Alpha Thalassemia

1. See Also
   1. Thalassemia
2. Epidemiology: Ethnicity
   1. African descent (2% Incidence)
   2. Asian patients (Incidence common)
3. Pathophysiology
   1. See Hemoglobin Production
   2. Autosomal recessive trait affecting two genes on each of the two Chromosome 16
   3. Results in decrease of absence of Hemoglobin Alpha chains and excess of beta chains
4. Types
   1. Asymptomatic
      1. Alpha Thalassemia Silent Carrier
         1. Chromosome 16 gene deletions: 1 of 4
      2. Alpha Thalassemia Trait (Alpha Thalassemia Minor)
         1. Chromosome 16 gene deletions: 2 of 4
         2. Peripheral Smear shows microcytosis without Anemia
   2. Mild symptoms
      1. Hemoglobin Constant Spring
         1. Reduced alpha globin output
   3. Moderate to severe symptoms
      1. Alpha Thalassemia Intermedia
         1. Significant Hemoglobin H present (Hemoglobin composed of 4 beta chains)
         2. Chromosome 16 gene deletions: 3 of 4
      2. Alpha Thalassemia Major
         1. Significant Hemoglobin Bart's present (Hemoglobin composed of 4 gamma chains)
         2. Chromosome 16 gene deletions: 4 of 4
         3. Results in non-immune Hydrops fetalis (lethal in most cases)
5. Signs
   1. Splenomegaly
      1. Seen in Alpha Thalassemia Intermedia and higher
6. Labs
   1. See Thalassemia
   2. Microcytosis
      1. Seen in Alpha Thalassemia trait and higher
   3. Hemolytic Anemia
      1. Seen in Alpha Thalassemia Intermedia and higher
      2. Typically more mild Anemia than seen in Beta Thalassemia
7. Diagnosis
   1. Hemoglobin Electrophoresis
8. Complications
   1. Alpha Thalassemia Intermedia
      1. Mild to moderate Hemolytic Anemia
   2. Alpha Thalassemia Major
      1. Hydrops fetalis in utero (fatal)
9. References
   1. Chui (2003) Blood 101(3):791-800
   2. Muncie (2009) Am Fam Physician 80(4): 339-44