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alpha thalassemia-2 (alpha-thalassemia trait, trans form)

Epidemiology: - found in African American populations Genetics: 1) - alpha/ - alpha (2 of 4 functional alpha globin genes) 2) one functional alpha globin gene on each (chromosome 1 & chromosome 16) (affected genes on different chromosomes) Clinical manifestations: 1) asymptomatic carrier state 2) hydrops fetalis unlikely Laboratory: 1) complete blood count a) mild anemia: blood hemoglobin 12-13 g/dL; 10 g/dL [3] b) MCV 70-80 fL (microcytosis); case presented with MCV of 62 fL [3] 2) peripheral smear: rare red blood cell inclusions 3) hemoglobin electrophoresis: - Hgb A (85-95%) - hemoglobin A2 normal - hemoglobin F normal [3]

References

  1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 585-86
  2. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 651
  3. Medical Knowledge Self Assessment Program (MKSAP) 18, 19 American College of Physicians, Philadelphia 2018, 2022