Frequency and Quantitative Levels of ^Tγ Chain (Hb F Sardinia) in the Fetal Hemoglobin of Newborn and Fetuses

Abstract

The fetal hemoglobin of 137 Dutch newborn has been examined by peptide mapping after digestion with trypsin, in order to detect the ^Tγ chain (γ chain bearing a replacement lle→Thr at position 75) and to assess its quantity relative to the total γ chains. Forty-two (31%) individuals were carriers of this variant, with an average amount of ^Tγ chain equal to 18.89% ± 4.12 (1 SD). Three babies had ^Tγ levels higher than 30%, outside, therefore, the upper limit of the distribution. If we consider these three children homozygous carriers and assume that the remaining thirty-nine are heterozygotes, the gene frequency of ^Tγ in this population is 0.16 and the observed frequencies of the three phenotypes (^Tγ-/-, ^Tγ+/- and ^Tγ+/+) agree closely with the expected ones.