SNPs for a universal individual identification panel

Non-invasive prenatal paternity testing using a standard forensic genetic massively parallel sequencing assay for amplification of human identification SNPs

Prenatal paternity testing often relies on invasive procedures that cause risk to both the mother and the foetus. Non-invasive, prenatal paternity testing by investigating paternally inherited single nucleotide polymorphisms (SNPs) in cell-free foetal DNA (cffDNA) in maternal plasma was performed at consecutive time points during early gestation. Plasma from 15 pregnant women was investigated at consecutive time points from gestational weeks (GWs) 4-20. The Precision ID Identity Panel and an Ion S5 Sequencer was used to analyse the cffDNA. Paternally inherited foetal SNP alleles were detected from GW7. The median foetal fractions were 0%, 3.9%, 5.1%, 5.2%, and 4.7% at GWs 4, 7, 12, 16, and 20, respectively. The corresponding median numbers of detected paternally inherited foetal autosomal SNP alleles were 0, 3, 9, 10, and 12, respectively. The typical (i.e. geometric mean) paternity indices at GW12 and GW20 were 24 (range 0.0035-8389) and 199 (range 5.1-30,137), respectively. The method is very promising. However, the method can be improved by shortening the lengths of the PCR amplicons and increasing the number of SNPs. To our knowledge, this is the first study to successfully identify paternally inherited foetal SNP alleles at consecutive time points in early gestation independently of the foetal gender.

Identity determination in diagnostic surgical pathology

From a technical perspective, specimen identity determination in surgical pathology over the last several decades has primarily focused on analysis of repetitive DNA sequences, specifically microsatellite repeats. However, a number of techniques have recently been developed that have similar, if not greater, utility in surgical pathology, most notably analysis of single nucleotide polymorphism (SNPs) and gene panels by next generation sequencing (NGS). For cases with an extremely limited sample or a degraded sample, sequence analysis of mitochondrial DNA continues to be the method of choice. From a diagnostic perspective, interest in identity determination in surgical pathology is usually centered on resolving issues of specimen provenance due to specimen labeling/accessioning deficiencies and possible contamination, but is also frequently performed in cases for which the patient's clinical course following definitive therapy is remarkably atypical, in cases of an unexpected diagnosis, and by patient request for "peace of mind". However, the methods used for identity determination have a much broader range of applications in surgical pathology beyond tissue provenance analysis. The methods can be used to provide ancillary information for cases in which the histomorphology is not definitively diagnostic, as for example for tumors that have a virtually identical microscopic appearance but for which the differential diagnosis includes synchronous/metachronous tumors versus a metastasis, and for the diagnosis of hydropic early gestations versus hydatidiform molar pregnancies. The methods also have utility in several other clinical settings, for example to rule out a donor-transmitted malignancy in a transplant recipient, to monitor bone marrow transplant engraftment, and to evaluate natural chimerism.

Hair Proteome Variation at Different Body Locations on Genetically Variant Peptide Detection for Protein-Based Human Identification

Human hair contains minimal intact nuclear DNA for human identification in forensic and archaeological applications. In contrast, proteins offer a pathway to exploit hair evidence for human identification owing to their persistence, abundance, and derivation from DNA. Individualizing single nucleotide polymorphisms (SNPs) are often conserved as single amino acid polymorphisms in genetically variant peptides (GVPs). Detection of GVP markers in the hair proteome via high-resolution tandem mass spectrometry permits inference of SNPs with known statistical probabilities. To adopt this approach for forensic investigations, hair proteomic variation and its effects on GVP identification must first be characterized. This research aimed to assess variation in single-inch head, arm, and pubic hair, and discover body location-invariant GVP markers to distinguish individuals. Comparison of protein profiles revealed greater body location-specific variation in keratin-associated proteins and intracellular proteins, allowing body location differentiation. However, robust GVP markers derive primarily from keratins that do not exhibit body location-specific differential expression, supporting GVP identification independence from hair proteomic variation at the various body locations. Further, pairwise comparisons of GVP profiles with 8 SNPs demonstrated greatest interindividual variation and high intraindividual consistency, enabling similar differentiative potential of individuals using single hairs irrespective of body location origin.

