How does deficiency of intrinsic factor lead to pernicious anemia?

Intrinsic factor is a glycoprotein produced by the parietal cells of the stomach, essential for the absorption of vitamin B12 in the intestines. A deficiency of intrinsic factor, often due to autoimmune destruction of parietal cells or gastric surgery, impairs vitamin B12 absorption, leading to its deficiency. Since vitamin B12 is crucial for red blood cell production and DNA synthesis, its lack results in the formation of abnormally large, immature red blood cells, characteristic of pernicious anemia. Consequently, this condition leads to symptoms like fatigue, weakness, and neurological issues.