Which of the following is the example of pleiotropic gene (1) Haemophilia (2) Thalassemia (3) Sickle cell anaemia (4) Colour blindness?

Question

Answer

Pleiotropic Genes and Examples

Pleiotropic genes are the genes that have multiple effects on the phenotype of an organism. These genes can influence multiple traits, and therefore, are responsible for multiple phenotypic expressions. Here are the examples of pleiotropic genes:

Haemophilia: Haemophilia is a genetic disorder that affects the blood's ability to clot. It is caused by mutations in the F8 or F9 gene, which encodes for clotting factors VIII and IX, respectively. These clotting factors not only help in blood clotting but also play a role in angiogenesis and wound healing.

Thalassemia: Thalassemia is a group of genetic blood disorders that affect the production of hemoglobin. It is caused by mutations in the HBA1, HBA2, HBB, or HBD gene, which encodes for the alpha and beta chains of hemoglobin. These chains are not only responsible for carrying oxygen but also play a role in red blood cell production, iron metabolism, and nitric oxide transport.

Sickle Cell Anemia: Sickle Cell Anemia is a genetic blood disorder caused by mutations in the HBB gene, which encodes for the beta chain of hemoglobin. This mutation causes the red blood cells to become sickle-shaped, leading to reduced oxygen-carrying capacity, increased risk of infections, and organ damage. However, this mutation also offers protection against malaria, a pleiotropic effect of the HBB gene.

Colour Blindness: Colour blindness is a genetic disorder that affects the ability to distinguish between different colours. It is caused by mutations in the OPN1LW, OPN1MW, or OPN1SW gene, which encodes for the three types of cone cells in the retina. These cone cells not only help in colour vision but also play a role in visual acuity, contrast sensitivity, and adaptation to light.

Therefore, all the above-mentioned disorders are examples of pleiotropic genes as they affect multiple traits and have multiple phenotypic expressions.

Answer

Sickle cell anemia is an pleiotropic as because the expression of a single mutated HBB gene produces numerous consequences throughout the body ..so the correct Answer is option 3 .

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