[A Study of a New Variation of α-1,3-Galactosyltransferase Gene in Pedigrees]

To investigate the association between genetic variation sites and blood group phenotypes in a family with the ABw subtype.

A 22-year-old male proband and six family members who underwent health examinations at the Department of Transfusion Medicine, 960th Hospital of the PLA Joint Logistics Support Force on April 8, 2023 were enrolled. ABO blood group phenotyping of the proband and family members was performed using the tube method. Direct sequencing of PCR products covering the ABO gene promoter region, intron 1, and exons 1-7 was conducted for the proband and family members. Clonal sequencing of exons 6 and 7 was performed for the proband.

The serological phenotype of the proband was identified as ABw. Direct sequencing of PCR products revealed that the proband's ABO gene promoter region contained two variants (c.-105G>C and c.-106G>C), intron 1 contained the variant c.28+5708G>A, and exon 6 contained the variant c.255C>T. Blood group genotype of the proband was ABO*A1.02/ABO*B with the c.255C>T variant. Family analysis showed that the proband's mother, brother, elder niece, and younger niece also carried the c.255C>T variant in exon 6. The proband's mother had variants c.-105G>C and c.-106G>C in the promoter region, c.28+6127T>C and c.28+6154A>G in the intron region, with a genotype of ABO*O.01.01/ABO*B and the c.255C>T variant. The proband's brother, elder niece, and younger niece exhibited no promoter region abnormalities but carried variants c.28+6272C>T, c.28+6173A>G, c.28+6284T>C, and c.28+6297A>T in intron 1. The brother's genotype was ABO*A1.02/ABO*B with c.255C>T, the elder niece's genotype was ABO*B.01/ABO*B with c.255C>T, and the younger niece's genotype was ABO* O.01.01/ABO*B with c.255C>T. The proband's father had a genotype of ABO*A1.02/ABO*A1.02, and the sister-in-law's genotype was ABO*O.01.01/ABO*B.01 .

The c.255C>T variant in exon 6 of the ABO blood group B allele (α-1,3-galactosyltransferase gene) exhibits hereditary characteristics and exerts a negative regulatory effect on glycosyltransferase activity to a certain extent.