Addisonian anemia is a blood condition resulting from a deficiency of a crucial component that aids in the absorption of vitamin B12 in the stomach. This component is known as intrinsic factor (IF). Patients with this condition lack the ability to produce IF, leading to the presence of large, immature, nucleated cells known as megaloblasts in the blood, which are precursors to red blood cells. Mature red blood cells are characterized by the absence of a nucleus. Thus, Addisonian anemia is a type of megaloblastic anemia.Pernicious anemia (PA) was first identified by English physician Thomas Addison in 1855, though not under that name. He referred to it as invariably fatal "idiopathic" anemia, openly admitting that the cause of the illness was unknown at the time. The term "pernicious anemia" was introduced in 1872 by German physician Anton Biermer, who provided a more comprehensive description than Addison. Groundbreaking studies by George H. Whipple, along with George R. Minot and Wm. P. Murphy, who demonstrated the beneficial effects of liver consumption on anemia, led to the cure of PA. Their work earned them the Nobel Prize in 1934.Today, pernicious anemia is no longer considered life-threatening and is effectively managed with vitamin B12 injections. These injections are necessary because individuals with PA lack functional IF, preventing them from absorbing oral vitamin B12.There is some indication that PA may have a genetic component, although its inheritance patterns are not well-documented. A specific form of PA caused by an IF defect is clearly inherited as an autosomal recessive trait, requiring the child to inherit two copies of the gene, one from each parent. The IF gene has been mapped to human chromosome 11.The term "pernicious" means highly damaging or deadly, derived from the Latin root "nex," which signifies "violent death." While PA was once a lethal condition, it is now manageable. Pernicious anemia has also been known by other names throughout history.
