[Molecular Biological Mechanism of Ael Novel Mutant Subtypes]

Genotyping was performed on a specimen whose blood type was inconsistent with positive and negative serological tests, and its family investigation and molecular biological mechanism were studied.

Blood group serology was used to identify the ABO blood group of the proband and her family members. ABO gene of proband and her family samples were sequenced by ABO gene direct sequencing (Sanger sequencing) and SMRT haplotype sequencing methods. AlphaFold software was used to simulate the three-dimensional structure of proteins, and the protein structures before and after mutation were compared to observe the changes in the intermolecular forces within the structure.

Blood group serological test showed that the proband had Ael/B phenotype, her mother and daughter had Ael/O phenotype, and the blood group results of other family members were consistent with positive and negative stereotypes. The sequencing results showed that there was a new mutation of c.1024 A>C in exon 7 of ABO gene in the proband and her mother and daughter, which led to the mutation of amino acid No. 342 from threonine to proline (p.Thr342Pro). The AlphaFold software modeling results showed that the mutation of p.Thr342Pro significantly reduced the number of hydrogen bonds formed with 215-bit Glu.

ABO gene exon 7 c.1024 A>C mutation leads to amino acid replacement of polypeptide chain, affects the stability of GTA protein structure, causes changes in enzyme activity, produces Ael phenotype, and this variant gene can be stably inherited.