Thursday, 28 April 2011

X is for X syndromes

You know most women have two X-chromosomes. Well, some women are born with XXX (3 X chromosomes), XXXX (4X) or even XXXXX (5X).

There are approximately 60 known females worldwide with this rare condition, although it is believed that there are probably many more who are undiagnosed.

More information about pentasomy X or 49,XXXXX:

Physical traits

XXXXX syndrome is associated with microcephaly (undersized skull), micrognathia (undersized jaw), and round face. The ears are generally low-set and malformed. Eyes are upslanting and show palpebral fissures, hypertelorism, and strabismus. Usually the nose is shaped with a broad and depressed nasal bridge and epicanthus, with the mouth having a cleft and highly arched palate, dental abnormalities, and thick, furrowed, and everted lips. The neck is webbed, much like the neck of a woman with Turner's syndrome.

Growth and development

XXXXX syndrome causes mental, growth, and motor retardation. There is occasional delayed puberty. Recent observations have indicated an average of a 10 to 15 IQ point decrease for each extra X chromosome. Thus, the average IQ of XXXXX individuals tends to be between 55 and 70.


Sources: http://www.genealogysource.com/tetra_x/information.htm
http://en.wikipedia.org/wiki/49,_XXXXX

18 comments:

  1. Wow. How sad for these poor woman.

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  2. Clarissa - I didn't know about this - thanks :-). I always learn from your blog.

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  3. It's interesting that every x drops the IQ by 10.

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  4. I had no idea about this condition. Great post.

    Jai

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  5. Hadn't heard about this x syndrome before.

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  6. How awful! :-(

    I hope these poor women are ok and have good happy lives. Take care
    x

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  7. Never knew anything like this existed. Interesting and sad all at the same time.

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  8. Wow. I--like many other readers--have never heard of this. It's so sad to think of something like this existing.

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  9. I didn't know there was such a condition. Wow. It's interesting it affects the IQ.

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  10. Recent observations have indicated an average of a 10 to 15 IQ point decrease for each extra X chromosome

    What does this say about the intelligence of the XY individual?

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  11. WOW! You certainly thought of something to write about - and you taught me something new! I had never heard of this condition before.

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  12. This is very sad for those women. I didn't know about it. There is X-Syndrome, isn't there, where the tendency is to put on weight. Most of us seem to have this one!

    Denise<3

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  13. Oh dear! It sound awful.

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  14. I love your blog, quite busy trying to find all participating in the challenge.

    So glad I have only a couple xtra 'x's, I think they are in my head.

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  15. I'd heard of XXX, but never XXXX or XXXXX. I really amazes me how many things can go wrong in human development, and yet, how rarely it actually does.

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  16. I'd never heard of such a thing!

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