Deck 14: Molecular Applications in Cytogenetics

Question 1

The class of FISH probe that consists of repetitive or satellite sequences is

A)Class I.
B)Class II.
C)Class III.
D)Class IV.

Answer 1

Class I.

Question 2

When indirectly labeled probes are used in FISH, what intermediary molecule(s)are usually used on the probes?

A)Digoxigenin
B)Haptens
C)Biotin
D)All of the above

Answer 2

All of the above

Question 3

Which of the following is FALSE regarding incident light fluorescent microscopes?

A)A condenser is not necessary.
B)The light source is positioned below the specimen.
C)Two filters are required, one for the excitation wavelength and one for the emission wavelength.
D)Fluorescent signals are stronger than those viewed with transmitted light fluorescent microscopes.
E)Mercury vapor lamps are common light sources.

Answer 3

The light source is positioned below the specimen.

Question 4

The class of FISH probe best able to identify a microdeletion in a cell population is

A)Class I.
B)Class II.
C)Class III.
D)Class IV.

Question 5

Which of the following will denature target DNA in a FISH procedure?

A)70% formamide
B)73° C for 2-3 minutes
C)300 mM NaCl, 30 mM sodium citrate, pH 7.0
D)All of the above combined

Question 6

What is the function of modified Carnoy's solution (3:1 methanol: glacial acetic acid)in preparing cells for classic cytogenetic analysis?

A)Inhibit mitosis and arrest cells at metaphase.
B)Act as a fixative and promote cell adherence to a slide.
C)Lyse red blood cells and expand the volume of nucleated cells.
D)Provide proper pH and cell stabilizers for cell growth in culture.
E)Dehydrate the chromosomes.

Question 7

Whole chromosome paints consist of

A)a mixture of DNA probes to various repeated internal sequences within the chromosome.
B)a single DNA probe that spans the length of the entire intact chromosome.
C)a mixture of probes to both repetitive and unique sequences within a particular chromosome.
D)a mixture of alpha- satellite and telomere probes unique to that particular chromosome.

Question 8

Which of the following is (are)findings/theories regarding contiguous gene syndromes discussed by Lupski?

A)Microdeletions probably occur during the first mitotic stages of the fertilized egg and are thus perpetuated throughout the entire body.
B)Frequent chromosome areas of microdeletion are sandwiched between areas of high copy repeats.
C)In theory for every microdeletion identified, there should be a corresponding microduplication.
D)All of the above.

Question 9

Which of the following will cause poor probe hybridization efficiency?

A)Overdenaturing target DNA
B)Underdenaturing target DNA
C)Both A and B
D)Exposure of the slide to cold after target DNA denaturation
E)Dehydration of the slide after target DNA denaturation

Question 10

Which of the following is (are)disadvantage(s)of using directly labeled probes in FISH?

A)Less signal strength
B)Less background staining
C)Fewer steps in the procedure
D)Less nonspecific binding
E)All of the above

Question 11

Of the disorders listed below, classic cytogenetics most poorly detects

A)extra chromosomes.
B)gene rearrangements.
C)chromosome translocations.
D)chromosome deletions.

Question 12

A clinical lab scientist was performing a cytogenetic analysis, and 10 of the chromosome spreads she analyzed had 46 normal chromosomes. In the 11th spread, she noticed 47 chromosomes. What is the first thing she should do?

A)Repeat the slide preparation to exclude errors that would cause chromosome artifacts.
B)Repeat the slide preparation with a different stain.
C)Examine more chromosomes spreads using to FISH try to confirm the presence of a genetic mosaic.
D)Report a normal karyotype of 46 chromosomes.

Question 13

Which of the following is(are)capability(s)of FISH (fluorescent in situ hybridization)?

A)Localize a particular nucleic acid sequence.
B)Identify the presence or absence of a particular nucleic acid sequence.
C)Analysis of either interphase or metaphase cells.
D)Determine the number of copies of a particular nucleic acid sequence.
E)All of the above.

Question 14

Which specimen type(s)below can be used for FISH analysis?

A)Paraffin embedded thin tissue sections
B)Blood/bone marrow smears
C)Gametes
D)Amniotic fluid
E)All of the above

Question 15

The acceptability for FISH analysis of cells on a prepared slide should be evaluated by

A)polarized light microscopy.
B)electron microscopy.
C)phase contrast microscopy.
D)light microscopy.
E)fluorescent microscopy.

Question 16

What is the major advantage of using uncultured cells for FISH analysis?

