Hemoglobin

Alpha Thalassemia

Alpha Thalassemia, Hemoglobin H Disease, HbH Disease, Hemoglobin H Constant Spring Thalassemia, Non-Immune Hydrops Fetalis, Alpha Thalassemia Trait, Alpha Thalassemia Minor, Alpha Thalassemia Intermedia, Alpha Thalassemia Major, Hemoglobin Bart's Hydrops Syndrome

See Also

Epidemiology
Ethnicity

African descent (2% Incidence)
Asian patients (Incidence common)

Pathophysiology

See Hemoglobin Production
Autosomal Recessive trait affecting two genes on each of the two Chromosome 16
Results in decrease of absence of Hemoglobin Alpha chains and excess of beta chains
Images

Types

Asymptomatic
1. Alpha Thalassemia Silent Carrier (Alpha Thalassemia Minima)
  1. Chromosome 16 gene deletions: 1 of 4
  2. Normal Hemoglobin And Hematocrit
2. Alpha Thalassemia Trait (Alpha Thalassemia Minor)
  1. Chromosome 16 gene deletions: 2 of 4
  2. Peripheral Smear shows microcytosis
  3. Typically no Anemia (although Hemoglobin may be borderline low)
  4. MCV <80 fl
Moderate to severe symptoms
1. Alpha Thalassemia Intermedia (Deletional HbH Disease)
  1. Significant Hemoglobin H present (Hemoglobin composed of 4 beta chains)
  2. Chromosome 16 gene deletions: 3 of 4
  3. Mild to moderate Anemia (Hgb 6.9 to 10.7 g/dl, MCV 46 to 76 fl), with ineffective Erythropoiesis
  4. Associated with skeletal abnormalities
2. Hemoglobin Constant Spring (Non-Deletional HbH Disease)
  1. Mutant Allele results in decreased alpha-globin activity
  2. Reduced alpha globin output
  3. More severe than deletional HbH
  4. Moderate to severe Anemia (Hgb 6.9 to 10.7 g/dl, MCV 48 to 80 fl) often requiring transfusion
  5. Also associated Splenomegaly, Gallstones, growth retardation, decreased Bone Mineral Density
3. Alpha Thalassemia Major (Hemoglobin Bart, Non-Immune Hydrops Fetalis)
  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)
  4. Transfusion dependent if survives

Signs

Splenomegaly
1. Seen in Alpha Thalassemia Intermedia and higher

Labs

See Thalassemia
Microcytosis
1. Seen in Alpha Thalassemia Trait and higher
Hemolytic Anemia
1. Seen in Alpha Thalassemia Intermedia and higher
2. Typically more mild Anemia than seen in Beta Thalassemia
Hemoglobin Electrophoresis
1. See Thalassemia for findings

Management

See Thalassemia

Complications

See Thalassemia
Alpha Thalassemia Intermedia
1. Mild to moderate Hemolytic Anemia
Alpha Thalassemia Major
1. Non-Immune Hydrops Fetalis in utero (fatal)
2. In-Utero transfusions have been performed to prevent Non-Immune Hydrops Fetalis

References