ABSTRACT
OBJECTIVE@#In this study, the results of forward and reverse blood typing of a male patient diagnosed as bronchiectasis were inconsistent, which were type O and type A respectively. Multiple experiments including genotyping and sequencing and family investigation were carried out to determine the subtype of ABO blood group and explore the serological characteristics of this subtype.@*METHODS@#Standard serological techniques were used to conduct forward and reverse typing, reverse blood typing enhancement test, H antigen identification, absorption-elution test, salivary blood group substances test, and PCR-SSP method for ABO genotyping and exon 6 and 7 sequencing.@*RESULTS@#The proband's blood group was type O by forward typing, but antigen A could be detected by absorption-elution test, anti-A1 could be detected by reverse blood typing enhancement test, it was found that there was substance H but no substance A in saliva, and the serological characteristics were consistent with Ael subtype. Gene sequencing analysis showed that there was a c.625T>G base substitution on the basis of A102, which had never been reported before. Family survey showed that c.625T>G base substitution appeared in three generations of the family.@*CONCLUSION@#In this study, a new subtype A with Ael serological characteristics caused by c.625T>G mutation was identified. c.625T>G base substitution results in the weakening of A antigen, and this mutation can be stably passed down to future generations.