Pre-Conception: Genetic Hemoglobin Disorders: Hemoglobinopathies and Thalessemias
Hemoglobin is a protein that binds and releases oxygen. Found in all red blood cells (RBCs), hemoglobin transports oxygen throughout the body and releases it to the cells and tissues. Each person inherits genes that make hemoglobin from both parents. Some individuals inherit abnormal genes that can cause hemoglobin disorders. In diseases called thalassemias, the hemoglobin genes make normal hemoglobin but not enough to supply the body with sufficient oxygen. Inheriting one or more thalassemia genes from one or both parents can cause mild to severe anemia and the production of smaller and paler RBCs.
In diseases called hemoglobinopathies, the hemoglobin genes make abnormal hemoglobin that may not function like normal hemoglobin. It usually takes two abnormal genes, one from each parent, to cause disease. The best known example is sickle cell disease, a serious hemoglobinopathy that causes anemia, susceptibility to infection, and organ damage in affected infants. Carriers of the sickle cell disease (those who have inherited only one sickle hemoglobin gene) do not get the disease but can pass their abnormal gene on to their children. If a carrier of the disease has a child with another carrier, their child is at risk of inheriting the sickle cell gene from each parent and having the disease.
If a woman or her partner has a strong family history of thalassemia or hemoglobinopathy or is of an ethnicity that has an increased prevalence of one of the diseases, she and her partner may want to talk to a genetic counselor about genetic testing before the pregnancy. For example, sickle cell disease is most common in people of African heritage. Thalassemias are most common in people of Mediterranean, African, or Asian descent.