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Klinefelter syndrome is a genetic condition that affects males. Klinefelter syndrome occurs when a boy is born with one or more extra X chromosomes. Most males have one Y and one X chromosome. Having extra X chromosomes can cause a male to have a variety of physical traits.
Many men with an extra X chromosome are not aware that they have it, and they lead normal lives. Klinefelter syndrome occurs in about 1 out of 1,000 males.
The presence of an extra X chromosome in males most often occurs when the genetic material in the egg splits unevenly. But it can also occur when the genetic material in the sperm splits unevenly. Even though Klinefelter syndrome is a genetic disorder, it is not passed down through families. So, parents who have a child with Klinefelter syndrome are not any more likely than other couples to have another child with the condition.
Many men who have Klinefelter syndrome do not have obvious symptoms. Others have sparse body hair, enlarged breasts, and wide hips. In almost all men the testicles remain small. In some men the penis does not reach adult size. Their voices may not be as deep. They usually have infertility. But they can have a normal sex life.
Some boys with Klinefelter syndrome have language and learning problems.
See a picture of a male with Klinefelter syndrome.
Klinefelter syndrome usually is not diagnosed until the time of puberty. At this point, the boy's testicles fail to grow and you may start to notice other symptoms.
To find out if your son has Klinefelter syndrome, your doctor will ask questions about his past health, do a physical examination, and order a chromosome test called a karyotype.
Sometimes Klinefelter syndrome is found before a baby is born (prenatally). Genetic tests on cells collected from amniocentesis or chorionic villus sampling (CVS) can show when a baby boy has Klinefelter syndrome. So the condition may be found when a pregnant woman has genetic tests for another reason.
In adult men, lab tests in addition to a karyotype may be done, such as hormone tests or a semen analysis, if Klinefelter syndrome is suspected.
Males with Klinefelter syndrome can be given testosterone, a hormone needed for sexual development. If treatment is started around the age of puberty, it can help boys with the sexual development of their bodies.
Testosterone is given by injection or through a skin patch or gel. The treatment usually continues throughout a man's life but does not help infertility.
Speech therapy and educational support can help boys who have language or learning problems.
If your son has been diagnosed with Klinefelter syndrome:
Current as of: July 17, 2020
Author: Healthwise StaffMedical Review: John Pope MD - PediatricsBrian D. O'Brien MD - Internal MedicineMartin J. Gabica MD - Family MedicineAdam Husney MD - Family MedicineStephen LaFranchi MD - Pediatrics, Pediatric EndocrinologySiobhan M. Dolan MD, MPH - Reproductive Genetics
Current as of: July 17, 2020
Author: Healthwise Staff
Medical Review:John Pope MD - Pediatrics & Brian D. O'Brien MD - Internal Medicine & Martin J. Gabica MD - Family Medicine & Adam Husney MD - Family Medicine & Stephen LaFranchi MD - Pediatrics, Pediatric Endocrinology & Siobhan M. Dolan MD, MPH - Reproductive Genetics
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