Van Hoofstat David

phone: ++32 9 264 80 62
fax: ++ 32 9 220 66 88

TITLE

Forensic DNA analysis

SUMMARY

The Laboratory of Pharmaceutical Biotechnology performs human identification by the use of DNA profiling techniques, meanly for the department of justice in Belgium. The laboratory is recognized by the department of justice as a forensic DNA laboratory in criminal cases and has a BELAC accreditation since September 15th, 1996 for DNA analysis which is one of the requirements stated in the Belgium DNA law of 1999.

DNA profiling can be very useful not only in forensic casework but also in paternity testing.

By combination of short tandem repeat loci (STR) in a multiplex polymerase chain reactions (PCR) individuals can be identified with very high levels of certainty. By using PCR technology profiles can be obtained (and thus identification) of very minute and old, badly stored samples.

A DNA profile can be obtained on almost any kind of biological material (e.g. blood(stains), saliva(stains), sperm(stains), skin debris, hair, biological tissues, bones, teeth, ...).

In our laboratory a total of 20 STR loci can be analysed including the 12 ESS loci (the European Set of Standard loci: D3S1358, vWA, FGA, TH01, D21S11, D8S1179, D18S51, D10S1248, D1S1656, D12S391, D2S441 and D22S1045). The remaining 8 STR loci are TPOX, CSF1PO, D16S539, D13S317, D5S818, D7S820, SE33 and CD-4. This means also that all 13 CODIS loci (loci recommended and validated by the FBI) can be analysed. In addition sex determination can also be performed by analyzing the amelogenin locus on the X- and Y-chromosome. All STR loci are analysed on an ABI3100 and/or ABI3500xL genetic analyzer.

Besides the commercially available kits we also created 2 multiplexes of respectively 15 and 9 STR loci in our laboratory. Those 2 multiplexes have 4 STR loci in common, which gives an extra control on the obtained profiles. These multiplexes are extensions of our original multiplex of 4 loci (CD4, TH01, D21S11 and SE33) which is described and published in 1998 in the scientific journal Electrophoresis. The great sensitivity and specificity of this multiplex (which is better than the available commercial kits) was presented on the Second European Symposium on Human Identification in June 1998 in Innsbruck (DNA typing of fingerprints on skin debris: Sensitivity of Capillary Electrophoresis in forensic applications using multiplex PCR).

In special, very urgent cases DNA identification can be performed within 24 hours after receipt of the samples (max. 2-3 samples). The regular cases are performed in 1 – 2 months on average.

A part of the analysis is automated by using liquid handlers. This way human errors are avoided. There is a liquid handler for pre-PCR set-up; a second one is used for processing post-PCR samples.

Besides autosomal STR analysis, we also perform Y-STR analysis. We created a multiplex of 8 STR loci: DYS 19, DYS385a/b, DYS 389I, DYS 389II, DYS390, DYS391, DYS392 and DYS393. This way the minimal haplotype is determined. A commercial kit containing 3 extra loci (DYS437, DYS438 and DYS439) besides the 8 STR mentioned above is also used.

Our lab can also perform analysis of mitochondrial DNA (mtDNA), specific on samples where nuclear typing has failed or can not be performed such as hair without a root.

A P.A.L.M. microdissection laser microscope is available in the laboratory. Using laser microdissection technique individual cells can be isolated very specifically for instance sperms cells from post coital samples. Our laboratory already published 3 scientific articles on this subject in “International Journal Of Legal Medicine” :

- Laser capture microdissection in forensic research : a review (2010)

- Automatic detection of spermatozoa for laser capture microdissection (2009)

- Suspension fluorescence in situ hybridization (S-FISH) combined with automatic detection and laser microdissection for STR profiling of male cells in male/female mixtures (2009)

RESEARCH

Besides the routine DNA typing for the department of justice, our lab performs research in the field of DNA analysis for optimising and improvement of the procedures. This includes:

- optimisation and expansion of the use of P.A.L.M. microlaser system in forensic cases

- optimisation of DNA extraction

- statistical interpretation of the data

PUBLICATIONS

http://lib.ugent.be/bibliografie/801001111517