Extraction and analysis of nuclear DNA from free margin of nail material

To investigate the feasibility of DNA analysis from free margin of the nail, genomic DNA was extracted from the free margin of nail clipping of 10 volunteers using the proteinase K/SDS -based organic method, the Chelex-100 method, or a combined method. Target DNA was simultaneously amplified using a fluorescent multiplex AmpFlSTR Identifier kit. The PCR products were analyzed on the ABI PRISM 3130 Genetic Analyzer. The results showed that, compared with profiles achieved by genotyping of blood samples from each volunteer as reference, 100% concordance was achieved using the combined method. The STR genotype profiles obtained through the organic method were acceptable, despite preferential amplification at some loci. In contrast, no readable profiles could be determined when DNA was extracted by the Chelex-100 method, and there were a large number of alleles missing. Our data suggest that free margin of nail can be used for nuclear DNA analysis, but the type of DNA isolation method used is critical. The traditional organic extraction method works reasonably well for free margin nail DNA isolation, and combination of organic extraction and the Chelex-100 method works best.