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We present a statistical method for biallelic SNP genotyping that reduces the risk of wrong SNP calls and gives fewer no-calls. The method uses a symmetric multinomial logistic regression model with an intuitive graphical interpretation. Its probabilistic nature gives the user control over the accepted risk through the estimated genotype probabilities. We compared the performance of our method with the HID SNP Genotyper v.4.3.1 plug-in (HSG) (Thermo Fisher Scientific) and the additional criteria of the University of Copenhagen (UCPH) through a series of six DNA dilutions from 500 pg to 16 pg DNA. The HSG method made wrong calls from 62.5 pg DNA and below, while the UCPH method made wrong calls at 16 pg DNA. Our method allowed SNP genotyping of 16 pg DNA without making wrong calls. Depending on the DNA dilution, our method also reduced the number of no-calls by 70–96 % compared to UCPH method and 59–69 % compared to the HSG method. Our method can be used for any biallelic genotyping.

The Illumina® ForenSeq™ kit amplifies in one multiplex PCR reaction 59 STRs and 172 SNPs relevant to forensic genetic case work. Typed markers include markers for identification, ancestry identification (AIMs) and pigmentary traits. The products were sequenced on the MiSeq FGx Forensic Genomics System and analysed with the ForenSeq™ Universal Analysis Software. Using this approach, we sequenced 10 Danish, 10 Italian, and 10 individuals from other populations, mostly non-europeans. The eye and hair colours as well as the bio-geographical ancestry of the individuals were known.Blue and brown eye colours were predicted accurately by the ForenSeq™ assay, whereas intermediate eye colours were not. The success of the hair colour prediction tool seemed population-dependent. The predictions matched the hair colours reported by the individuals themselves in twice as many Danes as Italians. The geographic ancestries of 22 out of 23 individuals of European or East Asian ancestry were correctly predicted. However, the ForenSeq™ Universal Analysis Software was unable to differentiate between individuals from Middle East/South Asia, South America and North Africa.We found no difference in STR typing results obtained with the ForenSeq™ kit and capillary electrophoresis.

The introduction of Next Generation Sequencing (NGS) techniques for forensic use has greatly expanded the possibilities of extracting information from biological stain materials in crime cases. However, the NGS workflows are not fully optimized for continuous, high-throughput processing of samples in forensic genetic laboratories. Although the Ion PGM™ has been on the market since 2010, the process of preparing samples for sequencing is still rather cumbersome and involves a large number of pipetting steps. This creates variability in the loading of the sequencing chips and in the sequencing coverage. This variability in turn complicates the interpretation of the results, i.e., low coverage leads to locus or allele dropout for poor performing markers. In order to automate a part of the sample preparation, we used the Ion Chef™ (Life Technologies) to prepare pooled Ion AmpliSeq™ libraries for emulsion PCR and loading onto sequencing chips. The workload and the number of manual pipetting steps were decreased while the chip loading efficiency, uniformity of loading and reproducibility was increased using the Ion Chef™ compared to the performance obtained with the more manual setup using the Ion OneTouch™ 2 system.

A concordance study of the results of PowerPlex(®) ESI 17 and AmpFℓSTR(®) NGM SElect™ kits obtained from 591 individuals from Somalia (N=198), Denmark (N=199) and Greenland (N=194) was performed. Among 9456 STR types, seven discordant results were found with the two kits: one observed in the D19S433 system in an individual from Denmark and six in the SE33 system in six individuals from Somalia. Sequencing of SE33 in the six samples with discordant results showed G>A transition 15bp downstream of the repeat unit in three of the individuals, and G>A transition 68bp downstream of the repeat unit in the other three individuals. Population data for 16 autosomal STR systems analyzed in 989 individuals from Somalia, Denmark and Greenland are also presented. The highest mean heterozygosity was observed in Danes (82.5%). With the exception of D8S1179 in Danes, no significant deviations from Hardy-Weinberg expectations were observed. Only one pair of systems (D12S391 and D18S51) showed significant allelic association in Greenlanders (after Holm-Šidák correction). A MDS plot drawn from pairwise FST values calculated between 21 populations showed a clear displacement of the Greenlandic population versus the other ones included in the analyses. The highest combined chance of exclusion and power of discrimination was observed for Danes reaching values of 99.9999987% and 1 in 1.8×10(21), respectively.

Non-uniform phenotyping of five case work samples were observed in the D12S391 locus. The samples were typed at least twice with the AmpFℓSTR(®) NGM SElect™ PCR Amplification Kit and different alleles were called with GeneMapper(®) ID-X in the different experiments. Detailed analyses of the electropherograms suggested that the individuals were heterozygous with two alleles that differed in size by one nucleotide. This was confirmed by amplifying the samples with the PowerPlex(®) ESX 17 system. D12S391 is a complex STR with variable numbers of AGAT and AGAC repeats. Second generation sequencing revealed that separation of two alleles differing by one nucleotide in length was poor if the number of AGAT repeats in the short allele was higher than in the long allele. A total of 45 individuals with microvariants or off-ladder alleles in D12S391 were sequenced. Thirty different alleles were detected and sixteen of these were not previously reported.

