Question

Describe the genetic defect responsible for sickle cell disease. How does this defect cause the symptoms of the disease? While there is currently no cure, describe an experimental approach that researchers are currently developing to cure patients.

Answer 1

Sickle cell anemia is an autosomal recessive disease caused due to a point mutation in one of the four polypeptides of hemoglobin. This mutation results in replacement of glutamic acid with valine in 6th position. This autosomal recessive disease results in change in shape of red blood cells (RBCs). The RBC appear in sickle shape due to which the ability to transport oxygen is reduced. The RBC undergo hemolysis and cause destruction of cells.

Gene therapy is a promising technology that can be used for replacement of defective gene. Therefore, to cure the sickle cell anemia, a normal gene is isolated and cloned in place of defective gene. The experimental procedure is as follows:

A normal gene encoding glutamic acid is isolated

This gene is cloned into organism with sickle cell trait

The efficiency of hemoglobin carrying oxygen is tested after gene replacement.