Thalassemias are blood disorders that affect the
body’s ability to produce hemoglobin and red blood cells. Red blood cells
transport oxygen throughout the body; hemoglobin is the protein in red blood
cells that actually carries the oxygen.
People who have thalassemia produce fewer healthy
hemoglobin proteins, and their bone marrow produces fewer healthy red blood
cells. With too few normal red blood cells, not enough hemoglobin is available
to help carry oxygen to the body.
Thalassemias can cause mild or severe anemia and other
complications that can occur over time. Symptoms of anemia include fatigue,
difficulty breathing, dizziness, and a pale skin tone.
Who is at risk for thalassemias?
Thalassemias occur more often among certain
ethnicities, including people of Italian, Greek, Middle Eastern, Asian, and
African descent. Thalassemias are an inherited disorder, which means they are
passed from parents to their children.
What are the types of thalassemia?
Four protein chains make up hemoglobin—two alpha globin and two beta globin chains.
There are two major types of thalassemia -- alpha thalassemia and beta thalassemia -- named after defects that can occur in these protein chains.
Alpha Thalassemia
Four genes, two from each parent, are required to make
alpha globin protein chains. When one or more genes are missing, it produces
alpha thalassemia. This chart describes the different types of alpha thalassemia.
| Missing alpha genes | Disorder | Anemia symptoms | Other names |
|---|
| 1 | silent carrier | none | Alpha thalassemia - 2 trait, alpha thalassemia minima |
| 2 | trait | mild | Alpha thalassemia - 1 trait, alpha thalassemia minor |
| 3 | Hemoglobin H | moderate | Hemoglobin H disease |
| 4 | major | fatal | Hydrops fetalis with Hemoglobin Barts |
What are the symptoms of alpha thalassemia?
People who are missing one alpha gene (silent
carriers) usually don’t have any symptoms. Hemoglobin H disease often causes
symptoms at birth and may cause moderate to severe lifelong anemia.
Beta Thalassemia
There are normally two beta globin genes, one from
each parent. Beta thalassemia is a change in one or both of the beta globin
genes. This chart describes the different types of beta thalassemia.
| Affected beta genes | Disorder | Anemia symptoms | Other names |
|---|
| 1 | silent carrier | mild | Beta thalassemia minor |
| 1 | trait | mild | |
| 2 | intermedia | moderate | |
| 2 | major | severe | Cooley's anemia |
What are the symptoms of beta thalassemia?
Symptoms of beta thalassemia include growth problems,
bone abnormalities such as osteoporosis, and an enlarged spleen (the organ in
the abdomen that plays a part in fighting infection).