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Clarification in Karyotyping Result
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Clarification in Karyotyping Result

My Four months old baby had undergone Karyotyping Test and got this result 46,XY/47,XY+21. What does this result mean.
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1227139_tn?1367231533
The 46, XY means 46 typical chromosomes and XY means a male.  The 47, XY +21 means that the baby has an extra chromosome, (the 47) and is male with the extra chromosome being the 21st choromsome; - meaning Down syndrome.

The thing is, usually in Karyotyping for Down syndrome, it just says 47 XY +21.  I am not sure why they also put the 46 XY.  Unless the karyotype suggests that the child has Mosaic Down syndrome, meaning not all the cells have the 47 XY +21.  Usually the report would say the form of Down sydnrome was Mosaic though. instead of only using what you gave me in the description.  In Mosaic Down syndrome, not all cells are affected with the extra chromosome.  Some have 46 and some have 47.  I think you need to get complete clarification, but this karyotype that you are giving me does indicate that there are cells that have 47 chromosomes with the extra being the 21st.

Did you suspect that your child had a chromosomal abnormality?  I was wondering if you knew that your child had Down syndrome, or the genetisicts thought so, and thus the test was ordered.

If you need more clarification regarding the difference between Non-disjunction Trisomy 21 (the regular most common type of Down syndrome) and the Mosaic Form of Down syndrome, please message me directly.

Often children who have the Mosaic form, (only 2-3% of all cases of Down syndrome) are less affected by the extra genetic material.  The characteristics often tend to be less noticeable.  There is a dispute with doctors as to whether or not the intellegence aspect is less affected or not.  However, there is much for you to understand if you had no idea about Down syndrome at all.  I have a very comprehensive website that I am putting together as we speak, and I have a current blog that does address the types of Down syndrome etc, at the top of the blog.  You can read about these in my reference section in the Down syndrome Group Forum, here:  http://www.medhelp.org/forums/Down-syndrome/show/749?camp=msc&personal_page_id=1186587
which includes my blog.

Please do send me a message if I can help you further.  I am a parent support guide for diagnosis of Down syndrome - appointed by the genetics department in the Rouge Valley Heath System Hospital here in Toronto.  

In addition to anything I have mentioned, please keep in mind, that while I or others may have extensive knowledge in many areas, you should always seek professional medical advice from your own physician, as it pertains to medical conditions or concerns.

Good luck, and if you have any other questions that I can help you with, please feel free to message me directly.

Sincerely,
Sandi (Dragon1973)
MedHelp Genetics Community Leader;
Children - Special Needs Community Leader;
Down syndrome Community Leader & Ds Group Forum Founder/Moderator
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419309_tn?1326506891
Sandi, you stated:
"Unless the karyotype suggests that the child has Mosaic Down syndrome, meaning not all the cells have the 47 XY +21.  Usually the report would say the form of Down sydnrome was Mosaic though..."
Indeed, the 46,XY/47,XY+21 karyotype would represent mosaicism -- just in scientific annotation.  The written interpretation would probably state such, but remember, each laboratory reports results differently, especially in other countries.  
Best regards as always. ~eureka
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1227139_tn?1367231533
Hi Eureka!

Thank you!  I inadvertently miss typed what I wanted to say.  I had meant to type, "Unless the karyotpye is suggesting that the child has Mosaic Ds" because I had originally typed I wasn't sure why the report had both, but I then realized that it was likely because the child was karyoypted as mosaic.  I wanted to let her know that I believed that the description she was asking about meant that the child has the Mosaic type of Down syndrome, and I think I was rushing far to fast to get out what I meant.  

I did send her a private message indicating the same.  What I wanted to make sure I mentioned to her is that further in the written interpretation/report it should somewhere indicate that Trisomy 21 was found in a Mosaic form, meaning that it was NOT found in all meta-phases, as it would have said if it were only 47, XY +21 such as my son's karyotype reads.

Thank you for correcting my typo.

In addition to anything I have mentioned, please keep in mind, that while I or others may have extensive knowledge in many areas, you should always seek professional medical advice from your own physician, as it pertains to medical conditions or concerns.

Good luck, and if you have any other questions that I can help you with, please feel free to message me directly.

Sincerely,
Sandi (Dragon1973)
MedHelp Genetics Community Leader;
Children - Special Needs Community Leader;
Down syndrome Community Leader & Ds Group Forum Founder/Moderator
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419309_tn?1326506891
The typo led me to misunderstand what you meant to say, and I'm glad you were able to clarify things individually.  With best wishes. ~eureka
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Ladies, you may have missed the most simple answer off all! Twins!!!!! Two different samples were found & typed. One was 46XY, the other was 47XY+21!!
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There are instances of one person with two different dna sequences where for instance a twin was absorbed.
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1227139_tn?1367231533
Hi 3beautifulbabies_1atrisomy18angel!

I personally don't know enough about twin absorption, and it could certainly make sense, but I would think in her case if that if that were true, they would have given her a more specific written result indicating why two results were found for one sample (her son).  I do believe though, if I recall right, it was actually the diagnosis Mosaic Trisomy 21 and that is/was how the karyotype is written where she is located - which is why we mentioned & also concluded Mosaic Ds based on that very annotation she provided.
Either way, I am very glad others were able to give their input, to help her while she was looking for answers - while awaiting the actual written explanation.

Sincerely,
Sandi (Dragon1973)
MedHelp Genetics Community Leader;
Children - Special Needs Community Leader;
Down syndrome Community Leader & Ds Group Forum Founder/Moderator;
MTHFR Group Forum Founder/Moderator;
Pregnancy: June 2011 Community Leader
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