Background: While there are many case reports dealing with ABO mosaicism and chimerism, there have been few attempts to determine the patient's genotype.
Study design and methods: Peripheral blood and buccal mucosa were obtained from three persons with ABO mosaicism or chimerism. DNA extracted from hematopoietic progenitor cell-derived colonies and from peripheral blood and buccal mucosa were analyzed by polymerase chain reaction-restriction fragment length polymorphism methods. In addition, analyses of short tandem repeat markers were carried out.
Results: Hematopoietic progenitor cell-derived DNA analysis revealed that, in two of the three persons there were 2 apparently distinct progenitor cell lineages whose percentages were close to those in the peripheral blood of the patients, as analyzed by flow cytometry; the exception was Subject 3, who had myelodysplastic syndrome (MDS). Short tandem repeat analysis showed that the former two subjects had two pairs of ABO alleles and the latter subject, with MDS, had loss of heterozygosity in some colony-derived DNA as well as blood DNA.
Conclusion: The subjects without MDS had two distinct hematopoietic cell lineages that led to their ABO chimeric status. The subject with MDS was assumed to have an ABO mosaicism caused by the somatic deletion of the ABO gene in the hematopoietic progenitor cells.