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Pathology - α-thalassemia trait
α-thalassemia trait (minor), a disease of α-chain synthesis more typically reported in African American and southeastern Asian cultures. In this variation, two α-chain deletions exist. In African Americans, the losses are on separate chromosomes (α/- α/-), but the losses are on the same chromosome (-/- α/α) in Asians. The lack of two chains results in a global drop in all normal adult hemoglobin synthesis (HbA, HbA 2 , HbF); consequently, the electrophoresis is normal (relative quantities are the same as all hemoglobin types require the α-chain and are equally affected). With normal ferritin, the diagnosis is made by microcytic anemia and an elevated erythrocyte count, which is peculiar to thalassemias in anemias. Teardrop erythrocytes are a result of membrane damage due to removal of excess globin. Other α-thalassemias result from deletion of one, three, and four α-chains. One deletion produces an asymptomatic carrier without anemia. Three deletions generate hemoglobin H (HbH) illness, which produces a severe hemolytic anemia with HbH (four β-chains) identifiable by electrophoresis. Four deletions resulted in hemoglobin Bart (four γ-chains) illness, which creates hydrops fetalis in utero and is incompatible with life.
α-thalassemia trait (minor), a disease of α-chain synthesis more typically reported in African American and southeastern Asian cultures. In this variation, two α-chain deletions exist. In African Americans, the losses are on separate chromosomes (α/- α/-), but the losses are on the same chromosome (-/- α/α) in Asians. The lack of two chains results in a global drop in all normal adult hemoglobin synthesis (HbA, HbA 2 , HbF); consequently, the electrophoresis is normal (relative quantities are the same as all hemoglobin types require the α-chain and are equally affected). With normal ferritin, the diagnosis is made by microcytic anemia and an elevated erythrocyte count, which is peculiar to thalassemias in anemias. Teardrop erythrocytes are a result of membrane damage due to removal of excess globin. Other α-thalassemias result from deletion of one, three, and four α-chains. One deletion produces an asymptomatic carrier without anemia. Three deletions generate hemoglobin H (HbH) illness, which produces a severe hemolytic anemia with HbH (four β-chains) identifiable by electrophoresis. Four deletions resulted in hemoglobin Bart (four γ-chains) illness, which creates hydrops fetalis in utero and is incompatible with life.
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