactyly , and flat feet pes planus.

Children with Klinefelter syndrome may have low muscle tone hypotonia and problems with coordination that may delay the development of motor skills, such as sitting, standing, and walking. Affected boys often have learning disabilities, resulting in mild delays in speech and language development and problems with reading. Boys and men with Klinefelter syndrome tend to have better receptive language skills the ability to understand speech than expressive language skills vocabulary and the production of speech and may have difficulty communicating and expressing themselves.

About 10 percent of boys and men with Klinefelter syndrome have autism spectrum disorder. Nearly half of all men with Klinefelter syndrome develop metabolic syndrome, which is a group of conditions that include type 2 diabetes , high blood pressure hypertension , increased belly fat, high levels of fats lipids such as cholesterol and triglycerides in the blood.

Compared with unaffected men, adults with Klinefelter syndrome also have an increased risk of developing involuntary trembling tremors , breast cancer if gynecomastia develops , thinning and weakening of the bones osteoporosis , and autoimmune disorders such as systemic lupus erythematosus and rheumatoid arthritis.

Autoimmune disorders are a large group of conditions that occur when the immune system attacks the body's own tissues and organs. Klinefelter syndrome affects about 1 in newborn boys. It is among the most common sex chromosome disorders, which are conditions caused by changes in the number of sex chromosomes the X chromosome and the Y chromosome. Klinefelter syndrome is a sex chromosome disorder in boys and men that results from the presence of an extra X chromosome in cells.

People typically have 46 chromosomes in each cell, two of which are the sex chromosomes. Most often, boys and men with Klinefelter syndrome have the usual X and Y chromosomes, plus one extra X chromosome, for a total of 47 chromosomes 47,XXY.

Boys and men with Klinefelter syndrome have an extra copy of multiple genes on the X chromosome. The activity of these extra genes may disrupt many aspects of development, including sexual development before birth and at puberty, and are responsible for the common signs and symptoms of Klinefelter syndrome. Researchers are working to determine which genes contribute to the specific developmental and physical differences that can occur with Klinefelter syndrome.

Some people with features of Klinefelter syndrome have an extra X chromosome in only some of their cells; other cells typically have one X and one Y chromosome.

Rarely, other cells may have additional chromosome abnormalities. It is thought that less than 10 percent of individuals with Klinefelter syndrome have the mosaic form. Boys who have Klinefelter syndrome are born with it. It's also called XXY because they have an extra X chromosome in most or all their cells. Usually, a person has 46 chromosomes in each cell, divided into 23 pairs, which includes two sex chromosomes.

Half the chromosomes are inherited from the father and the other half from the mother. The chromosomes contain genes, which determine an individual's characteristics, such as eye color and height. Klinefelter syndrome is not caused by anything the parents did or did not do. The disorder is a random error in cell division that happens when a parent's reproductive cells are being formed. If one of these defective cells contributes to a successful pregnancy, the baby will have the XXY condition in some or all his cells.

When a boy is born with the XXY condition in only some cells, it's called mosaic Klinefelter syndrome. Often, boys and men with this condition have milder signs and symptoms than others with the XXY condition. Not all boys with Klinefelter syndrome will have noticeable symptoms.

Other boys can have symptoms that are physically apparent or problems with speech, learning, and development. Babies with Klinefelter syndrome typically have weak muscles, reduced strength, and quiet personalities.

They also can take longer to do things like sit up, crawl, walk, and speak. Compared with other kids their age, boys with Klinefelter syndrome might have some or all of these symptoms:. Klinefelter syndrome typically causes a boy's testicles to grow at a slower rate than those of other boys.

It also prevents the testicles from producing normal amounts of sperm and the hormone testosterone. Testosterone affects the way a boy develops both physically and sexually.

Low hormone levels and problems with sperm production make it difficult or sometimes impossible for a boy with Klinefelter syndrome to father a child later in life. Many boys with Klinefelter syndrome show symptoms related to their development of social and language skills. They may have trouble paying attention. A lot of boys learn to talk late or have trouble using words to express their emotions.

They also can have trouble with things like learning to spell, read, and write. Socially, they tend to have quiet personalities. They rarely cause trouble and are often more helpful and thoughtful than other boys. Treatment may include: [1] [3] [4] Testosterone replacement: About half of people with SK have low testosterone levels, which may be raised by taking supplemental testosterone.

Having a more normal testosterone level can help affected people develop bigger muscles, a deeper voice, and facial and body hair, and may also increase sexual desire, enlarge the testes , improve mood, self-image, and behavior; it may also protect against osteoporosis and decrease the risks of autoimmune disease and breast cancer. Breast removal or reduction surgery.

Educational interventions: As children, many people with Klinefelter syndrome qualify for special services to help them in school. Teachers can also help by using certain methods in the classroom, such as breaking bigger tasks into small steps. Several forms of therapy such as physical, speech, occupational, behavioral, mental health, and family therapy can often help reduce or eliminate some of the symptoms of Klinefelter syndrome such as poor muscle tone; speech and language problems; or low self-confidence.

Prognosis Prognosis. Babies with the 47, XXY form of Klinefelter differ little from healthy children. The results of one study on non- mosaic XXY infants younger than 2 years indicated that most XXY babies had normal external genitalia and facial features with height and weight in the normal range. Early diagnosis of Klinefelter syndrome is shown to be important to monitor potential developmental problems. However, most move toward full independence from their families as they enter adulthood.

Some have completed graduate education and have a normal level of functioning. Lifespan is not affected by Klinefelter syndrome. Statistics Statistics. It is estimated that 1 in every to 1, newborn males has an extra X chromosome, making Klinefelter syndrome one of the most common chromosomal disorders seen among newborns.

In addition, the features of this condition vary and can overlap significantly with those of other conditions. Do you have updated information on this disease? We want to hear from you. Research Research. Clinical Research Resources ClinicalTrials.

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To search for studies, enter the disease name in the "Text Search" box. Then click "Submit Query". Organizations Organizations. Organizations Supporting this Disease. InterConnect E-mail: info interconnect. Living with XXY W.

Point Loma Blvd. Do you know of an organization? Living With Living With. Their Web site offers general and condition-specific education resources to help teachers and parents better understand the needs of students who have genetic conditions.

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