thalassemia, alpha

thalassemia, alpha A form of thalassemia that involves the hemoglobin alpha chain. If a fetus inherits two genes for alpha thalassemia, one from each parent, the disorder is lethal before birth: No alpha chains can be made, and without alpha chains, there can be no fetal hemoglobin. If the fetus inherits only one alpha thalassemia gene, it will survive and have no or few symptoms as a child, as there is another gene that is still able to make alpha chains. See also thalassemia.