Development and validation of a multiplex insertion/deletion marker panel, SifaInDel 45plex system

In addition to commonly used short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs), insertion and deletion polymorphisms (InDels) have considerable potential in the field of forensic genetics because they combine desirable characteristics of both STRs and SNPs. In the present study, the SifaInDel 45plex system was designed to amplify 45 InDel markers, including 27 autosomal InDels (A-InDels), 16 X chromosome InDels (X-InDels) and two Y chromosome InDels (Y-InDels), simultaneously in a single PCR procedure and then detect products by capillary electrophoresis (CE). We also optimized the PCR conditions for the novel panel and performed several validation studies including repeatability/reproducibility, concordance, accuracy, sensitivity, stability, species specificity and population genetics. The results confirmed that full profiles could be obtained from ≥62.5 pg of input DNA and from a series of challenging samples encountered in routine casework. The SifaInDel 45plex panel could tolerate different concentrations of inhibitors, such as ≤50 μM hematin, ≤20 ng/μL nigrosine and ≤8000 ng/μL urea. In a population investigation, for the 27 A-InDels, the combined power of discrimination (CPD) exceeded 0.999999, and the combined power of exclusion in duos (CPE_D) and trios (CPE_T) was 0.955118 and 0.997754, respectively. For the 16 X-InDels, the combined PD_Male and PD_Female was computed as 0.999845 and 0.999998, respectively, and the combined mean exclusion chance in father/daughter or mother/son duos (MEC_Duo) and mean exclusion chance in standard trios involving daughters (MEC_Trio) was 0.976220 and 0.998163, respectively. In addition, the two Y-InDels could play a role in correctly determining gender. Overall, the established SifaInDel 45plex panel is a well-performing, reliable and robust multiplex system that stands out for combining a considerable number of A-indels, X-indels and Y-indels based on a CE platform. The population study results also demonstrated that the SifaInDel 45plex panel could be a valid complementary approach for human identification and complex kinship analysis.

A Phase I Study to Assess the Safety and Cancer-Homing Ability of Allogeneic Bone Marrow-Derived Mesenchymal Stem Cells in Men with Localized Prostate Cancer

Animal models show that systemically administered bone marrow‐derived mesenchymal stem cells (MSCs) home to sites of primary and metastatic prostate cancer (PC)—making them candidates to selectively deliver cytotoxic agents. To further assess this potential as a cell‐based therapeutic vehicle, a phase I study testing homing of systemically infused allogeneic MSCs preprostatectomy was conducted. The primary objective was to assess safety and feasibility and to determine if MSCs accumulate within primary PC tissue. MSCs were quantified using beads, emulsion, amplification, magnetics digital polymerase chain reaction (limit of detection: ≥0.01% MSCs) to measure allogeneic MSC DNA relative to recipient DNA. MSCs were harvested from healthy donors and expanded ex vivo using standard protocols by the Johns Hopkins Cell Therapy Laboratory. PC patients planning to undergo prostatectomy were eligible for MSC infusion. Enrolled subjects received a single intravenous infusion 4–6 days prior to prostatectomy. The first three subjects received 1 x 10⁶ cells per kilogram (maximum 1 x 10⁸ cells), and subsequent four patients received 2 x 10⁶ cells per kilogram (maximum 2 x 10⁸ cells). No dose‐limiting toxicities were observed and all patients underwent prostatectomy without delay. Pathologic assessment of prostate cores revealed ≥70% tumor involvement in cores from four subjects, with benign tissue in the others. MSCs were undetectable in all subjects, and the study was stopped early for futility. MSC infusions appear safe in PC patients. Although intended for eventual use in metastatic PC patients, in this study, MSCs did not home primary tumors in sufficient levels to warrant further development as a cell‐based therapeutic delivery strategy using standard ex vivo expansion protocols. stem cells translational medicine2019;8:441–449

Improving cost-efficiency of faecal genotyping: New tools for elephant species

Despite the critical need for non-invasive tools to improve monitoring of wildlife populations, especially for endangered and elusive species, faecal genetic sampling has not been adopted as regular practice, largely because of the associated technical challenges and cost. Substantial work needs to be undertaken to refine sample collection and preparation methods in order to improve sample set quality and provide cost-efficient tools that can effectively support wildlife management. In this study, we collected an extensive set of forest elephant (Loxodonta cyclotis) faecal samples throughout Gabon, Central Africa, and prepared them for genotyping using 107 single-nucleotide polymorphism assays. We developed a new quantitative polymerase chain reaction (PCR) assay targeting a 130-bp nuclear DNA fragment and demonstrated its suitability for degraded samples in all three elephant species. Using this assay to compare the efficacy of two sampling methods for faecal DNA recovery, we found that sampling the whole surface of a dung pile with a swab stored in a small tube of lysis buffer was a convenient method producing high extraction success and DNA yield. We modelled the influence of faecal quality and storage time on DNA concentration in order to provide recommendations for optimized collection and storage. The maximum storage time to ensure 75% success was two months for samples collected within 24 hours after defecation and extended to four months for samples collected within one hour. Lastly, the real-time quantitative PCR assay allowed us to predict genotyping success and pre-screen DNA samples, thus further increasing the cost-efficiency of our approach. We recommend combining the validation of an efficient sampling method, the build of in-country DNA extraction capacity for reduced storage time and the development of species-specific quantitative PCR assays in order to increase the cost-efficiency of routine non-invasive DNA analyses and expand the use of next-generation markers to non-invasive samples.

