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Klinefelter Syndrome
Alternate Names : 47 X-X-Y Syndrome
Definition Klinefelter syndrome is a chromosome abnormality that affects only men and causes hypogonadism.
Overview, Causes, & Risk Factors
A person's sex is determined by the X and Y chromosomes. Normally, men have an X and a Y and women have two X's. In Klinefelter syndrome, a male has two X's and a Y.
The condition is common and affects 1 in 500 men. The infant appears normal at birth, but the defect usually becomes apparent in puberty when secondary sexual characteristics fail to develop (or develop late). At this time, testicular changes occur that eventually result in infertility in the majority of those affected. Some mild cases may go undetected, with no abnormalities present except infertility.
One risk factor for this condition is the mother giving birth at an older age. In most cases, the problem develops during fetal development and is not inherited from one or both parents.
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Jump to another section
• Definition
• Klinefelter Syndrome Overview, Causes, & Risk Factors
• Klinefelter Syndrome Symptoms & Signs
• Klinefelter Syndrome Diagnosis & Tests
• Klinefelter Syndrome Treatment
• Klinefelter Syndrome Prognosis
• Klinefelter Syndrome Complications
• Klinefelter Syndrome Support Groups
• Calling Your Health Care Provider
Topics that might be of interest to you Diseases & Conditions
• Breast Cancer
• Hypogonadism
• Infertility
• Lung Disease
• Osteoporosis
• Varicose Veins
Tests & Exams
• FSH
• Karyotyping
• LH Blood Test
• Semen Analysis
• Testosterone
Other Topics
• Gynecomastia
• Penis
• Testes
Review Date : 2/5/2003
Reviewed By : Douglas R. Stewart, M.D., Division of Medical Genetics, Hospital of the University of Pennsylvania, Philadelphia, PA. Review provided by VeriMed Healthcare Network.
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