A)More metaphase cells for analysis
B)Decreased turnaround time
C)Decreased false positives
D)More viable cells for analysis

Question 17

The acceptability for FISH analysis of cells on a prepared slide is most influenced by

A)temperature and humidity while fixed cells are drying on the slide.
B)pH of the fixative solution.
C)ionic strength of the fixative solution.
D)detergent used to permeabilize the cell and nuclear membranes.
E)detergent used to rupture the cell and nuclear membranes.

Question 18

For which of the testing situations listed is FISH (fluorescent in situ hybridization)most appropriate?

A)A complete chromosome count with examination of chromosomes for abnormalities must be done.
B)A previously undescribed genetic defect is suspected.
C)Karyotype appears normal by classic cytogenetics but phenotype suggests genetic abnormality.
D)All of the above.

Question 19

When FISH protocols call for the use of "aged" slides of cells, how can this be accomplished?

A)Baking slides at 60° C for 4-16 hours.
B)Soaking slides in pH 7.0 TRIS buffer and 1% ethanol.
C)Washing slides in pH 6.5 normal saline followed by 1% methanol.
D)Freezing slides at - 70° C for 1 week prior to analysis.

Question 20

When slides are prepared for FISH analysis,

A)they must be used immediately for optimal sensitivity.
B)they can be stored at 37° C prior to analysis.
C)they can be stored at - 4° C prior to analysis.
D)they can be stored at 60° C prior to analysis.
E)they can be stored at - 20° C prior to analysis.

Question 21

In order for a probe to bind in FISH, the target DNA must be in single- stranded form.

Question 22

Diseases caused by disruption of adjacent groups of genes are called _ syndromes.

Question 23

In which situation below is FISH not very useful?

A)The genetic abnormality is unique to a particular family.
B)Analysis time must be less than one week for results to be clinically useful.
C)Analysis of telomere region is needed.
D)Analysis of centromere region is needed.
E)Cells in the specimen are not viable.

Question 24

Fusion probes are typically used to detect

A)microduplications.
B)translocations in which genetic areas are split apart.
C)translocations in which genetic areas are brought together.
D)aneuploidies.
E)microdeletions.

Question 25

After target DNA is denatured for a FISH procedure, the denatured state is maintained by washing the slides in cold _.

Question 26

Cytogenetic and FISH results should be reported using the International Classification of Disease (ICD)nomenclature.

Question 27

If cells are not perfectly flat on a prepared slide, the hybridization efficiency in FISH procedures suffers.

Question 28

Which of the following best describes uniparental disomy?

A)Since the normal amount of DNA is present, there are no diseases associated with uniparental disomy.
B)It is best detected using whole paint chromosome FISH analysis.
C)It is a situation in which an individual inherits both chromosomes of a particular pair from one parent.
D)All of the above.

Question 29

Even small alterations of subtelomeric regions can cause grossly abnormal phenotypes.

Question 30

An individual who possesses two distinct cell types, each with a different chromosome population, is a genetic .

Question 31

The best means of detecting contiguous gene syndromes is conventional cytogenetic analysis.

Question 32

If a specimen is suspected to be a genetic mosaic, analysis should be repeated with a different stain to confirm the two cell populations.

Question 33

FISH procedures are only accurate on metaphase cells.

Question 34

The most useful probe to use for enumerating the number of chromosomes in a products of conception specimen is a telomere probe.

Question 35

Metaphase nuclei are typically required for accurate use of _ FISH probes.

Question 36

Expression of Her2/neu in malignant cells is important prognostic information in

A)prostate cancer.
B)breast cancer.
C)colon cancer.
D)lung cancer.
E)leukemia.

Question 37

In terms of disease prevalence and detection capability, cytogenetic and FISH analysis of prenatal specimens mostly detect

A)microdeletions.
B)aneuploidies.
C)microduplications.
D)translocations.

Question 38

The chromosomes from cultured cells are prepared as "spreads" on a slide for classic cytogenetic analysis.

Question 39

The composition of an individual's chromosomes is called the .

Question 40

An advantage of indirectly labeled probes in FISH is that slides archived at -20° C for a year can be rewashed and stained with fresh labeling agent to revive the signal and allow rereading of the slides.

Question 41

Define conditions of stringency as it relates to work with probes in FISH.

Question 42

Explain the function of counterstain in a FISH procedure and how the most appropriate counterstain is chosen.

Question 43

Explain the difference between the two FISH Class I probes: alpha satellite and telomere probes.

Question 44

Describe cell preparation for classic cytogenetic analysis.

Question 45

List at least five criteria for quality control and assurance of FISH procedures.