Klinefelter Syndrome

Klinefelter Syndrome is a chromosome disorder occurring in males. The male has an extra X chromosome, leading to an XXY pattern rather than the normal XY pattern in males (females are XX). Men with Klinefelter Syndrome often appear normal, but are infertile due to a lack of sperm production. Hence ...

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Introduction: Klinefelter Syndrome

Klinefelter syndrome (KS) is a condition that occurs in men who have an extra X chromosome. The syndrome can affect different stages of physical, language, and social development. The most common symptom is infertility. Boys may be taller than other ...1

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Symptoms of Klinefelter Syndrome

What are common symptoms of Klinefelter syndrome (KS)? Because XXY males do not really appear different from other males and because they may not have any or have mild symptoms, XXY males often don't know they have KS.1,2 ...2

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Complications of Klinefelter Syndrome

Are there disorders or conditions associated with KS? Males with KS are at higher risk for some other health conditions, for reasons that are not fully understood. But these risks can be minimized by paying attention to symptoms and treating ...3

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Causes of Klinefelter Syndrome

What causes Klinefelter syndrome (KS)? The extra chromosome results from a random error that occurs when a sperm or egg is formed; this error causes an extra X cell to be included each time the cell divides to form new ...4

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Causes List for Klinefelter Syndrome

Some possible causes of Klinefelter Syndrome or similar disorders may include:5

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Types of Klinefelter Syndrome

Some males with KS may have both XY cells and XXY cells in their bodies. This is called "mosaic" (mo-ZAY-ik). Mosaic males may have fewer symptoms of KS depending on the number of XY cells they have in ...6

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Diagnosis of Klinefelter Syndrome

How do health care providers diagnose Klinefelter syndrome (KS)? The only way to confirm the presence of an extra chromosome is by a karyotype (pronounced care-EE-oh-type) test. A health care provider will take a small blood or ...7

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Genetics of Klinefelter Syndrome

Genetic Changes: Klinefelter syndrome is a condition related to the X and Y chromosomes (the sex chromosomes ). People typically have two sex chromosomes in each cell: females have two X chromosomes (46,XX), and males have one X and one ...8

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Risk Factors for Klinefelter Syndrome

Scientists are not sure what factors increase the risk of KS. The error that produces the extra chromosome occurs at random, meaning the error is not hereditary (pronounced huh-RED-i-ter-ee) or passed down from parent to child ...9

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Treatments: Klinefelter Syndrome

What are the treatments for symptoms in Klinefelter syndrome (KS)? It's important to remember that because symptoms can be mild, many males with KS are never diagnosed ore treated.1 The earlier in life that KS symptoms are recognized and ...10

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Research for Klinefelter Syndrome

The NICHD, part of the NIH within the U.S. Department of Health and Human Services, has supported research on the many facets of Klinefelter syndrome (KS) and its symptoms to improve the health of males with this condition. NICHD ...11

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Names and Terminology

Common Name

  • Klinefelter syndrome

Medical or Scientific Names

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  1. Source: MedLinePlus (NIH): medlineplus.gov/ klinefelterssyndrome.html
  2. Source: NICHD (NIH): nichd.nih.gov/ health/ topics/ klinefelter/ conditioninfo/ Pages/ symptoms.aspx
  3. Source: NICHD (NIH): nichd.nih.gov/ health/ topics/ klinefelter/ conditioninfo/ Pages/ faqs.aspx
  4. Source: NICHD (NIH): nichd.nih.gov/ health/ topics/ klinefelter/ conditioninfo/ Pages/ Default.aspx
  5. Source: Algorithmically Generated List
  6. Source: NICHD (NIH): nichd.nih.gov/ health/ topics/ klinefelter/ conditioninfo/ Pages/ Default.aspx
  7. Source: NICHD (NIH): nichd.nih.gov/ health/ topics/ klinefelter/ conditioninfo/ Pages/ diagnosed.aspx
  8. Source: GHR (NLM/NIH): ghr.nlm.nih.gov/ condition/ klinefelter-syndrome
  9. Source: NICHD (NIH): nichd.nih.gov/ health/ topics/ klinefelter/ conditioninfo/ Pages/ risk.aspx
  10. Source: NICHD (NIH): nichd.nih.gov/ health/ topics/ klinefelter/ conditioninfo/ Pages/ treatments.aspx
  11. Source: NICHD (NIH): nichd.nih.gov/ health/ topics/ klinefelter/ researchinfo/ Pages/ default.aspx

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