[Maryhosier]

FISH results - positive for MAF deletion?

by Maryhosier on Wed May 06, 2015 10:38 am

I just received results of my bone marrow biopsy (BMB). It showed 10% plasma cells, and FISH results were positive for MAF deletion and 13Q deletion.

I know what 13Q is but don't understand MAF. Can anyone give me help with this?

Thanks. Mary

[TerryH]

Re: FISH results - positive for MAF deletion?

by TerryH on Wed May 06, 2015 3:38 pm

Hello Mary,

You generally have to dig through the details of a FISH report to know for certain what is meant by the results. However, my guess based on what you've written is that a "MAF deletion" is another way of saying deletion(16q), or "del(16q)".

I say this partly based on what you'll find in this journal article,

MW Jenner et al, "Gene mapping and expression analysis of 16q loss of heterozygosity identifies WWOX and CYLD as being important in determining clinical outcome in multiple myeloma," Blood, Nov 1 2007 (full text of article [PDF])

where the authors state that "del(16q) was deduced from loss of the MAF part of the Abbott IgH/MAF probe combination".

The IGH/MAF probe is used in FISH studies to test for the presence of the t(14;16) chromo­somal abnormality.

There is some research that suggests that del(16q) is a higher-risk chromosomal abnormality, but I don't think that is really a settled issue. The article I listed above says that the authors found the abnormality in about 20 percent of newly diagnosed myeloma patients.

Hope this helps a bit.

[Dr. Ken Shain]

Re: FISH results - positive for MAF deletion?

by Dr. Ken Shain on Thu May 07, 2015 8:47 pm

I think that TerryH has summed up the data story quite well.

Really, the bottom line is that the MAF deletion – del(16q) – has been shown to correlate with poorer outcomes in newly diagnosed patients (see the paper TerryH mentioned). However:

1. This has not been confirmed;
2. del(16q) is not a component of our molecular risk stratification systems or International Myeloma Working Group (IMWG) risk assessment; and
3. We do not know if it the associated molecular events are contributing on their own to outcomes in the patients studied. The Jenner et al paper mentioned above, for example, showed that del(16q) appears at the same time as a number of other molecular features, including high risk del(17p) and aneuploidy (decreased number of chromosomes).

As such, today I keep an eye out for it, but do not change therapy because of it, by itself.

Best of luck and keep us updated on your course.