Project description:On the purpose of enhancing the forensic efficiency of CODIS STR loci, new STR loci have been gradually discovered and developed into some commercial multiplex systems. Recently, 22 STR loci including 18 non-CODIS STR loci and four CODIS STR loci were investigated in 501 unrelated healthy individuals of Kazakh ethnic group. Seven to 20 alleles at the different loci were identified and altogether 276 alleles for 22 selected loci were detected with the corresponding allelic frequencies ranging from 0.0010 to 0.3623. No significant deviation was observed from the Hardy-Weinberg equilibrium test for any of the 22 STRs. The value of cumulative power of discrimination in Kazakh group was 1-1.00E-28. Analyses of population differentiations and genetic distances between Kazakh and other Chinese groups presented that the Kazakh group with the Uygur group. These 22 STR loci evenly distributed on 22 different autosomal chromosomes were characterized by high genetic diversities and therefore could be utilized in the forensic cases to further increase the discrimination performance.
Project description:The aim of the study is to evaluate the suitability of STRs for molecular characterization and forensic applications in unrelated Brahmins of Rajasthan and Haryana states, India.Materials and methodsA total of 203 male DNA samples from various districts of Haryana (n=104) and Rajasthan (n=99) were genotyped using the GlobalFiler® PCR Amplification Kit. Allelic frequencies and different forensic parameters like PD, PE, PIC, PM, Ho, He, UHe, and TPI were calculated with different software.ResultsMore than 200 alleles were present in both populations, ranging from 6.0 to 35.2 and SE33 was the most polymorphic marker. The combined power of discrimination was 1. To know the relatedness with other Indian Brahmin populations, the UPGMA dendrogram and principal component analysis plot were visualized to show that both populations are close to each other and in nearby Saraswat Brahmins of Himachal Pradesh. This study showed a genetic relationship and forensic examination in the Haryana and Rajasthan Brahmin populations and various ethno-linguistically diverse populations of India.ConclusionThe results imply that the highly polymorphic 21 autosomal STR loci might be applied for individuals' forensic identification and parentage testing. This study also suggests that the kit having both autosomal and Y-STR markers is appropriate for a better understanding of the genetic and forensic examination in the Brahmin population of Haryana and Rajasthan.
Project description:The interpretation of matching between DNA profiles of a person of interest and an item of evidence is undertaken using population genetic models to predict the probability of matching by chance. Calculation of matching probabilities is straightforward if allelic probabilities are known, or can be estimated, in the relevant population. It is more often the case, however, that the relevant population has not been sampled and allele frequencies are available only from a broader collection of populations as might be represented in a national or regional database. Variation of allele probabilities among the relevant populations is quantified by the population structure quantity FST and this quantity affects matching proportions. Matching within a population can be interpreted only with respect to matching between populations and we show here that FST, can be estimated from sample allelic matching proportions within and between populations. We report such estimates from data we extracted from 250 papers in the forensic literature, representing STR profiles at up to 24 loci from nearly 500,000 people in 446 different populations. The results suggest that theta values in current forensic use do not have the buffer of conservatism often thought.
Project description:We investigated the allelic frequencies and forensic descriptive parameters of 23 autosomal short tandem repeat loci in a randomly selected sample of 1218 unrelated healthy Uyghur individuals residing in the Xinjiang Uyghur Autonomous Region, northwest China. A total of 281 alleles at these loci were identified and their corresponding allelic frequencies ranged from 0.0004 to 0.5390. The combined match probability and combined probability of exclusion of all loci were 5.192 × 10-29 and 0.9999999996594, respectively. The results of population genetic study manifested that Uyghur had close relationships with those contiguous populations, such as Xibe and Hui groups. In a word, these autosomal short tandem repeat loci were highly informative in Uyghur group and the multiplex PCR system could be used as a valuable tool for forensic caseworks and population genetic analysis.
Project description:The Yi is one of fifty-six ethnic populations and one of the most ancient ethnic groups in China. The Liangshan Yi Autonomous Prefecture (LYAP) in Sichuan Province has the single largest Yi community in China. To establish a Yi population database in the LYAP of Sichuan in China, a Goldeneye™ DNA Identification System 20A Kit with 19 autosomal STRs (short tandem repeats) was used. As a result, the total discrimination power (TDP) and the cumulative probability of exclusion (CPE) for these STRs in 1016 unrelated individuals were 0.999999999999999999999897 and 0.9999999597, respectively. Totals of 273 alleles for 19 STRs and 8-22 alleles for each locus were found. The allelic frequencies ranged from 0.0005 to 0.5084. The forensic parameter averages of these STRs were as follows: observed heterozygosity (Hobs) of 78.44%, expected heterozygosity (Hexp) of 79.89%, discrimination power (DP) of 92.66%, and probability of exclusion (PE) of 57.68%. Penta E presented the highest levels of Hobs and DP, whereas TPOX showed the lowest Hobs and DP values. Nei's standard genetic distance matrix among 31 populations found that the nearest genetic distance to the Yi population was the Sichuan Han (0.0056). Altogether, we first reported the forensic parameters and allele frequencies of 19 autosomal STRs of the Yi group in Liangshan. These 19 STR makers could provide highly informative polymorphisms for individual identification, paternity testing and genetic population analyses.
