Internal validation study of a newly developed 24-plex Y-STRs genotyping system for forensic application

Simultaneous sequencing of 102 Y-STRs on Ion Torrent ™ GeneStudio ™ S5 System

The Precision ID NGS System from Thermo Fisher Scientific is a mainstream next-generation sequencing (NGS) platform used in forensic laboratories to detect almost all commonly used forensic markers, except for Y-chromosomal short tandem repeats (Y-STRs). This study aimed to: 1) develop a Y-STR panel compatible with the automatic workflow of the NGS system using Ion AmpliSeq Technology, 2) evaluate the panel performance following the SWGDAM guidelines, and 3) explore the possibility of using a combination workflow to detect autosomal STRs and Y-STRs (AY-STR NGS workflow). The GrandFiler Y-STR Panel was successfully designed using the 'separating' and 'merging' strategies, including 102 Y-STRs and Amelogenin with an average amplicon length of 133 bp. It is a mega Y-STR multiplex system in which up to 16 samples can be sequenced simultaneously on an Ion 530 ™ Chip. Developmental validation studies of the performance of the NGS platform, species specificity, reproducibility, concordance, sensitivity, degraded samples, case-type samples, and mixtures were conducted to unequivocally determine whether the GrandFiler Y-STR Panel is suitable for real scenarios. The newly developed Y-STR panel showed compelling run metrics and NGS performance, including 92.47% bases with ≥ Q20, 91.80% effective reads, 2106 × depth of coverage (DoC), and 97.09% inter-locus balance. Additionally, it showed high specificity for human males and 99.40% methodological and bioinformatical concordance, generated complete profiles at ≥ 0.1 ng input DNA, and recovered more genetic information from severely degraded and diverse case samples. Although the outcome when used on mixtures was not as expected, more genetic information was obtained compared to that from capillary electrophoresis (CE) methods. The AY-STR NGS workflow was established by combining the GrandFiler Y-STR Panel with the Precision ID GlobalFiler ™ NGS STR Panel v2 at a 2:1 concentration ratio. The combination workflow on NGS performance, reproducibility, concordance, and sensitivity was as stable as the single Y-STR NGS workflow, providing more options for forensic scientists when dealing with different case scenarios. Overall, the GrandFiler Y-STR Panel was confirmed as the first to effectively detect a large number of Y-STR markers on the Precision ID NGS System, which is compatible with 51 Y-STRs in commercial CE kits and 51 Y-STRs in commercial NGS kits and the STRBase. The panel is as robust, reliable, and sensitive as current CE/NGS kits, and is suitable for solving real cases, especially for severely degraded samples (degradation index > 10).

Internal validation of an improved system for forensic application: a 41-plex Y-STR panel

Y-chromosome short tandem repeats (Y-STRs) have a unique role in forensic investigation. However, low-medium mutating Y-STRs cannot meet the requirements for male lineage differentiation in inbred populations, whereas rapidly mutating (RM) high-resolution Y-STRs might cause unexpected exclusion of paternal lineages. Thus, combining Y-STRs with low and high mutation rates helps to distinguish male individuals and lineages in family screening and analysis of genetic relationships. In this study, a novel 6-dye, 41-plex Y-STR panel was developed and validated, which included 17 loci from the Yfiler kit, nine RM Y-STR loci, 15 low-medium mutating Y-STR loci, and three Y-InDels. Developmental validation was performed for this panel, including size precision testing, stutter analysis, species specificity analysis, male specificity testing, sensitivity testing, concordance evaluation, polymerase chain reaction inhibitors analysis, and DNA mixture examination. The results demonstrated that the novel 41-plex Y-STR panel, developed in-house, was time efficient, accurate, and reliable. It showed good adaptability to directly amplify a variety of case-type samples. Furthermore, adding multiple Y-STR loci significantly improved the system's ability to distinguish related males, making it highly informative for forensic applications. In addition, the data obtained were compatible with the widely used Y-STR kits, facilitating the search and construction of population databases. Moreover, the addition of Y-Indels with short amplicons improves the analyses of degraded samples.

Key Points

A novel multiplex comprising 41 Y-STR and 3 Y-InDel was developed for forensic application.The multiplex included rapidly mutating Y-STRs and low-medium mutating Y-STRs, which is compatible with many commonly used Y-STR kits.The multiplex is a powerful tool for distinguishing related males, familial searching, and constructing DNA databases.

