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Disease Profile
Klinefelter syndrome
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
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Age of onset
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ICD-10
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Inheritance
Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.
Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.
X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.
X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.
Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.
Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.
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Other names (AKA)
Klinefelter's syndrome; XXY syndrome; 47,XXY syndrome;
Categories
Congenital and Genetic Diseases
Summary
Klinefelter
In some cases, there is more than one X chromosome in each cell (for example, 48,XXXY or 49,XXXXY). These conditions, which are often called "variants of Klinefelter" syndrome usually have more serious problems (
Symptoms
- Small, firm testicles
- Delayed or incomplete puberty with lack of secondary sexual characteristics resulting in sparse facial, body, or sexual hair a high-pitched voice and body fat distribution resulting in a rounder, lower half of the body, with more fat deposited in the hips, buttocks and thigh instead of around the chest and abdomen
- Breast growth (
gynecomastia ) - Reduced facial and body hair
- Infertility
- Tall stature
- Abnormal body proportions (long legs, short trunk, shoulder equal to hip size)
- Learning disability
- Speech delay
- Crypthochirdism
- Opening (meatus) of the urethra (the tube that carries urine and sperm through the penis to the outside) on the underside of the penis (hypospadias) instead of the tip of the head of the penis
- Social, psychologic and behavioral problems
Whether or not a male with KS has visible symptoms depends on many factors, including how much testosterone his body makes, if he is mosaic (with both XY and XXY
Some people with features of Klinefelter syndrome have more than one extra
Intellectual disability - Distinctive facial features
- Skeletal abnormalities
- Poor coordination
- Severe speech difficulties
- Behavioral problems
- Heart defects
- Teeth problems.
Cause
Most often, Klinefelter syndrome is caused by a single extra copy of the X chromosome, resulting in a total of 47 chromosomes per cell. Males normally have one X chromosome and one
It is estimated that about half of the time, the cell division error occurs during development of the sperm, while the remainder are due to errors in egg development. Women who have pregnancies after age 35 have a slightly increased chance of having offspring with this syndrome.[5]
The features of Klinefelter syndrome are due to the extra copies of
Some people with features of Klinefelter syndrome have conditions known as "variants of Klinefelter syndrome" where there is more than one extra
Diagnosis
It is also possible to diagnosis Klinefelter syndrome before birth through chorionic villous sampling or
Treatment
- 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 againstosteoporosis and decrease the risks ofautoimmune disease and breastcancer . - 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.
Organizations
Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.
Organizations Supporting this Disease
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Association for X and Y Chromosome Variations (AXYS)
P.O. Box 861
Mendenhall, PA 19357
Toll-free: 1-888-999-9428
E-mail: [email protected]
Website: https://genetic.org/
Learn more
These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.
Where to Start
- The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) provides information related to the health of children, adults, and families. Click on the link to view information on this topic.
- MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
- MedlinePlus Genetics contains information on Klinefelter syndrome. This website is maintained by the National Library of Medicine.
- The National Human Genome Research Institute's (NHGRI) website has an information page on this topic. NHGRI is part of the National Institutes of Health and supports research on the structure and function of the human genome and its role in health and disease.
- The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.
In-Depth Information
- Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
- The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
- Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
- PubMed is a searchable database of medical literature and lists journal articles that discuss Klinefelter syndrome. Click on the link to view a sample search on this topic.
References
- Klinefelter syndrome. Eunice Kennedy Shriver National Institute of Child Health and Human Development. November 2013; https://www.nichd.nih.gov/health/topics/klinefelter/Pages/default.aspx.
- Klinefelter syndrome. Genetics Home Reference. January 2013; https://ghr.nlm.nih.gov/condition=klinefeltersyndrome.
- Kirmse B. Klinefelter syndrome. MedlinePlus. November 2014; https://www.nlm.nih.gov/medlineplus/ency/article/000382.htm.
- Chen H. Klinefelter syndrome. Medscape Reference. 2018; https://emedicine.medscape.com/article/945649-overview.
- Learning about Klinefelter syndrome. National Human Genome Research Institute. October 2011; https://www.genome.gov/19519068.
- Klinefelter Syndrome. National Organization for Rare Disorders. 2014; https://rarediseases.org/rare-diseases/klinefelter-syndrome/.
- Klinefelter syndrome. Genetics Home Reference (GHR). January 2013; https://ghr.nlm.nih.gov/condition/klinefelter-syndrome. Accessed 4/14/2015.
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