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Table 20-4

Findings in Thalassemiaa

GenotypebLab/Clinical FindingsSpecifics
α-Thalassemias
Silent carrier-α/ααNormal or slight microcytosisAsymptomatic; 25%-30% of African Americans
α-Thalassemia trait

  • - -/αα (Asian)

  • -α/-α (African)

  • Mild microcytic, hypochromic

  • Normal Hb electrophoresis

  • Asymptomatic anemia not treatable with iron

  • Both genotypes identical clinically; position of deleted genes determines severity in offspring (- -/αα at risk for fetus with HbH or hydrops)

HbH disease- -/-α

  • Moderate to severe microcytic, hypochromic anemia (Hb 8-10 g/dL)

  • ↑reticulocytes (5%-10%)

  • HbH = 2%-40%; ↓ HbA2, HbF normal

  • Normal serum iron

  • Heinz bodies on peripheral smear

  • Splenomegaly, bony abnormalities

  • Anemia worsens during pregnancy, infection, and with oxidant drugs.

  • Treat with long-term transfusion, splenectomy, and iron chelation.

  • May have cholelithiasis

Hydrops fetalis (Hb Bart disease)- -/- -

  • Marked anemia (Hb 3-10), ↑ nucleated erythrocytes, 80%-90% Hb Bart; 10%-20% HbH, no HbA

  • Hydrops, heart failure, pulmonary edema, transverse limb reduction defects, hypospadias

  • Diagnosis often made in pregnancy by sonogram noting hydropic fetus

  • Usually results in death

  • Survival possible with intrauterine transfusion

β-Thalassemias
β-Thalassemia minorβ0/β

  • Asymptomatic or mild microcytic anemia (Hb 8-10 g/dL)

  • ↑HbA2, ↑ HbF, ↓ HbA

  • Heterozygous

  • Confers resistance to falciparum malaria

  • Often misdiagnosed as iron deficient

β-Thalassemia traitβ+/β

  • Mild or no anemia

  • Basophilic stippling↔↑ erythrocytes

  • No splenomegaly, MCV 60 to normal

β-Thalassemia intermediaVaries, 2 β mutations (at least 1 mild)

  • Mild to moderate anemia

  • Prominent splenomegaly, bony deformities, growth retardation, iron overload

  • Clinical diagnosis

  • May be asymptomatic to severely symptomatic

  • Present with symptoms later in life

  • Chronic transfusions not required

Thalassemia major (Cooley anemia)

  • β0/β0

  • β+/β+

  • Hb as low as 2-3 g/dL

  • MCV ,67 fL

  • ↓reticulocytes

  • ↑↑HbF, variable HbA2, no HbA

  • ↑HbF, ↓ HbA, variable HbA2

  • Splenomegaly; bone changes (increased hematopoiesis), severe iron overload

  • Homozygous

  • Severity depends on amount of globin produced (β0/β0 more severe—no globin)

  • Manifests at age 6-9 months when HbF changes to HbA

  • With transfusions and chelation, may survive into third to fifth decade

  • Die young from infectious or cardiac complications

Abbreviations: ↓, decreased; ↑, increased; ↔, unchanged; Hb, hemoglobin; MCV, mean corpuscular volume.


aAdapted with permission from American College of Obstetricians and Gynecologists Committee on Practice Bulletins—Obstetrics. ACOG Practice Bulletin No. 78: hemoglobinopathies in pregnancy. Obstet Gynecol. 2007;109(1):229-237. (Reaffirmed 2018). Copyright © 2007 by The American College of Obstetricians and Gynecologists.
bGenotype: β and δ—single gene per chromosome. α Gene is duplicated producing two genes per haploid and four per diploid.