Observations on the levels of Hb A2 in patients with different β-thalassemia mutations and a δ chain variant

J. F. Codrington, H. W. Li, F. Kutlar, L. H. Gu, M. Ramachandran, T. H.J. Huisman

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


Hb A2 and its variant B22δ2 16(A13)Gly→Arg) were quantitated in the blood of subjects with three different types of β-thalassemia and with the δ-B2 anomaly in cis or in trans to the β-thalassemia determinant. In one family, the δ-B2 mutation was in cis to a newly discovered codon 47 (+A) frameshift. The levels of Hbs A2 and B2 were nearly the same and approximately 70% higher than those in simple Hb B2 heterozygotes. In two additional families, the δ-B2 variant was in trans to either a deletion β-thalassemia (1,393 bp) involving part of the β-globin gene and part of the β-globin gene promoter, or to the - 88 C→T promoter mutation. In both instances, the Hb B2 level was increased by approximately 80%, but the Hb A2 level was increased by approximately 270% and 200%, respectively. These data indicate two mechanisms that will cause an increase in δ chain production. One is consistent with a general mechanism concerning the relative excess of α chains in β chain deficiencies which will combine with δ chains to form variable levels of Hb A2 dependent on the severity of the β chain deficiency. The second concerns the loss of β-globin gene promoter activity, perhaps by an absence of (or decreased) binding of specific protein(s) to this segment of DNA and a concomitant increase in δ-globin gene promoter activity in cis.

Original languageEnglish (US)
Pages (from-to)1246-1249
Number of pages4
Issue number6
StatePublished - 1990
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology


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