The subject was a 28-year-old Japanese woman whose red blood cells had two populations of A, CCDee, Jk (a+b-), and AB, CcDEe, Jk (a+b+), at 95% and 5%, respectively. The karyotype for her lymphocytes was a female type of 46, XX, 100%. She was not a twin and had no history of chimeric features such as hermaphroditism, patchy skin pigmentation, or heterochromia iridis, as is often seen in dispermic chimeras. Her chimerism was further investigated using genomic DNA from leukocytes and nails as a somatic sample. Amelogenin genes specific for Y chromosome were not detected in her nails. Analyses of microsatellite and blood group genes were carried out by a PCR-SSCP method. Analysis of ABO gene revealed that A, B, and O gene coexisted in not only her peripheral blood but also her nails, and that the amount of B gene was less than that of A or O gene, corresponding to the rate of red blood cells. Rh blood group gene analyses showed the same result. Furthermore, a double contribution of alleles from her father was suggested both in her peripheral blood and nails by microsatellite analysis at the D1S102 locus. Therefore, on the basis of these findings, we considered this was a case of dispermic chimera.
