Analysis of the 5' flanking sequence of the G gamma globin gene by denaturing gradient gel electrophoresis confirms the heterogeneity of the Bantu beta S haplotype.

The GC-->TT polymorphism recently described at positions -1106 and -1105 in the 5' flanking region of the G gamma globin gene for the Bantu beta S haplotype was analysed by denaturing gradient gel electrophoresis. We studied 108 beta S chromosome and 122 beta A chromosomes. The TT sequence was found as follows: in all of 80 chromosomes bearing the Bantu beta S haplotype with the 6-bp deletion -400 nt from the G gamma gene in 3 out of 5 Bantu beta S chromosomes without the deletion, in 1 out of 122 beta A chromosomes from different ethnic origins but in none of 23 beta S chromosomes bearing the Senegal, Benin or Cameroon haplotypes. These results confirm the heterogeneity of the Bantu beta S haplotype and allow a tentative evolutionary sequence for the different alleles at this locus to be presented.