A single nucleotide polymorphism panel for individual identification and ancestry assignment in Caucasians and four East and Southeast Asian populations using a machine learning classifier

Single nucleotide polymorphism (SNP) profiling is an effective means of individual identification and ancestry inferences in forensic genetics. This study established a SNP panel for the simultaneous individual identification and ancestry assignment of Caucasian and four East and Southeast Asian populations. We analyzed 220 SNPs (125 autosomal, 17 X-chromosomal, 30 Y-chromosomal, and 48 mitochondrial SNPs) of the DNA samples from 563 unrelated individuals of five populations (89 Caucasian, 234 Taiwanese Han, 90 Filipino, 79 Indonesian and 71 Vietnamese) and 18 degraded DNA samples. Informativeness for assignment (In) was used to select ancestry informative SNPs (AISNPs). A machine learning classifier, support vector machine (SVM), was used for ancestry assignment. Of the 220 SNPs, 62 were individual identification SNPs (IISNPs) (51 autosomal and 11 X-chromosomal SNPs) and 191 were AISNPs (100 autosomal, 13 X-chromosomal, 30 Y-chromosomal, and 48 mitochondrial SNPs). The 51 autosomal IISNPs offered cumulative random match probabilities (cRMPs) ranging from 1.56 × 10^-21 to 3.16 × 10^-22 among these five populations. Using AISNPs with the SVM, the overall accuracy rate of ancestry inference achieved in the testing dataset between Caucasian, Taiwanese Han, and Filipino populations was 88.9%, whereas it was 70.0% between Caucasians and each of the four East and Southeast Asian populations. For the 18 degraded DNA samples with incomplete profiling, the accuracy rate of ancestry assignment was 94.4%. We have developed a 220-SNP panel for simultaneous individual identification and ethnic origin differentiation between Caucasian and the four East and Southeast Asian populations. This SNP panel may assist with DNA analysis of forensic casework.

DNA identification of compromised samples with massive parallel sequencing

Genetic profiling is a standard procedure for human identification, i.e. in criminal cases and mass disasters, and has been proven to be an important part in the process in the repatriation of victims to their relatives. In the event of a catastrophe whether it be a natural disaster, terror attack or accident, fatalities of many nationalities may be a consequence and international collaboration becomes necessary. Current DNA techniques used on a routine basis at forensic laboratories world-wide are very useful, and results reported from different labs are compared, making it possible to be matched in order to declare the identification of a victim. Statistical calculations of possibilities of a random match are achievable since population data from many parts of the world are available. However, decomposition and degradation of the remains are not uncommon in the aftermath of a catastrophe and hence it may be difficult to retrieve detailed DNA profiles from such samples. Massive parallel sequencing (MPS) is a technique capable of producing a vast amount of DNA sequence data in a high-through put manner, and panels of single nucleotide polymorphism (SNP) markers allow the amplification of small DNA fragments, often seen in compromised samples. Here, we report the results from a set of 10 samples from missing person identification cases, analyzed with an MPS based method comprising 131 SNP markers and compared with direct reference material or buccal swab samples collected from relatives of the deceased. We assess the weight of evidence of a match by statistical calculation. Furthermore, we compare results reported on different platforms using different SNP panels, and conclude that more work has to be done if results from missing person identification cases analyzed on MPS with SNP panels at different laboratories are to be fully reliable and thus comparable.

Microhaplotypes in forensic genetics

Microhaplotype loci (microhaps, MHs) are a novel type of molecular marker of less than 300 nucleotides, defined by two or more closely linked SNPs associated in multiple allelic combinations. The value of these markers is enhanced by massively parallel sequencing (MPS), which allows the sequencing of both parental haplotypes at each of the many multiplexed loci. This review describes the features of these multi-SNP markers and documents their value in forensic genetics, focusing on individualization, biogeographic ancestry inference, and mixture deconvolution. Foreseeable applications also include missing person identification, relationship testing, and medical diagnostic applications. The technique is not restricted to humans.

