6 replies to this topic

[Melanie]

Is testing for the BCR ABL gene the same as testing for the Philadelphia chromosome on a fish test? I can't seem to grasp the terminology...I'm blaming brain fog. 😜

[snowbear]

No, the FISH looks at a sample of about 200 chromosomes with special staining to detect the Philadelphia chromosome.  The PCR is used to detect the BCR-ABL gene out of millions of cells.

 

Hope that helps.

[Trey]

Both PCR and FISH test for BCR-ABL, which is produced in and by the Philadelphia Chromosome.  The FISH is more accurate above CCyR, but cannot measure below CCyR, so zero FISH equals CCyR.

 

A PCR breaks apart the white blood cells then replicates only the BCR-ABL portion of the cell's DNA (RNA, actually) by growing it using heating/cooling cycles until the BCR-ABL can be measured.  Sort of like making bread rise before cooking it.  (Billie: I do NOT advocate making BCR-ABL bread, especially using telomere shortening -- this is just an illustration).

 

The FISH test leaves the WBCs intact and uses dyes to color the BCR green and the ABL red.  Only WBCs in the metaphase portion of cell division can be measured.  When a chromosome has both red and green together, it is BCR-ABL positive.  Two reds or two greens together are negative.

http://www.molecular...re/F2?highres=y

Edited by Trey, 30 October 2015 - 03:23 PM.

[tiredblood]

Both PCR and FISH test for BCR-ABL, which is produced in and by the Philadelphia Chromosome.  The FISH is more accurate above CCyR, but cannot measure below CCyR, so zero FISH equals CCyR.

 

A PCR breaks apart the white blood cells then replicates only the BCR-ABL portion of the cell's DNA (RNA, actually) by growing it using heating/cooling cycles until the BCR-ABL can be measured.  Sort of like making bread rise before cooking it.  (Billie: I do NOT advocate making BCR-ABL bread, especially using telomere shortening -- this is just an illustration).

 

The FISH test leaves the WBCs intact and uses dyes to color the BCR green and the ABL red.  Only WBCs in the metaphase portion of cell division can be measured.  When a chromosome has both red and green together, it is BCR-ABL positive.  Two reds or two greens together are negative.

http://www.molecular...re/F2?highres=y

Thanks, I've been intending to ask about this.

[Anti-Matters]

I thought one test came with tartar sauce and one didn't.

[rcase13]

Hush puppies alone is proof there is a God.

CML is proof that he is a strange God.

[Trey]

Can FISH test abnormality of chromosomes? If it can ,why is it necessary to do Bone marrow biopsy?

 

FISH for BCR-ABL (there are many other types of FISH tests) can only see that there are cells where BCR and ABL reside together.  This only happens in the Philadelphia Chromosome. 

 

A BMB shows whether there are other chromosome mutations, the health of the marrow, fibrosis, and other issues not detectable by any other means.  For instance, the only way to know that a person has a three-way translocation or to discover other types of unusual chromosome abnormalities is the BMB. And BMB is the only way to properly categorize the CML Phase at diagnosis.  It is important to know the blast count of the marrow to properly assess advanced CML Phases.

 

It makes no sense to avoid a BMB at diagnosis for such a serious disease as CML.  This is not a head cold we are talking about.

 

http://www.esciencec...7.php?aid=13128