Distinctive swann blood group genotypes: Molecular investigations

Background and Objectives: Phenotypically, Sw(a+) erythrocytes have been cl assified as either 700:4,41 or 700:4,-41. Since anti-700.4, in particular, and sometimes anti-700.41 are contained in reagents defining other low-inci dence antigens that are members of the Diego blood group system, we underto ok the current investigation in an attempt to establish whether or not Swan n antigens are also Diego system members. Materials and Methods: DNA from t he members of th ree un related kind reds whose red cells type as Sw(a+) wa s isolated and analyzed for variation in SLC4A1 (solute carrier family, ani on exchanger member 1 gene) by single-strand conformational polymorphism (S SCP) and DNA sequence analyses. Results: Polymerase chain reaction-amplifie d exon 16 SLC4A1 products from the DNA of all Sw(a+) individuals displayed a mobility shift by SSCP. A similar mobility shift was not observed in the DNA from Sw(a-) family members or in the amplified DNA from control individ uals. DNA sequencing revealed different mutations, CGG-->CAG and CGG-->TGG, that result in Arg646Gln and Arg646Trp substitutions in erythroid protein band 3, respectively. Conclusion: Through genotypic analyses, we have chara cterized two point mutations related to the Swann blood group. The possible relationship between the resultant amino acid substitutions and the expres sion of Swann antigens has been discussed. Copyright (C) 2000 S. Karger AG, Basel.