Megaloblastic type of anemia due to vitamin B 12 or folic acid deficiency. Thalassemias many, especially those with variations in the content of individual chains, present as microcytic anemias. Some anemias are the result of problems in the bone marrow where blood cells are produced. Red blood cell production may be reduced or affected by chemicals or viruses that attack the bone marrow. The goal of treatment is to determine the cause of anemia and treatment depends on the cause. Anemias related to vitamin deficiencies are discussed separately. Pernicious anemia refers to a type of autoimmune anemia. In addition the cells are very large, the inner contents of each cell are not fully developed. The disease was called pernicious anemia, because it was fatal before treatment was available for the first time as a therapy for liver and later as a purified vitamin B-12. The term pernicious is no longer appropriate, but is kept for historical reasons. Diseases of the small intestine causing malabsorption can cause vitamin B12 deficiency. Vegans (people who eat absolutely no animal foods) are at risk of inadequate vitamin B12 because of this vitamin in their diet. But it takes a long time to exhaust all the vitamin B12 is stored in the liver. There is a congenital form of pernicious anemia due to a defect of intrinsic factor in the birth that is clearly inherited as an autosomal recessive trait with the affected child having received two copies of the gene, one from each parent. Vitamin B12 helps in the process of contraction. Without vitamin B12, there are not enough red blood cells, and those in circulation are large and quickly damaged. This leads to anemia, which means that there is a deficiency of normal red cells. Symptoms, which usually start gradually, include loss of appetite, diarrhea, pallor, fatigue and headache. Tingling in hands and feet as well as the appearance of spastic movements, may indicate that the nervous system is affected. The word “pernicious” is highly injurious, destructive or deadly. “Pernicious” comes from the Latin root “nex” meaning “violent death”. Pernicious anemia was once quite deadly.