MCQs on Genes and haemoglobin

Question 1

Normal adult haemoglobin (Hb A) consists of:
Your answer:
a) two a (alpha) and two b (beta) chains.
Feedback:
Fetal haemoglobin contains two α and two γ chains, Hb A2 contains two α and two δ chains. Hb Barts contains four γ chains.
Page reference: 154

Question 2

Severe anaemia at birth is a feature of what?
Your answer:
a) Alpha-thalassaemia
Feedback:
Beta chain synthesis does not begin until after birth so that disorders involving primary defects in β-globin chain synthesis do not present until later in infancy.
Page reference: 154-155

Question 3

The mutation in sickle-cell disease consists of:
Your answer:
a) a deletion.
Correct answer:
d) a point mutation.
Feedback:
The sickle-cell mutation consists of an A to T transversion resulting in substitution of valine for glutamic acid.
Page reference: 157

Question 4

The common mutation in α-thalassaemia consists of:
Your answer:
c) an insertion.
Correct answer:
a) a deletion.
Feedback:
The most common mutational mechanism is deletion of one or both contiguous α-globin genes.
Page reference: 159

Question 5

The mutational mechanism in δβ-thalassaemia consists of:
Your answer:
c) an insertion.
Correct answer:
a) a deletion.
Feedback:
This is caused by deletion of the contiguous δ- and β-globin genes.
Page reference: 162

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