Hemoglobina Fetal (HbF): Estrutura, Função e Significado Clínico

Fetal hemoglobin (HbF, α₂γ₂) is the primary oxygen carrier during fetal life, replacing embryonic hemoglobins by 10–12 weeks gestation.

Key Properties

• Structure: Two α-globin and two γ-globin chains (vs. adult HbA: α₂β₂).
• High oxygen affinity: Left-shifted dissociation curve due to low 2,3-BPG binding—facilitates placental oxygen transfer.
• Alkaline resistance: Stable in the fetal alkaline environment.
• Production timeline: Liver/spleen → bone marrow; declines postnatally to <1% by 6–12 months.

Clinical Relevance

• Hereditary persistence of HbF (HPFH): Benign condition with elevated HbF in adulthood.
• Therapeutic induction: Hydroxyurea increases HbF in sickle cell disease and β-thalassemia, reducing sickling and globin imbalance.
• Diagnostic marker: Elevated HbF seen in β-thalassemia, HPFH, and some leukemias.

HbF ensures fetal oxygenation; its pharmacologic reactivation is a cornerstone of hemoglobinopathy treatment.