Solution to a case involving the interpretation of trace degraded DNA mixtures.

DNA mixture analysis poses a significant challenge in forensic genetics, particularly when dealing with degraded and trace amount DNA samples. Multi-SNPs (MNPs) are genetic markers similar to microhaplotypes but with smaller molecular sizes (< 75 bp), making them theoretically more suitable for analyzing degraded and trace amount samples. In this case report, we investigated a cold case involving a campstool stored for over a decade, aiming to detect and locate the suspect's DNA. We employed both conventional capillary electrophoresis-based short tandem repeat (CE-STR) analysis and next-generation sequencing-based multi-SNP (NGS-MNP) analysis. The typing results and deconvolution of the mixed CE-STR profiles were inconclusive regarding the presence of the suspect's DNA in the mixed samples. However, through NGS-MNP analysis and presence probability calculations, we determined that the suspect's DNA was present in the samples from Sect. 4-1 with a probability of 1-8.41 × 10- 6 (99.999159%). This evidence contradicted the suspect's statement and aided in resolving the case. Our findings demonstrate the significant potential of MNP analysis for examining degraded and trace amount DNA mixtures in forensic investigations.

Forensic efficiency and population genetic construction of Guizhou Gelao minority from Southwest China revealed by a panel of 23 autosomal STR loci.

Short tandem repeats (STRs) are the most common genetic markers in forensic and human population genetics due to their high polymorphism, rapid detection, and reliable genotyping. To adapt the rapid growth of forensic DNA database and solve problems in disputed cases, a panel of 23 autosomal STR loci with high discriminating ability was constructed recently. The Tai-Kadai-speaking Gelao is the most ancient indigenous minority in Guizhou province, however, the forensic efficiency and population genetic structure remain poorly explored. Here, 490 Guizhou Gelao individuals from Southwest China were genotyped with the panel of 23 STRs using the Huaxia Platinum Kit. A total of 265 alleles were screened. The combined discrimination power and the combined probability of paternity were 0.9999 and 0.9999, respectively. This indicated the 23 loci had higher discrimination power in Guizhou Gelao and could be applied to forensic practice. Comprehensive population structures with reference populations from China and abroad using the neighbour-joining phylogenetic tree (N-J tree), multidimensional scaling, principal component analysis and heatmap demonstrated that Guizhou Gelao was genetically closer to Guizhou Han than other populations. Moreover, our results showed that a complex phylogenetic model was influenced by ethnic, geographic, and linguistic factors. Key points: The first batch of genetic data for 23 autosomal STRs in 490 Geolao individuals from Guizhou was provided.The 23 STR panel can afford high genetic polymorphisms and discrimination power and can be efficiently applied to forensic practice in Guizhou Gelao population.A complex phylogenetic model influenced by ethnic, geographic, and linguistic factors was uncovered.

Traceability of Geographic Origin Using Human Skin and Oral Microbiota.

OBJECTIVES: To explore the possibility of using human skin and oral microorganisms to estimate the geographic origin of an individual through the sequencing analysis of bacterial 16S rRNA gene. METHODS: Microbial DNA was extracted from the palm and oral microorganisms of the Han population in Shanghai and Chifeng, Inner Mongolia, and the composition and diversity of the microbiota were analyzed by full-length 16S rRNA gene sequencing. Then, differential species were screened and a geographic location prediction model was constructed. RESULTS: The compositions of palm and oral microorganisms between Shanghai and Chifeng samples were both different. The abundance and uniformity of palm side skin microorganisms were higher in Chifeng samples than in Shanghai samples, while there was no significant difference in oral microorganisms. Permutational multivariate analysis of variance (PERMANOVA) confirmed that the ß-diversity between the samples from the two places were statistically significant, and the coefficients of determination (R2) for skin and oral samples were 0.129 and 0.102, respectively. Through principal co-ordinates analysis (PCoA), the samples from the two places could be preliminarily distinguished. The predictive model had the accuracies of 0.90 and 0.83 for the geographic origin using the skin and oral samples, respectively. CONCLUSIONS: There are differences in the compositions of palm and oral microbiota between Han populations in Shanghai and Chifeng. The prediction model constructed by the random forest algorithm can trace the unknown individuals from the above two places.

Establishing an integrated pipeline for automatic and efficient detection of trace DNA encountered in forensic applications.

