Arrays, NGS and Epigenetics Flashcards

exam 2

1
Q

method to screen specimens for genome wide variation

A

Arrays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

identify difference between the test DNA and the control DNA

A

Comparative Genomic Hybridization array

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

velocardial facial syndrome

A

DiGeorge syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Di George is a

A

microdeletion disorder 22q11.2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

SNP array asks

A

which SNPs are present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

measure changes in gene regulation via gene expression levels

A

expression arrays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

characterize tumors; used to guide tx. based on resistance or response of tumors with similar expression patterns

A

expression arrays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

when do we use arrays?

A

used pretty often when we don’t have a clear clinical picture and can be used to identify genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

limitations of arrays (3)

A

(1) may not detect low level mosaicism
(2) only look at quantity, not location
(3) can not detect: translocations or inversion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

known translocation or inversion should be followed up with an

A

array

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

gold standard for validation of variants found in NGS

A

sanger sequencing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

sequencing:

I Kb read length

A

sanger

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

sequencing:

30-400 bp read length

A

Next generation sequencing (NGS)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

predominantly on a research basis, but is coming to clinical practice

A

WGS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

capture DNA fragments which contain exons prior to sequencing

A

Whole Exome sequencing (WES)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

sequencing for a specific list of genes associated with the clinical phenotype

A

panel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

NGS potential results: what is it and what sign is it?

Benign

A

(-)

  • does not affect gene function
  • not included in clinical report
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

NGS potential results: what is it and what sign is it?

variant of uncertain significance (VUS)

A

(?)

  • must meet threshold of evidence
  • not enough evidence to determine if change is pathogenic or benign
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

NGS potential results: what is it and what sign is it?

Pathogenic

A

(+)

  • disrupts gene function
  • potential to cause health effects
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are medically actionable genes?

A

pathogenic mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

can patients opt-out of receiving this information of secondary findings?

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

medically actionable genes are those that have

A
  • high penetrance

- established interventions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Potential results:

focused (4)

A

(1) mutations definitely related to phenotype
(2) variants possibly related to phenotype
(3) medically actionable mutations (secondary findings)
(4) carrier status for Mendelian disorders (AR or X-linked)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

limitation of NGS;

can not detect (4)

A

(1) triplet repeat expansions
(2) methylation /imprinting
(3) structural rearrangements
(4) copy number variation- not as reliable as other methods

25
True or False: WES/WGS is a "one size fits all" tests
false, it is not
26
modification of gene expression without alteration of underlying DNA sequence
epigenetics
27
Epigenetics changes (3)
(1) methylation (2) nucleosome positioning (3) Histone Modification
28
evidence for epigenetic modifications
concordance (or not) of disease between monozygotic twins
29
evidence for epigenetic modifications
concordance (or not) of disease between monozygotic twins
30
high throughout sequencing
Next Generation Sequencing
31
modification of gene expression without changing DNA sequence
Epigenetics
32
Level of resolution: 2-3 Mb
karyotype
33
Level of resolution: 120-400 kb
FISH
34
Level of resolution: 500bp
Array
35
Level of resolution: 1 bp
NGS
36
may or may not result in a change of the aa sequence
SNP
37
SNPs observed in groups =
haplotype
38
can be used for gene mapping
SNP
39
CGH array: Red=more of the patient DNA
duplication
40
CGH array: Green= more of the control
deletion
41
one thing we need to assume with SNPs
that all SNPs occur with similar frequency
42
for SNP array we should expect _____ and to have ____ copies at each position
for SNP array we should expect heterozygosity and to have two copies at each position
43
How can we determine UPD/IBD vs deletion?
Both have drop out of the AB trace and we need to see the log-ratio data
44
provide more information than CGH arrays
SNP
45
SNP arrays reports on ___________, with ___________ being more easily recognized
SNP arrays reports on amount of DNA with deletions being more easily recognized
46
SNP arrays can identify _____ of heterozygosity or _______
SNP arrays can identify loss of heterozygosity or uniparental disomy
47
with SNP arrays we can only identify _______ (meiosis 2 error) and _____can't be identified (meiosis 1 error)
with SNP arrays we can only identify isodisomy (meiosis 2 error) and heterodisomy can't be identified (meiosis 1 error)
48
why do we care about loss of heterozygosity? (4)
(1) Uniparental disomy UPD (2) Imprinting (3) consaguinity (4) autosomal recessive conditions
49
Arrays are valuable for assessing for _______ in apparently ________ rearrangements found on karyotype
Arrays are valuable for assessing for small deletions in apparently balanced rearrangements found on karyotype
50
NGS that takes into about 180,00 exons, 3% of the genome
WES
51
NGS that takes in from one to a few thousand genes
Panels
52
secondary findings
when you find something that you were not looking for
53
ACMG recomendations (3)
(1) 1 of the 59 genes (2) high penetrance (3) interventions in place
54
Potential Results: Expanded (3)
(1) mutations in genes unrelated to phenotype (2) variants in genes unrelated to phenotype (3) deleterious mutations in genes with no disease association
55
what is a variant of uncertain significance (VUS)
A change in a gene for which there is not enough information to determine its health effect
56
epigenetic modifications lead to changes in the _______ of genes
expression
57
Epigenetic modifications _____ over time and are ______
Epigenetic modifications change over time and are reversible
58
can affect the adult human methylome
early gestation changes in methylation