Human Embryonic ζ-Globin Chains in Fetal and Newborn Blood

A sensitive and specific radioimmunoassay (RIA) for human embryonic ζ-globin chains was used to study normal fetal blood and newborn cord blood as well as cord blood from newborns with α-thalassemias. From 17 weeks until 37 weeks of gestation, ζ-globin chains were present in almost all fetal and cord blood samples (0.27% ± 0.15% in samples of weeks 17 through 30; 0.14% ± 0.11% in samples of weeks 31 through 37). ζ-Globin chains were present in >80% of cord blood hemolysates from normal, full-term newborns (0.15% ± 0.11%) as well as from 16 near-term newborns of diabetic mothers (0.13% ± 0.13%). ζ-Globin chains were not detected in normal infants aged 3 months to 2 years. In cord blood hemolysates from α-thalassemic newborns, the levels of ζ-globin chain content varied from very high to undetectable levels. Gene mapping of the ζ-α-globin gene cluster was performed in 12 newborns in whom cord blood ζ-globin chains had been determined. Newborns who were carriers of α-thalassemia-1 due to the (–SEA/) deletion had very high levels of ζ-globin chains (>1.5%).