Klinefelter syndrome

Injury	Disease	Nutrition	Poison

Symptoms	Surgery	Test	Special Topic

Overview

Symptoms

Treatment

Prevention

Klinefelter syndrome

Definition:

Klinefelter syndrome is a condition that occurs in men as a result of an extra X chromosome. The most common symptom is infertility.

Alternative Names:

47 X-X-Y syndrome

Causes, incidence, and risk factors:

Humans have 46 chromosomes, which contain all of a person’s genes and DNA. Two of these chromosomes, the sex chromosomes, determine a person’s gender. Both of the sex chromosomes in females are called X chromosomes. (This is written as XX.) Males have an X and a Y chromosome (written as XY). The two sex chromosomes help a person develop fertility and the sexual characteristics of their gender.

Klinefelter syndrome results in males who have at least one extra X chromosome. Usually, this occurs as a result of one extra X (written as XXY).

Klinefelter syndrome is found in about 1 out of every 500-1,000 newborn males. Women who have pregnancies after age 35 are slightly more likely to have a boy with this syndrome than younger women.

Review Date: 10/27/2004
Reviewed By: Celeste Krauss, M.D., Board Certified Clinical Genetics, Clinical Cytogenetics, Pediatrics and a Founding Fellow, of the American College of Medical Genetics. Review provided by VeriMed Healthcare Network.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.