Deleting two of four alpha chain gene loci results in a minor alpha thalassemia. The deletions may be heterozygous (two on the same chromosome, inherited from either mother or father) or homozygous (one from each of two chromosomes, inherited from both mother and father). Alpha thalassemia minor is not a clinical disease but may be discovered upon routine testing.
Both the heterozygous and homozygous forms of alpha thalassemia minor are common in Southeast Asians. The homozygous form has also been shown in African Americans.
