Y-STR genetic diversity in Moroccans from the Figuig oasis.

Seventeen Y-chromosomal short tandem repeats (STRs) (DYS392, DYS437, DYS448, GATAH4.1, DYS389II, DYS439, DYS635, DYS393, DYS438, DYS391, DYS389I, DYS390, DYS19, DYS458, DYS456 and DYS385a,b) were typed in DNA samples from 96 unrelated Moroccan men from the Figuig oasis. Fifty-two haplotypes were identified, of which 36 were unique. The overall haplotype diversity was 0.966, and the discrimination capacity was 0.542. Population comparisons with previously published data revealed significant genetic heterogeneity between the Figuig Moroccans and other North African populations. Results also showed that the minimal haplotype 11-30-13-10-13-25-15 (DYS392-DYS389II-DYS393-DYS391-DYS389I-DYS390-DYS19) was the most frequent haplotype observed in Figuig men.

STR analysis of artificially degraded DNA-results of a collaborative European exercise.

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.

[Genetic fingerprints and computerised databases]. / Empreintes génétiques et base de données informatisée.

The computerised databases of genetic fingerprints are laboratory tools and by extension law enforcement tools, for which the European Union has defined the applications. As these genetic profiles give no information on specific hereditary characteristics, these bases have been established in order to respect the rights and fundamental liberties of each individual. Compatible at the international level, nobody contests today their rewards in the fight against crime.