The analysis of trace DNA is a crucial component in forensic applications. Biological materials containing low-level DNA collected at crime scenes, such as fingerprints, can be valuable as evidence. Automatic detection of biological samples has been largely embraced in forensic applications to meet the increasing throughput requirements. However, the amount of DNA automatically retrieved from trace evidence often tends to be small and unstable, ultimately resulting in poor detection of DNA profiles. Thus, in this work, we introduced a robust DNA extraction and purification platform named Bionewtech® BN3200 (Bionewtech®, Shanghai, China) with the goal of constructing a rapid automatic detection system for trace DNA. The establishment of automatic detection system for trace DNA mainly encompassed two parts: assessing the sensitivity of automatic extraction platform and screening the optimal short tandem repeat (STR) typing kit. The sensitivity of Bionewtech® BN3200 platform based on Ultra-sensitive DNA Extraction kit was initially estimated, demonstrating that this extraction platform might contain large potential in the trace DNA extraction. For the amplification part, three sets of commercial multiplex STR typing kits were selected as candidates, and the amplified products were further genotyped on the Applied Biosystems 3500xl Genetic Analyzer. After comparation, SiFa™ 23 Plex Kit was determined as the most suitable amplification system for trace DNA. Eventually, the newly exploited trace DNA detection system was successfully implemented in the detection of fingerprints derived from glass surfaces with the five-seconds contact time. As a result, the DNA recovered from the fingerprints fluctuated approximately from 57.60 pg to 18.05 ng, in addition, over 70% of the total STR loci were detected in 75% of the fingerprint samples.

Investigation of 12 X-STR loci in Mongolian and Eastern Han populations of China with comparison to other populations.

Due to the unique inheritance pattern, X-chromosomal short tandem repeats (X-STRs) have several advantages in complex kinship cases, such as deficiency cases or grandparent-grandchild and half-sisters testing. In our study, 541 unrelated individuals gathered from Mongolian and Eastern Chinese Han populations were successfully genotyped using the Investigator Argus X-12 kit. We calculated allele/haplotype frequencies and other forensic parameters of the two populations and further explored their genetic distance with already published Chinese populations and six global populations. Our results showed that the 12 X-STR markers were highly informative in the two populations when compared with nine other Chinese populations: significant differences were found at several loci. Geographically neighboring populations or different ethnic groups within the same area appeared to have closer evolutionary relationships. We also analyzed population genetic structure by performing clustering with the STRUCTURE program and Principal Coordinate Analysis (PCoA), and we found that the Chinese and other populations enrolled in this study could be distinguished. Furthermore, Mongolian males were distinguishable from the other studied males by a moderate genetic distance. Our study also expanded the X-STR database, which could facilitate the appropriate application of the 12 X-STR markers in the forensic field in China.

Population genetics of 30 insertion/deletion polymorphisms in Han Chinese population from Zhejiang Province.

Insertion/deletion (InDels) markers can serve as a useful supporting tool to short tandem repeat (STR) typing systems for human identification. The Qiagen DIPplex Investigator kit, which contains 30 biallelic autosomal InDels and amelogenin, has been developed for forensic use. To estimate the genetic diversity of the 30 markers in Han Chinese individuals living in Zhejiang and to further evaluate their applicability in forensic science, 246 unrelated Han Chinese from Zhejiang were genotyped at these loci. No significant departures from Hardy-Weinberg equilibrium were observed at these loci in these participants. The combined power of discrimination was over 0.99999999 and the combined probability of exclusion was over 0.9901. Results demonstrated that the 30 InDel markers could be used as a supporting tool for the human identification of specific Han Chinese individuals from Zhejiang. The genetic differences and phylogenetic relationships among Han Chinese from Zhejiang, Han Chinese from five other areas, nine minority ethnic groups, as well as two other East Asian populations were also investigated. Two InDel markers, HLD39 and HLD40, showed significant allele-frequency differences between Han Chinese from Zhejiang and ethnic minorities. Further analysis can be used to evaluate their role in forensic science.

Analysis of genetic admixture in Uyghur using the 26 Y-STR loci system.

The Uyghur population has experienced extensive interaction with European and Eastern Asian populations historically. A set of high-resolution genetic markers could be useful to infer the genetic relationships between the Uyghur population and European and Asian populations. In this study we typed 100 unrelated Uyghur males living in southern Xinjiang at 26 Y-STR loci. Using the high-resolution 26 Y-STR loci system, we investigated genetic and phylogenetic relationship between the Uyghur population and 23 reference European or Asian populations. We found that the Uyghur population exhibited a genetic admixture of Eastern Asian and European populations, and had a slightly closer relationship with the selected European populations than the Eastern Asian populations. We also demonstrated that the 26 Y-STR loci system was potentially useful in forensic sciences because it has a large power of discrimination and rarely exhibits common haplotypes. However, ancestry inference of Uyghur samples could be challenging due to the admixed nature of the population.

[Genetic Polymorphisms of 26 Y-STR Loci in Fujian She Nationality and Its Forensic Application].

