Serological and genotyping study of rare cis-AB01/O01 in the area of Inner Mongolia - with a case report

The antigen gene of ABO blood group system, called ABO, is located on human chromosome 9, with a total length of 19.5 kb. It is the first blood group system found by human beings.[1] ABO blood group subtypes are formed by ABO genovariation, i.e., gene A variation for A subtype, gene B variation for B subtype and gene O variation for new O alleles. ABO subtypes contain A3, Ax, Ael, Aw, Am, B3, Bx, Bel, Bw, cis-AB, B (A). Generally, an individual with AB blood group has an A allele on one chromosome, with B allele on its paired chromosome. This phenomenon is called trans-AB. However, cis-AB is a unique ABO phenotype that A and B alleles are located on the same chromosome, so that it can be inherited by the next generation.[2] This special mode of inheritance often causes a discrepancy of ABO blood grouping and then reduces the effectiveness and safety of blood transfusion.Therefore, to accurately identify the blood group of cis-AB is a precondition for the safety of blood transfusion.[3] The serological and genotyping analysis on a case of cis-AB patient in our hospital is reported as follows.