Techniques of chromosome analysis

Question 1

Which of the following is used to analyse the whole genome?

1) G banding
2) FISH
3) MLPA
4) Next generation sequencing
5) Microarrays
6) QF-PCR or qPCR

Answer 1

The following are used to analyse the whole genome:

1) G banding
4) Next gen sequencing
5) Microarrays

The following methods are used for targeted testing:

2) FISH
3) MLPA
6) QF-PCR or qPCR

Question 2

FISH is a molecular cytogenic technique used for targeted testing. What does FISH stand for?

Answer 2

Fluorescent in situ hybridisation

Question 3

MLPA is a molecular cytogenic technique used for targeted testing.What does MLPA stand for

Answer 3

Multiplex ligation dependent probe amplification

Question 4

What molecular cytogenic technique detects DNA material on slides using fluorescent dyes and UV light?

Answer 4

FISH
(flourescent in situ hybridisation)
detects DNA material on slides by using fluorescent dyes and UV light.

Question 5

What are the different types of probes used in FISH.

Answer 5

• unique sequence
• centromeric
• paints

Question 6

When can FISH be used?

Answer 6

1) Aneuploidy (abnormal numbers of chromosomes)
2) confirmation of G-banding test
3) confirmation of array CGH test
4) identifying specific abnormalities in cancer
5) copy number imbalance (repeats of dna)

Question 7

What diseases can occur due to copy number imbalances?

Answer 7

Autism (congenital)

cancer (acquired)

Question 8

What molecular cytogenetic methods are used to assess copy number?

Answer 8

1) FISH
2) MLPA
3) Microarray CGH
4) Next generation sequencing
5) QF-PCR / qPCR

(not G banding)

Question 9

What does QF-PCR stand for? what is it?

Answer 9

Quantitative Flourescent polymerase chain reaction.

PCR amplification of short DNA sequences using fluorescent primers.

Question 10

What is used to detect prenatal aneuploidy ?

Answer 10

QF-PCR

• DNA is extracted from the amniotic fluid / chorionic villi
• PCR amplification looking for aneuploidy of chromosomes 13, 18, 21, X and Y

Question 11

trisomy 13

Answer 11

patau syndrome

Question 12

patau syndrome

Answer 12

trisomy 13

Question 13

Which analysis takes the shortest amount of time?

Answer 13

1) MLPA / QF-PCR = 10mins / 30mins/case

Question 14

trisomy 18

Answer 14

edwards syndrome

Question 15

edwards syndrome

Answer 15

trisomy 18

Question 16

turners syndrome

Answer 16

45, X

Question 17

45, X

Answer 17

turners syndrome

only affects females

Question 18

In what situations would we ask for a blood cytogenetic study?

Answer 18

1) dysmorphic newborns
2) Gender assignment
3) Developmental problem
4) heart defect
5) reproductive problem
6) family studies

Question 19

In a suspected case of down’s syndrome what are the 3 possible cytogenics?

Answer 19

1) free trisomy 21 (90-95%)
2) Translocation (robertsonian 2-5%)
3) Mosaic trisomy 21 (2-5%)

Question 20

what is robertsonian translocation?

Answer 20

When the entire chromosomal arm is swapped

Question 21

What is amniocentesis?

Answer 21

prenatal testing for chromosomal abnormalities, fetal infection, sex dertemination.

Question 22

What is chorionic villus sampling?

Answer 22

Chorionic villus sampling (CVS) is a prenatal test in which a sample of chorionic villi is removed from the placenta for testing. The sample can be taken through the cervix (transcervical) or the abdominal wall (transabdominal).

Question 23

what cytogenetic techniques are used to analyse amniotic fluid and chorionic villi?

Answer 23

QF-PCR

G-banded analysis