n WHAT IS THALASSEMIA? Thalassemia is a group of inherited blood disorders that affect the body’s ability to produce normal hemoglobin. Hemoglobin is a protein in the blood that carries oxygen to the cells in the body. To understand how thalassemia affects the body, it helps to know a little more about blood.
n WHAT IS BLOOD? Blood is a mixture of cells, proteins, and a watery substance called plasma. Blood cells are made in our bone marrow, the sponge-like center in the skull, spine, pelvis, and rib bones. Similar to water being pumped through a hose, the heart pumps blood through small tubes called blood vessels. There are two types of blood vessels: arteries and veins. The arteries carry blood away from the heart and bring oxygen to the body’s tissues. The veins then return the oxygen-poor blood from the tissues back to the heart. Blood carries nutrients to and from the tissues and organs. Blood also helps fight infection and heal wounds. Blood has four major components:
• Red blood cells—Red blood cells pick up the oxygen we breathe in while traveling through the small blood vessels of the lungs. They deliver the oxygen to all the cells in the body’s tissues and organs. The body’s cells use the oxygen and create carbon dioxide, which is a waste product. The red blood cells then pick up the carbon dioxide and deliver it to the lungs, where it is exhaled from the body. • White blood cells—White blood cells are part of the immune system and protect the body from infection. • Platelets—Platelets help stop bleeding by forming a plug after skin or tissue has been injured. • Plasma—Plasma is a yellowish liquid that is mostly water. It helps white blood cells, red blood cells, and platelets to flow freely through the blood vessels. Plasma also carries nutrients, hormones, proteins, and waste products around the body. n WHAT CAUSES THALASSEMIA? Genes are passed along from parents to their children. Genes determine all the traits and characteristics of the body. We have tens of thousands of genes, which are located on 46 chromosomes. These chromosomes work in pairs with half of the pair inherited from the father and half from the mother. These pairs are numbered 1 through 23. Hemoglobin is the protein in red blood cells that carries oxygen. In order for the body to produce hemoglobin normally, we need two types of genes: alpha ( α ) globin and beta ( β ) globin. Normally, a child inherits two alpha globin genes from each parent and one beta globin gene from each parent. The alpha globin genes are divided, two on each half of chromosome 16. There is one beta globin gene on each half of chromosome 11. Thalassemia occurs when one or more of these inherited genes are missing or abnormal. The missing or abnormal genes will decrease the amount of hemoglobin made by the body. When the amount of hemoglobin is low, it is called anemia . The severity of the anemia depends on how many genes are missing or abnormal. Mild anemia may go undetected, but severe anemia can cause a person to be very tired and make activity difficult.
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