Project description:Match probabilities calculated during the evaluation of DNA evidence profiles rely on appropriate values of the population structure quantity θ. NGS-based methods will enhance forensic identification and with the transformation to such methods comes the need to facilitate NGS-based population genetics analysis. If NGS data are to be used for match probabilities there needs to be a way to accommodate population structure, which requires values for θ for those data. Such estimates have not been available. This study assesses population structure for sequence-based data using a relatively new approach applied to STR data over 27 loci in five different geographic groups. Matching proportions between individuals or groups are used to obtain locus-specific θ estimates as well as estimates per geographic group and a global measure. The results demonstrate similar effects of sequencing data on θ estimates compared to what has been seen for CE-based results.
Project description:This study evaluates the forensic utility of 23 autosomal short tandem repeat markers in 400 samples from the Kuwaiti population, of which four markers (D10S1248, D22S1045, D2S441 and SE33) are reported for the first time for Kuwait. All the markers were shown to exhibit no deviation from Hardy-Weinberg equilibrium, nor any linkage disequilibrium between and within loci, indicating that these loci are inherited independently, and their allele frequencies can be used to estimate match probabilities in the Kuwaiti population. The low combined match probability of 7.37 × 10-30 and the high paternity indices generated by these loci demonstrate the usefulness of the PowerPlex Fusion 6C kit for human identification in this population, as well as to strengthen the power of paternity testing. Off-ladder alleles were seen at several loci, and these were identified by examining their underlying nucleotide sequences. Principal component analysis (PCA) and STRUCTURE showed no genetic structure within the Kuwaiti population. However, PCA revealed a correlation between geographic and genetic distance. Finally, phylogenetic trees demonstrated a close relationship between Kuwaitis and Middle Easterners at a global level, and a recent common ancestry for Kuwait with its northern neighbours of Iraq and Iran, at a regional level.
Project description:Life span is a complex and multifactorial trait, which is shaped by genetic, epigenetic, environmental, and stochastic factors. The possibility that highly hypervariable short tandem repeats (STRs) associated with longevity has been largely explored by comparing the genotypic pools of long lived and younger individuals, but results so far have been contradictory. In view of these contradictory findings, the present study aims to investigate whether HUMTHO1 and HUMCSF1PO STRs, previously associated with longevity, exert a role as a modulator of life expectancy, as well as to assess the extent to which other autosomal STR markers are associated with human longevity in population from northern Spain. To that end, 21 autosomal microsatellite markers have been studied in 304 nonagenarian individuals (more than 90 years old) and 516 younger controls of European descent. Our results do not confirm the association found in previous studies between longevity and THO1 and CSF1PO loci. However, significant association between longevity and autosomal STR markers D12S391, D22S1045, and DS441 was observed. Even more, when we compared allelic frequency distribution of the 21 STR markers between cases and controls, we found that 6 out of the 21 STRs studied showed different allelic frequencies, thus suggesting that the genomic portrait of the human longevity is far complex and probably shaped by a high number of genomic loci.
Project description:Non-CODIS STRs, with high polymorphism and allele frequency difference among ethnically and geographically different populations, play a crucial role in population genetics, molecular anthropology, and human forensics. In this work, 332 unrelated individuals from Sichuan Province (237 Tibetan individuals and 95 Yi individuals) are firstly genotyped with 21 non-CODIS autosomal STRs, and phylogenetic relationships with 26 previously investigated populations (9,444 individuals) are subsequently explored. In the Sichuan Tibetan and Yi, the combined power of discrimination (CPD) values are 0.9999999999999999999 and 0.9999999999999999993, and the combined power of exclusion (CPE) values are 0. 999997 and 0.999999, respectively. Analysis of molecular variance (AMOVA), principal component analysis (PCA), multidimensional scaling plots (MDS) and phylogenetic analysis demonstrated that Sichuan Tibetan has a close genetic relationship with Tibet Tibetan, and Sichuan Yi has a genetic affinity with Yunnan Bai group. Furthermore, significant genetic differences have widely existed between Chinese minorities (most prominently for Tibetan and Kazakh) and Han groups, but no population stratifications rather a homogenous group among Han populations distributed in Northern and Southern China are observed. Aforementioned results suggested that these 21 STRs are highly polymorphic and informative in the Sichuan Tibetan and Yi, which are suitable for population genetics and forensic applications.
Project description:Like DIP-STR markers (deletion/insertion polymorphism-short tandem repeat combinations), SNP-STR markers (single nucleotide polymorphism-STR combinations) are also valuable in forensic DNA mixture analysis. In this study, eight SNP-STRs were selected, and a stable and sensitive multiplex polymerase chain reaction (PCR) assay was developed for amplifying these SNP-STRs and the Amelogenin gender marker according to the principle of amplification refractory mutation system (ARMS). This novel multiplex set allows detection of the minor DNA contributor in a DNA mixture of any gender and cellular origin with high resolution (beyond a DNA ratio of 1:20). In addition, SNP-STR haplotype frequencies were estimated based on a survey of 350 unrelated individuals from Chinese Han population, and the combined power of discrimination (PD) and power of exclusion (PE) of the eight SNP-STRs were calculated as 0.99999999965 and 0.9996, which were obviously higher than that of the eight STR loci: 0.9999999954 and 0.9989 respectively. The results indicated that the SNP-STR compound markers have higher application value in forensic identification compared to standard autosomal STRs, especially in the analysis of imbalanced DNA mixtures.