A POWERFUL NEW APPROACH TO MEASURING ENGRAFTMENT USING COPY NUMBER VARIATIONS AND DROPLET DIGITAL PCR, EXEMPLIFIED IN A COMPLEX ALLOGENEIC BONE MARROW TRANSPLANTATION CASE. (February 2015) - Ling, Ling
Abstract : Aim: To measure engraftment of a bone marrow transplant from an unrelated male to an 18-year-old male with an immune deficiency disorder (Wiskott–Aldrich syndrome), who had previously received a transplant (failing) from his similarly affected brother who had himself received a transplant from a female relative. Methods: The test uses 15 copy number variant deletion polymorphisms (CNDs) and droplet digital PCR. It requires null CNDs in the recipient, where the donor is heterozygous or wild type. Results: The pre- and post-transplant blood samples showed 3 donor-specific CNDs. The 24 and 53d post-transplant blood samples showed only donor CNDs with no detectable pre-transplant CNDs, consistent with 100% engraftment; the levels were approximately 2000 CND copies/μL with a limit of detection of 3 CND copies/μL. Discussion: Standard monitoring methods (FISH and microsatellite testing) were precluded in this case by the donors' genetic complexity. The results correlated with the patient's clinical status and the levels of Wiskott Aldrich syndrome protein (WASP). This method can be used for any donor-recipient pair other than identical twins and this complex case indicates its potential use for general transplantation monitoring. Reference Bruno DL, Ganesamoorthy D, Thorne NP, et al . Use of copy number deletion polymorphisms to assess DNA chimerism. Clin Chem 2014; 60: 1105–14.