Thalassemia consists of a group of inherited diseases of the blood. About 100,000 babies worldwide are born with severe forms of the disease each year. Thalassemia occurs most frequently in people of Italian, Greek, Middle Eastern, Southern Asian and African ancestry.

What Are the Different Kinds of Thalassemia?
Thalassemia includes a number of different forms of anemia (red blood cell deficiency). The two main types are called alpha and beta thalassemias, depending on which part of an oxygen-carrying protein (called hemoglobin) is lacking in the red blood cells.

The most severe form of alpha thalassemia, which affects mainly individuals of Southeast Asian, Chinese and Filipino ancestry, results in fetal or newborn death. Most individuals with alpha thalassemia have milder forms of the disease, with varying degrees of anemia.

The remainder of this information sheet focuses on beta thalassemias, which range from very severe to having no effect on health.

• Thalassemia major, the most severe form, is also called Cooley's anemia, named after the doctor who first described it in 1925.
• Thalassemia intermedia is a mild Cooley's anemia.
• Thalassemia minor (also called thalassemia trait) may cause no symptoms, but changes in the blood do occur.

How Does Thalassemia Affect a Child?
Most children with thalassemia major appear healthy at birth, but during the first year or two of life they become pale, listless and fussy, and have a poor appetite. They grow slowly and often develop jaundice (yellowing of the skin).

Without treatment, the spleen, liver, and heart soon become greatly enlarged. Bones become thin and brittle; face bones become distorted, and children with thalassemia often look alike. Heart failure and infection are the leading causes of death among children with untreated thalassemia major.

Children with thalassemia intermedia may develop some of the same complications, although in most cases, the course of the disease is mild for the first two decades of life.

How Is the Disease Transmitted?
All forms of thalassemia are transmitted only through heredity. It cannot be caught from another child who has it. The disease is passed on through parents who carry the thalassemia gene in their cells. A "carrier" has one normal gene and one thalassemia gene in all body cells, a state sometimes called "thalassemia trait." Most carriers lead completely normal, healthy lives.

When two carriers become parents, there is a one-in-four chance that any child they have will inherit a thalassemia gene from each parent and have a severe form of the disease. There is a two-in-four chance that the child will inherit one of each kind of gene and become a carrier like its parents; and a one-in-four chance that the child will inherit two normal genes from its parents and be completely free of the disease or carrier state. These odds are the same for each pregnancy when both parents are carriers.

Information provided by the March of Dimes