Klinefelter Syndrome and 47,XXY – Same or Different?

September 20, 2018 / Comments (7)


There are frequent discussions in Facebook groups regarding the question on whether KS and XXY represent the same or different conditions. AXYS has had the opportunity to discuss this with several physicians and research scientists that are considered experts in the field and would like to share their information below:

Dr. Harry Klinefelter was a physician and endocrinologist at Massachusetts General Hospital who originally described a syndrome in 1942 that was based on 9 patient case histories and examinations. The primary common characteristics he found in this group included small testes, sterility, increased FSH levels and gynecomastia. He wrote a paper titled, “Syndrome Characterized by Gynecomastia, Aspermatogenesis without A-Leydigism, and Increased Excretion of Follicle-Stimulating Hormone”. The term Klinefelter Syndrome was later adopted to describe these clinical characteristics. Chromosome technology was not yet available so genetic profiles were not part of the original syndrome.

By the late 1950’s, chromosome technology had improved and it was determined that individuals with KS characteristics frequently had a genetic signature of 47,XXY. It was also recognized there were 47,XXY individuals that sometimes had other common characteristics outside of the typical clinical presentation of tall stature, small testes, sterility and increased FSH levels. This included blood disorders, osteoporosis, anxiety and depression, speech and learning disorders, etc. In addition, there was a wide range of body shapes and sizes.

The term KS was in common use in the medical literature by this time, so scientists simply expanded their definition of KS to include the new characteristics and phenotypes that were found to be associated with the genetic signature of 47,XXY. They did not limit the use of the KS term to just identify individuals that demonstrated the original classic endocrinology characteristics…..they applied the term to anyone that was determined to have a 47,XXY signature.

Dr Klinefelter published a second paper in 1986 that briefly discussed this issue of chromosome analysis and genetic signatures. He suggested all 47,XXY individuals should actually be identified as having Klinefelter’s disease which would help distinguish them from other people that have the endocrinology characteristics of KS but do not have a genetic signature of 47,XXY. He was very much aware by then that 47,XXY individuals had a wide range of phenotypes (physical and clinical characteristics) and felt it was appropriate to use the term KS or 47,XXY to describe these individuals, regardless of the exact clinical characteristics they expressed. The one constant in all of these individuals was their genetic signature of 47,XXY.
His suggestion was never adopted so the medical profession has continued to use the KS and XXY terms equally. Some non-medical people would prefer to use these terms differently, but this is not how it is recognized by the medical or research communities…..KS and 47,XXY remain synonymous.

Written by Gary Glissman (AXYS USA)

7 Responses to :
Klinefelter Syndrome and 47,XXY – Same or Different?

  1. Free Stuff says:

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  2. Graeme Tucker says:

    Dr Arthur Robinson in Understanding Klinefelter Syndrome: A Guide for XXY Males and their Families stated on page 5 “I never refer to newborn babies as having Klinefelter’s because they don’t have a syndrome” and “Presumably some of them will grow up to develop the syndrome Dr Klinefelter described, but a lot of them won’t” and “For this reason “Klinefelter syndrome” has fallen out of favour with medical researchers. Most prefer to describe men and boys having the extra chromosome as “XXY Males.”

    So as XXY males aren’t born with a syndrome, when does it develop, and I can tell you, I got my information from the medical textbook my Endocrinologist used for most of the time he treated me for, until it was updated, “Williams Textbook of Endocrinology 8th Edition” page 879 under the title Seminiferous Tubule Dysgenesis <—- the name of the disease we're treated for, of which Klinefelters syndrome is the symptoms of: "The characteristic feature which first become manifest in adolescence……" there you have it, KS develops after the onset of puberty.

    Klinefelters syndrome is hypogonadism and is easily fixed, XXY is everything else and not so easily alleviated. Also a great many karyotypes can bring about KS even merely a repeat sequence of X genes on the one and only X an XY man has. I know such a man, officially diagnosed with KS.

    It is wrong to refer to the prenatally discovered as having KS, just as it is wrong to refer to all XXY and other supernumerary X males before the onset of puberty as having KS. And it's so much simpler to refer to people by their genetics rather than a disease they might never develop.

    The entire booklet in JPG format


  3. Graeme Tucker says:

    Gutted my comment disappeared, not even a statement about if it’s to be reviewed. If I don’t see it here I will be saying online how only one point of view is published here.

  4. Graeme Tucker says:

    Your writer, thank you so much, cites “Syndrome Characterized by Gynecomastia, Aspermatogenesis without A-Leydigism, and Increased Excretion of Follicle-Stimulating Hormone”

    BUT failed to tell the TRUTH, this is the opening line of the abstract:

    “THE SYNDROME under discussion begins during adolescence ”

    End of story.

  5. Graeme Tucker says:

    This might get you thinking?

  6. Graeme Tucker says:

    This comment is not true “they applied the term to anyone that was determined to have a 47,XXY signature. ”

    In reality anybody with any degree of additional X genetic material was assigned the title “Klinefelters syndrome” regardless of symptoms or age. So males with severe educational issues who were XXYY or XXXY or XXXXY or XXXXXY were all said to have KS, and I believe many XXY foetuses were aborted as a result.

    Not all the medical profession uses XXY and KS interchangeably, but the source of your information either doesn’t know that, or chooses to ignore it?

  7. Graeme Tucker says:

    This is the only way I can communicate with you people, you know that? Well you’re going to have to decide, you want my money or you don’t want my money, if you don’t want my money give it back, it’s no big deal, no skin off my nose. Obviously you don’t want to post my incredible opinion, you’ve had plenty of time to read it and see there are excellent reasons for me to have it, but you only want the approved opinion here, I can see the last thing you want is anything that challenges what you want to promote, regardless of how wrong you know you are. You don’t want to rock the boat, it might sink! How come the second article by Dr Klinefelter is not named here, did the author forget some XXY men can actually read? Did he never expect to be challenged to produce the name of it, or provide a link to its whereabouts?

    Oh and it would be very nice if when I press “post comment” that I got a notification like “Your comment is unwanted, we only ask to make ourselves look reasonable, otherwise we’re not interested.” Or words to that effect. Just so the writer can know he’s not completely wasting his time.

    Nanu nanu, live long and prosper, may the force be with you.

    Graeme Tucker,

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