Biological identification and molecular structure model analysis of Bx02 / 中国输血杂志

【Objective】 To identify two ABO discrepancy samples and explore the molecular mechanism. 【Methods】 The serological phenotype of the proband was determined with standard serological methods. ABO genotype was determined by polymerase chain reaction-sequence specific primer (PCR-SSP). Exon 6 and 7 of the ABO gene were amplified with PCR and sequence-based typing (SBT). The amplicon of exon 6 and 7 was also cloned and sequenced. Pymol software was used to simulate the 3D structural model and predict the effect of GTB protein mutation on the structure. The sample were collected from proband’s father and analyzed. 【Results】 The proband’s erythrocytes were detected with B antigens, along with the presence of anti-B in serum. The genotype O1/B of the proband was identified by PCR-SSP. Direct sequencing of the proband revealed 261delG/G, 297A/G in exon 6 and 526C/G, 646A/T, 657C/T, 681A/G, 703A/G, 771C/T, 796A/C, 803C/G, 829A/G, 905A/G, 930A/G, 1096A/G heterozygote in exon 7, which was assigned as Bx02/O02 genotype. Clone sequencing showed that a 905 A>G mutation in the ABO*B.01 allele. The 3D structure simulation suggested that Asp302Gly may cause the change of GTB enzyme activity or function. 【Conclusion】 Two cases of Bx02 allele were identified. Combined detection of serological and genotyping methods is important for identification of ABO blood group.

Molecularmechanism of Bel subtype caused by mutation p.R168W of glycosyltransferase B / 中国输血杂志

Objective To study the molecular mechanism of Bel subtype caused by mutation p.R168W of glycosyltransferase B.Methods Serological test,SSP-PCR and direct sequence the Exon6 and Exon 7 of the ABO gene.Construct a 3D molecular model and predict the structural impact of GTB protein mutations.Results A antigen or B antigen can't be detected on the surface of the propositus' RBC,and only anti-A antibodies were detected in her serum.But serological test indicated her daughter's blood type was a normal B type.SSP-PCR test indicated propositus' ABO gene type is O1 B.By gene sequencing the Exon 6 and Exon 7 of the ABO gene,a ABO Bel allel(c.502C＞T,p.R168W)was discoverd in both the propositus and her daughter.Through the propositus' daughter coexisted Bel gene with normal B gene,her blood type was a normal B type.Conclusions ABO gene c.502C＞T mutations cause Bel phenotypes in patients by reducing the stability of GTB.