Beta-thalassemia major and beta-thalassemia intermedia are usually inherited in an autosomal recessive manner, which means both copies of the HBB gene in each cell have mutations. The parents of a person with an autosomal recessive condition each carry one copy of the mutated gene and are referred to as carriers. When two carriers have children, each child has a 25% (1 in 4) chance to be affected, a 50% (1 in 2) chance to be a carrier like each parent, and a 25% (1 in 4) chance to be unaffected and not be a carrier. Sometimes, people with only one HBB gene mutation in each cell (carriers) do have mild anemia. These people are said to have ‘beta-thalassemia minor’ or ‘beta-thalassemia trait.
Beta thalassemia is most often found in persons who are of Mediterranean ancestry (Greek or Italian). Each child of two carrier parents is at 25 percent risk for the disease. Carrier status can be determined by the following:
- Complete blood count (CBC) – a measurement of size, number, and maturity of different blood cells in a specific volume of blood.
- Hemoglobin electrophoresis with A2 quantitation – a lab procedure that differentiates the types of hemoglobin present
These studies can be performed from a single blood sample. Prenatal diagnosis is determined from CVS (chorionic villus sampling) or amniocentesis. Treatment for beta thalassemia may include:
- Regular blood transfusions
- Medications (to decrease amount of iron in the body, called chelation therapy)
- Surgical removal of the spleen (if necessary)
- Daily doses of folic acid
- Possible surgical removal of the gallbladder
- No iron supplements
- Bone marrow transplantation