OBJECTIVE: To study the forensic application of Goldeneye DNA ID 26Y Kit in the She nationality. METHODS: Through capillary electrophoresis, the genotype of 26 Y-STR loci were analyzed in 53 unrelated male individuals from Fujian She nationality. The population genetics parameters such as allele frequency and haplotype diversity were calculated. The comparisons among the She nationality and the other nationalities were analyzed. RESULTS: A total of 126 alleles were observed on the 26 Y-STR loci of 53 unrelated male individuals. The allele frequencies and GD value ranged from 0.010 1 to 0.886 8 and 0.211 2 to 0.846 2, respectively. The GD value was greater than 0.5 in the 19 loci. A total of 47 haplotypes were observed. Based on R(ST), multidimensional scaling plot indicated that the genetic relationship among Fujian She nationality and Minnan Han nationality was closest, followed by Southern China Han nationality and Northern China nationality. CONCLUSION: Goldeneye™ DNA ID 26Y Kit including 26 Y-STR loci has good polymorphism in the She nationality. As an additional system, it has forensic application value in some special cases.

Differentiating between monozygotic twins through next-generation mitochondrial genome sequencing.

Monozygotic (MZ) twins, considered to be genetically identical, cannot be distinguished from one another by standard forensic DNA testing. A recent study employed whole genome sequencing to identify extremely rare mutations and reported that mutation analysis could be used to differentiate between MZ twins. Compared with nuclear DNA, mitochondrial DNA (mtDNA) has higher mutation rates; therefore, minor differences theoretically exist in MZ twins' mitochondrial genome (mtGenome). However, conventional Sanger-type sequencing (STS) is neither amenable to, nor feasible for, the detection of low-level sequence variants. The recent introduction of massively parallel sequencing (MPS) has the capability to sequence many targeted regions of multiple samples simultaneously with desirable depth of coverage. Thus, the aim of this study was to assess whether full mtGenome sequencing analysis can be used to differentiate between MZ twins. Ten sets of MZ twins provided blood samples that underwent extraction, quantification, mtDNA enrichment, library preparation, and ultra-deep sequencing. Point heteroplasmies were observed in eight sets of MZ twins, and a single nucleotide variant (nt15301) was detected in five sets of MZ twins. Thus, this study demonstrates that ultra-deep mtGenome sequencing could be used to differentiate between MZ twins.

Logical Framework of Forensic Identification: Ability to Resist Fabricated DNA.

Over the past 30 years, DNA analysis has revolutionized forensic science and has become the most useful single tool in the multifaceted fight against crime. Today, DNA profiling with sets of highly polymorphic autosomal short tandem repeat markers is widely employed and accepted in the courts due to its high discriminating power and reliability. However, an artificial bloodstain purposefully created using molecular biology techniques succeeded in tricking a leading forensic DNA laboratory. The disturbing possibility that a forensic DNA profile can be faked shocked the general public and the mass media, and generated serious discussion about the credibility of DNA evidence. Herein, we present two exemplary assays based on tissue-specific methylation patterns and cell-specific mRNA expression, respectively. These two assays can be integrated into the DNA analysis pipelines without consumption of additional samples. We show that the two assays can not only distinguish between artificial and genuine samples, but also provide information on tissue origin. The two assays were tested on natural and artificial bloodstains (generated by polymerase chain reaction and whole genome amplification technique) and the results illustrated that the logical framework of forensic identification is still useful for forensic identification with the high credibility.

A case of false mother included with 46 autosomal STR markers.

BACKGROUND: For solving a maternity case, 19 autosomal short tandem repeats (STRs) were amplified using the AmpFℓSTR(®) Sinofiler(TM) kit and PowerPlex(®) 16 System. Additional 27 autosomal STR loci were analyzed using two domestic kits AGCU 21+1 and STRtyper-10G. The combined maternity index (CMI) was calculated to be 3.3 × 10(13), but the putative mother denied that she had given birth to the child. In order to reach an accurate conclusion, further testing of 20 X-chromosomal short tandem repeats (X-STRs), 40 single nucleotide polymorphism (SNP) loci, and mitochondrial DNA (mtDNA) was carried out. FINDINGS: The putative mother and the boy shared at least one allele at all 46 tested autosomal STR loci. But, according to the profile data of 20 X-STR and 40 SNP markers, different genotypes at 13 X-STR loci and five SNP loci excluded maternity. Mitochondrial profiles also clearly excluded the mother as a parent of the son because they have multiple differences. It was finally found that the putative mother is the sister of the biological father. CONCLUSIONS: Different kinds of genetic markers needfully supplement the use of autosomal STR loci in case where the putative parent is suspected to be related to the true parent.

[Linkage disequilibrium and mutation rate analysis of sixteen X-STR loci].

