Question

Sickle cell anaemia is because of

• A. More population of house flies.
• B. Change in sequences of amino acids in alpha-chain of haemoglobin.
• C. Change in sequences of amino acids in beta-chain of haemoglobin.
• D. Poor hygienic conditions.

Answer 1

Answer: (C)

Change in sequences of amino acids in beta-chain of haemoglobin.

Sickle cell anaemia is a genetic disorder caused by a mutation that affects the normal development of haemoglobin. The haemoglobin inside blood cells clumps together into solid structures. The clumping distorts the normal shape of the red blood cells, causing them to take on a rigid, sickle shape. The most common haemoglobin of adult humans is known as haemoglobin A (HbA). However, other variant forms of hemoglobin are called hemoglobin S (HbS). Individuals who manufacture HbS exclusively suffer from sickle-cell disease. Individuals with sickle-cell disease have inherited from each parent a gene S encoding the beta chain of haemoglobin. The amino acid sequences of the beta chains of HbA and HbS are identical except for the amino acid at position 6. This position is occupied by glutamic acid in HbA chains, but in HbS beta chains, valine is found there instead.