Objective data on DNA success rates can aid the selection process of crime samples for analysis by rapid mobile DNA technologies.

Mobile Rapid-DNA devices have recently become available on the market. These devices can perform DNA analyses within 90min with an easy 'sample in-answer out' system, with the option of performing comparisons with a DNA database or reference profile. However, these fast mobile systems cannot yet compete with the sensitivity of the standard laboratory analysis. For the future this implies that Scene of Crime Officers (SoCOs) need to decide on whether to analyse a crime sample with a Rapid-DNA device and to get results within 2h or to secure and analyse the sample at the laboratory with a much longer throughput time but with higher sensitivity. This study provides SoCOs with evidence-based information on DNA success rates, which can improve their decisions at the crime scene on whether or not to use a Rapid-DNA device. Crime samples with a high success rate in the laboratory will also have the highest potential for Rapid-DNA analysis. These include samples from e.g. headwear, cigarette ends, articles of clothing, bloodstains, and drinking items.

Results of collaborative study regarding the standardization of the Y-linked STR system DYS385 by the European DNA Profiling (EDNAP) group.

Y-chromosome linked short tandem repeat (STR) loci are inherited as a closely linked haplotype, which appears to remain stable in a given paternal lineage over many generations. In forensic cases, Y-linked STRs are particularly useful for the identification of human remains as well as in rape cases with mixed male/female stain samples. DYS385 is derived from tandemly duplicated segments of the Y chromosome thus giving rise to two fragments of variable length which do not behave like alleles but genotypes. The European DNA Profiling (EDNAP) group has carried out a collaborative exercise among 14 participating laboratories using DYS385 for typing of five unknown bloodstains and a control sample. Furthermore, population data from eight different European countries with samples sizes between 91 and 150 male individuals were collected. The results confirm previous observations that DYS385 is one of the most informative Y-linked STR loci. It could also be demonstrated that reproducible results can be obtained independently from the electrophoretic separation and detection methods used. Thus DYS385 may serve as a useful complementation to the routinely used autosomal STR systems in special cases.

On the consequences of DNA profile mismatches for close relatives of an excluded suspect.

If the DNA profiles of a crime stain and the reference sample from the suspect do not match, the suspect is excluded as the donor of the crime stain. However, in some situations the DNA evidence can suggest that a close relative of the suspect might match the stain, in particular when the reference sample from the suspect and the crime stain share rare alleles. This finding can be important for the authorities. The forensic scientist has to decide whether or not to notify the authorities in these circumstances. To the best of our knowledge there is not yet an objective rule for making this decision. We propose such a decision rule for brothers of the suspect, investigate its performance and address some ethical, legal, and practical aspects. Our calculations can be simply adjusted for other relatives of the suspect.

Report of the European DNA Profiling Group (EDNAP)--an investigation of the hypervariable STR loci ACTBP2, APOAI1 and D11S554 and the compound loci D12S391 and D1S1656.

This paper describes the results of three collaborative exercises which continues the EDNAP theme to explore whether uniformity of DNA profiling results could be achieved between European laboratories using STRs. In an earlier exercise, complex hypervariable AAAG-repeat STR loci were investigated, but reproducibility was found to be poor because of the variation of techniques used by participating laboratories. In the exercise reported here, an internal allelic ladder composed of ACTBP2 and D11S554 fragments was distributed. This ladder was used to size ACTBP2 analysed by a "singleplex" PCR amplification and D11S554 combined with APOAI1 in a separate "duplex" reaction. Laboratories were asked to test 7 blood stains, one of which was a known control, and to report the results to the co-ordinating laboratory. The exercise demonstrated that ACTBP2 showed good reproducibility between laboratories, whereas further testing would be needed to validate APOAI1 and D11S554 for interlaboratory comparisons. In separate exercises, the simple loci D12S391 and D1S1656 were tested; both of these showed excellent reproducibility between laboratories.

Report of the European DNA profiling group (EDNAP): an investigation of the complex STR loci D21S11 and HUMFIBRA (FGA).

