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Understanding Klinefelter Syndrome: What it is, its Cause, Symptoms and Diagnosis – With Pictures

Updated on October 2, 2013
Principal physical symptoms observed in males with Klinefelter Syndrome
Principal physical symptoms observed in males with Klinefelter Syndrome | Source

Brief Introduction

The study of human chromosomes is now one of the most widely researched subjects in the fields of biology and health (disorders and diseases). With the aid of scientific and technological progress, scientists were able to advance complex studies and research on the human chromosomes – which are microscopic elements present at each human cell of the body. For decades of extensive research, scientists have examined chromosomal behavior and its structural pattern. It was during the late 1950’s that scientists discovered an extra chromosome in patients with a certain genetic disorder. This incidence shed a light to a new area of interest; the Chromosomal Aberration or Chromosomal Abnormality. It was discovered then that most cases of genetic disorders are caused by Chromosomal abnormality (structural or number patterns). Among of the most known genetic disorders caused by chromosomal abnormalities are Down’s syndrome (which is also known as trisomy 21), Turner syndrome and Klinefelter syndrome – which will be the central topic of discussion for this hub.

What is Chromosomal Aberration?

Chromosomal aberration refers to the disruption or to any change in the chromosomal content of a cell. The abnormality is observed either in the structural arrangement or in the number pattern (sequence) of the chromosome/s. Chromosomal aberration is the leading cause responsible for genetic disorders and also plays a great role in evolution.


In 1942, Dr. Harry Klinefelter and his colleagues at the Massachusetts General Hospital in Boston first published a written report of nine men who were observed to have a number of symptoms which was later identified as a type of genetic disorder. These symptoms include atypical enlargement of breasts, less facial and body hair, small testes and low sperm count. This condition which affects only males was later known as Klinefelter Syndrome. In 1959, it was revealed that these men had XXY genotype; an unusual occurrence as compared to genetically normal males who have an XY chromosomal makeup.

What is an Aneuploidy?

An Aneuploidy is the term used to describe the gain or loss of chromosomes/s from the genetically normal number of chromosomes found in each human cell which is 46 (44 autosomes and 2 sex chromosomes).

Klinefelter syndrome which is caused by the addition of X chromosome is one example of Aneuploidy.

How frequent does this condition occurs?

The probability of males acquiring an additional X chromosome is about 1 out of every 500 to 1000 newborn males. This condition becomes one of the most frequently occurring chromosomal aberrations; being the most common aneuploidy of sex chromosome in males. Though a large number of males acquire the condition, many of them are not observed to have developed the syndrome described by Dr. Klinefelter and his colleagues. Moreover, patients with the condition have acquired varied symptoms and/or its severity. Because of this, medical researchers prefer to use the term XXY condition or XXY syndrome and refer the men and boys with this condition as XXY males.

Did you know…

that chromosomes play a very important role in determining who we are and what we are? Yes! Chromosomes decide whether we are to be a male or a female, our skin complexion, if we are to grow with a blonde or black hair, tall or short and such. A huge job for a very tiny part in each of us!

What causes XXY condition?

Normally, we humans have 46 chromosomes found in each of our cell. Twenty-three of these chromosomes we inherit from our mother and the other half we inherit from our father. These 46 chromosomes are comprised of 44 autosomes and a pair of sex chromosomes (X and Y chromosomes). When a pair of X chromosome is formed during cell production, a female baby is born. When it’s an XY chromosome, a male baby is born.

XXY condition is caused by the addition of an extra female sex chromosome (X chromosome) to the actual diploid set of 46 chromosomes (thus, XXY). The addition brings the total number of chromosomes to 47, which is why XXY condition is also known as 47,XXY condition.

What causes the addition of an X chromosome?

The XXY condition is a type of disorder associated with Aneuploidy. This incidence of gaining or losing of chromosome/s is a result from a “nondisjunction” event during cell division. Nondisjunction occurs when chromosomes fail to separate during meiosis. When this happens, one gamete will have an extra chromosome while the other one will be lacking. Under these circumstances, the offspring produce through fertilization by a normal gamete have either an extra chromosome or a missing chromosome.

In XXY condition, nondisjunction occurs during meiosis I in male or either during meiosis II in female. A picture illustrating the nondisjunction incidence during cell division is shown below.


The first illustration shows an X chromosome retained because of a nondisjunction during meiosis I in the male. The incidence resulted to a sperm with a pair of XY chromosome. When this gamete (XY) fertilizes a normal egg (X), an XXY male offspring is conceived.

The second illustration shows an X chromosome retained during meiosis II in the female producing an XX egg. When the XX egg is fertilized by a normal sperm (Y), an XXY male offspring is also conceived.

An XXY male developing Gynecomastia (breast enlargement)
An XXY male developing Gynecomastia (breast enlargement) | Source

Symptoms and Variations

The XXY condition can/may cause problems on the physical and cognitive development of the patient. However, these symptoms are not readily apparent after birth. In fact, many of the men and boys who have the condition don’t show any symptoms. These affected individuals may not even have the slightest hint that they have the condition. Also, the symptoms observed vary from one patient to another. Even the severity of the developed symptoms varies significantly.

Principally, the XXY condition affects the physical and cognitive development of the XXY males. These effects – depending on how the people
(around the social environment) attend to the needs of the affected individual – may also have a negative impact on the social development.

Symptoms caused by XXY condition are widely observed during childhood, adolescence and adulthood stages undergo by XXY males.

XXY males also develop higher-risks of obtaining several health problems which typically affects females. These health-problems include Osteoporosis, breast cancer and autoimmune disorders (i.e. rheumatoid arthritis).

There are also reported cases of XXY condition variants. One is the so called 46,XY/47,XXY mosaic. In this variation, not all cells have the extra X chromosome. The symptoms are also milder as compared to the symptoms observed in XXY males. Another variation is the 48,XXXY condition but this condition is extremely rare (1 in 18,000 to 50,000 male births) and few reports were recorded about this. Symptoms associated with this condition are similar to XXY condition, more severe though. The severity of occurring symptoms is directly proportional to the number of extra X chromosome retained.

Quick discussion: Does the condition be inherited?

No. XXY condition can’t be passed on from family generation down to the next family generation. The only way of developing the condition is when a disjunction occurs during cell division (meiosis) as discussed above.

Can the condition be cured?

Certainly no. Like all of genetic disorders caused by chromosomal aberrations, the XXY condition can’t be cured. Chromosomal variation is irreversible or at least today the method of normalizing chromosomally variant gene/s is beyond the knowledge and ability of human race.

However symptoms caused by genetic and/or chromosomal variation/s can be treated. For XXY condition, principal symptoms can be treated by injecting testosterone (synthetic) to the affected male. Successful submission to regular schedule of testosterone injections will result to significant improvement in strength, muscular development, and growth of body and facial hair. This may also result into improvement on the psychological and social aspects of the affected male. Upon seeing the physical progress induced by the treatment, an XXY male will feel more positive about his appearance; feeling more manly and energetic. This also significantly enhances self-esteem and develops fulfilling disposition. Added result is that, an XXY male will become socially interactive and start widening his circle of friends.

Each XXY male may respond differently to the treatment, thus the observed development varies to some degree. While few individuals have not benefited, most XXY males have observed significant improvement.

A small number of cases reported few side-effects. It is highly-desirable to ask for the help and assistance of a medical specialist when one is undergoing the hormonal treatment.

How is XXY condition diagnosed?

The condition can be diagnosed during prenatal stage and adulthood. The method used during prenatal diagnosis is called amniocentesis. Through amniocentesis, fetal cells acquired from the fluid surrounding the fetus is checked for chromosomal abnormalities. Another method is called Chorionic Villus Sampling or CVS. The procedure is similar to amniocentesis except it is done during the first prenatal trimester. Performance

The diagnosis is mostly done during adulthood or at least when a person has aged. The procedure involves an analysis of the chromosomes’ karyotype (karyotyping as referred by some) observed from the drawn white blood cells (lymphocytes). The samples are then examined for any chromosomal abnormality.

There are several methods used to diagnose XXY condition, but the two most common are the methods discussed above.

To shame and to ridicule XXY males is cruel and inhumane. Instead, individuals with the condition should be treated well. This goes same to all people who have certain conditions. We should realize that they are not less like us; in fact they are very much like us – humans!


Information presented in this article were viewed and checked several times to ensure consistency and reliability of facts. Organization of these facts was based on the writer’s knowledge and awareness of the topic and was essentially supplemented with deep-research personally furthered by the writer.

All information presented herein is for educational purpose only and thus, should NOT be employed for professional medical purposes.

© 2013 Lanao G


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    • kat11 profile image

      kat11 3 years ago from Illinois

      I have a young adult son that for the past 3 years have been going through hormonal placement therapy because his estrogen levels are high and testosterone is not there. Currently he is taking shots one in the stomach and one in the hip twice a month. So I understand this hub. i don't know if they have they checked for genetic defects since he has gone away to college. Hub very informative and well written. Thanks for the insight. voted up

    • light20 profile image

      Lanao G 3 years ago from Ozamiz City, Philippines

      Hi kat11

      Your welcome...and thank you...I'm glad.

      I hope your son is doing well...

      Have a good day Kat.

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