Selecting microhaplotypes optimized for different purposes

Massively parallel sequencing is transforming forensic work by allowing various useful forensic markers, such as STRPs and SNPs, to be multiplexed providing information on ancestry, individual and familial identification, phenotypes for eye/hair/skin pigmentation, and the deconvolution of mixtures. Microhaplotypes also become feasible with massively parallel sequencing, these are DNA segments (smaller than 300 nucleotides) that are selected to contain multiple SNPs unambiguously defining three or more haplotype alleles occurring at common frequencies. The physical extent of a microhaplotype can thus be covered by a single sequence read making these loci phase-known codominant genetic systems. Such microhaplotypes supply significantly more information than a single SNP can. Our efforts to develop useful sets of microhaplotypes have already identified 182 such loci that we have studied on a large number of human populations from around the world. We present various analyses on 83 populations in our ongoing study for a subset of the best microhaplotypes currently available illustrating their characteristics and potential utility for ancestry, identification, and mixture deconvolution.

Accurate filtering of privacy-sensitive information in raw genomic data

Sequencing thousands of human genomes has enabled breakthroughs in many areas, among them precision medicine, the study of rare diseases, and forensics. However, mass collection of such sensitive data entails enormous risks if not protected to the highest standards. In this article, we follow the position and argue that post-alignment privacy is not enough and that data should be automatically protected as early as possible in the genomics workflow, ideally immediately after the data is produced. We show that a previous approach for filtering short reads cannot extend to long reads and present a novel filtering approach that classifies raw genomic data (i.e., whose location and content is not yet determined) into privacy-sensitive (i.e., more affected by a successful privacy attack) and non-privacy-sensitive information. Such a classification allows the fine-grained and automated adjustment of protective measures to mitigate the possible consequences of exposure, in particular when relying on public clouds. We present the first filter that can be indistinctly applied to reads of any length, i.e., making it usable with any recent or future sequencing technologies. The filter is accurate, in the sense that it detects all known sensitive nucleotides except those located in highly variable regions (less than 10 nucleotides remain undetected per genome instead of 100,000 in previous works). It has far less false positives than previously known methods (10% instead of 60%) and can detect sensitive nucleotides despite sequencing errors (86% detected instead of 56% with 2% of mutations). Finally, practical experiments demonstrate high performance, both in terms of throughput and memory consumption.

TIA: algorithms for development of identity-linked SNP islands for analysis by massively parallel DNA sequencing

Background

Single nucleotide polymorphisms (SNPs) located within the human genome have been shown to have utility as markers of identity in the differentiation of DNA from individual contributors. Massively parallel DNA sequencing (MPS) technologies and human genome SNP databases allow for the design of suites of identity-linked target regions, amenable to sequencing in a multiplexed and massively parallel manner. Therefore, tools are needed for leveraging the genotypic information found within SNP databases for the discovery of genomic targets that can be evaluated on MPS platforms.

Results

The SNP island target identification algorithm (TIA) was developed as a user-tunable system to leverage SNP information within databases. Using data within the 1000 Genomes Project SNP database, human genome regions were identified that contain globally ubiquitous identity-linked SNPs and that were responsive to targeted resequencing on MPS platforms. Algorithmic filters were used to exclude target regions that did not conform to user-tunable SNP island target characteristics. To validate the accuracy of TIA for discovering these identity-linked SNP islands within the human genome, SNP island target regions were amplified from 70 contributor genomic DNA samples using the polymerase chain reaction. Multiplexed amplicons were sequenced using the Illumina MiSeq platform, and the resulting sequences were analyzed for SNP variations. 166 putative identity-linked SNPs were targeted in the identified genomic regions. Of the 309 SNPs that provided discerning power across individual SNP profiles, 74 previously undefined SNPs were identified during evaluation of targets from individual genomes. Overall, DNA samples of 70 individuals were uniquely identified using a subset of the suite of identity-linked SNP islands.

Conclusions

TIA offers a tunable genome search tool for the discovery of targeted genomic regions that are scalable in the population frequency and numbers of SNPs contained within the SNP island regions. It also allows the definition of sequence length and sequence variability of the target region as well as the less variable flanking regions for tailoring to MPS platforms. As shown in this study, TIA can be used to discover identity-linked SNP islands within the human genome, useful for differentiating individuals by targeted resequencing on MPS technologies.

