Hemoglobin
Alpha Thalassemia
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Alpha Thalassemia
See Also
Thalassemia
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 A
lpha chains and excess of beta chains
Types
Asymptomatic
Alpha Thalassemia Silent Carrier
Chromosome
16 gene deletions: 1 of 4
Alpha Thalassemia Trait (Alpha Thalassemia Minor)
Chromosome
16 gene deletions: 2 of 4
Peripheral Smear
shows microcytosis without
Anemia
Mild symptoms
Hemoglobin
Constant Spring
Reduced alpha globin output
Moderate to severe symptoms
Alpha Thalassemia Intermedia
Significant
Hemoglobin H
present (
Hemoglobin
composed of 4 beta chains)
Chromosome
16 gene deletions: 3 of 4
Alpha Thalassemia Major
Significant
Hemoglobin Bart
's present (
Hemoglobin
composed of 4 gamma chains)
Chromosome
16 gene deletions: 4 of 4
Results in non-immune
Hydrops fetalis
(lethal in most cases)
Signs
Splenomegaly
Seen in Alpha Thalassemia Intermedia and higher
Labs
See
Thalassemia
Microcytosis
Seen in Alpha Thalassemia trait and higher
Hemolytic Anemia
Seen in Alpha Thalassemia Intermedia and higher
Typically more mild
Anemia
than seen in
Beta Thalassemia
Diagnosis
Hemoglobin
Electrophoresis
Complications
Alpha Thalassemia Intermedia
Mild to moderate
Hemolytic Anemia
Alpha Thalassemia Major
Hydrops fetalis
in utero (fatal)
References
Chui (2003) Blood 101(3):791-800 [PubMed]
Muncie (2009) Am Fam Physician 80(4): 339-44 [PubMed]
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