The following information may help to address your question:
Is 47, XYY syndrome inherited?
47, XYY syndrome
is usually not inherited
from a parent. Instead, it is typically caused by a random event that happens during the formation of a sperm cell
before conception (when the sperm fertilizes the egg). Even though this random event occurs in the sperm cell
of the father of a person with 47, XYY syndrome, the syndrome is not inherited from the father because the father himself typically does not have the syndrome.
It is uncommon for more than one person in a family to have 47, XYY syndrome. If a couple has a child with 47, XYY syndrome, the chances for the couple or family members to have another child with the syndrome are not increased. Men who have 47, XYY syndrome themselves are also not thought to be at an increased risk to have a child with chromosome
differences. Some sperm cells of a man with 47, XYY syndrome will have an extra Y chromosome
. However, it is thought that these cells are less likely to be able to survive to fertilize an egg. Therefore, the chances for a man with 47, XYY syndrome to have a child with a sex chromosome
abnormality are not thought to be increased.
People with questions about the chance to have a child with a chromosome abnormality
are encouraged to speak with a genetic counselor
or other genetics professional.
Last updated: 1/14/2018
What causes 47, XYY syndrome?
47, XYY syndrome is caused by having an extra copy of the Y chromosome
in each cell of the body.
The Y chromosome is one of the sex chromosomes, and the other sex chromosome is called the X chromosome
. Most people have two sex chromosomes, with girls having two X chromosomes, and boys having one X and one Y chromosome.
Boys with 47, XYY syndrome have one X chromosome and two Y chromosomes in each cell of the body. This typically happens due to a random event when a sperm cell
is formed that causes the sperm cell to have two Y chromosomes. When a sperm that has two Y chromosomes fertilizes an egg (which has an X chromosome), the resulting baby will be a male with two Y chromosomes and one X chromosome.
It is also possible that a similar random event could occur very early in an embryo’s development. This can produce a boy who has some cells that have two sex chromosomes and some cells that have an extra Y chromosome.
It is not fully understood why an extra copy of the Y chromosome causes the features associated with 47, XYY syndrome. It is thought that the tall stature seen in some males with the syndrome is caused by having an extra copy of a gene
that is located on the sex chromosomes called the SHOX
gene. This gene provides instructions to the body to control growth of the bones. People who have an extra copy of the Y chromosome also have an extra copy of the SHOX
gene, which could explain why they may be taller than expected. Another gene that is thought to cause the signs and symptoms of 47, XYY syndrome is called NLGN4Y. This gene is located on the Y chromosome and provides instructions to the body that helps form connections between the cells in the brain. It is thought that having an extra copy of this gene may cause the learning problems associated with 47, XYY syndrome.
Last updated: 1/14/2018
How can I find a genetics professional in my area?
Last updated: 12/6/2017
We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please
GARD Information Specialist
Please see our Disclaimer.