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 bone marrow transplantation (BMT). Most DNA typing procedures discriminate allogeneic engraftment on the basis of DNA length polymorphisms or sequence variations found in variable number of tandem repeat (VNTR) loci, or the presence of Y chromosome-specific DNA We have compared 3 types of VNTR analysis, their respective mode of allele detection and Y chromosome DNA detection in order to assess the strengths and limitations of each approach. Chimerism was assessed in 8 recipients after allogeneic BMT. Samples were subjected to 6 restriction fragment length polymorphism (RFLP) loci-analysis using radioactivity, 2 amplified fragment length polymorphism (AmpFLP) loci-analysis using a silver-stain mode of detection, 12 short tandem repeat (STR) loci-analysis using fluorescence detection and Y chromosome analysis. We evaluated each procedure for its ability to (1) discriminate sibling donor-recipient pairs 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, AmpFLPs proved to be a rapid and efficient procedure with sufficient discriminating capability and sensitivity to warrant their use in clinical settings. STRs are rapid as well but require a larger loci complement to discriminate efficiently and they do not currently detect, under our conditions, all mixed chimeras. RFLPs are clearly superior at discriminating siblings but are time-consuming and serve best in cases where AmpFLP and STR analyses fail.