ABO sequence analysis in an AB type with anti-B patient

ABO blood group system is the first to be discovered and the most clinically important in transfusion medicine.1The ABO gene encodes a glycosyltransferase which synthesize the oligosaccharide epitopes.The difference between the consensus A gene （A101 allele） usually used as the reference and the consensus B gene （B101 allele） are 7 in-frame single nucleotide polymorphisms （SNPs）,among which only 4 alleles cause amino acid mutations in the enzyme.When A allele was inherited from one parent and B allele was inherited from the other which produced the AB blood group,this is known as trans-AB.Cis-AB is characterized as mutant ABO alleles encoding a glycosyltransferase capable of synthesizing both A and B antigens which is very rare.