I was told at diagnosis that I was Trisomy 12 by FISH. Does that mean there was a certain percentage and that the remaining percentages

[keepfit123]

i.e.to total 100, are made up of 11q, 17p and normal?

[HAIRBEAR_UK Founder Admin]

Hi Keepfit

I am sure others with greater research knowledge and clinical experience will chime in.

My understanding is If a particular kareotype was identified using a FISH test it is possible that there may be different aberrations that the test did not pick up as it only focuses on the few commonly recognised loci. if it did not identify the targeted loci of 17p and 11q mutations then they are most probably not part of your current CLL picture.

Normal Kareotype does not mean normal as we have CLL/SLL so often people get a FISH test result saying normal. This means that the test could not identify the specific mutation/s that are attributable to that particular CLL/SLL case because they are present at other loci..

The future will employ greater use wider array testing and genome studies as part of the diagnostic work up and will identify a greater number of clone types or mutations that make up an individuals CLL/SLL profile. Chris posted fairly recently about this:

There is much discussion within the clinical scientific community about the diversity of clones and differing mutations that make up an individuals profile and the significance of the homeostasis created by this population. New ones are being discovered with increasing frequency but their action is not yet understood.

I understand it is fair to say that at one moment in time the 100% that makes up your population of B- lympmocytes is made up of the known trisomy 12 discovered by FISH testing and as well as unknown mutations and the healthy unmutated cells?

I am a fellow trisomy 12 and what else I don't know. But bear in mind that CLL evolves with and without treatment. that is why we are retested at treatment . Trisomy 12 is considered of intermediate prognostic value and new mutations within the group have helped narrow down this further. NOTCH one being one of these.

Dr Sharman recently discussed this in his blog:

Under CLL biology - stereotyping - CLL Prognosis Markers Defined - CLL Prognosis - : cll-nhl.com/search/label/CL...

Trisomy 12 in CLL / Notch Mutations: cll-nhl.com/2012/08/trisomy...

I hope this is of some help.

Nick

[AussieNeil Administrator]

It helps if you realise that FISH (Fluorescence In Situ Hybridisation) testing is a method of testing for specific genetic markers that have been previously been identified as being of value in prognostic testing and for assessing whether certain treatments will be effective. See:

genome.gov/10000206

Which markers are checked for depends on the FISH probe set used (basically specific fluorescing complementary molecules that attach to the sought after gene). Then it is a 'simple' matter of measuring the relative fluorescence.

Have a look at all the different FISH tests Mayo Clinic can provide:

mayomedicallaboratories.com...

If you click on the tab "Clinical and Interpretive" you'll see more information about the cut off points for the different abnormalities (outside of the normal reference range) including Trisomy 12 in the Interpretive paragraph.

Without knowing what specific probe set was used, it's a bit like saying you had a blood test - but for what?

If you don't already have a copy of your FISH test report, ask for it. It should state what probe set was used, which includes a list of the genetic markers tested.

(I only know this because I recently decoded my results after having them for 4 years. Even then I needed Chris's help to make sense of it.)

Neil

[Cllcanada Top Poster CURE Hero]

Thanks Neil! Yup on most FISH tests only 200 B-cells are looked at ...for Trisomy 12 the tipping point is > 1.5% of those 200 cells, according to the Mayo labs, that Neil noted.

Tiny numbers ... nothing to do with millions of white blood cell count (WBC) produced everyday... but for us... they really matter.

~chris