[Serological feature and molecular mechanism for a case with A307 subgroup].

OBJECTIVE: To explore the serological feature and molecular mechanism for a case with A307 subgroup of the ABO blood group system. METHODS: Serological assay was carried out to determine the ABO blood group of the proband and his family members. Genotypes for exons 1 to 7 of the ABO gene were determined with sequence-specific primer polymerase chain reaction (SSP-PCR) and direct sequencing. The impact of the variant on the stability of alpha-1,3-N-acetylgalactosaminyltransferase (GTA) was predicted through construction of a 3D molecular model. RESULTS: The proband, his brother and daughter were diagnosed with Aend phenotype by serological analysis. Their ABO genotype was determined as A307/O02, with heterozygous c.467C>T (p.P156L) and c.745C>T (p.R249W) variants identified in exon 7 of the ABO gene. Molecular modeling suggested that the p.R249W variant may alter the number of hydrogen bonds between the amino acids. The protein was predicted to have a decreased Δ Δ G value of thermodynamic stability. CONCLUSION: The p.R249W variant may give rise to the A307 subgroup by reducing the stability of the GTA enzyme, leading to serological features of Aend phenotype.