Recent advances in forensic biology and forensic DNA typing: INTERPOL review 2019-2022

This review paper covers the forensic-relevant literature in biological sciences from 2019 to 2022 as a part of the 20th INTERPOL International Forensic Science Managers Symposium. Topics reviewed include rapid DNA testing, using law enforcement DNA databases plus investigative genetic genealogy DNA databases along with privacy/ethical issues, forensic biology and body fluid identification, DNA extraction and typing methods, mixture interpretation involving probabilistic genotyping software (PGS), DNA transfer and activity-level evaluations, next-generation sequencing (NGS), DNA phenotyping, lineage markers (Y-chromosome, mitochondrial DNA, X-chromosome), new markers and approaches (microhaplotypes, proteomics, and microbial DNA), kinship analysis and human identification with disaster victim identification (DVI), and non-human DNA testing including wildlife forensics. Available books and review articles are summarized as well as 70 guidance documents to assist in quality control that were published in the past three years by various groups within the United States and around the world.

Allelic and haplotypic polymorphisms and paternal genetic analysis of Chinese Shaanxi Han population utilizing a multiplex Y-STR set

BACKGROUND

The analysis of Y chromosomal genetic markers is of great significance in human genetic fields related to male individuals. The Han nationality is the most populous ethnic group. It is critical to investigate the Y-chromosome short tandem repeat (Y-STR) genetic informativeness of Han nationalities in different Chinese regions in order to gain a comprehensive understanding of their paternal genetic relationships and origin.

AIM

To assess the allelic and haplotypic polymorphisms of the novel AGCU Y SUPP STR amplification system containing seven Y-STRs in the maximal dataset of the Y-STR Haplotype Reference Database (YHRD) and 17 newly included Y-STRs, and explore the genetic relationships among the Shaanxi Han population and 12 reference populations from China.

SUBJECTS AND METHODS

A total sample of 220 Han male subjects were obtained from the Shaanxi Province, China, and genotyped by the novel AGCU Y SUPP STR amplification system. Multiplex population genetic analyses derived from the same 16 Y-STR loci were carried out among the Shaanxi Han population and 12 reference populations from China.

RESULTS

The gene diversities (GD) ranged from the maximum value of 0.9609 (DYS385a,b) to the minimum value of 0.5441 (DYS531). Besides, 217 distinct haplotypes were detected wholly in 220 individuals, of which 214 (98.62%) were exclusive. The entire haplotype diversity (HD) and discrimination capacity (DC) were 0.9999 and 0.9864, respectively, while the haplotype match probability (HMP) was 0.0045. Among the reference populations, the obtained results of population genetic analyses revealed that the Shaanxi Han population had the largest genetic distance with the Guangxi Yao group, but the smallest genetic distance with the Hunan Tujia group.

CONCLUSIONS

These Y-STR loci in the AGCU Y SUPP STR amplification system were of high genetic polymorphisms and the amplification system could be used as a prospective complementary tool for forensic application and paternal genetics in the Shaanxi Han population.

Genetic admixture history and forensic characteristics of Tibeto-Burman-speaking Qiang people explored via the newly developed Y-STR panel and genome-wide SNP data

Fine-scale patterns of population genetic structure and diversity of ethnolinguistically diverse populations are important for biogeographical ancestry inference, kinship testing, and development and validation of new kits focused on forensic personal identification. Analyses focused on forensic markers and genome-wide single nucleotide polymorphism (SNP) data can provide new insights into the origin, admixture processes, and forensic characteristics of targeted populations. Qiang people had a large sample size among Tibeto-Burmanspeaking populations, which widely resided in the middle latitude of the Tibetan Plateau. However, their genetic structure and forensic features have remained uncharacterized because of the paucity of comprehensive genetic analyses. Here, we first developed and validated the forensic performance of the AGCU-Y30 Y-short tandem repeats (STR) panel, which contains slowly and moderately mutating Y-STRs, and then we conducted comprehensive population genetic analyses based on Y-STRs and genome-wide SNPs to explore the admixture history of Qiang people and their neighbors. The validated results of this panel showed that the new Y-STR kit was sensitive and robust enough for forensic applications. Haplotype diversity (HD) ranging from 0.9932 to 0.9996 and allelic frequencies ranging from 0.001946 to 0.8326 in 514 Qiang people demonstrated that all included markers were highly polymorphic in Tibeto-Burman people. Population genetic analyses based on Y-STRs [RST, FST, multidimensional scaling (MDS) analysis, neighboring-joining (NJ) tree, principal component analysis (PCA), and median-joining network (MJN)] revealed that the Qiang people harbored a paternally close relationship with lowland Tibetan-Yi corridor populations. Furthermore, we conducted a comprehensive population admixture analysis among modern and ancient Eurasian populations based on genome-wide shared SNPs. We found that the Qiang people were a genetically admixed population and showed closest relationship with Tibetan and Neolithic Yellow River farmers. Admixture modeling showed that Qiang people shared the primary ancestry related to Tibetan, supporting the hypothesis of common origin between Tibetan and Qiang people from North China.

