EVIDENCE FOR A NEW-TYPE OF O-ALLELE AT THE ABO LOCUS, DUE TO A COMBINATION OF THE A(2) NUCLEOTIDE DELETION AND THE A(EL) NUCLEOTIDE INSERTION

Using a recently introduced multiplex polymerase chain reaction and re striction fragment length polymorphism ABO genotype screening method w e have found an anomalous ABO genotype (A(2Ol variant)) not correlatin g with the serological phenotype (blood group O). The blood group was confirmed by absorption/elution and detection of blood group substance s in saliva. Sequencing of exons 6 and 7 in the ABO genes of the propo situs indicated an A(2) gene (C467T and C1060-) apparently inactivated by the same single nucleotide insertion recently reported in individu als with the ABO subgroup A(el). Investigation of relatives confirmed the inheritance of this new inactive hybrid allele.