Cord blood findings show HbB 95%, HbP 5%, HbA 0%, HbA2 0%, HbF 0%; Hgb 30 g/L; RBC 1.9 x 10^12/L; MCV 60 fL; what is the presumptive diagnosis?

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Multiple Choice

Cord blood findings show HbB 95%, HbP 5%, HbA 0%, HbA2 0%, HbF 0%; Hgb 30 g/L; RBC 1.9 x 10^12/L; MCV 60 fL; what is the presumptive diagnosis?

This pattern shows the fetus cannot make alpha globin chains. In cord blood, predominance of Hb Bart’s (gamma4) with little to no HbA or HbA2 means all four alpha-globin genes are deleted (--/--). Hb Bart’s is the abnormal hemoglobin that forms when gamma chains pair without any alpha chains, and its dominance in the sample plus the absence of other adult hemoglobins points to alpha-thalassemia major causing hydrops fetalis. The severe anemia (very low hemoglobin and low RBC count) and microcytosis (low MCV) further reflect the profound ineffective erythropoiesis seen in this condition. Thus the presumptive diagnosis is alpha-thalassemia major with hydrops fetalis. Sideroblastic anemia and iron deficiency anemia would not show a dominant Hb Bart’s pattern; beta-thalassemia major would typically involve presence of HbA and elevated HbF after birth, not the near-absence of all HbA and HbA2 seen here.

This pattern shows the fetus cannot make alpha globin chains. In cord blood, predominance of Hb Bart’s (gamma4) with little to no HbA or HbA2 means all four alpha-globin genes are deleted (--/--). Hb Bart’s is the abnormal hemoglobin that forms when gamma chains pair without any alpha chains, and its dominance in the sample plus the absence of other adult hemoglobins points to alpha-thalassemia major causing hydrops fetalis. The severe anemia (very low hemoglobin and low RBC count) and microcytosis (low MCV) further reflect the profound ineffective erythropoiesis seen in this condition. Thus the presumptive diagnosis is alpha-thalassemia major with hydrops fetalis.

Sideroblastic anemia and iron deficiency anemia would not show a dominant Hb Bart’s pattern; beta-thalassemia major would typically involve presence of HbA and elevated HbF after birth, not the near-absence of all HbA and HbA2 seen here.

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