Klinefelter's Syndrome
Association UK

Charity Number 1058319 (Keywords: XXY, 47XXY Klinefelter)

An Introduction to KS from one of our Members

Although Klinefelter's Syndrome (47-XXY, 48-XXXY, 49-XXXXY, 48-XXYY and mosaic combinations) is probably one of the most common chromosomal variations it is not well known to the general public or even, in many cases, to the medical profession. This is because the majority of affected males live their lives without being aware that they have an extra chromosome. They probably lead as happy, or unhappy, successful, or unsuccessful, lives as the rest of us. Unlike Down's Syndrome and even Fragile X Syndrome there are often no very obvious physical or psychological effects.

The four most likely times for diagnosis are :-

(1) During pregnancy if routine screening is carried out for Down's Syndrome etc. the extra chromosome would be discovered.

(2) Pre-school if the child has a language delay or disorder.

(3) During schooling if the youngster is having difficulties either socially or academically.

(4) In Adulthood as a result of fertility investigations.

As the rate of diagnosis is very low this suggests that the majority of males do not experience problems of sufficient severity to warrant them seeking help or advice.

As the youngsters whose parents join the KSA are often those who are more affected we probably get a biased view. The adult male members are a more balanced selection as very many of them will have been identified only by fertility tests. There are very successful businessmen running their own companies, computer experts, doctors and managers - and those are just a few whom I know!

Often the only common factors are that the men have an extra chromosome and will have undeveloped testes and hence be infertile - [unless they have a mosaic (46XY, 47XXY)] they may be taller than average, but not usually excessively, they may have less body hair than average, but not necessarily, they may have a more "female" weight distribution, but if they enjoy sport and exercise they may not. KS males are like the rest of the population. No two are the same. Some are clever, some are not. Some are musical, some are not. Many are more sensitive and perceptive, some are not - more' s the pity!

I have just read the "physical characteristics" information. Read on, but remember your best friend, your physics teacher or even your milkman may also have an extra X or two.

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The Scientific Background in Brief

In 1942 Dr Harry Klinefelter and his co-workers published a study about nine men who had enlarged breasts, sparse facial & body hair & small, firm, infertile testes. (See HERE for information about the Klinefelter Syndrome Awareness Day on 20th March each year)

By the late 1950s other researchers discovered that men with Klinefelter's Syndrome had an extra sex chromosome giving 47XXY instead of the more usual 46XY.

Based on studies in the US in the 1970s it is clear that KS is one of the commonest genetic abnormalities known; 1 in 500 to 1 in 1000 live births.

Women usually inherit two X chromosomes; one from each parent.

Men inherit an X from their mothers and a Y from their fathers.

However the meiosis that occurs in the cells destined to become eggs & sperm occasionally gives rise to an egg with two Xs or a sperm with both an X and a Y.

There are two chances to produce an XXY male. Either an XY sperm fertilises an X egg or a Y sperm fertilises an XX egg.

There are other less common variations; for example 48XXXY or 49XXXXY. There is also a mosaic type where some body cells are 46XY

Physical characteristics

Boys with or without KS tend to look very similar, but when puberty occurs the testes remain small and this persists into adult life.

Infertility is usual & a lack of libido is likely. Some breast development is possible. A KS male may develop a pear-shaped body.

Men with KS tend to be tall but their limbs are disproportionately long compared with their bodies. Many also have big feet and obviously have problems getting clothing to fit.

Body hair may fail to appear and facial hair rarely attains the level that feelings of masculinity may desire.

Boys developing these characteristics are often teased at school and this may give rise to a boy "turning off" & exhibiting behavioural problems.

Many of these characteristics, but not the height or Infertility, may be relieved by Testosterone Replacement Therapy given from Puberty onwards. The level should be determined by GP & Endocrinologist since some KS males can make their own Testosterone to some extent.

Where insufficient Testosterone is present bone density may be reduced when the body fails to lay down sufficient calcium & this may give rise to bone disease such as Osteoporosis. For this reason all KS males should request Bone-Density Scans at least every two years.

Development

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KS Booklets

Please check out the two booklets produced by the Klinefelter's Syndrome Association Here

There is a good book of facts on the Turner's Syndrome website.  This great site has simple, yet valuable info, and reflects the good work put in by this Danish organisation.

In the past, before we had our new "Guide for..." series of booklets, we issued a booklet written by Dr SG Ratcliffe, the renown guru of KS in young people.  This booklet is reproduced here as a web page and as a printable PDF document.

Guy's & St. Thomas' Hospital (NHS) produce a short leaflet for their doctors to distribute.  Click HERE to open their download page in a new widow