Hemoglobin A2 is comprised of 2 alpha and 2 delta globin chains. Hemoglobin A2 usually represents 1.5 to 3% of total hemoglobin.


Conditions associated with reduced hemoglobin A2:

(1) iron deficiency anemia

(2) hemoglobinopathies:

(2a) heterozygous hemoglobin Lepore

(2b) heterozygous hereditary persistence of hemoglobin F (HPHF), deletional type

(2c) a variant hemoglobin A2

(3) thalassemias

(3a) alpha-thalassemia

(3b) delta-beta thalassemia

(3c) delta thalassemia

(4) hematologic disorders:

(4a) sideroblastic anemia

(4b) juvenile chronic granulocytic leukemia

(4c) acute myeloid leukemia


The expected decrease in hemoglobin A2 may be masked if there is a concurrent condition that increases hemoglobin A2 (sse previous section).


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