This paper describes a collaborative exercise which was intended to demonstrate whether uniformity of DNA profiling results could be achieved between European laboratories using two complex short tandem repeat (STR) loci. The loci D21S11 and HUMFIBRA (FGA) were chosen because they are commonly used by different European laboratories. D21S11 has approximately 14 common alleles (f > 0.001), whereas HUMFIBRA has 19 common alleles. Laboratories were asked to test seven blood stains, one of which was a known control, and to report the results to the coordinating laboratory. The exercise demonstrated that complex STRs were amenable to standardisation.

Report on the second EDNAP collaborative STR exercise. European DNA Profiling Group.

The European DNA Profiling Group (EDNAP) has previously carried out collaborative exercises to determine which STR systems will produce results that can be reproduced by different laboratories. The first EDNAP exercise involving STR systems focused on different types of loci: a simple locus with six common alleles (HUMTH01) and a complex locus with > 35 alleles (ACTBP2). Generally the simpler STR system was found to be readily amenable for use across a wide range of different technologies, whereas a more complex locus presented difficulties. The second EDNAP STR exercise was intended to take the process of investigation a stage further. Some laboratories are developing automation, coupled with fluorescent methods of detection and multiplex applications, whereas others use manual methods involving visual detection techniques such as silver staining. The purpose of this exercise was to determine whether loci amenable to multiplexing with automation (as a quadruplex reaction) could also be successfully used with manual methods, either by multiplexing in duplex reactions or alternatively by using just a single pair of PCR primers.

Dutch Caucasian population data on the loci LDLR, GYPA, HBGG, D7S8, and GC.

To introduce the loci LDLR, GYPA, HBGG, D7S8, and GC (PM loci) in Dutch forensic identity testing, allele and genotype frequencies were determined in a Dutch Caucasian population sample, which had previously been typed for the HLADQA1 locus [12]. All 6 loci met Hardy-Weinberg equilibrium expectations, and there is little evidence for association between pairs of loci. The combined power of discrimination for all 6 loci is 0.9997. The allele frequencies of the PM loci were similar to 2 other Caucasian populations [3, 10], and differed from 3 non-Caucasian populations [3].

Report of the European DNA profiling group (EDNAP)--towards standardisation of short tandem repeat (STR) loci.

This paper describes a collaborative exercise intended to demonstrate whether uniformity of DNA profiling results could be achieved between European laboratories using short tandem repeat (STR) loci. Two different STRs were chosen--HUMTH01 and the AT-rich HUMACTBP2 (SE33). The former locus has only five common alleles, whereas the latter is complex and has at least 30 alleles. Laboratories were asked to test seven blood stains and to report the results to the coordinating laboratory. The exercise demonstrated that the simple STR systems such as HUMTH01 are more amenable to adoption as standard loci than complex AT-rich systems.

Population data of the HLA DQ alpha locus in Dutch Caucasians. Comparison with other population studies.

The HLA DQ alpha amplification and typing kit has been designed to be used by the forensic community for purposes of identity testing. The introduction of any new DNA marker in forensic identity testing requires the establishment of a population database for the relevant population(s). To this end allele and genotype frequencies for the HLA DQ alpha locus were determined in a Dutch Caucasian population sample and compared with 7 other population genetic studies. In our population sample the HLA DQ alpha genotype frequencies did not deviate from Hardy-Weinberg expectations and for this locus the power of discrimination is 0.94. A test for homogeneity of the HLA DQ alpha population data based on the allele frequency counts for 8 Caucasian population samples was performed and significant differences were found (P = 0.007). The differences in the frequency of the HLA DQ alpha 2 and 3 alleles are the major cause of this deviation. No deviation from population homogeneity was observed when we compared the genotype frequency distributions among the 8 Caucasian population samples. Combined with the extensive validation studies from Comey and Budowle and Helmuth et al. this population genetic study will allow HLA DQ alpha typing to be used in forensic identity testing in the Netherlands.

PCR-amplification and detection of the human D1S80 VNTR locus. Amplification conditions, population genetics and application in forensic analysis.

