Flashcards in Lecture 24-Molecular Cytogenetics Deck (25):
How did FISH improve clinical cytogenetic diagnoses?
- it allowed cytogenetic diagnoses to be made irregardless of whether or not the cell is in metaphase
- this is good because looking at cells in interphase can allow you to look at both the morphologic changes as well as genetic changes in the cell
CGH is important for measuring what?
chromosomal gains, losses and aneuploidy
What's a constitutional abnormality?
- a chromosomal abnormality resulting in a birth defect
What's an acquired abnormality?
- a chromosomal abnormality usually associated with cancer
FISH can detect _______ syndromes to up to what resolution (i.e., how many bps)?
- ~1 Mb--higher resolution than G banding
Name the cytogenetic diagnostic techniques from greatest to smallest resolution.
- CGH: individual bases
- FISH: ~1 Mb resolution
- have the highest concentration of genes out of all chromosome regions so deletions/duplications here have significant phenotypic effects.
Telomeric rearrangements cannot be seen by _______. Why?
- all telomeres have similar G-band light regions
Subtelomeric rearrangements not visible by G-banding have been found in 4-9% of individuals who________
have idiopathic mental retardation.
Can FISH give info about fixed cells?
Because FISH doesn't require dividing cells (like G banding) it can be used to detect chromosomal abnormalities in people who _______ (2).
- are on chemotherapy
- post bone marrow transplant
In interphase FISH analyses the probes target _______ of what chromosomes?
- 13, 18, 21, X, Y to look for trisomies
What other uses are there for interphase FISH analysis?
- when being used on uncultured amniotic cells and time is an issue
- fixed cells (tumor evaluation)
- low mitotic index samples (patients on chemo, post bm transplant)
Chromosome analysis is used in cancer to look for _______.
- recurrent chromosome abnormalities (abnormal clone)
What can be a prognostic indicator of leukemia? What would indicate a poor prognosis?
- acquisition of additional karyotypic abnormalities after diagnosis signaling evolution
What is a "masked" translocation in CML?
- when its a microscopic translocation. This is seen in 5% of CML patients
Can you have CML without some combination of bcr and abl?
CML has what translocation?
What is an inhibitor of bcr-abl?
- gleevac: an inhibitor of the abl tyr kinase
Which has higher resolution FISH or whole chromosome painting?
When do you use whole chromosome painting?
- when theres a marker chromosome and you don't know which chromosome its from so you don't know what sequences to probe for
What is a marker chromosome?
- a small chunk of chromosome that has unknown origin usually, but you can use chromosome painting to figure it out
What population are chromosome markers more common in?
- 10X more common in "mentally subnormal"
If a marker is not inherited and is an autosomal ring ______.
- there is a 30% chance of abnormalities