Genetic Control And Regulation Of Haemoglobin Synthesis

Question 1

On what chromosome is the beta-like globin gene cluster?

Answer 1

11

Question 2

On what chromosome is the alpha-like glob in gene cluster?

Answer 2

16

Question 3

What is the order of expression in the beta-like globin gene cluster?

Answer 3

Epsilon, Gamma, Delta and Beta

Question 4

What are the two types of gamma globin genes?

Answer 4

GGamma and AGamma (two separate genes)
GGamma: glycine at position 136*
AGamma: alanine at position 136*

*this is a good example of duplication and diversion

Question 5

What is the order of expression of alpha-like globin genes

Answer 5

5’ Zeta, alpha 2 (>60%), alpha 1 (<40%) 3’

Question 6

What Hb expression is present in the embryonic stage?

Answer 6

Hb Gower 1 Zeta2Epsilon2
Hb Gower 2 Alpha2Epsilon2
Hb Portland Zeta2Gamma2

Question 7

What Hb expression is present in the foetal stage?

Answer 7

HbF α2 Gγ2 and α2 Aγ2

Question 8

What Hb expression is present in the adult stage?

Answer 8

HbA alpha2beta2
HbA2 Alpha2Delta2

Question 9

What controls the expression of the Beta globin gene cluster and where on the gene is it found?

Answer 9

Locus control region 5’end close to the epsilon gene

Question 10

In the Beta globin gene, where is the DNase 1 hypersensitive region found?

Answer 10

3’end downstream of beta globin gene

Question 11

Where is the DNase hypersensitive site found in the alpha globin gene?

Answer 11

HS40

Question 12

Give two examples of duplication and divergence (Alpha and Beta)

Answer 12

Alpha: Split to give Zeta and Alpha
Beta: Split twice to give embryonic Epsilon and foetal Gamma and adult Delta and Beta