Developmental Validation of a Rapidly Mutating Y-STR Panel Labeled by Six Fluoresceins for Forensic Research

The male-specific region of the human Y chromosome is a useful genetic marker for genealogical searching, male inheritance testing, and male DNA mixture deconvolution in forensic studies. However, the Y chromosomal short tandem repeats (Y-STRs) are difficult to distinguish among related males due to their low/medium mutation rate. In contrast, rapidly mutating (RM) Y-STRs exhibit unusually high mutation rates and possess great potential for differentiating male lineages. In this study, we developed a novel Y-STRs multiplex amplification assay of 32 RM Y-STRs by fragment analysis using six dye-labeled technologies (FAM, HEX, TAMRA, ROX, VIG, and SIZ). The development and the validation of the kit were carried out in accordance with the Scientific Working Group guidelines on DNA Analysis Methods. Identical allelic profiles of the 32 RM Y-STRs using a DNA 9948 sample as the positive control could be observed at different concentrations of PCR reagents. Further, the RM Y-STRs did not show cross-reactions with other common animal species, and the developed assay could tolerate interferences from common PCR inhibitors and mixed DNA samples. More importantly, the kit showed relatively high sensitivity and could detect trace DNA samples. Genetic distributions of 32 RM Y-STRs in the Guizhou Han population revealed that these RM Y-STRs showed relatively high genetic diversities. In conclusion, the RM Y-STR assay developed here showed good species specificity, high sensitivity, tolerance to inhibitors, and sample compatibility, which can be viewed as a highly efficient tool with high discrimination capacity for forensic male differentiation.

Determination of a criminal suspect using environmental plant DNA metabarcoding technology

There are criminal cases that no frequently used evidence, for example, human DNAs from the criminal, is available. Such cases usually are unresolvable. With the advent of DNA metabarcoding, evidences are mined from environmental DNA and such cases become resolvable. This study reports how a criminal suspect was determined by environmental plant DNA metabarcoding technology. A girl was killed in a rural wet area in China without a witness or video record. Pants with dried mud was found from one of her classmate's house. The mud was removed from the pants and 11 more mud or soil samples surrounding murder scene were collected. DNA was extracted from the soil. Chloroplast rbcL gene were amplified and sequenced on a next generation sequencing platform. After bioinformatics analysis, ZOTU composition of 12 samples demonstrated that the mud on the suspect's pants was from the criminal scene. The suspect finally made a clean breast of his crime. This case implies that plant DNA in the environment soil is a new source of evidence in determination of suspects using DNA metabarcoding technology and has high potentials of extensive applications in criminal cases.

Analytical validation of an RI sample cartridge with the RapidHIT® ID system

Evaluating the short tandem repeat (STR) in the field is important for the timely identification of a suspect. Several lines showed that the RapidHIT® ID system is reliable for DNA genotyping with buccal swabs and naked DNA. However, the application of this approach with blood samples has been poorly investigated. Because blood samples are among the most common forensic samples in our laboratory, further studies should be conducted. Here, we assessed the analytical performance of 19 STR loci with a newly developed RapidINTEL (RI) Sample Cartridge Kit by using the blood samples with known genotypes. Several commonly used substrates were included in the sensitivity study, and FTA cards proved to be the most promising sample carrier for blood storage and later identification. There was superior sensitivity and specificity with a 100% concordance rate for 0.5 μL of blood or 7 ng of genomic DNA. The performance for blood samples was comparable with that for the standard protocol. High success rate (90.57%) and high-concordance (100%) genotyping were automatically achieved over a wide range of operating conditions except for TH01. No contamination was observed throughout the study. Hematin, indigo, and humic acid had limited influence on the instrument system, while urea and melanin dramatically affected the genotyping results. Generally, the newly developed RI sample cartridge provided an alternative method for the STR genotyping of single-source blood samples over a wide range of operating conditions.

