Question

Read the following statements on sickle cell anaemia:
A. It is a monogenetic disorder due to single base pair mutation in $\beta$-globin gene.
B. It occurs due to substitution of amino acid valine from glutamic acid.
C. It is a genetic disorder where a person is born with an extra copy of chromosome 21.
D. It is an autosomal recessive genetic disorder that prevents the body from removing excess copper and accumulates copper in body.
E. The point mutation in sickle cell anaemia changes the codon from GAG to GUG.
Choose the correct answer from the options given below:

• A. A, B, C and D only
• B. A, B and E only
• C. B, D and E only
• D. A, D and E only

Hint:

Sickle cell anaemia: $\beta$-globin mutation, GAG → GUG, Glutamic acid → Valine.

Answer 1

The Correct Option is B

Step 1: Recall cause of sickle cell anaemia.
Sickle cell anaemia is caused by a point mutation in the $\beta$-globin gene of hemoglobin.
This mutation substitutes valine for glutamic acid at position 6 of the $\beta$-chain.
Step 2: Analyze statements.
- (A) True: It is monogenetic due to mutation in $\beta$-globin.
- (B) True: Valine replaces glutamic acid.
- (C) False: Describes Down’s syndrome (trisomy 21).
- (D) False: Describes Wilson’s disease (copper accumulation).
- (E) True: Mutation changes codon from GAG (glutamic acid) to GUG (valine).
Step 3: Correct group.
A, B, E are correct.
Step 4: Conclusion.
Correct answer = (B) A, B and E only.