Question

A harmful condition, which is also a potential saviour form a mosquito borne infectious disease is

• A. Thalassemia
• B. Sickle cell anaemia
• C. Leukemia
• D. Pernicious anaemia

Answer 1

The correct option is B Sickle cell anaemia

Sickle cell anaemia is caused by a mutation in $H{b}^b$ gene, that codes the $\beta$-chain, causes replacement of A by T at the 17th nucleotide of the Hbb gene changes the codon GAG (glutamic acid) to GTG (which encodes valine). The mutated allele $H{b}^s$ encodes the abnormal haemoglobin molecules which stick to one another and cause stiffness and sickle shape of red blood cells. The heterozygotes, $H{b}^b$$H{b}^s$, show increased resistance to malaria and therefore have the survival advantage in regions where malaria is a common disease. That’s why sickle cell anaemia has not been eliminated from African population who reside in malaria-prone area. Pernicious anemia is a deficiency of RBC production caused by vitamin B12 deficiency. Thalassemia is a group of blood disorders which are caused by mutations in the HbB and HbA genes present on chromosome 11 and chromosome 16 respectively that results in the production of an abnormal form of haemoglobin. Blood cell cancer is called as leukemia. The correct answer is B.