16. Chromosome Abnormalities

Question 1

Outline some reasons for cytogenetic analysis.

Answer 1

Assess reproductive risks
Accurate diagnosis
Better management
Prenatal diagnosis

Question 2

What phase of the mitosis are chromosomes stained for karyotyping?

Answer 2

Metaphase

Question 3

What can karyotyping identify?

Answer 3

Number of chromosomes - aneuploidy

Alterations in bands of chromosomes

Question 4

What is an example of a disease characterised by monosomy 45, X?

Answer 4

Turners syndrome

Question 5

How does aneuploidy arise?

Answer 5

Errors in meiosis

Question 6

What does non-dysfunction in meiotic cell division cause?

Answer 6

Gametes with a missing chromosome or extra chromosome

Question 7

What does non-dysjuction during mitotic division cause?

Answer 7

Mosaicism

Question 8

How does anaphase lag affect chromosome number?

Answer 8

Chromosomes ‘left behind’ at cell division and may be lost completely

Question 9

What chromosomes are involved in Robertsonian translocations?

Answer 9

Acrocentric chromosomes fuse together.

Question 10

How will a patient with a robertsonian translocation be affected?

Answer 10

Clinically normal as all genes present

Can only father monosomy or trisomy as chromosome stuck together

Question 11

What are 2 types of reciprocal translocation?

Answer 11

balanced - no genetic information lost

Unbalanced- genetic information lost