Analysis in non-human primates reveals that the ancestral Band 3 gene encodes Dib and the Band 3-Memphis phenotype.

Background: The anion exchanger, Band 3, carries antigens in the Diego blood group system, and can carry the Band 3-Memphis phenotype. Although Di(b) is of high prevalence and Band 3-Memphis is of low prevalence in humans, it has been suggested that both are on the ancestral gene. We determined the orthologue nucleotide sequences corresponding to these two polymorphic sites, Di(a)/Di(b) (2561T > C; Leu854Pro) and Band 3-Memphis(166A > G; Lys56Glu) in several nonhuman primates.

Methods: Genomic DNA was extracted from blood samples of great apes, lesser apes, old world monkeys, new world monkeys and prosimians. PCR amplifications were done with primer pairs that were located in the flanking intronic regions of Exon 4 and Exon 19; and the amplified products were sequenced.

Results: Amino acid sequence alignment of nonhuman primates band 3 with that of human showed extensive homologies. In exon 4, Glu56Lys polymorphic site showed Glu similar to Band 3-Memphis type and in exon 19, Leu854Pro polymorphic site showed Pro indicating Di(b) phenotype.

Conclusions: The nonhuman primates have nucleotide sequences of Di(b)(2561C) in cis to Band 3-Memphis (166G), which is consistent with the assertion that the Di(b) and Band 3-Memphis phenotype represents the ancestral Band 3 gene.