Lecture 24-Molecular Cytogenetics Flashcards Preview

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Flashcards in Lecture 24-Molecular Cytogenetics Deck (25):
1

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

2

CGH is important for measuring what?

chromosomal gains, losses and aneuploidy

3

What's a constitutional abnormality?

- a chromosomal abnormality resulting in a birth defect

4

What's an acquired abnormality?

- a chromosomal abnormality usually associated with cancer

5

FISH can detect _______ syndromes to up to what resolution (i.e., how many bps)?

- microdeletion
- ~1 Mb--higher resolution than G banding

6

Name the cytogenetic diagnostic techniques from greatest to smallest resolution.

- CGH: individual bases
- FISH: ~1 Mb resolution

7

Subtelomeres

- have the highest concentration of genes out of all chromosome regions so deletions/duplications here have significant phenotypic effects.

8

Telomeric rearrangements cannot be seen by _______. Why?

- G-banding

- all telomeres have similar G-band light regions

9

Subtelomeric rearrangements not visible by G-banding have been found in 4-9% of individuals who________

have idiopathic mental retardation.

10

Can FISH give info about fixed cells?

yes

11

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

12

In interphase FISH analyses the probes target _______ of what chromosomes?

- centromeres
- 13, 18, 21, X, Y to look for trisomies

13

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)

14

Chromosome analysis is used in cancer to look for _______.

- recurrent chromosome abnormalities (abnormal clone)

15

What can be a prognostic indicator of leukemia? What would indicate a poor prognosis?

- CNVs

- acquisition of additional karyotypic abnormalities after diagnosis signaling evolution

16

What is a "masked" translocation in CML?

- when its a microscopic translocation. This is seen in 5% of CML patients

17

Can you have CML without some combination of bcr and abl?

- no

18

CML has what translocation?

9:22
NOTE: t(9:22)(q34;q11.2)

19

What is an inhibitor of bcr-abl?

- gleevac: an inhibitor of the abl tyr kinase

20

Which has higher resolution FISH or whole chromosome painting?

- FISH

21

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

22

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

23

What population are chromosome markers more common in?

- 10X more common in "mentally subnormal"

24

If a marker is not inherited and is an autosomal ring ______.

- there is a 30% chance of abnormalities

25

Give 2 examples of cancer genes that are amplified in turmors and thus, discovery of these can impact treatment.

- HER2/NEU: breast cancer
- MYCN: neuroblastoma