OBJECTIVE: To assess the patterns of linkage disequilibrium (LD) of 16 STR loci on X chromo- some and investigate the genetic stability. METHODS: Genomic DNA samples extracted from blood stains from 500 unrelated individuals and 885 lineage members from Eastern Chinese Han population were genotyped through multiplex amplification using IDtyperX-16 kit by our independent research followed by capillary electrophoresis. LD was assessed by PowerMarker v3.25 software and mutation rate of every locus was analyzed. RESULTS: LD were not found at the 16 X-STR loci. Allele mutations were observed at 10 loci. Among them, mutation rates of DXS6809 and DXS7132 were both up to 0.0048. CONCLUSION: When the 16 X-STR loci included in IDtyperX-16 kit were used for parentage testing, product princi- ples can be applied to calculate the likelihood, but mutation should be taken into consideration in the case that the genotypes do not meet the genetic law (especially at DXS6809 and DXS7132).

[Forensic application of 30 InDel loci in Han and She nationalities of Eastern China].

OBJECTIVE: To evaluate the forensic application value of 30 insertion/deletion (InDel) loci included in Investigator DIPplex Kit in Han and She nationalities of Eastern China. METHODS: A total of 565 unrelated individuals in Han nationality and 119 ones in She nationality of Eastern China were investigated using Investigator DIPplex Kit. Allele frequencies, population genetics parameters of the 30 InDel loci were statistically calculated. RESULTS: In Han nationality, the mean Ho was 0.413 3, the mean DP was 0.551 1, the mean PIC was 0.320 0. And in She nationality, the mean Ho was 0.389 6, the mean DP was 0.543 3, the mean PIC was 0.310 0. No deviation from Hardy-Weinberg equilibrium was observed in Han and She nationalities (P > 0.05). CONCLUSION: The 30 loci in Investigator DIPplex Kit show good genetic diversity in Han and She nationalities, and could be used as a supplemental tool for some special paternity cases.

[Progress in InDel as a new generation of genetic marker].

As forensic DNA typing experienced three generations of genetic marker researching stage, short tandem repeat (STR) has been widely used in forensic identification as a mature tool. Further exploration of the human genome led to the discovery of polymorphism markers of single nucleotide polymorphism (SNP) and Insertion/Deletion (InDel). InDel, which combines the desirable characteristics of previous genetic markers as a new type of genetic marker, has got extensive concern in fields like medical molecular biology and forensic biology. This paper generally reviews the history of research and the corresponding results of InDel along the line of time axis as well as the different aims of these research focusing on the progress in the multiple amplification system with several InDel as the genetic marker (autosomal or X chromosome) in forensic biology and anthropology. Finally, the direction of research in this field and the problems to be solved have been put forward.

Genetic polymorphisms of 12 X-STR for forensic purposes in Shanghai Han population from China.

X-chromosomal short tandem repeats (X-STR) loci are used for forensic practice in recent years in some complex kinship cases. The commercially available kit of Investigator Argus X-12 (Qiagen, Hilden, Germany) makes it possible to examine the markers of DXS10148-DXS10135-DXS8378, DXS7132-DXS10079-DXS10074, DXS10103-HPRTB-DXS10101 and DXS10146-DXS10134-DXS7423, which belong to four linkage groups of X-chromosome. In this study, a total of 309 unrelated individuals (200 males and 109 females) from Shanghai Han population were successfully analyzed with this kit. Hardy-Weinberg equilibrium tests demonstrated no significant deviation from expected values (P > 0.05) for all of the 12 X-STR loci in the Shanghai Han population. Linkage disequilibrium tests were performed for all pairs of loci by the Arlequin v3.1 software and only DXS10103-DXS10101 remained significant after adjustment for multiple testing (P < 0.05/66). The combined power of discrimination in males (CDP(M)) was 0.999999996 while in females (CDP(F)) was 0.999999999999995, and the combined mean exclusion chance in duo cases (CMEC(D)) was 0.999998 while in trio cases (CMEC(T)) was 0.999999986. The results suggest that the twelve X-STR loci may provide high polymorphic information for paternity testing and forensic identification in Chinese Han population from Shanghai.

[Forensic application of investigator Argus X-12 kit in Han population from East China].

OBJECTIVE: To investigate the genetic data of the 12 X-STR included in Investigator Argus X-12 kit and to evaluate the forensic application in Han population from East China. 9: By detecting 309 unrelated individuals with Investigator Argus X-12 kit, allele frequencies, population genetics parameters and the information of linkage disequilibrium of the 12 X-STR were analyzed by statistics and were compared with available data of other Han populations from different regions. RESULTS: No deviations from Hardy-Weinberg equilibrium were detected. Except loci of DXS10103 and DXS10101 linked closely, all other loci were independent while HET exceed 0.5 and PIC all above 0.4. Distributions of allele frequencies of all loci were not significant statistically except for locus of DXS10146 in Han population from Guangdong. CONCLUSION: Loci of Investigator Argus X-12 kit were highly polymorphic in Han population from East China, which is suitable for forensic application in paternity testing and individual identification.