Population-dependent migration shift caused by sequence variation at the alpha fibrinogen (FGA) short tandem repeat (STR) locus.

The alpha fibrinogen (FGA) is a core short tandem repeat (STR) locus commonly used in forensic laboratories and is part of most of the commercial multiplex forensic STR kits. There are two distinct groups of FGA alleles based on their size: alleles 16-34.2 and 42.2-51.2. A thorough survey revealed that the long (>33) FGA alleles appear exclusively in populations of sub-Saharan Africans, Caribbean of African descent, non-African Arabs and peoples of non-African Arab descent. Our survey revealed that the long FGA alleles are rare and appear in only 0.01-1% of these populations, with the rarest allele being 47.2. The Israel Police DNA database includes about 470,000 DNA profiles, of which 193 bear an FGA allele longer than 33.2 and only 64 bearing the 47.2 allele. 30 samples with DNA profiles known to contain long FGA alleles were re-analyzed using three different STR multiplex kits. The regions of each long allele were sequenced in addition to STR analysis. The allele sequences revealed a striking difference in the pattern of repeats between the population groups of African and Arab descent. Eight of our samples contained the 47.2 allele, with a clear distinction between 47.2 sequences derived from African vs. Arab populations. In STR analysis, all 47.2 alleles displayed a shift from the allelic ladder bin center in all three kits. In all kits, the shift was significantly larger in the Arab population than in the African population. Hence, there is a population-dependent migration shift which may help differentiate profiles derived from different populations.

Reduction of Powerplex(®) Y23 reaction volume for genotyping buccal cell samples on FTA(TM) cards.

PowerPlex(®) Y23 is a novel kit for Y-STR typing that includes new highly discriminating loci. The Israel DNA Database laboratory has recently adopted it for routine Y-STR analysis. This study examined PCR amplification from 1.2-mm FTA punch in reduced volumes of 5 and 10 µL. Direct amplification and washing of the FTA punches were examined in different PCR cycle numbers. One short robotically performed wash was found to improve the quality and the percent of profiles obtained. The optimal PCR cycle number was determined for 5 and 10 µL reaction volumes. The percent of obtained profiles, color balance, and reproducibility were examined. High-quality profiles were achieved in 90% and 88% of the samples amplified in 5 and 10 µL, respectively, in the first attempt. Volume reduction to 5 µL has a vast economic impact especially for DNA database laboratories.

Long allele designations at D2S1338 and D19S433 loci as influenced by various multiplex STR kits.

European forensic laboratories are replacing the STR multiplex kits with the new generation 16/17 STR kits. This study examines the influence of the new generation kits and the new Applied Biosystems 3500xL Genetic Analyzer on the designation of long D2S1338 and D19S433 off-ladder alleles. Different allele calls were obtained using the new NGM™ (Applied Biosystems) and PowerPlex(®) ESI™ (Promega) kits compared with AmpFℓSTR(®) SGM Plus™ kit (Applied Biosystems). Sequence analysis was used to determine accurate allele designation. The new multiplex kits and the 3500xL Genetic Analyzer improved accuracy of long allele designations. DNA databases worldwide include countless profiles obtained by previous kits. Discrepancies between the new and former technologies may cause failure to detect hits. Discordance is expected due to primer sequence differences between various kits. An additional discordance, occurring in long alleles, independent of primer sequence is reported in this study.

Recognizing the advantage of employing the PowerPlex(®) ESI and PowerPlex(®) ESX complementary kits for purposes of clarification in routine casework.

In an effort to promote European cross-border cooperation in fighting crime and international terrorism the Treaty of Prüm was drafted and accepted within the European forensic community. This move led to the commercial development of new multiplex kits which introduced five new STR loci and promised better performance. Recently the Israel Police DNA Casework and Database laboratories adopted the PowerPlex(®) ESI kit for routine use in our laboratories. Presented in this paper are examples of three types of ambiguous results encountered during the implementation of the PowerPlex(®) ESI kit into routine work. These ambiguous products presented themselves in the form of (1) extreme variants outside of loci borders, (2) failure to amplify sister allele pairs or expression of null alleles and (3) episodes of loss of separation of adjacent microvariants primarily in mixture samples. The re-analysis of all these samples using the PowerPlex(®) ESX kit successfully and rapidly clarified all three categories of anomalies. Spotlighting such events to the forensic community, especially regarding the novel loci introduced in these next generation kits, can aid in raising the analyst's awareness to their future appearances and prevent possible erroneous conclusions. In addition, providing timely DNA results to investigating teams is of great importance and operational forensic laboratories do not have at their immediate disposal methods such as sequencing to elucidate such manifestations. We suggest that the complementary use of the PowerPlex(®) ESI and PowerPlex(®) ESX can provide a benefit for clarification purposes in routine casework.

The Israel DNA database--the establishment of a rapid, semi-automated analysis system.

The Israel Police DNA database, also known as IPDIS (Israel Police DNA Index System), has been operating since February 2007. During that time more than 135,000 reference samples have been uploaded and more than 2000 hits reported. We have developed an effective semi-automated system that includes two automated punchers, three liquid handler robots and four genetic analyzers. An inhouse LIMS program enables full tracking of every sample through the entire process of registration, pre-PCR handling, analysis of profiles, uploading to the database, hit reports and ultimately storage. The LIMS is also responsible for the future tracking of samples and their profiles to be expunged from the database according to the Israeli DNA legislation. The database is administered by an in-house developed software program, where reference and evidentiary profiles are uploaded, stored, searched and matched. The DNA database has proven to be an effective investigative tool which has gained the confidence of the Israeli public and on which the Israel National Police force has grown to rely.