Comparison of automated short tandem repeat and manual variable number of tandem repeat analysis of chimerism in bone marrow transplant patients

Hematopoietic chimerism can be monitored in bone marrow transplant patients at DNA polymorphic sites. In this study, allele detection and quantificati on by ethidium bromide-stained agarose gels were compared with automated fl uorescent sizing on an artificially mixed system and on chimeric post-trans plant whole blood and sorted cell populations. A panel of five variable num ber of tandem repeats (VNTRs) were amplified and quantified visually on an ethidium bromide-stained gel. The ten short tandem repeats (STRs) were ampl ified as a multiplex polymerase chain reaction (PCR) and fluorescently dete cted on a DNA sequencer. Fluorescent band intensities were converted to flu orescent peak areas for allele quantification. Using mixed DNA of different proportions, both STRs and VNTRs showed linearity and appeared equally sen sitive. However, case studies showed STRs to be more sensitive (<5%) than V NTRs (<10%). The STRs more accurately quantified the minor DNA component at low concentrations.