Chapter 5: Principals of Clinical Cytogenetics

Question 1

What are Clinical Cytogenetics?

Answer 1

the study of chromosomes, their structure, and their inheritance

Question 2

Giemsa stain ~400 bands/haploid karyotype at metaphase

Answer 2

G banding

Question 3

stain with quinacrine mustard, results in
a specific pattern of bright and dim bands under the
fluorescent microscope (bright = dark after G banding)

Answer 3

Q Banding

Question 4

reverses the usual white and black pattern
seen with G- and Q banding; requires heat treatment ->
is the standard method in many labs in Europe

Answer 4

R Banding

Question 5

central centromere and equal arms

Answer 5

metacentric

Question 6

off-center centromere

Answer 6

submetacentric

Question 7

centromere near one end

Answer 7

acrocentric

Question 8

What are the acrocentric chromosomes?

Answer 8

13, 14, 15, 21, 22

Question 9

What are the satellites on the acrocentric chromosomes?

Answer 9

small distinctive masses of chromatin attached to the short arms by short stalks

Question 10

What stains the centromere region and other regions of constiutive heterochromatin?

Answer 10

C banding

Question 11

What is fragile site detection?

Answer 11

• It identifies non-staining gaps to observe fragile sites.
• It is usually necessary to expose cells to growth conditions or chemicals that alter or inhibit DNA synthesis

Question 12

probes hybridize along the entire chromosome or chromosome arm

Answer 12

chromosome painting

Question 13

This is used to diagnose specific deletions or rearrangements and evaluates the karyotype of all 24 chromosomes

Answer 13

spectral karyotyping (SKY)

Question 14

-cells or individuals with an abnormal number of

chromosomes (not 46)

Answer 14

Heteroploid

Question 15

-exact multiple of the haploid (n) chromosome number,
have the complete normal chromosome complement (46) that
is characteristic of humans

Answer 15

Euploid

Question 16

-any multiple of the basic haploid chromosome number

other than the diploid number 3n=69, 4n=92

Answer 16

Polyploid

Question 17

-any other abnormal number

Answer 17

Aneuploidy

Question 18

2n + 1 or 47

Answer 18

Trisomy

Question 19

2n -1 or 45

Answer 19

Monosomy

Question 20

4n or 92 chromosomes

Answer 20

Tetraploidy

Question 21

-46 chromosomes from the mother-spontaneously aborted earlier in pregnancy

Answer 21

Digynic

Question 22

-46 chromosomes from the father -> make up 65-75% of cases -> develop an abnormal placenta that is classified as a partial hydatidiform mole

Answer 22

Diandric

Question 23

-a union of two or more digits that occurs in humans often as a hereditary disorder marked by the joining or webbing of two or more fingers or toes

Answer 23

Syndactyly

Question 24

What is a mole?

Answer 24

the placenta is converted into a mass of tissue resembling a bunch of grapes called a hydatid cyst ->no fetus or small atrophic fetus present