D16S539 microvariant or D2S1338 off-ladder allele? A case report about a range overlapping between two loci

All forensic laboratories routinely use commercial kits and softwares for automated typing; in rare cases genotyping misinterpretations or mislabellings occur. This study refers to the investigation on a D2S1338 off-ladder allele mislabelling observed in DNA profile of murdered woman.The Identifiler^® revealed heterozygosity in the range of D16S539, with a presumptive microvariant allele “14.2”, based on assigned size, while PowerPlex^®16 resulted in a homozygosity of allele “11”. Singleplex amplification of D16S539 locus confirmed homozigosity. D2S1338 locus, the closest to D16S1338 in Identifiler^®, genotyped as homozigote “19”, was singleplex amplified. The off-ladder peak was gel-isolated, sequenced and designed as a rare “11” allele variant [(TGCC)6(TTCC)5]. Genotype was finally designed as D16S539 “11,11” and D2S1338 “11,19”.To avoid genotyping misinterpretations or mislabelling, ambiguous genotypes should be established by two commercial kits at least. Furthermore, off ladder alleles as well as allele microvariants should be assigned by direct sequencing. This issue should be considered in Criminal DNA database requirements, that is still under debate in Italy.     

New alleles and mutational events at 14 STR loci from different German populations

The molecular origin of DNA mutations and the mutation rates were analyzed at 14 short tandem repeat (STR) loci with samples from trio cases derived from 10 different German population samples. STR loci comprised of D2S1360, D3S1744, D4S2366, D5S2500, D6S474, D7S1517, D8S1132, D10S2325, D12S391, D18S51, D19S246, D20S480, D21S226, and D22S689. In a total of 488 meioses, 16 isolated genetic inconsistencies in 8 different STRs were observed, whereas no mutations were found at the other loci. The data of five mutations suggested the presence of silent or null alleles due to sequence variation in primer binding site. This could be confirmed for four suspected cases by the use of alternative primer sets and by DNA sequence analyses. Furthermore, this study revealed nine new allelic variants at five different loci.     

一体解决微距摄影问题的实验研究

研究思路:对震动变抑震为同震,对配光变光动为物动,对调焦变像距调焦为物距精调。解决方案:近摄避震器。技术特 色:零振差消震,自适应配光,系统互操作。     

Estimating the Number of Contributors to Forensic DNA Mixtures: Does Maximum Likelihood Perform Better Than Maximum Allele Count?

Abstract: Determining the number of contributors to a forensic DNA mixture using maximum allele count is a common practice in many forensic laboratories. In this paper, we compare this method to a maximum likelihood estimator, previously proposed by Egeland et al., that we extend to the cases of multiallelic loci and population subdivision. We compared both methods’ efficiency for identifying mixtures of two to five individuals in the case of uncertainty about the population allele frequencies and partial profiles. The proportion of correctly resolved mixtures was >90% for both estimators for two‐ and three‐person mixtures, while likelihood maximization yielded success rates 2‐ to 15‐fold higher for four‐ and five‐person mixtures. Comparable results were obtained in the cases of uncertain allele frequencies and partial profiles. Our results support the use of the maximum likelihood estimator to report the number of contributors when dealing with complex DNA mixtures.     

Discordance at D3S1358 locus involving SGM Plus™ and the European new generation multiplex kits

During the course of routine database sample analysis in the Israel Police DNA database, an off-ladder D3S1358 allele, calculated to be >22.1, extending into the adjacent vWA locus was observed using Applied Biosystems SGM Plus™ kit.To verify the size of this D3S1358 long allele and to ensure it was not part of a trialle pattern in the neighboring locus, the sample was amplified using three of the European new generation STR multiplex kits: NGM^TM (Applied Biosystem), Powerplex™ ESX and ESI (Promega). The results of these amplifications determined the variant to be a 22 allele. Subsequent sequencing confirmed this designation and revealed a nucleotide polymorphism. Ten additional SGM Plus™ profiled samples with D3S1358 alleles larger than 19, were re-analyzed using NGM^TM and Powerplex™ ESX which also showed discordance in the calculated results between original SGM Plus™ designations and those obtained with the European new generation multiplexes.     

