Which of the following is an example of Pleiotropy?
A.Haemophilia
B.Thalassemia
C.Sickle cell anaemia
D.Colour blindness

Hint: Pleiotropy is defined as the special condition when one gene is responsible for controlling two distinct phenotype traits and these traits are unrelated to each other in all ways. Pleiotropy is seen in different genetic disorders in human beings.

Complete answer:
1.Haemophilia :- Haemophilia is the disease which is caused by the changes or mutation in the 12th chromosome of the human DNA, only a single gene is responsible for these diseases. It doesn't control any other function or phenotype in the human body.
2.Thalassemia :- it is a recessive inherited genetic disorder which is also a result of a number of small mutations in the beta globin chain. It didn't come across the Pleiotropy disorders. It reduces the oxygen carrying property of the blood.
3.Sickle cell anaemia :- sickle cell anaemia is an example of pleiotropic gene because here the mutation in the single gene carries out a number of changes throughout the body and affects the body in different ways. Here mutation occurs in only HBB genes.
4.Colour blindness :- colour blindness is a sex linked recessive inherited genetic disorder which is pass from the parents to the offspring. It is mainly transferred from the carrier mother to the son . The gene which is responsible for this is present on the 23rd chromosome.

Hence the correct answer is OPTION(C)

Note: In sickle cell anaemia the red blood cells lose their normal shape to sickle like shape and also break down of red blood cells can be seen in different cases.
Pain and fatigue are the symptoms for sickle cell anaemia.