Turner's Syndrome- X0 (45, X)

Turner's syndrome is a genetic or chromosomal disorder in which an individual only has one sex chromosome, an X chromosome.

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 turner's syndrome lacks having a pair of sex chromosomes. The individual has only a single sex chromosome, an X chromosome. The individual with turner's syndrome is a female, as she lacks a Y chromosome to have male identity. With this chromosomal abnormality, as with all genetic ones, the woman will have many developmental issues in life, which will 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 turner's syndrome who only has 45 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 female individual:

Normal, healthy female karyotype

The sex chromosomes are the last pair of chromosomes, for which you can see an X under the pair, signaling that both sex chromosomes are X, meaning the individual is female.

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

Turner's Syndrome- X0 (45,X)

However, not all females are born with an XX set of chromosomes. Some females are born with only 1 sex chromosome, an X chromosome, for an X0 set of sex chromosomes. In other words, they are born missing a sex chromosome.

Turner's syndrome is also referred to as X0, because instead of there being another sex chromosome present, a X for a healthy female individual or a Y for a male individual, there is none. So the pair is labeled as X0. Turner's syndrome is also referred to as 45,X, because a normal, healthy individual has 46 chromosomes, 44 autosomes and 2 sex chromosomes. However, a person with turner's syndrome has only 45 chromosomes, with the sex chromosome being an X chromsome.

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

Turner's Syndrome (XO or  45,X) Karyotype

You can see the missing X chromosome in the sex chromosomes, without any chromosome to complement it.

Symptoms of Turner's Syndrome

The symptoms that result from an individual who has turner's syndrome are sexual infantilism, short stature, and webbing of the neck.

  • Sexual infantilism- Sexual infantilism refers to a woman having sexual immaturity, meaning she is not able to develop fully secondary sexual characteristics, such as enlarged breasts, which are characteristic and distinguished traits for females.
  • Short Stature- Apart from sexual immaturity, individuals with turner's syndrome also have stunted physical growth and normally have short stature.
  • Webbing of the Neck- A webbed neck is one in which congenital skin folds run along the sides of the neck and down to the shoulders. It can be very severe or mild.

Below is a picture of a woman who has turner's syndrome:

Woman with turner's syndrome

You can see her webbed neck (mild) and lack of developed breasts. She is also of short stature.

Incidence of Turner's Syndrome

The incidence of individuals having turner's syndrome is 1 out of 10,000 live births.

Related Resources

Down's Syndrome

Edward's Syndrome

Patau's Syndrome

Klinefelter's Syndrome

Supermale- XYY Syndrome

Superfemale- XXX Syndrome

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