Choose the correct statement with respect to sickle cell disease.

1. Sickle-shaped cells are eliminated rather quickly by the body than the normal RBCs
2. It is a sex-linked disease occuring more in males than females
3. Bone marrow transplant has no effect in this condition
4. Infected individuals have abnormally high level of haemoglobin

The correct option is A Sickle-shaped cells are eliminated rather quickly by the body than the normal RBCs
Sickle cell anaemia is an autosomal recessive disorder in which the RBCs become sickle-shaped. This is due to formation of an abnormal haemoglobin called haemoglobin-S. These cells are identified as 'problem cells' by the body and are eliminated rather quickly. Unlike normal RBCs, sickle RBCs (sRBC) may survive just 10–20 days due to increased haemolysis. These sickle-shaped RBCs cannot pass through narrow capillaries. This condition causes anaemia in patients and many a times blood transfusion may be required to correct the falling haemoglobin levels.

Bone marrow transplant, although carries a lot of risks, may be performed in life-threatening conditions. According to some sources, this technique indicates an event-free survival rate of approximately 91% and a mortality rate of less than 5%.