ABSTRACT
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.
ABSTRACT
<p><b>OBJECTIVE</b>To explore the molecular mechanism of a case of ABO discrepancies based on the results of blood group serology.</p><p><b>METHODS</b>Five cases of the two-generation pedigrees were analyzed. ABO genotypes were determined using serological tests. DNA sequence analysis was performed on exon 6, exon 7 and intron 3 of the 5 cases to confirm the genotypes of a proband with B subgroup and 4 family members.</p><p><b>RESULTS</b>There were 3 cases of subgroup AB3 and 1 case of subgroup B3 among the 5 family members. The genotypes were identified as A102/B303 and O02/B303, respectively. B303 differed from B101 by intron 3 point mutation (intron3 + 5G>A).</p><p><b>CONCLUSION</b>The point mutation of intron 3 (intron 3+5G>A) is specific in B303.</p>