Fetal hemoglobin in sickle cell anemia: relation to regulatory sequences cis to the beta-globin gene. Multicenter Study of Hydroxyurea

Blood. 1996 Feb 15;87(4):1604-11.


Very different fetal hemoglobin levels among adult sickle cell anemia patients suggest genetic modulation of gamma-globin gene expression. In sickle cell anemia, different fetal hemoglobin levels are associated with distinct beta-globin gene haplotypes. Haplotype may be a marker for linked DNA that modulates gamma-globin gene expression. From 295 individuals with sickle cell anemia, we chose for detailed studies 53 patients who had the highest or the lowest fetal hemoglobin levels and 7 patients whose fetal hemoglobin levels were atypical of their haplotype. In these individuals, we examined portions of the beta-globin gene locus control region hypersensitive sites two and three, an (AT)x(T)y repeat 5' to the beta-globin gene, a 4-bp deletion 5' to the A gamma T gene, promoters of both gamma-globin genes, 5' flanking region of the G gamma-globin gene, and A gamma-globin gene IVS-II. Of the regions we studied all polymorphisms were always haplotype-linked and no additional mutations were present. This suggested that variations in these areas are uncommon mechanisms of fetal hemoglobin modulation in sickle cell anemia. Whereas unexamined cis-acting sequences may regulate gamma-globin gene transcription, trans-acting factors may play a more important role.

Publication types

  • Multicenter Study
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Anemia, Sickle Cell / genetics*
  • Base Sequence
  • DNA Primers
  • Fetal Hemoglobin / genetics*
  • Gene Expression Regulation
  • Globins / genetics*
  • Haplotypes
  • Humans
  • Hydroxyurea / therapeutic use
  • Molecular Sequence Data
  • Regulatory Sequences, Nucleic Acid*


  • DNA Primers
  • Globins
  • Fetal Hemoglobin
  • Hydroxyurea