We aimed to establish a method for quantitative analysis of mixed haematopoietic
chimerism based on microchip electrophoresis of selected molecular markers following PCR
amplification for accurate monitoring of graft status post-transplantation. A 12-year-old girl with
relapsed acute lymphoblastic leukaemia who underwent allogeneic bone marrow transplantation had
qualitative chimerism analysis using short tandem repeat markers at three time points following the
procedure. Her archived DNA samples were then used to test the ability to correlate her clinical course
with changes in the quantity of donor chimerism at the different time points. Quantitative chimerism
analysis was performed on the Agilent 2100 bioanalyser and donor-recipient ratios were calculated
from generated electropherograms. Complete donor chimerism (98%) was demonstrated three weeks
post- transplantation. Decreasing amount of donor chimerism to 24% was shown after three months
and this concurred with clinical relapse. Following a second transplant, full donor chimerism was reestablished
where donor chimerism rose to 100%. High resolution microchip electrophoresis could be
useful in predicting the occurrence of increasing recipient chimerism which may herald impending
relapse in patients while the disease burden is still low. This investigational approach may provide
useful information for clinicians to select appropriate intervention strategies to ensure successful
transplantation.