Question

Select the correctly matched pair about sickle cell anaemia:
Genotype: Phenotype
(A) Hb^A Hb^A : Diseased phenotype
(B) Hb^A Hb^S: Diseased phenotype
(C) Hb^S Hb^S: Diseased phenotype
(D) Hb^S Hb^A : Carrier of disease
Choose the correct answer from the options given below:

• A. (C) and (D) only
• B. (A) and (C) only
• C. (B), (C) and (D) only
• D. (A), (B) and (C) only

Answer 1

The Correct Option is C

(A) HbA HbA : Diseased phenotype

This pair is incorrect. The genotype HbA HbA (homozygous for normal hemoglobin) results in a normal phenotype, not a diseased one.

(B) HbA HbS : Diseased phenotype

This pair is correct. The genotype HbA HbS (heterozygous for sickle cell trait) results in a carrier phenotype, not a diseased one. Carriers typically do not show severe symptoms of sickle cell disease.

(C) HbS HbS : Diseased phenotype

This pair is correct. The genotype HbS HbS (homozygous for sickle cell hemoglobin) results in a diseased phenotype, characterized by sickle cell anemia.

(D) HbS HbA : Carrier of disease

This pair is correct. The genotype HbS HbA (heterozygous for sickle cell trait) results in a carrier phenotype. Carriers are typically healthy but can pass the sickle cell gene to their offspring.

Conclusion

The correct answer is (3) (B), (C) and (D) only. These pairs correctly describe the genotypes and their corresponding phenotypes in sickle cell anaemia.