Translocations

Question 1

Interstitial deletion/duplication

Answer 1

Within the chromosome

Question 2

Insertion

Answer 2

A segment of one chromosome is inserted into another chromosome

Question 3

Inversion

Answer 3

Reversal of orientation of the intervening portion between breaks in the chromosome

Question 4

Paracentric

Answer 4

2 breaks in one arm

Question 5

Pericentric

Answer 5

One break in each arm

Question 6

Isochromosome

Answer 6

Complete absence of one of the chromosome arms with complete duplication of the other chromosome arm

Question 7

Balanced translocation

Answer 7

No essential chromosome material is lost and no genes are damaged during break and reunion

Question 8

Reciprocal translocation

Answer 8

Exchange of chromosomal material between non-homologous chromosomes

Question 9

Robertsonian translocation

Answer 9

Between two acrocentric chromosomes by fusion at the centromere with loss of the short arm and satellites

Question 10

Single segment exchange

Answer 10

When one of the translocated segments is very small and comprises only the telomeric region of a chromosome

Question 11

Double segment exchange

Answer 11

When both translocated segments are large

Question 12

2:2 segregation

Answer 12

Two chromosomes go to one cell and two to the other

Question 13

3:1 segregation

Answer 13

3 chromosomes go to one cell and one to the other

Question 14

4:0 segregation

Answer 14

All 4 homologs go to one cell

Not viable

Question 15

Alternate segregation

Answer 15

Balanced

Question 16

Adjacent-1 segregation

Answer 16

Unlike centromeres travel together

More viable

Question 17

Adjacent-2 segregation

Answer 17

Like centromeres travel together

Not very viable

Question 18

Tertiary trisomy

Answer 18

Two normal chromosomes and 1 translocation chromosome

Question 19

Interchange trisomy

Answer 19

2 translocation chromosomes and 1 normal chromosome

Question 20

Robertsonian Alternate Segregation

Answer 20

Produces normal and balanced gametes

Question 21

Robertsonian Adjacent Translocations

Answer 21

2 types of disomic and nullisomic gametes

Question 22

Terminal deletion/ duplication

Answer 22

At the end of a chromosome

Question 23

4 factors that affect the risk of translocations leading to abnormal birth

Answer 23

1. The mode of ascertainment
2. The expected mode of segregation leading to potential viable gametes
3. The sex of the transmitting parent
4. The assessed imbalance of the potentially viable gamete

Question 24

3 possible mechanisms for robertsonian heterologous translocations

Answer 24

1. Centric fusion
2. Union following breakage in one short arm and one long arm
3. Union following breakage in both short arms