The GenPlex (TM) HID System (Applied Biosystems - AB) offers typing of 48 of the 52 SNPforID SNPs and amelogenin. Previous studies have shown a high reproducibility of the GenPlex (TM) HID System using 250500 pg DNA of good quality. An international exercise was performed by 14 laboratories (9 in Europe and 5 in the US) in order to test the robustness and reliability of the GenPlex (TM) HID System on forensic samples. Three samples with partly degraded DNA and 10 samples with low amounts of DNA were analyzed in duplicates using various amounts of DNA. In order to compare the performance of the GenPlex (TM) HID System with the most commonly used STR kits, 500 pg of partly degraded DNA from three samples was typed by the laboratories using one or more STR kits. The median SNP typing success rate was 92.3% with 500 pg of partly degraded DNA. Three of the fourteen laboratories counted for more than two thirds of the locus dropouts. The median percentage of discrepant results was 0.2% with 500 pg degraded DNA. An increasing percentage of locus dropouts and discrepant results were observed when lower amounts of DNA were used. Different success rates were observed for the various SNPs. The rs763869 SNP was the least successful. With the exception of the MiniFiler (TM) kit (AB), GenPlex (TM) HID performed better than five other tested STR kits. When partly degraded DNA was analyzed, GenPlex (TM) HID showed a very low mean mach probability, while all STR kits except MiniFiler (TM) had very limited discriminatory power. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

The GenPlex (TM) HID System (Applied Biosystems - AB) offers typing of 48 of the 52 SNPforID SNPs and amelogenin. Previous studies have shown a high reproducibility of the GenPlex (TM) HID System using 250500 pg DNA of good quality. An international exercise was performed by 14 laboratories (9 in Europe and 5 in the US) in order to test the robustness and reliability of the GenPlex (TM) HID System on forensic samples. Three samples with partly degraded DNA and 10 samples with low amounts of DNA were analyzed in duplicates using various amounts of DNA. In order to compare the performance of the GenPlex (TM) HID System with the most commonly used STR kits, 500 pg of partly degraded DNA from three samples was typed by the laboratories using one or more STR kits. The median SNP typing success rate was 92.3% with 500 pg of partly degraded DNA. Three of the fourteen laboratories counted for more than two thirds of the locus dropouts. The median percentage of discrepant results was 0.2% with 500 pg degraded DNA. An increasing percentage of locus dropouts and discrepant results were observed when lower amounts of DNA were used. Different success rates were observed for the various SNPs. The rs763869 SNP was the least successful. With the exception of the MiniFiler (TM) kit (AB), GenPlex (TM) HID performed better than five other tested STR kits. When partly degraded DNA was analyzed, GenPlex (TM) HID showed a very low mean mach probability, while all STR kits except MiniFiler (TM) had very limited discriminatory power., Funding Agencies|Ellen and Aage Andersens Foundation

Udgivelsesdato: 1996-Nov, We have previously reported that, unlike their rat counterparts, the survival of mouse cerebellar granule cells is independent of chronic stimulation whether owing to elevated K(+)-induced depolarization or NMDA (N-methyl-D-aspartate) receptor activation. One explanation could be that during the critical period mouse granule cells are very sensitive to NMDA receptor stimulation by endogenous glutamate released in the cultures. If so, this might be reflected by an increased expression of NMDA receptors or an increased response to their activation. We tested this hypothesis by measuring (a) the concentration of mRNA for the obligatory NMDA receptor subunit, NMDAR1, and (b) the glutamate/NMDA stimulated increase in cytosolic Ca(2+)-ion concentration in cultures at physiological or elevated K(+)-ion concentration. The expression of NMDAR1 mRNA was measured by competitive PCR of reversely transcribed mRNA and was normalized to that of the constitutively expressed H3.3 histone mRNA. The glutamate and NMDA stimulated increase in cytosolic Ca(2+)-ion concentration was measured using the fluorescent Ca(2+)-chelator Fluo3. In contrast to the hypothesis, we found NMDAR1 mRNA expression to be lower in mouse than in rat granule cells cultured for 4 days at physiological K(+)-ion concentration. However, the NMDA stimulated increase in cytosolic Ca(2+)-ion concentration did not differ in 4-day rat and mouse cultures. Although the glutamate-stimulated increase in cytosolic Ca(2+)-ion concentration in 2-day cultures was higher in mouse granule cells than in rat granule cells, the developmental profile of the glutamate-stimulated increase in cytosolic Ca(2+)-ion concentration was the same in both cases. In conclusion, we found no obvious evidence for increased NMDA receptor activity in mouse cerebellar granule cells cultured at physiological K(+)-ion concentration.