Hemoglobin Hopkins-2 (Hb Hop-2) is a mutation of the protein hemoglobin, which is responsible for the transportation of oxygen through the blood from the lungs to the musculature of the body in vertebrates. The specific mutation in Hemoglobin Hopkins-2 results in two abnormal α chains (human hemoglobin consist of 2 α and 2 β polypeptides usually termed chains). The mutation is the result of histidine 112 being replaced with aspartic acid in the protein's polypeptide sequence. Additionally, within one of the mutated alpha chains, there are substitutes at 114 and 118, two points on the amino acid chain. This mutation can cause sickle cell anemia. Following the initial discovery of hemoglobin, two researchers working at Johns Hopkins Hospital in the mid-twentieth century, Ernest W. Smith and J.V. Torbert, discovered the Hopkins-2 mutation of hemoglobin. Work by Harvey A. Itano and Elizabeth A. Robinson in 1960 confirmed Smith's and Torbert's finding and emphasized the importance of the alpha loci in the mutation. Later in the twentieth century, Samuel Charache, another Hopkins affiliated scientist and doctor, studied the physiological impacts of the variant on health. His findings suggest that the variant plays no effect clinically. History In the mid-1900s, many factors prompted hemoglobin research in Baltimore, Maryland and ultimately led to the discovery of Hemoglobin Hopkins-2. First, the development of new technology, including x-ray crystallography and protein chemistry, that could be utilized in molecular biology studies catalyzed research. Furthermore, the large presence of thalassemia (Hb H), a disorder in which the alpha gene is dysfunctional, in Southeast Asia and southern China further concerned researchers as, if left untreated, the mutation could result in bone deformities, swelling of the spleen, slowed growth rate, or cardiac dysfunction. Additionally, Max Perutz's, a Cambridge researcher, discovery of hemoglobin's basic tertiary structure in 1962 catalyzed research in hematology. Vernon Ingram's research surrounding sickle cell anemia in 1956 revealed that variants, or mutations, in hemoglobin's RNA resulted in the sickle cell disease. Ernest W. Smith and J.V. Norbert examined Ingram's discovery and, in 1958, they discovered the hemoglobin Hopkins-2 mutation. Smith and Torbert, research fellows working in Lockard Conley's Hematology Research Department at Johns Hopkins University, proved that recombination of non-allelic genes resulted in two variants of the gene that produced hemoglobin. Variants of the "normal" hemoglobin gene result in mutation in the hemoglobins produced. In other words, the researchers discovered two versions of hemoglobin: the [Hb-Hop2] and