As mentioned previously, gene deletions that cause alpha thalassemia can be homozygous or heterozygous deletions. Homozygous alpha thalassemia (alpha thalassemia major), also known as hydrops fetalis, is a lethal hemoglobin disorder which usually results in stillborn infants. In this condition, both alpha chain loci on each chromosome of the pair are deleted, resulting in a total absence of alpha chains. These chains are needed for all normal hemoglobins.
If born live, infants with alpha thalassemia major exhibit hepatosplenomegaly, ascites, edema, low birth weight and die within a few hours. Ethnic groups most commonly associated with this form of alpha thalassemia include those of primarily Southeast Asian and occasionally Mediterranean decent.