Search for Quantitative PCR Markers on Diallelic Short Insertion/Deletion Polymorphism for Transplant Chimerism---Establishing Data Base and Evaluating Clinical Impact

Mixed chimerism quantification has been proposed as an important method in monitoring post-HSCT outcome. An accurate analysis of chimerism kinetics would permit early differentiation between the absence of engraftment and a delay in engraftments as well as early detection of patients of high risks of GVHD or those liable to relapse. An early diagnosis is an important aspect of the prognosis since relapsing patients may enter durable second remission through suitable measures, such as tapering or withdrawal of immunosuppressive treatment or donor lymphocyte infusion. Substantial differences in the mean concentratons of donor-derived DNA in sera of patients with and without rejection was observed by Gadi et al. This finding illustrated the diagnostic potential of cell-free-DNA in blood for rejection episodes after organ transplantation. Similarly, in HSCT, since relapse is resulted from graft failure, sera MC may also reflect the same. The gold standard for quantitative chimerism analysis so far is based on PCR analysis of short tandem repeats (STRs). Since STR-PCR has a relatively low sensitivity of 05%-5% mainly as a consequence from competition biases, the detection of low MC is usually delayed, which may seriously affect the outcome of the HSCT. Thus, in this project, we plan to apply a sensitive quantitative real-time PCR method by detecting diallelic insertion/deletion polymorphic markers (DIDPs) in monitoring MC, in order to explore into understanding the kinetics of the MC. In the first year we shall screen about 300 DIDPs and establish basic data bases on these DIDPs. In the second year, we shall test archieved whole blood DNA samples for MC analysis on 131 HSCT patients in our laboraties since 1998. In the third year we shall extend our study to analyse T-cell DNA and cell-free DNA samples collected on the new cases since 2007.

Project ID:PC9706-0485
External Project ID:NSC96-2320-B182-025-MY3