Step-by-step explanation:
Pleiotropism refers to a condition in organisms when a single gene which controls one trait indirectly influences other unrelated traits in the organism.
The case of sickle cell anaemia can be considered a pleiotropic case as the gene which causes the mutation in the haemoglobin gene changes the shape of the red blood cell also causes the change in the fibrosis of the spleen due to accumulation of the RBC in the spleen, blockage of blood flow which leads to pain in different parts of the body and the kidney and heart failure.
Thus, a single gene can control more than one phenotype and sickle cell is considered pleiotropic effect.