Hemoglobin bart's disease in an italian boy: Interaction between α-thalassemia and hereditary persistence of fetal hemoglobin

HEMOGLOBIN is a tetramer consisting of two pairs of globin chains, each of which is associated with a heme group. In adults, the predominant hemoglobin — hemoglobin A — is composed of two α-globin and two β-globin chains (α₂β₂); the principal fetal hemoglobin — hemoglobin F — is made up of two α-globin and two γ-globin chains (α₂γ₂). α-Globin chains are coded for by two adjacent α-globin genes on the short arm of each chromosome 16. The embryonic ζ-globin chains, which resemble α-globin chains, are coded for by a ζ-globin gene on.