rapid detection of chimerism with amelogenin marker in bone marrow transplants from sex-mismatched donors

introduction: monitoring the engraftment of donor cell after allogeneic blood stem cell transplantation is important for the early diagnosis of graft failure or relapse of disease. so analysis of donor chimerism has become a routine method for documentation of engraftment after allogeneic stem cell transplantation. in humans, the amelogenin gene is present on both the x and the y chromosomes. however, there are size differences in this gene between these chromosomes, which have been utilized for sexing in forensic casework and prenatal identification. the aim of the present study was to evaluate the application of the amelogenin gene for assessment of chimerism in pbl and/or bm samples of patients who received sex-mismatched bmt. material and methods: pcr techniques using a set of amelogenin gene primer were preformed on whole wbc and/or bma samples, and in some cases on isolated t-cell and granulocytes subsets of recipient patients. we have investigated 30 allogeneic stem cell transplantation suffering from different types of leukemia (n=18) or non-malignant hematologic disorders (n=12) by close molecular monitoring during 1-12 months after transplantation. results: the pcr amplification of this gene resulted in 106 bp and 112 bp amplicons from the x- and y-chromosome respectively. the ratio of x/y fragments was reported as the mixed chimerism. the sensitivity of the test was as low as 1-2%. conclusion: the advantage of this approach is the use of a single set of primer to amplify both x and y chromosomes. the pcr-based assay was extremely sensitive and did not need donor and recipient samples for the assessment of chimerism. the test can be used routinely, alone or in conjunction with str-pcr, to analyze bm and pbl of post allogenic sex- mismatched bmt to detect early engraftment or rejection and for observing kinetics of engraftment.