Question

Pleiotropy is the term that refers to the situation in which a gene influences more than one trait. Its example is given by
A. Sickle cell anemia
B. Hemophilia
C. Color blindness
D. Only (a) and (b)

Answer 1

Hint: When one gene influences two or more seemingly unrelated phenotypic traits, pleiotropy occurs. Pleiotropic genes generate multiple phenotypic expressions. Due to the gene coding for a product used by a myriad of cells or different targets which has the same signaling function, the mutation in pleiotropic may have an effect on several traits simultaneously.

Complete answer:
Option A. Sickle cell anemia: A group of inherited red blood cell disorders that affects hemoglobin, the protein which carries oxygen through the body is known as the sickle cell disease. Red blood cells are normally disc shaped and are flexible to move easily through the blood vessels. But a person having sickle cell anemia will have crescent or “sickle” shaped red blood cells, which can disrupt and block flow of blood in the rest of the body. Sickle cell anemia occurs due to the expression of a single mutated HBB gene which produces numerous consequences throughout the body and is a pleiotropic disease.
Hence option A is correct.
Option B. Hemophilia: Hemophilia is a disorder in which blood doesn't clot normally. A mutation or change in one of the genes that provide the instructions for creating the clotting factor proteins needed to produce a blood clot causes it. It is not pleiotropic.
Hence option B is not correct.
Option C. Color blindness: The decreased ability to see color or differences in color is known as color blindness. It is usually X-linked genetic disorder. Color blindness is not pleiotropic.
Hence option C is not correct.
Option D. Only (a) and (b): Option A is correct but since option B is not correct.
So, option D is also not correct.

Therefore, Option A. sickle cell anemia is the correct answer.

Note:
One of the most common inherited blood anemias is the Sickle cell anemia. Africans and African Americans are the ones disease primarily affects. In the United States, it is estimated that some \[90,000\] to \[100,000\] Americans have been affected with sickle cell anemia. The current estimates suggest that \[1\] in every \[500\] U.S. African American births have been affected with sickle cell anemia.