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A method has been developed for the forensic analysis of faeces by DNA amplification and direct sequencing of a polymorphic segment of mitochondrial DNA. Starting from as little as 10 mg wet weight of faeces, DNA was extracted by a variety of protocols and amplified using primers specific to hypervariable region 1 of the mitochondrial control region. The resulting amplification products were sequenced in solid phase using an automated DNA sequencer. In total, mtDNA sequences were generated from the faeces of nine Caucasians and compared with sequences generated from their respective blood samples. Sequences of faeces and blood samples from the same individual were identical in every case, but a range of 1-10 nucleotide differences was observed between individuals, with an average sequence variation of approximately 4.88 per 400 bp. Of the various extraction protocols assessed in this study, greatest success rates were achieved using magnetisable beads to bind and purify the DNA. STR analysis of DNA extracted from faeces was not routinely possible.

Gender identification of forensic samples was determined by amplifying a segment of the X-Y homologous gene amelogenin. Using a single pair of primers spanning part of the first intron, 106 bp and 112 bp PCR products were generated from the X and Y homologues respectively, which were then resolved by agarose gel electrophoresis. This test enabled as little as 20 pg of DNA from severely degraded bones to be amplified and typed in a single tube reaction. Furthermore, using dye-labelled primers, it was possible to quantitate, by automated fluorescence detection, the relative yields of X and Y-specific PCR products generated from mixtures of male and female DNA. The versatility of this sex test was further demonstrated by co-amplifying with the HLA-DQA1 Amplitype kit in a combined gender/identity DNA test.