Sequence characterization of microvariant alleles at DYS627 and DYS458

Y chromosome short tandem repeats (Y-STRs) have been widely used in genetic applications and forensic casework. Recently, we found two intermediate alleles, the DYS627 allele 24.1 and the DYS458 allele 15.3, from Chinese Han population. The two allelic variants have not been recorded by the YHRD database. We have examined the molecular structure of these allelic variants by Sanger sequencing. The results showed that this intermediate allele at DYS627 was confirmed as 24.1, the sequence of which showed a base “A” insertion in the 13th repeat unit, and the intermediate allele at DYS458 was confirmed as 15.3, the sequence of which showed a base “G” deletion in the 12th repeat unit. This may be important for individual identification and paternal kinship testing. Besides, more allelic variants detected can be enriched in the Y-STR database.     

A rare mutation in the primer binding region of the Amelogenin X homologue gene

Use of Amelogenin locus typing as a gender marker incorporated in STR multiplexes is common practice in forensic genetics analysis. Among 5534 Polish male individuals tested using the SGMPlus kit, one was found to lack the amelogenin X-specific homologue (0.02%). The same result was obtained with other commercial kits which also amplify the amelogenin locus, namely ProfilerPlus and PowerPlex16. When alternative amelogenin primers external to but encompassing the initial amplicon were applied, an X homologue product was seen. Sequencing of the X homologue amelogenin allele revealed C to G mutation located at the most 3′ base of the commonly used amelogenin reverse primer. To our knowledge, this mutation and failure to amplify the X homologue of the amelogenin gene has not been reported for the European population.     

Updated allelic structures of the DXS10135 and DXS10078 STR loci

DXS10135 and DXS10078 are two highly polymorphic STR loci situated in two different linkage groups on the short arm of the human X chromosome. Both loci comprise complex tetrameric repeat units which may partially explain their high degree of polymorphism. DXS10135 is relatively well characterized and is included in a commercially available kit, while DXS10078 has not been well described. We sequenced a large number of alleles of both loci to try and understand the allelic variation and as a prelude to construct allelic ladders from cloned alleles. Our data show interesting features and should encourage other workers to use these loci in forensic genetic investigations.     

Distribution of Chemical Phenotypes (Chemotypes) in European Agricultural Hemp (Cannabis sativa L.) Cultivars

In Europe, more than 50 approved cultivars of fiber hemp (Cannabis sativa L.) are in agricultural production. Their content of psychoactive tetrahydrocannabinol (THC) is legally restricted to <0.2% (%w/w in the dry, mature inflorescences). Cannabis strains with much higher THC contents are also grown, illegally or under license for drug production. Differentiation between these two groups relies on biochemical quantification of cannabinoid contents in mature floral material. For nonflowering material or tissue devoid of cannabinoids, the genetic prediction of the chemical phenotype (chemotype) provides a suitable method of distinction. Three discrete chemotypes, depending on the ratio of THC and the noneuphoric cannabidiol (CBD), can be distinguished: a “THC-predominant” type, a “CBD-predominant” type, and an intermediate chemotype. We present a systematic genetic prediction of chemotypes of 62 agricultural hemp cultivars grown in Europe. The survey reveals the presence of up to 35% B_T allele-carrying individuals (representing either a THC-predominant or an intermediate chemotype) in some cultivars—which is unexpected considering the legal THC limit of 0.2% THC. The fact that 100% of the seized drug-type seeds in this study revealed at least one B_T allele, reflects that plant breeding efforts have resulted in a fixation of the B_T allele in recreational Cannabis. To guarantee a sincere forensic application based on a genetic chemotype prediction, we recommend not to classify material of unknown origin if the samples size is below nine genetically independent individuals.     

History education in schools in Iraqi Kurdistan: representing values of peace and violence

The Kurdistan Regional Government has implemented a wide range of reforms in Iraqi Kurdistan’s education system since its establishment in 2003. This qualitative study utilises critical discourse analysis to investigate the content of History Education (HE) textbooks (grades five to eight) and to assess how far peace education values and principles have been integrated into the curriculum. The ME’s top-down approach has faced significant resistance from teachers and it fails to consider the importance of hidden and null curricula. It focuses on the history of Iraq, Kurdistan, and Islam, glorifies war, excludes different narratives or interpretations, and fails to foster critical debate or enquiry. The curriculum appears to encourage violence and foster divisions between Muslims and non-Muslims, and the null curriculum is regulated to maintain the dominance of the group in power.