Sickle-cell anaemia is a disease caused due to the abnormality in

Sickle-cell anaemia is a genetic blood disorder characterized by an abnormality in the red blood cells (RBCs). The disease is caused by a mutation in the HBB gene, which leads to the production of an altered form of hemoglobin known as hemoglobin S (HbS). When deoxygenated, this abnormal hemoglobin polymerizes, causing the red blood cells to lose their flexible, disc-like shape and assume a rigid, sickle or crescent shape. These distorted RBCs are prone to premature destruction, leading to hemolytic anemia, and can become trapped in small blood vessels, causing vaso-occlusive crises and organ damage [1]. While blood also contains white blood cells for immunity and platelets (thrombocytes) for clotting, sickle-cell anaemia specifically targets the structure and function of the red blood cells.

Sources

1. [1] https://pmc.ncbi.nlm.nih.gov/articles/PMC3222266/