Which condition is often associated with a deficiency of vitamin B12?

Pernicious anemia is a condition that is specifically characterized by a deficiency of vitamin B12. This deficiency is primarily due to the lack of intrinsic factor, a protein produced in the stomach that is necessary for the absorption of vitamin B12 in the intestines. Without intrinsic factor, the body cannot effectively absorb vitamin B12 from food, leading to a deficiency that impairs red blood cell production and results in megaloblastic anemia. Patients with pernicious anemia often exhibit symptoms such as fatigue, weakness, and neurological issues due to the crucial role of vitamin B12 in both red blood cell formation and maintaining the health of nerve cells.

Other conditions listed, such as iron deficiency anemia, thalassemia, and hemolytic anemia, have distinct etiologies unrelated to vitamin B12 metabolism, making them not directly linked to the deficiency in question. Thus, pernicious anemia stands out as the condition uniquely connected with a vitamin B12 deficiency.