A series of experiments has been performed to evaluate amplification and typing of the D1S80 VNTR locus. The validation study that has been carried out showed that correct D1S80 typing results can be obtained when a defined amplification protocol and a high-resolution polyacrylamide gel electrophoresis method are used. The use of the Chelex extraction protocol has substantially reduced the processing time. DNA-extraction, amplification and subsequent typing can be performed in one day. The discrimination power of this locus is 0.94 in a Dutch Caucasian population sample. The system is extremely sensitive: 0.1 ng of genomic DNA gave a correct typing result. The test could also detect the correct genotypes in mixed samples containing DNA from different individuals. Even if the major type was in a 20-fold excess, the minority type could still be amplified and typed correctly. We have found no deviation from Hardy-Weinberg equilibrium in a Dutch Caucasian population sample. Evidence for the somatic stability of this locus was obtained from a set of experiments where we compared DNA-profiles from corresponding blood, semen and saliva samples. The results of this study suggest that in the near future analysis of the D1S80 locus by DNA-amplification can be applied in actual forensic case work.

A report of an international collaborative experiment to demonstrate the uniformity obtainable using DNA profiling techniques.

This paper describes a collaborative exercise intended to demonstrate whether uniformity of DNA profile results could be achieved between different European laboratories. It was shown that this goal can be obtained provided that a common protocol is followed (specifically the use of a common electrophoretic buffer as being the most important parameter). Generally, lower molecular weight loci (with lower molecular weight fragments) such as YNH24 perform better than higher molecular weight loci such as MS43a. The results of the exercise are discussed in relation to the objectives of the European DNA profiling group (EDNAP).

Report of a European collaborative exercise comparing DNA typing results using a single locus VNTR probe.

A collaborative exercise was carried out in 1989 among 12 European forensic laboratories using the single locus VNTR probe pYNH24, the restriction enzyme HinfI, the same set of human genomic DNA samples, and a standardized DNA size marker. The objectives of the exercise were: (1) to study the degree of variation within and between laboratories, (2) to obtain information on requirements for technical standardization allowing the exchange of typing results and (3) to compare different approaches for the identification of allelic DNA fragments of unknown size. Each laboratory carried out up to 10 independent typing experiments using the same DNA samples. The results were analysed independently by two laboratories using three different methods. The results of the exercise demonstrate the correlation of typing that can be achieved within and between laboratories under conditions of minimal standardization.

Comparison of enzyme assay and radioimmunoassay for the measurement of human acid phosphatase in cases of sexual assault.

We investigated whether a radioimmunoassay for prostatic acid phosphatase might be used as a more specific test for the identification of semen in samples from cases of sexual assault than the measurement of total acid phosphatase enzyme activity. The results of the measurement of acid phosphatase by enzyme assay in semen and vaginal swab extracts were compared with the results of the radioimmunoassay. It was found that the radioimmunoassay is a sensitive and more specific method than the enzymic determination of acid phosphatase. Incidentally we have found that a low concentration of an immunological cross reacting acid phosphatase is present in semen free vaginal swab extracts.

Some properties of phospholipid exchange proteins from rat liver.

The phospholipid exchange proteins of rat liver that catalyze the transfer of phosphatidylcholine and phosphatidylinositol from rat liver microsomes to liposomes, have been purified and characterized. Two proteins were detected with dual specificities catalyzing the transfer of both phosphatidylinositol and phosphatidylcholine. Both proteins showed a strong preference for phosphatidylinositol transferring 8 to 9 times as much of the microsomal phosphatidylinositol pool as the microsomal phosphatidylcholine pool. The two proteins had iso-electric points of 5.1 and 5.3 and were purified 300-fold and 500-fold, respectively. A protein that catalyzed specifically the transfer of phosphatidylcholine, was purified 7000-fold. This protein had an iso-electric point of 8.4 and a molecular weight of approximately 16000 calculated from Sephadex G-50 chromatography and sodium dodecylsulfate-polyacrylamide gel electrophoresis; the amino acid composition was determined. An antiserum against this protein was raised in rabbits. Treatment of a rat liver supernatant fraction with the antiserum immunoglobulin fraction demonstrated that 60% of the phosphatidylcholine transfer activity is due to this protein.