Genetic polymorphisms of 44 Y chromosomal genetic markers in the Inner Mongolia Han population and its genetic relationship analysis with other reference populations

Y chromosomal genetic markers in the non-recombining region are commonly used for human evolution research, familial searching, and forensic male differentiation since they strictly follow paternal inheritance. Y chromosomal short tandem repeats (Y-STRs) possess extraordinarily advantages in forensic applications because of their high polymorphisms and special genetic pattern. Here, we assessed the genetic diversities of 41 Y-STRs and three Y chromosomal insertion/deletion (Y-InDels) loci in the Chinese Inner Mongolia Han population; besides, genetic differentiation analyses among the studied Han population and other previously reported populations were conducted based on 27 same Y-STRs. Totally, 425 alleles were observed in 324 Inner Mongolia Han individuals for these Y-markers. Gene diversities of these Y-markers distributed from 0.0306 to 0.9634. The haplotype diversity and discriminatory capacity of these Y-markers in the Inner Mongolia Han population were 0.9999 and 0.98457, respectively. Haplotype resolution comparisons of different Y-marker groups in the studied Han population revealed that higher haplotype resolution could be achieved for these 44 Y-markers. Population genetic analyses of the Inner Mongolia Han population and other reference populations demonstrated that the studied Han population had relatively closer genetic affinities with Northern Han Chinese populations than Southern Han and other minority groups. To sum up, these 44 Y-markers can be utilized as a valuable tool for male differentiation in the Inner Mongolia Han population.

Validation of the Microreader 40Y ID System: a Y-STR multiplex for casework and database samples

Y-chromosome-specific short tandem repeat loci (Y-STRs) are commonly analysed in forensic science for paternity testing, familial searches, and, in sexual assault cases, to determine male DNA identity from mixed sources with high background female DNA content. The Microreader 40Y ID System is a six-dye multiplex amplification kit that contains 17 Y-STR loci from the Yfiler Plus PCR Amplification Kit and the powerplex Y23 system (DYS19, DYF385a/b, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS549, DYS635(Y GATA C4), DYS643, Y GATA H4, DYS460, DYS481, DYS533, DYF387S1, DYS449, DYS518, DYS570, DYS576, and DYS627), plus six high polymorphic loci (DYS444, DYS447, DYS557, DYS596, DYS527 a/b) as well as 4 additional candidate Y-STR loci (DYS593, DYF404S1, DYS645) and a Y-Indel loci (Rs2032678), thereby providing greater efficiency, compatibility, and accuracy. The Microreader 40Y ID System can directly amplify markers from blood or saliva on filter paper or FTA cards, without template extraction or purification, and can also be used for extracted DNA templates. To verify the efficiency and accuracy of the kit, the Microreader 40Y ID System was validated by investigating sensitivity, amplification conditions, male-male and male-female mixtures, PCR inhibition, species specificity, reproducibility, and efficacy with degraded samples. The Y-STR loci were also tested using 437 male samples from Tibet, Han, and Yi. The Microreader 40Y ID System was able to compensate for some of the shortcomings of Y-STR markers in practical applications, such as cost and profile interpretation, and fully meets the domestic Y chromosome database construction specifications and requirements.

Developmental validation study of a 24-plex Y-STR direct amplification system for forensic application

In the present study, validation data for 24 Y-STR loci from the Microreader™ 24Y Direct ID System was presented. Eight Y-STR loci have PCR product sizes with less than 220 bp in this multiplex amplification system, which can better detect degraded DNA samples from a crime scene. Developmental validation studies were conducted following the SWGDAM guidelines and consisted of PCR-based studies, sensitivity testing, species specificity, stability studies, accuracy and reproducibility evaluation, mixture studies, and case-type samples. The genetic diversities and forensic parameters of the 24 Y-STR loci were also investigated in Jiangsu Han population. Results demonstrated that this kit had the characteristics of high detection accuracy, strong species specificity, favorable anti-inhibition effect, and high sensitivity, and the minimum detection amount was 125 pg. When the mixed female template amount was below 3.2 times that of the male, or the male-male mixed ratio did not exceed 1:9, the typing results produced by 24Y Direct System still exhibited a higher discriminating ability for the mixture. The system was compatible with some typical biological samples such as bloodstain, hair, buccal swab, rib cartilage, and nail. The haplotype diversity (HD) and discrimination capacity (DC) of the 24 Y-STR loci were 0.9952 and 0.8500, respectively. The results revealed that the 24 Y-STR loci were highly polymorphic in Jiangsu Han population and could be useful for forensic cases and population genetic studies.