Biermer's anemia is a blood disorder resulting from a deficiency of a specific substance. Individuals with this condition lack a component in their stomach necessary for absorbing vitamin B12. This component is known as intrinsic factor (IF). Commonly referred to as pernicious anemia (PA), this disorder is distinguished by the presence of large, immature, nucleated cells in the blood, known as megaloblasts, which are precursors to red blood cells. Mature red blood cells, in contrast, do not have a nucleus. Hence, PA is classified as a type of megaloblastic anemia.Though not originally named as such, pernicious anemia was initially described in 1855 by English physician Thomas Addison, who termed it an invariably fatal "idiopathic anemia." The term "idiopathic" indicated that the cause of the illness was unknown. The name "pernicious anemia" was later introduced in 1872 by German physician Anton Biermer, whose description of the disease surpassed Addison's. Research by George H. Whipple on the benefits of liver consumption in anemia, followed by studies by George R. Minot and Wm. P. Murphy on its specific effects in treating pernicious anemia, led to a cure for the condition. This work earned them the Nobel Prize in 1934.Today, pernicious anemia is no longer life-threatening. It is simply treated with vitamin B12, which must be administered via injection because individuals with PA lack effective intrinsic factor and cannot absorb oral vitamin B12. There is some indication that PA may have a genetic component, although its pattern of inheritance is not well-documented. A particular form of PA, resulting from an intrinsic factor defect, is clearly inherited as an autosomal recessive condition, where the affected child receives two copies of the gene, one from each parent. The gene for intrinsic factor has been located on human chromosome 11.The term "pernicious" implies something highly harmful, destructive, or deadly, originating from the Latin root "nex," meaning "violent death." Once a deadly condition, pernicious anemia is now manageable. PA is also known as Addison's anemia.