DNA TYPING FOR BONE-MARROW ENGRAFTMENT FOLLOW-UP AFTER ALLOGENEIC TRANSPLANT - A COMPARATIVE-STUDY OF CURRENT TECHNOLOGIES

DNA typing is widely used to document engraftment after allogeneic bon e marrow transplantation (BMT), Most DNA typing procedures discriminat e allogeneic engraftment on the basis of DNA length polymorphisms or s equence variations found in variable number of tandem repeat (VNTR) lo ci, or the presence of Y chromosome-specific DNA, We have compared 3 t ypes of VNTR analysis, their respective mode of allele detection and Y chromosome DNA detection in order to assess the strengths and limitat ions of each approach, Chimerism was assessed in 8 recipients after al logeneic BMT, Samples were subjected to 6 restriction fragment length polymorphism (RFLP) loci-analysis using radioactivity, 2 amplified fra gment length polymorphism (AmpFLP) loci-analysis using a silver-stain mode of detection, 12 short tandem repeat (STR) loci-analysis using fl uorescence detection and Y chromosome analysis, We evaluated each proc edure for its ability to (1) discriminate sibling donor-recipient pair s in our samples; (2) generate a concordant chimerism diagnosis; and ( 3) detect and assess the contribution of minority components in mixed- chimera situations, In sex-mismatched BMTs with a female graft donor, Y chromosome probing has proven most efficient, In all other cases, Am pFLPs proved to be a rapid and efficient procedure with sufficient dis criminating capability and sensitivity to warrant their use in clinica l settings, STRs are rapid as well but require a larger loci complemen t to discriminate efficiently and they do not currently detect, under our conditions, all mixed chimeras, RFLPs are clearly superior at disc riminating siblings but are time-consuming and serve best in cases whe re AmpFLP and STR analyses fail.