Serological characteristic and molecular basis of A2 subgroup in the Chinese population.

BACKGROUND: A2 phenotype is a common subgroup of blood group A, but the serological characteristic and genetics basis of A2 phenotype currently was rare reported in the Chinese Han population. Here, a large scale study of the serology and genetics of A2 and A2B phenotypes was performed. METHODS/MATERIALS: 11263 Chinese individuals with group A and AB phenotypes were determined for A2 antigen with the standard serological method. The full coding region of the ABO gene was sequenced in the individuals with A2 and A2B phenotypes. Some samples including each ABO genotypes were chosen for determining the activity of glycosyltransferase A (GTA) in plasma. RESULTS: 134 individuals were assigned as A2 and A2B phenotypes in 11263 individuals. There was imbalance in A2 and A2B phenotypes and the proportion of A2B among AB samples was significantly higher than that of A2 in group A samples. All samples of the A2 and A2B phenotypes were classified into A2-related allele group, A1-related allele group and the other group based on kind of the ABO genotype. Four novel A2-related alleles (A217, A218, A219, A220) were identified. The individuals with same genotype showed different agglutination strength with anti-A1 and anti-H on their RBCs. The plasma from individuals with A2-related allele had almost no GTA activity, while plasma from individuals with A1-related allele had some GTA activity. CONCLUSION: A2 and A2B phenotypes could derive from different genotypes and the serological characteristic may be heterogeneity in the Chinese Han population.

A dispermic chimera was identified in a healthy man with mixed field agglutination reaction in ABO blood grouping and mosaic 46, XY/46, XX karyotype.

BACKGROUND: Chimerism is the presence of two or more genetically distinct cell populations in one organism. Here, we reported the identification of dispermic chimerism in a 25-year-old male. METHODS: Blood grouping was performed with standard gel centrifugation test cards. ABO and HLA-A,-B,-C,-DRB1 and -DQB1 loci genotyping was determined with PCR sequence-based typing. A quantitative analysis of dual red cells populations was measured by flow cytometer. The karyotype was analyzed by G-banded chromosomes. Short tandem repeat (STR) analysis was performed on blood, buccal mucosal and hair shafts samples. RESULTS: A mixed-field agglutination with anti-B antibody was observed with gel centrifugation tests, which showed a double populations of O and B groups RBCs. Two groups RBCs were also observed by flow cytometer with nearly 90% O group cells and 10% B group cells. The normal O01,O02,B101 alleles were identified in DNA sample of the proband. STR analysis revealed three alleles for D8S1179,D3S1358,TH01,D13S317,D16S539,D2S1338,D19S433,TPOX and D18S51 loci. HLA-DRB1 and -DQB1 loci had three alleles and a karyotypic mosaic was found with 60% 46, XY and 40% 46, XX karyotype in the proband. In all studies, the third allele was attributable to a dual paternal contribution. CONCLUSION: A individual with dispermic chimerism was identified, which would generate by fertilization of an oocyte and the corresponding second polar body by two different sperms.