Difference between sickle cell anemia and thalassemia

This article was published in December 2008 as part of the special ASH anniversary brochure, Sickle cell disease and thalassemia are genetic disorders caused by errors in the genes for hemoglobin, a substance composed of a protein ("globin") plus an iron molecule ("heme") that is responsible for carrying oxygen within the red blood cell. These disorders can cause fatigue, jaundice, and episodes of pain ranging from mild to very severe. They are inherited, and usually both parents must pass on an abnormal gene in order for a child to have the disease. When this happens, the resulting diseases are serious and, at times, fatal. Sickle Cell Disease Sickle cell disease was first discovered in the early 1900s, described as "peculiar, elongated sickle-shaped erythrocytes [red blood cells]." With further study, a noted pathologist later suggested that the pain experienced by sickle cell patients resulted from the blockage of tiny blood vessels. In a landmark 1949 study, Dr. Linus Pauling concluded that sickle cell disease is caused by abnormal hemoglobin, referred to as "hemoglobin S." The disease was among the first to be understood fully at the biochemical level, as researchers learned that the abnormal hemoglobin was actually changing shape (called "sickling") due to a single amino acid error in hemoglobin S. Even though the underlying molecular cause of the disease was understood more than half a century ago, progress in translating this knowledge into improved patient care ha...

Sickle Cell Beta Thalassemia HbSC and HbSThal subjects tend to have substantially higher hematocrits than HbSS subjects, contributing to higher viscosity with potentially more pronounced vaso-occlusion in the retinal microvasculature during any given sickling event. From: Retina (Fourth Edition), 2006 Related terms: • Hemoglobinopathy • Thalassemia • Alpha-Thalassemia • Beta Thalassemia • Embryonic Hemoglobin • Sickle-Cell Disease • Erythrocyte • Patient John Old, in Emery and Rimoin's Principles and Practice of Medical Genetics (Sixth Edition), 2013 71.9.9.5 β-Thalassemia/Hb S Hb S/β-thalassemia is characterized by microcytic red and target cells with occasionally sickled forms. Hemoglobin electrophoresis reveals 60–90% Hb S, 0–30% Hb A, 1–20% Hb F, and an increased Hb A 2 level. The percentages of Hb S and Hb A vary depending on whether the β-thalassemia gene is β + or β o type. Coexisting α-thalassemia increases the Hb concentration, the MCV, and MCH. The clinical course of sickle-cell β-thalassemia is very variable, ranging from a disorder identical with sickle-cell anemia to a completely asymptomatic condition. The Hb concentration varies from 5g/dl to a level within the normal range. The heterogeneity is mostly due to the type of β-thalassemia mutation that is co-inherited. It tends to be very mild in Africans because of the likelihood of the co-inheritance of one of the three mild β + mutations commonly found in this racial group (−88, C→T; −29, A→G; CD24, T→A). How...

Sickle cell disease is an inherited blood disorder that affects the ability of red blood cells, or hemoglobin, to carry oxygen to the cells throughout the body. The disease mostly affects African-Americans, Hispanics, and people of Caribbean descent, though it has been found in individuals of Middle Eastern, Indian, Latin American, Native American, and Mediterranean heritage. Each year, an estimated 1,000 children are born with sickle cell disease in the United States. One in 12 African-Americans has the sickle cell trait. Symptoms and Crises All major organs can be affected by sickle cell disease. The spleen, in particular, suffers damage from the sickle cells blocking healthy oxygen-carrying cells. Without a normal functioning spleen, individuals with sickle cell are more at risk for infections. Infants and young children are at risk for life-threatening infections. Other risk factors include: • Acute Chest Syndrome: Also called sickling in the chest, can be a life-threatening complication of sickle cell disease; often occurs suddenly, when the body is under stress from infection, fever, or dehydration, causing the sickle cells to stick together and block the flow of oxygen in the tiny vessels of the lungs; resembles pneumonia and can include fever, pain, and a violent cough • Anemia: The most common symptom of all the sickle cell diseases; can make a person pale and tired when severe, due to reduced oxygenation of tissues; can delay normal growth and development • Jaund...