A GLY(565)-]ALA SUBSTITUTION IN HUMAN ERYTHROID BAND-3 ACCOUNTS FOR THE WU BLOOD-GROUP POLYMORPHISM

BACKGROUND: Reports published in 1976 and 1980 described the low-incid ence red cell antigen Wu. Distinction of Wu from all other known low-i ncidence antigens and from the ABO, Rh, Lutheran, Duffy, Kidd, P, and X-linked blood group systems allowed Wu to be placed in the Internatio nal Society of Blood Transfusion's 700 series, designated as 700013. R ecently, a blood donor apparently homozygous for Wu has been identifie d.This report documents the serologic and molecular findings of sample s from this individual and the members of his family STUDY DESIGN AND METHODS: Blood samples from 26 members of a kindred of Dutch descent s egregating for Wu were collected and analyzed. Red cells were subjecte d to titration and enzymatic tests, while DNA was analyzed by polyacry lamide gel electrophoresis for single-strand conformational polymorphi sm (SSCP) and nucleotide differences by DNA sequencing. RESULTS: Serol ogic investigations conducted on red cells of the propositus and two o f his siblings consistently revealed higher titers with various sera c ontaining anti-Wu than did cells from their parents or children. Treat ment of intact red cells with a-chymotrypsin completely abolished Wu r ecognition. Because erythroid band 3 is cleaved by cc-chymotrypsin, th e possible relationship between Wu and AE1 (the gene controlling eryth roid band 3 expression) was investigated by molecular methods. SSCP an alysis of DNA revealed that all Wu+ family members exhibited a mobilit y shift in exon 14 of AE1. The nature of the SSCP was defined by DNA s equencing as a G-->C mutation that resulted in a Gly(565)-->Ala substi tution in human erythroid band 3. CONCLUSIONS: Three members of the ki ndred are homozygous for the low-incidence red cell antigen Wu. A G--> C mutation in AE1 gives rise to a Gly(565)-->Ala substitution in band 3, thereby accounting for the Wu red cell polymorphism. In light of th ese findings, the International Society of Blood Transfusion Working P arty has provisionally assigned Wu to the Diego blood group system (de signated 010009 or DI9).