Other types of hemoglobinopathies result from reduced production of hemoglobin proteins that otherwise are normal. This hemoglobin is found most commonly in people of African ancestry. Hemoglobin E this hemoglobin varient is found commonly in people of Asian descent. This variant hemoglobin produces few, if any problems. A significant exception is the co-inheritance of hemoglobin E and beta thalassemia.
Fetal hemoglobin arises from a gene different from that which produces hemoglobin.
The genes for hemoglobin F and hemoglobin A are closely related, however. Hemoglobin F production falls dramatically after birth, although some people continue to produce small amounts of hemoglobin F for their entire lives. The thalassemias are a group of disorders in which the normal hemoglobin protein is produced in lower amounts than usual. The thalassemias are a complex group of disorders because of the genetics of hemoglobin production and the structure of the hemoglobin molecule. This refers to a condition in which a person has inherited two genes for hemoglobin S, one from each parent.