What is Klinefelter Syndrome?
In 1942, Harry Klinefelter described the syndrome as seminiferous tubule dysgenesis, but when he published a scientific paper about it, the syndrome was named after him. Klinefelter syndrome, also known as the XXY condition, is a term used to describe males who have an extra X chromosome in most of their cells. About one of every 500 males has an extra X chromosome, but many don't have any symptoms.
How is Klinefelter Syndrome Recognised?
Klinefelter Syndrome is NOT hereditary and the most common form of KS (XXY) is diagnosed in 1 in 500 - 1000 males. The chances of a baby having this syndrome is not affected by the age of the mother or father. People with this condition have the same average lifespan compared to normal males. It is caused by a replication error in meiosis stage I or II anaphase. One of the chromosomes that are meant to be separated in these phases will be stuck together and will not replicate correctly. This can be known as nondisjunction and will result in either the sperm or egg to have an extra X chromosome and when this sec cell meets a 'normal' sperm or egg at conception the embryo will have what is known as a sex chromosome trisomy.
It is also useful to mention something called mosaic KS. Mosaic KS is a type of Klinefelter that occurs in only some of the body's cells because they have an extra X chromosome, and the individuals may have weaker symptoms depending on how many cells have an extra X chromosome.
This video by Andrology Australia might give you a better understanding of XXY Syndrome:
This video by Andrology Australia might give you a better understanding of XXY Syndrome: