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Klinefelter Syndrome: Men and the Extra X

By HERWriter Guide
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Klinefelter Syndrome is something many women (and men) don't know about and they should -- if having children with their spouse is important to them, if they have a son, and to understand why diagnosis is important for a variety of reasons.

Men are born with an X chromosome from their mothers and a Y chromosome from their fathers. Those born with KS inherit an extra X chromosome from their mothers so instead of being a normal XY male, they are an XXY male.

KS is sometimes called 47 XXY since people normally have 46 chromosomes and are XY only.

There's no way to avoid having a child with this syndrome as there does not appear to be a genetic link. However, older mothers (over the age of 35) are more likely to have a son with this syndrome.

Many men with this syndrome (about one in every one thousand men are born with it) don't have any symptoms at all but those that do tend to adopt physical traits seen in females. This includes breast development (and an increased risk for breast cancer), wider hips, less body hair and smaller than average male genitals.

Another aspect of KS that is often seen is learning disabilities and difficulties with socialization as well as lowered sex drive or possible sexual dysfunction.

KS can also cause infertility in males and is one of the leading causes of infertility in males. For some men, a diagnosis only comes when they cannot have children and are tested for infertility.

Other ways to diagnose are:

Taking a test called a karyotype. In the case of KS, there are usually 47 chromosomes rather than the normal 46.

Many men with XXY do not know they have the condition. The diagnosis may be found:

• When amniocentesis is done
• In babies— undescended testes or very small penis
• In children—when the child is having problems learning
• In adolescents—when the child has excessive breast development

There are various treatments for males with KS. The main one is testosterone shots that increase "maleness" in men with KS, including increased strength, body hair and sexual performance. Men with KS can also receive speech and language therapy.

Add a Comment3 Comments

The symptoms of disease you have listed here are derived from every possible karyotype that has been associated with Klinefelter's syndrome, but since the vast majority of males with KS are likely to have the 47XXY karyotype, which occurs between 1:500 to 1:1000 live male births, then those symptoms of disease ought to be given greater emphasis as they're the ones most likely to be seen.

The vast majority of XXY males are not diagnosed at all, whereas those with more the 1 additional X are very likely to be diagnosed, in comparison to XXY's as they have much more obvious symptoms, such as mental subnormality, or much more severe learning difficulties.

I recommend this page for New Zealanders to visit as even though the booklet presented was originally written by the American's (thank you very much) this version has specific to New Zealand education information. The site has also been designed for smartphone access.

August 11, 2013 - 6:45pm
EmpowHER Guest

Seminiferous tubule dysgenesis is the only cause of Klinefelter's syndrome, as the word 'syndrome' means 'a collection of symptoms indicative of disease' there has to be a disease that causes it, stands to reason, if you think about it?

XXY foetuses, infants, children before puberty can't have Klinefelter's syndrome as the testes are not diseased until after the onset of puberty in males with some degree of additional X genetic material, in their testes. It is quite conceivable that a male with the additional X in his white blood cells, has none in his testes, therefore he will not develop the symptoms of the disease, as he won't have the disease.

It is just laziness of the medical professions to say all XXY males at whatever stage of life have Klinefelter's syndrome.
XXY and Klinefelter's syndrome are not the same thing.

Such as what symptoms of disease are XXX females known by? What symptoms of disease are XYY males known by? What symptoms of disease are Fragile X people known by? The answer is NONE for ALL. It is simply because symptoms of disease were described before the karyotype was discovered that the symptoms of disease became the primary focus.

I encourage people to think KARYOTYPE not SYMPTOMS of DISEASE when considering actions regarding results of prenatal testing for XXY

August 11, 2013 - 6:10pm

Thank you for publishing this. Awareness about these conditions is very low, especially considering that they affect 1 in 500 individuals.

The information is generally correct, but there is one important error. The extra X chromosome can come from either the father or the mother. Another important point is that 47,XXY is the condition and Klinefelter Syndrome is a suite of symptoms and comorbid conditions that often, but not always, accompany XXY. These variations are formally known as sex chromosome aneuploidy. Other variations include 47,XYY, Trisomy X and a broad spectrum of other variations including mosaics.

AAKSIS is an excellent resource. We have partnered with them for our annual conference for the past three years. You should know that KS&A is the world's oldest and largest organization dedicated to X and Y chromosome variations, including 47,XXY.

Jim Moore
Executive Director
P.O. Box 461047
Aurora, CO 80046-1047
Toll-Free Helpline: 888-999-9428 (Denver/International: 303-400-9040)

February 7, 2012 - 6:55pm
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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.

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