RESUMO
BACKGROUND: When discrepancies in ABO blood typing emerge, ABO subgroups should be considered. Serological procedures such as the adsorption-elution test, the salivary ABH inhibition test, and the antiA1 (lectin) saline technique might be employed. These serological approaches, however in rare blood types are difficult to understand. As a result, a dependable and cost-effective approach for determining ABO subgroups is of special relevance. METHODOLOGY: for this purpose, DNA sequencing is most reliable solution for accurate results. Exon 1 to 7 5' 3' UTR and intron 6 of ABO gene of a Chinese individual was sequenced because the laboratory was unable to determine the blood group by traditional method. RESULTS: The analysis of the blood showed weak B antigens on their surface. Gene sequencing results revealed a novel B allele, that has one novel identified nucleotide difference from T to C at nucleotide 425. CONCLUSION: The results reported novel B allele which cannot be confirmed by conventional serological methods. Owing to the peculiarity of ABO blood types of inheritance, findings on the incidence and molecular causes of rare blood groups in the Chinese population have substantial therapeutic implications and are worthy of additional investigation in the future.