Microdeletions and Genomic Imbalance Flashcards Preview

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Flashcards in Microdeletions and Genomic Imbalance Deck (21)
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1
Q

What is Wolf-Hirschhorn Karyotype and what chromosomes does it involve?

A

caused by terminal deletion of chromosome 4p

2
Q

What is the critical region?

A

deletion of a particular chromosome segment that is related with a specific abnormal phenotype

3
Q

What is contiguous gene syndrome?

A

??

4
Q

What is segmental aneuploidy syndrome?

A

??

5
Q

What is microdeletion syndrome?

A

chromosome deletions (partial monosomies) that cause genetic abnormalities

6
Q

What is pathogenic CNV?

A

copy number variation that can cause abnormal phenotypes

7
Q

What is DNA dosage gain or loss?

A

??

8
Q

Are telomeres commonly affected by microdeletions?

A

yes. they are often the target of microdeletions.

9
Q

What is Prader-Willi syndrome?

A

interstitial deletion encompassing on the proximal 15q arm. 15q12 is deleted. Causes hypotonia in infancy, childhood hyperphagia and obesity, mental retardation.

10
Q

Describe normal crossing over.

A

exchange between homologous chromosomes with perfect alignment and equal exchange.

11
Q

What are low copy repeats (LCRs)?

A

small segments of DNA in a chromosome that are highly homologous and repeated. They have greater potential to misalign and cause genetic replication errors.

12
Q

What is FISH? What is a limitation of it?

A

fluorescence in situ hybridization is a technique to detect absence or presence of specific chromosome segments using fluorescent probes.
Limited because it only tests for absence of one small segment. If test is negative, you only know that there was nothing wrong with that segment.

13
Q

What is a chromosomal microarray?

A

looks for genetic imbalances across entire genome. Doesn’t tell you anything about what the chromosomes look like though

14
Q

What color is a monosomy on a chromosomal microarray?

A

red spot for loss (the control chromosomal set is red so it binds more than the missing, green unknown with the monosomy)

15
Q

What color is a trisomy in a chromosomal microarray?

A

green spot for gain

16
Q

What color is a normal chromosome pair on a chromosome microarray?

A

yellow for no change

17
Q

Will a microarray detect a balanced chromosome rearrangement?

A

No. It only detects imbalances

18
Q

Will arrays pick up triploidy?

A

No. Even though this is a huge imbalance, the chromosomes are the same size and do not show up as imbalanced.

19
Q

Which is usually more severe: monosomy or trisomy?

A

monosomy. Trisomy you have all the necessary genes, just too much of them. Monosomy you are missing things

20
Q

Which is generally more severe: microdeletion or microduplication?

A

microdeletions are generally more severe because you are missing material instead of having too much

21
Q

Do older mothers have a higher risk of microdeletions in offsrping?

A

no. The risk increases for nondisjunction