A novel DI*A allele without the band 3-Memphis mutation in Amazonian Indians

Background and Objectives The blood-group antigens Di(a) and Di(b) are carried on erythrocyte band 3 and are defined by a single amino acid substitution at position 854 (Leu for Di(a) and Pro for Di(b) ). The Band 3-Memphis variant has a point mutation (166A>G) in the SLC4A1 gene, which encodes the amino acid substitution Lys56Glu. Two types of Band 3-Memphis, variants I and II, are distinguished by their susceptibility to covalent labelling with 4,4'-diisothiocyanato-1,2-diphenylethane-2,2'-disulphonic acid (H-2 DIDS). Memphis II is more readily labelled than Memphis I or normal band 3. It is reported that Memphis II is associated with Di(a) . In a study designed to determine the frequency of the DI *A /DI *B and 166A>G polymorphisms in different populations in Brazil, we found a new DI *A allele. Materials and Methods We studied DNA samples from 70 Amazonian Indians, 71 individuals of Japanese descent, 93 random Brazilian blood donors and 84 blacks with sickle cell disease. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analyses were performed on all samples, using Msp I for DI *A/DI *B (exon 19) and Mnl I for 166A>G (exon 4). Exon 4 and exon 19 from four outliers were sequenced. Results Among Amazonian Indians, DI *A and 166G mutations both had a high frequency (0.57 and 0.54, respectively). In individuals of Japanese descent, these alleles were moderately frequent (0.07 and 0.19, respectively). We identified a new allele with DI *A and 166A (56Lys) in four Amazonian Indians. Conclusions Our results revealed that DI *A does not have a strict association with 166G . They also show the relevance of testing a cohort of different populations.