Evaluation of ABO and Lewis genotypes using primer extension preamplification

There are some difficulties with blood typing from ABO variant bloodstains and Lewis negative samples using serologic methods. In these samples, DNA analysis should be employed simultaneously to avoid errors in typing. Primer extension preamplification (PEP) produces copies of template DNA. The minimum quantity to examine nucleotide substitutions of ABO and Lewis genotypes by PCR ranged from 1 to 3 ng DNA. The PCR products with or without PEP treatment showed identical ABO and Lewis genotyping results. Performing both serologic and PCR testing served to crosscheck the ABO and Lewis grouping of such specimens. Errors in ABO and Lewis typing can be avoided as discrepancies are investigated further. The application of the PEP method to limited amounts of DNA samples for ABO and Lewis blood groupings is useful.