The hemoglobin molecule is a tetramer consisting of two α-globin-like polypeptide chains and two β-globin-like chains. The human hemoglobin genes are expressed in a tightly developmentally controlled fashion.ε-globin (HBE1) is the predominantly expressed gene during the embryonic stage. The epsilon hemoglobin chain seems to be the best marker for fetal nucleated red blood cells (NRBCs). Anti-HBE1 may be used to label and isolate fetal cells from maternal blood and can be useful in prenatal diagnosis. This antibody specifically recognizes the HBE1 and doesn't cross-react with other globin chains.