Electronic supplementary material

The online version of this article (10.1186/s12859-018-2133-2) contains supplementary material, which is available to authorized users.

Genome-wide screen for universal individual identification SNPs based on the HapMap and 1000 Genomes databases

Differences among SNP panels for individual identification in SNP-selecting and populations led to few common SNPs, compromising their universal applicability. To screen all universal SNPs, we performed a genome-wide SNP mining in multiple populations based on HapMap and 1000Genomes databases. SNPs with high minor allele frequencies (MAF) in 37 populations were selected. With MAF from ≥0.35 to ≥0.43, the number of selected SNPs decreased from 2769 to 0. A total of 117 SNPs with MAF ≥0.39 have no linkage disequilibrium with each other in every population. For 116 of the 117 SNPs, cumulative match probability (CMP) ranged from 2.01 × 10-48 to 1.93 × 10-50 and cumulative exclusion probability (CEP) ranged from 0.9999999996653 to 0.9999999999945. In 134 tested Han samples, 110 of the 117 SNPs remained within high MAF and conformed to Hardy-Weinberg equilibrium, with CMP = 4.70 × 10-47 and CEP = 0.999999999862. By analyzing the same number of autosomal SNPs as in the HID-Ion AmpliSeq Identity Panel, i.e. 90 randomized out of the 110 SNPs, our panel yielded preferable CMP and CEP. Taken together, the 110-SNPs panel is advantageous for forensic test, and this study provided plenty of highly informative SNPs for compiling final universal panels.

A 472-SNP panel for pairwise kinship testing of second-degree relatives

Kinship testing based on genetic markers, as forensic short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs), has valuable practical applications. Paternity and first-degree relationship can be accurately identified by current commonly-used forensic STRs and reported SNP markers. However, second-degree and more distant relationships remain challenging. Although ∼10⁵-10⁶ SNPs can be used to estimate relatedness of higher degrees, genome-wide genotyping and analysis may be impractical for forensic use. With rapid growth of human genome data sets, it is worthwhile to explore additional markers, especially SNPs, for kinship analysis. Here, we reported an autosomal SNP panel consisted of 342 SNP selected from >84 million SNPs and 131 SNPs from previous systems. We genotyped these SNPs in 136 Chinese individuals by multiplex amplicon Massively Parallel Sequencing, and performed pairwise gender-independent kinship testing. The specificity and sensitivity of these SNPs to distinguish second-degree relatives and the unrelated was 99.9% and 100%, respectively, compared with 53.7% and 99.9% of 19 commonly-used forensic STRs. Moreover, the specificity increased to 100% by the combined use of these STRs and SNPs. The 472-SNP panel could also greatly facilitate the discrimination among different relationships. We estimated that the power of ∼6.45 SNPs were equivalent to one forensic STR in the scenario of 2nd-degree relative pedigree. Altogether, we proposed a panel of 472 SNP markers for kinship analysis, which could be important supplementary of current forensic STRs to solve the problem of second-degree relative testing.

Biological Sexing of a 4000-Year-Old Egyptian Mummy Head to Assess the Potential of Nuclear DNA Recovery from the Most Damaged and Limited Forensic Specimens

High throughput sequencing (HTS) has been used for a number of years in the field of paleogenomics to facilitate the recovery of small DNA fragments from ancient specimens. Recently, these techniques have also been applied in forensics, where they have been used for the recovery of mitochondrial DNA sequences from samples where traditional PCR-based assays fail because of the very short length of endogenous DNA molecules. Here, we describe the biological sexing of a ~4000-year-old Egyptian mummy using shotgun sequencing and two established methods of biological sex determination (R_X and R_Y), by way of mitochondrial genome analysis as a means of sequence data authentication. This particular case of historical interest increases the potential utility of HTS techniques for forensic purposes by demonstrating that data from the more discriminatory nuclear genome can be recovered from the most damaged specimens, even in cases where mitochondrial DNA cannot be recovered with current PCR-based forensic technologies. Although additional work remains to be done before nuclear DNA recovered via these methods can be used routinely in operational casework for individual identification purposes, these results indicate substantial promise for the retrieval of probative individually identifying DNA data from the most limited and degraded forensic specimens.

