Addisonian anemia: A blood disorder caused by a lack of vitamin B12. Patients who have this disorder do not produce the substance in the stomach that allows the body to absorb vitamin B12. This substance is called intrinsic factor (IF).
Addisonian anemia, also called pernicious anemia (PA), is characterized by the presence in the blood of large, immature, nucleated cells (megaloblasts) that are forerunners of red blood cells. (Red blood cells, when mature, have no nucleus). It is thus a type of megaloblastic anemia.
Pernicious anemia (PA) was first described (although not by that name) in 1855 by the English physician Thomas Addison. He called it an invariably fatal “idiopathic anemia.” The “idiopathic” was a frank admission that the cause of this illness was wholly unknown. The name “pernicious anemia” was coined in 1872 by the German physician Anton Biermer whose description of the disease was superior to that of Addison. The studies of George H. Whipple on the effects of feeding liver in anemia followed by those of George R. Minot and Wm. P. Murphy on the effects of feeding liver specifically in pernicious anemia (PA) led to the cure of PA and to their receiving the Nobel Prize in 1934.
Nowadays PA is an unpernicious anemia. It is simply treated with vitamin B12. The vitamin B12 has to be administered by injection (parenterally) because people with PA do not have IF (or an effective form of IF) and so cannot absorb vitamin B12 taken by mouth.
There is some evidence that PA may be genetic although its mode of inheritance is poorly documented. There is a congenital form of PA due to defect of IF that is clearly inherited as an autosomal recessive trait with the affected child having received two copies of the gene, one from each parent. The IF gene itself has been localized to human chromosome 11.
The word “pernicious” means highly injurious, destructive, or deadly. “Pernicious” comes from the Latin root “nex” meaning “violent death.” Pernicious anemia was once quite deadly. Today it fortunately is not.
PA has also been called Addison anemia and Biermer’s anemia.
- Additive genetic effects
Additive genetic effects: A mechanism of quantitative inheritance such that the combined effects of genetic alleles at two or more gene loci are equal to the sum of their individual effects.
- Adducted thumbs with mental retardation
Adducted thumbs with mental retardation: A syndrome with the following characteristic features: neurologically: mental retardation and aphasia (lack of speech) limbs: adducted (clasped) thumbs, absent extensor pollicis longus and/or brevis muscles to the thumb, shuffling gait, and leg spasticity growth: small body size skeleton: lumbar lordosis (sway back) The syndrome is inherited as an X-linked […]
Adduction: Movement of a limb toward the midline of the body. The opposite of adduction is abduction.
- Adductor muscle
Adductor muscle: Any muscle that pulls a body part toward the midline. For example, the adductor muscles of the legs pull the legs toward the midline of the body so the legs are closer together. The word “adductor” comes from the Latin prefix “ad” meaning “toward” + “ducere” meaning “to draw or lead” = “to […]
- Adenine (A)
Adenine (A): One member of the A-T (adenine-thymine) base pair in DNA. The other base pair in DNA is G-C (guanine-cytosine).