These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Beta-thalassemia with exceptionally high hemoglobin A2. Differential expression of the delta-globin gene in the presence of beta-thalassemia.
    Author: Steinberg MH, Coleman MB, Adams JG.
    Journal: J Lab Clin Med; 1982 Oct; 100(4):548-57. PubMed ID: 6288819.
    Abstract:
    Hemoglobin A2 levels in normal adults are rarely greater than 3.5%. In patients heterozygous for beta-thalassemia, they average about 5% but do not usually exceed 7%. We studied a family in which four patients with heterozygous beta-thalassemia had HbA2 levels of 8.4% to 11.2%. Globin biosynthesis studies and restriction endonuclease mapping of the alpha-globin loci showed homozygous or heterozygous alpha-thalassemia-2 as well as beta-thalassemia in some family members. The delta- and beta-globin genes were examined by using the restriction enzymes Eco RI, Pvu II, and Xba I, which cut both within and outside the coding portions of the delta- and beta-loci. Only the expected delta- and beta-globin gene containing fragments were present, excluding a crossover event producing a fusion gene that would code for delta-globin but possibly be under the regulatory influence of nucleotide sequences that control the expression of the beta-gene. This kindred provides evidence that in the presence of beta-thalassemia, expression of the delta-gene, beyond that commonly seen, is possible. This could be a direct result of the gene defect producing beta-thalassemia or be due to differences in the delta-globin gene linked to this beta-thalassemia gene. The interactions of alpha- and beta-thalassemia may alter tetramer assembly and increase HbA2 levels; however, this possibility seems less likely.
    [Abstract] [Full Text] [Related] [New Search]