Klinefelter's Syndrome- XXY

Klinefelter's syndrome is a genetic or chromosomal disorder in which an individual only has 3 sex chromosomes, a set of XXY sex chromosomes.

In human beings, a normal, healthy individual has 2 sex chromosomes. A normal, healthy male has an X and a Y chromosome, for an XY pair, whereas a normal, healthy female has 2 X chromosomes, for a XX pair.

However, an individual with klinefelter's syndrome has an extra sex chromosome, so, in total, containing 3 sex chromosomes. An individual with klinefelter's syndrome is a male, since he has a Y chromosome in his sex chromosomes. However, the extra X chromosome gives this man some female traits, which would not be characteristic of a typical male. All of the issues and symptoms which accompany klinefelter's syndrome will all be discussed in this article.

Chromosomes of a Normal Healthy Individual

To show the contrast between a normal individual who has 23 pairs of chromosomes for a total of 46 chromosomes and an individual with klinefelter's syndrome who has 47 chromosomes, we will look at the karyotype of both individuals, which shows the profile of each's chromosomes.

Below is the karyotype of a normal and healthy male individual:

Normal male karyotype

The sex chromosomes are the last pair of chromosomes, for which you can see an X and a Y under the pair, signaling that there is 1 X chromosome and 1 Y chromosome, meaning the individual is male.

You can see that in a normal, healthy male individual, there are 2 sex chromosomes present, an XY set.

Klinefelter's Syndrome- XXY

However, not all males are born with an XY set of chromosomes. Some males are born with only 3 sex chromosomes, 2 X chromosomes and 1 Y chromosome, for an XXY set of sex chromosomes. In other words, they are born with an extra X chromosome.

Below is the karyotype of an individual with klinefelter's syndrome:

Klinfelter's Syndome (XXY) karyotype

You can see the extra X chromosome present in the sex chromosomes.

Symptoms of Klinefelter's Syndrome (XXY)

The symptoms that result from an individual who has klinefelter's syndrome are half-normal-sized male sex organs, testes having an absence of spermatozoa, and the male having a possible presence of gynecomastia.

  • Male Sex Organs- Even when a male is born with XXY sex chromosomes, he still has male sex organs, meaning a penis, testes, etc. However, typically with this syndrome, the sex organs are about half the sex as in a normal male.
  • Absence of Spermatozoa- Usually males with XXY are not able to produce generative sperm, so they are sterile, meaning they cannot produce generative sperm to impregnate a woman.
  • Possible Presence of Gynecomastia- Gynecomastia is enlarged breatsts in men. A man with XXY may not have very enlarged breasts but he will still have larger-than-normal breast tissue than the average normal man has.

Below is a picture of a man who has klinfelter's syndrome:

Man with Klinefelter's Syndrome (XXY syndrome)

You can see the slightly enlarged breast tissue than he has and smaller-than-normal sex organs.

Incidence of Klinefelter's Syndrome

The incidence of individuals having klinefelter's syndrome is 1 out of 1000 live births.

Related Resources

Down's Syndrome

Edward's Syndrome

Patau's Syndrome

Turner's Syndrome

Supermale- XYY Syndrome

Superfemale- XXX Syndrome

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