Changes in the G gamma- and A gamma-globin mRNA components of fetal hemoglobin during human development.

To determine the postnatal developmental changes in (G)gamma- and (A)gamma-globin mRNAs of HbF, blood samples were obtained from 28 pre-term infants born at < or = 33 weeks of gestation (27.9 +/- 2.5), 9 term-born infants and 26 adults. Adult samples were used to determine the relationship between the levels (G)gamma- and (A)gamma-mRNAs of HbF and the-158 (C-->T) variation in the promoter region of the (G)gamma-globin gene. The results showed that (G)gamma-globin mRNA to total gamma-globin mRNAs remained around 66% (66.2 +/- 4) until the 44 week of postconceptual age when a change in the (G)gamma- and (A)gamma-globin mRNA proportions occurred. The immature red cells of adults had a range of (G)gamma-globin mRNA to total gamma-globin mRNAs varying from 20 to 74% (53.1 +/- 16.9). The high levels of (G)gamma-globin mRNA to total gamma-globin mRNAs are associated with the presence of a -158 (C-->T) polymorphism. The gene frequency of polymorphism was 0.32.