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An idiot's guide to cytogenetic abnormalities.

Posted Sep 19 2013 12:00am
This will be a curious post in some ways, because it will provide partial answers and half-truths.  Not in the sense that I'm keeping anything or being intentionally misleading, but in the sense that my understanding is not fully formed.

In keeping with the philosophy of this blog, I report things as they occur, to record my understanding of events as they happen.  Other blogs will fully research something and present it in a way that is clinically correct, but may be less penetrable and will be less personal.

So the upshot of this is to give you a glimpse into a complex topic in a way that reflects my own limited understanding at this time.  It can be seen (I hope, anyhow!) as an invitation to other MM patients to learn more about their own condition -- and also as a platform for correction and further illumination.

So without further ado...

Cytogenetic abnormalities refer to tweaked (highly clinical word there) chromosomes within one's cells (in this case, myelomic plasma cells).   A normal cell has 46 chromosomes (23 "diploids" which consist of 23 from the mother and 23 from the father).

The severity of one's Myeloma can be impacted by both the number of cytogenetic abnormalities, and the type of cytogenetic abnormalities.  Typically, these abnormalities take the place of either an extra copy of a chromosome (which results in a "hyperdiploid" -- too many chromosomes -- characteristic to the cell), the deletion of a chromosome ("hypodiploid"), or a translocation of chromosome pairs (like let's say the 4th chromosome of one pair has gone off and paired up with the 14th chromosome of another pair and vice-versa, resulting in what's called translocation (4;14).

Some of the more well-known cytogenetic abormalities include del 13 (deletion of the 13th chromosome, which used to be perceived as a high-risk trait), del 17 (which remains a high-risk trait), translocation (4;14) as noted (formerly high-risk but responsive to Velcade), etc.  Additionally, a "hyperdiploid" diagnosis (too many chromosomes) is generally a better factor than a "hypodiploid" diagnosis.  I have no idea why this is -- others may be able to inform.  Particularly SuzieRose who again knows more about this stuff than any other patient I've encountered.

I was aware that I was hyperdiploid, but didn't ever really know the extent of my cytogenetic abnormalities.  How many did I have?  They are "nearly universal" in Myeloma cells -- in fact I'm not sure how one could have Myeloma without any.

At any rate, when I was last in Arkansas, I dug through my file and took a photo of the result of the marrow analysis that was done at "baseline" -- before treatment started.

Here's what it looks like.

54,XY,+2,der(2)t(2;2)(p11.1;q21),der(2;3)(p10;q10),+3,der(4)t(1;4)(q12;p16),+5,+6,+9,+11,+15,+18,+19[cp22]/46,XY[cp8]

Yikes!  It's a miracle I wasn't staggering into the emergency room with smoke pouring out of my butt with that much wrong with me.

(pause for laughter...thank you, thank you)

I refer back to part of BB's recent dictation when he commented, in reference to my current (normal) marrow, "flow cytometry [the test through which this is assessed] was negative, and originally had shown rather profound hyperdiploid lambda light chain restricted disease."

By "rather profound" he probably means that's a long string of gobbeldygook up above, versus a short string.

I recognized only a few things in here, and I was able to determine a few things on my own, but to really make sense of this without calling a microbiologist, I reached out to SuzieRose to see if she could help decipher it.  She was kind enough to invest some time in doing so, noting that every lab reports this stuff differently.

My sole contributions to the deciphering were (1) to note that the "cp" refers to "cell population."  By looking at the two numbers, there were 30 cells analyzed, of which 22 had all the crap wrong with them that is delineated, and 8 of them were nice, pretty, 46 chromosome cells that had their act together; and (2) that the 54 referred to the number of chromosomes, so I had 8 extra copies somewhere versus a normal cell.

As a quick aside, subsequent bone marrow analyses show that after one cycle of VDT-PACE, in a 20 cell sample, I had 3 goofy looking ones exactly like the ones above, and 17 normal ones.  After my first transplant, I had only normal ones.

So, to the goofiness.

Of the 22 messed up cells, here's how SuzieRose helped me decipher it.

* When there are translocations, they leave a piece of the chromosome behind at the site of the translocation.  This is said to be a "derivative" of the chromosome that was translocated and is appreviated "der".  So in my case, I had a derivative of chromosome 2, and a derivative of chromosome 4

* Whey they catalogue the chromosome changes they pinpoint them to a specific "address" on the cell, and in this case the changes occurred at 2p11.1 and 2q21, as well as 2p10 and 3q10.   I also had a translocation of chromosomes 1 and 4 that occurred at 1q12 and 4p16, respectively.

I don't know what p and q refer to -- perhaps they are the two strings where the pairs of chromosomes are supposed to align?  I don't know.  I suppose I haven't...wait for it...been minding my P's and Q's.

(pause for groan...these are the jokes, people -- they can't all be gems).

I continue.

I gather that the first marker in a pair is the "long arm" and the second is the "short arm."  So Suzierose said I have a translocation of chromosome 2 on the long arm of p at band 11.1 and on the short arm of q at band 21.

All those plusses refer to trisomies -- an extra copy of the chromosome.  I had nine of them, of chromosomes 2, 3, 5, 6, 9, 11, 15, 18 and 19.

What does all this mean?

Not much, to me, anyhow.

UAMS uses more advanced genetic analysis to determine risk characteristics of Myeloma.  So this is interesting information insofar as it shows how mangled my marrow was and shows the impact of therapy (significant reduction after one cycle of induction) -- and if there were any high-risk signs (for example, del 17p, del 1p, gain 1q) it would be valuable to know.  But in Arkansas, the real value is from the gene array that draws upon thousands of marrow samples and can assign risk based on a profile of characteristics from studying 80 different genes.

Maybe I'll take a picture of my gene array analysis next time and try to figure that one out!  : )

Special thanks again to SuzieRose -- or maybe I should call her SuzieRosettaStone.  : )
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