Assessment of donor chimerism. Electrophoretic profiles of informative variable number of tandem repeat PCR products¹⁸  of the recipient and donor (before transplant) and serial posttransplant samples from the recipient bone marrow at indicated time points after HSCT. The donor and recipient are both heterozygous with one shared allele. Thus, one informative donor allele (644 bp) and one informative recipient allele (578 bp) are observed.