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XYY Syndrome is a genetic condition that occurs when a male’s genes have an extra Y chromosome. Females typically have two X chromosomes (XX). Males typically have one X chromosome and one Y chromosome (XY). Males with this genetic condition have an extra copy of the Y chromosome in each of their cells (XYY).
Most people have 46 chromosomes in each cell. Males with XYY syndrome have 47 because of the extra copy of the Y chromosome. However, sometimes this mutation is only present in some cells. According to the National Institutes of Health, XYY syndrome occurs in 1 out of every 1,000 boys (Genetics Home Reference).
XYY Syndrome is also sometimes called Jacob’s Syndrome, XYY Karyotype, or YY Syndrome.
Males with XYY Syndrome live typical lives for the most part. Some males with XYY Syndrome may be taller than average and face learning difficulties or speech problems. They may also grow up with minor physical differences, such as weaker muscles and bones and delayed puberty. When they are older, men with the syndrome may face fertility issues and complications related to low testosterone levels. Besides these complications, however, males with XYY syndrome do not usually have any distinguishing physical features or complications, and have normal sexual development.
XYY Syndrome is the result of a random mix-up during the creation of a male’s genetic code. Most cases of XYY Syndrome are not inherited, and researchers do not believe that there is any genetic predisposition to it. Men with XYY Syndrome are not more or less likely to pass the syndrome on to their male children. Because the error is random and occurs at different times during cell division, a male with XYY syndrome may have some cells that are not affected—some cells may have XY chromosomes while others have XYY chromosomes.
XYY Syndrome is not inherited. All males are at the same risk for the condition.
The signs and symptoms of XYY Syndrome differ from patient to patient and age to age.
The following signs may be an indication that a baby boy has XYY Syndrome:
The following signs may be an indication that a young boy or teenager has XYY Syndrome:
In addition to the signs above, the following signs may be an indication that an adult male has XYY Syndrome:
XYY Syndrome may remain undiscovered and undiagnosed until a male reaches adulthood. That’s when fertility problems, such decreased sperm counts, alert doctors to a possible undiagnosed condition.
Two tests may be used to diagnose XYY Syndrome:
The XYY Syndrome cannot be cured, but treatments can help reduce symptoms and the effects caused by it, especially if it is discovered and diagnosed early. Patients can work with health care providers to address any symptoms they may have, such as speech disabilities, hormonal imbalances, and learning problems. As a man gets older, he may want to work with a reproductive specialist to address any infertility concerns.
The following treatment options may be used to address some of the most common effects of XYY Syndrome:
Gynecomastia. Men with excess breast tissue as a result of XYY Syndrome may want plastic surgery to remove the breast tissue.
Men with XYY Syndrome can—and very often do—live completely normal lives with the condition. XYY Syndrome can remain undiagnosed throughout a man’s lifetime. If it is diagnosed, however, individuals with XYY Syndrome can find the help they might need.
Written by: Kimberly Hollandon: Oct 27, 2016
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