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In 2010, it is the 25th anniversary of the first paper describing the genetic identification of human individuals by DNA fingerprint analysis. Since then DNA analysis has become a major tool to relate biological evidence to the persons involved in a crime or to determine the biological relationship among individuals. The currently used methodology is the result of major technological changes that were partly driven by criticism on previous methodologies, and partly driven by demand especially due to mass disasters such as the '9/11 attack' on the World Trade Center in New York. This review will give an overview of the current methodology in genetic identification and new developments that will have a future impact on forensic identification., (Copyright 2010 Elsevier Ireland Ltd. All rights reserved.)

Allele frequencies and haplotypes for 12 Y-chromosomal STR loci included in the Powerplex System (Promega, Madison, USA) were determined in a sample of 113 unrelated males of Belgian origin. Ninety-nine different haplotypes were observed with an overall haplotype diversity of 0.997.

Degradation of human DNA extracted from forensic stains is, in most cases, the result of a natural process due to the exposure of the stain samples to the environment. Experiences with degraded DNA from casework samples show that every sample may exhibit different properties in this respect, and that it is difficult to systematically assess the performance of routinely used typing systems for the analysis of degraded DNA samples. Using a batch of artificially degraded DNA with an average fragment size of approx. 200 bp a collaborative exercise was carried out among 38 forensic laboratories from 17 European countries. The results were assessed according to correct allele detection, peak height and balance as well as the occurrence of artefacts. A number of common problems were identified based on these results such as strong peak imbalance in heterozygous genotypes for the larger short tandem repeat (STR) fragments after increased PCR cycle numbers, artefact signals and allelic drop-out. Based on the observations, strategies are discussed to overcome these problems. The strategies include careful balancing of the amount of template DNA and the PCR cycle numbers, the reaction volume and the amount of Taq polymerase. Furthermore, a careful evaluation of the results of the fragment analysis and of automated allele calling is necessary to identify the correct alleles and avoid artefacts.

The allele and genotype distributions for 15 STR loci included in the AmpFlSTR SGM Plus and AmpFlSTR Profiler kits (Applied Biosystems, Foster City, USA) were determined in a sample of 222 unrelated individuals of Belgian origin.

A total of 280 unrelated males from the three largest population groups in Bulgaria: Bulgarians, Bulgarian Turks and Gypsies, were analyzed for seven Y-chromosome STRs (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392 and DYS393). Comparison of the allele frequency distributions revealed significant differences between the three ethnic groups which were confirmed with haplotype analysis. This permits us to suggest that population differentiation should be taken into account in forensic case analysis and paternity testing in Bulgaria.

A protocol for simultaneous amplification of the tetrameric STR loci HUMVWA, HUMTH01, D21S11 and HPRT has been developed in this study. Fluorescent amplified alleles were detected by laser scanning on the ALF DNA sequencer, and identified with locus specific allelic ladders. A sequencing survey of these STR loci was performed in 40 selected individuals from three major ethnic groups and confirmed the data reported previously. At the D21S11 locus, a new allele of 207 bp, was found in a Belgian Caucasian individual and designated as allele 25.2. Sequence analysis of this allele revealed that it contained a 14 bp deletion of (TCTA)3 TA at the beginning of the constant region. A nonconsensus allele of 245 bp, described and designated as allele 33.2.3(2x) by Brinkmann et al. (1996), was identified in an individual of central African origin. In addition, three new sequence variants of the allele 29, 30 and 32 were observed at D21S11.

Mitochondrial DNA (mtDNA) sequencing is a powerful and sensitive method to identify the donor of shed hairs found at a crime scene. Because of the low amounts of DNA in shed hair and the sensitivity of PCR, contaminating cells (e.g. saliva, blood), sometimes present on these hairs, will be co-amplified. This will result in ambiguous sequencing results and might even lead to erroneous exclusions of suspects. We have evaluated a strategy for effectively removing saliva and blood contamination from hair samples. Unambiguous mtDNA results were obtained by incubating the hair samples in a differential lysis buffer (which contains no DTT) prior to DNA extraction. Since the nuclear DNA of the hair root is affected, this procedure should be restricted to hair shaft proportions.