Amino acid substitutions in human erythroid protein band 3 account for thelow-incidence antigens NFLD and BOW

BACKGROUND: The low-incidence red cell antigens NFLD (700.37) and BOW (700. 46) were first described in 1984 and 1988, respectively. Recent investigati ons showed that antigens of the Diego blood group system (including a numbe r of low-incidence antigens) are coded by SLC4A1 (solute carrier family 4, anion exchanger member 1 gene). Among these newly characterized Diego syste m antigens is Wu (designated Dig). Because a serologic relationship among W u, NFLD, and BOW has been established, a series of genetic and molecular in vestigations of SLC4A 1 in relation to NFLD and BOW were undertaken. STUDY DESIGN AND METHODS: By the use of exon-specific primers, single-stran d conformational polymorphism (SSCP) analysis of SLC4A1 was performed on DN A isolated from an NFLD+ person from Japan, from the members of a Canadian kindred segregating for NFLD, and from two unrelated BOW+ persons. Exons di splaying SSCPs were subjected to genetic linkage analysis (for NFLD only) a nd DNA sequencing. RESULTS: SSCPs in DNA amplified from exons 12 and 14 of SLC4A I were observ ed for all NFLD+ subjects. Linkage between each of these polymorphisms and NFLD was established with peak lods = 4.82 at theta = 0.00 for combined pat ernal and maternal meiosis. DNA sequencing of exons 12 and 14 of SLC4A I fr om NFLD+ persons identified A-->T and C-->G mutations that underlie Glu429A sp and Pro561Ala substitutions in human erythroid band 3 protein (band 3). DNA from the two unrelated BOW+ persons only exhibited an SSCP in exon 14 o f SLC4A1. Subsequent DNA sequencing revealed a C-->T mutation that accounts for a Pro561Ser substitution in band 3. CONCLUSION: SLC4A I codes for the low-incidence red cell antigens NFLD and BOW. In light of these findings, both antigens have been assigned to the Di ego blood group system.