Deficiency of which vitamin results in disease Pernicious anaemia?

Question

Accepted Answer

The correct option is (2):

Pernicious anemia is a type of megaloblastic anemia caused by a deficiency of vitamin $B_{12}$, also known as cobalamin. This deficiency usually arises not from inadequate dietary intake, but rather from the body's inability to absorb vitamin $B_{12}$ from the digestive tract. This malabsorption is often due to an autoimmune condition where the body attacks the parietal cells in the stomach, which are responsible for producing intrinsic factor. Intrinsic factor is a protein essential for the absorption of vitamin $B_{12}$ in the small intestine. Without sufficient intrinsic factor, dietary vitamin $B_{12}$ cannot be effectively absorbed, leading to its deficiency. Vitamin $B_{12}$ is crucial for DNA synthesis, red blood cell formation, and the proper functioning of the nervous system. Its deficiency leads to the production of abnormally large, immature red blood cells (megaloblasts) that cannot function properly, causing anemia. Neurological symptoms can also occur due to its role in myelin sheath formation.

The incorrect option is (1): Vitamin $B_{1}$ (Thiamine) deficiency causes beriberi, which affects the cardiovascular and nervous systems, and Wernicke-Korsakoff syndrome, but not pernicious anemia.

The incorrect option is (3): Vitamin $B_{6}$ (Pyridoxine) deficiency can lead to various neurological symptoms, skin problems, and microcytic anemia, but it is not directly associated with pernicious anemia.

The incorrect option is (4): Vitamin $B_{2}$ (Riboflavin) deficiency causes a condition called ariboflavinosis, characterized by symptoms like cracked lips, sore throat, and inflammation of the tongue, but it does not cause pernicious anemia.