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

BackgroundChimerism 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.MethodsBlood 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.ResultsA 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.ConclusionA individual with dispermic chimerism was identified, which would generate by fertilization of an oocyte and the corresponding second polar body by two different sperms.