MAPPING THE ALPHA-GLOBIN GENES IN AN ALGERIAN HBH PATIENT AND HIS FAMILY

  • 1 January 1980
    • journal article
    • research article
    • Vol. 55  (3) , 511-516
Abstract
The organization of .alpha.-globin genes in normal white European, normal Algerian and .alpha.-thalassemic Algerian DNA was examined by restriction endonuclease mapping using HindIII, Hpal, BamHl, EcoI, BGIII and Pstl. The results for normal DNA confirm and add to the findings of Surrey et al. and Orkin; the 2 .alpha.-genes are approximately 3.0 kb [ kilobases] apart. The restriction enzymes BgIII and HpaI cut between the 2 .alpha.-genes. Four PstI sites are located: 2 surrounding each .alpha.-gene. The physical maps for a number of Algerian controls (normal .alpha. and .beta.-globin biosynthesis profiles) are identical to that of the European controls. The Algerian .alpha.-thalassemic presenting with HbH disease was homozygous for a 3.5-3.7 kb deletion at the .alpha.-gene locus, leaving 1 .alpha.-gene per chromosome. The patient''s mother and father are heterozygous for this deletion. An unaffected sibling carries normal chromosomes. The deletion could be the result of a Lepore-like crossover fusion event between the 2 .alpha.-globin genes, or of a 3.7 kb deletion of the entire 5'' .alpha.-gene or the entire 3'' .alpha.-gene. The Algerian case of HbH disease studied differs from Asian cases in the mode of inheritance and the molecular pathology of the .alpha.-thalassemia mutation. If this type of deletion is the major cause of Algerian .alpha.-thalassemia, it would explain the apparent absence of hydrops fetalis in this geographical area.