Question

Thalassemia and Sickle cell anaemia are due to a problem in globin molecule synthesis. Select the correct statement.

• A. Sickle cell anaemia is due to a quantitative problem of globin molecule.
• B. Both are due to qualitative defects in globin chain synthesis.
• C. Both are due to quantitative defects in globin chain synthesis.
• D. Thalassemia is due to less synthesis of globin molecules.

Hint:

Thalassemia = Quantitative (too few chains produced).
Sickle Cell Anaemia = Qualitative (chains are produced in normal amounts, but they are defective/mutated).

Answer 1

The Correct Option is D

Step 1: Understanding the Problem:
While both Thalassemia and Sickle Cell Anaemia are autosomal recessive genetic disorders affecting hemoglobin, they compromise the hemoglobin molecule's function through entirely different mechanisms.
Step 2: Approach and Formula:
Distinguish between the two genetic disorders based on whether the fundamental defect is qualitative (a structural abnormality) or quantitative (a reduced production rate).
Step 3: Detailed Explanation:
- Sickle Cell Anaemia is caused by a point mutation leading to a single amino acid substitution. The globin chain produced is structurally defective and abnormal. Therefore, it is a qualitative problem.
- Thalassemia is caused by mutations or deletions that significantly decrease or entirely stop the synthesis of one of the globin chains ($\alpha$ or $\beta$). The chains that are produced are perfectly normal in structure, but there are far too few of them. Therefore, it is a quantitative problem characterized by less synthesis.
Evaluating the options:
(A) Incorrect. Sickle cell is qualitative, not quantitative.
(B) Incorrect. Thalassemia is not qualitative.
(C) Incorrect. Sickle cell is not quantitative.
(D) Correct. Thalassemia is accurately described as being due to less synthesis (a quantitative issue) of normal globin molecules.
Step 4: Final Answer:
The correct statement is (D).