A SNP panel for identification of DNA and RNA specimens

BACKGROUND

SNP panels that uniquely identify an individual are useful for genetic and forensic research. Previously recommended SNP panels are based on DNA profiles and mostly contain intragenic SNPs. With the increasing interest in RNA expression profiles, we aimed for establishing a SNP panel for both DNA and RNA-based genotyping.

RESULTS

To determine a small set of SNPs with maximally discriminative power, genotype calls were obtained from DNA and blood-derived RNA sequencing data belonging to healthy, geographically dispersed, Dutch individuals. SNPs were selected based on different criteria like genotype call rate, minor allele frequency, Hardy-Weinberg equilibrium and linkage disequilibrium. A panel of 50 SNPs was sufficient to identify an individual uniquely: the probability of identity was 6.9 × 10^- 20 when assuming no family relations and 1.2 × 10^- 10 when accounting for the presence of full sibs. The ability of the SNP panel to uniquely identify individuals on DNA and RNA level was validated in an independent population dataset. The panel is applicable to individuals from European descent, with slightly lower power in non-Europeans. Whereas most of the genes containing the 50 SNPs are expressed in various tissues, our SNP panel needs optimization for other tissues than blood.

CONCLUSIONS

This first DNA/RNA SNP panel will be useful to identify sample mix-ups in biomedical research and for assigning DNA and RNA stains in crime scenes to unique individuals.

Applications of Probe Capture Enrichment Next Generation Sequencing for Whole Mitochondrial Genome and 426 Nuclear SNPs for Forensically Challenging Samples

The application of next generation sequencing (NGS) for the analysis of mitochondrial (mt) DNA, short tandem repeats (STRs), and single nucleotide polymorphism (SNPs) has demonstrated great promise for challenging forensic specimens, such as degraded, limited, and mixed samples. Target enrichment using probe capture rather than PCR amplification offers advantages for analysis of degraded DNA since two intact PCR primer sites in the template DNA molecule are not required. Furthermore, NGS software programs can help remove PCR duplicates to determine initial template copy numbers of a shotgun library. Moreover, the same shotgun library prepared from a limited DNA source can be enriched for mtDNA as well as nuclear markers by hybrid capture with the relevant probe panels. Here, we demonstrate the use of this strategy in the analysis of limited and mock degraded samples using our custom probe capture panels for massively parallel sequencing of the whole mtgenome and 426 SNP markers. We also applied the mtgenome capture panel in a mixed sample and analyzed using both phylogenetic and variant frequency based bioinformatics tools to resolve the minor and major contributors. Finally, the results obtained on individual telogen hairs demonstrate the potential of probe capture NGS analysis for both mtDNA and nuclear SNPs for challenging forensic specimens.

Searching for ancient balanced polymorphisms shared between Neanderthals and Modern Humans

Hominin evolution is characterized by adaptive solutions often rooted in behavioral and cognitive changes. If balancing selection had an important and long-lasting impact on the evolution of these traits, it can be hypothesized that genes associated with them should carry an excess of shared polymorphisms (trans- SNPs) across recent Homo species. In this study, we investigate the role of balancing selection in human evolution using available exomes from modern (Homo sapiens) and archaic humans (H. neanderthalensis and Denisovan) for an excess of trans-SNP in two gene sets: one associated with the immune system (IMMS) and another one with behavioral system (BEHS). We identified a significant excess of trans-SNPs in IMMS (N=547), of which six of these located within genes previously associated with schizophrenia. No excess of trans-SNPs was found in BEHS, but five genes in this system harbor potential signals for balancing selection and are associated with psychiatric or neurodevelopmental disorders. Our approach evidenced recent Homo trans-SNPs that have been previously implicated in psychiatric diseases such as schizophrenia, suggesting that a genetic repertoire common to the immune and behavioral systems could have been maintained by balancing selection starting before the split between archaic and modern humans.

Genetic variants determining survival and fertility in an adverse African environment: a population-based large-scale candidate gene association study

Human survival probability and fertility decline strongly with age. These life history traits have been shaped by evolution. However, research has failed to uncover a consistent genetic determination of variation in survival and fertility. As an explanation, such genetic determinants have been selected in adverse environments, in which humans have lived during most of their history, but are almost exclusively studied in populations in modern affluent environments. Here, we present a large-scale candidate gene association study in a rural African population living in an adverse environment. In 4387 individuals, we studied 4052 SNPs in 148 genes that have previously been identified as possible determinants of survival or fertility in animals or humans. We studied their associations with survival comparing newborns, middle-age adults, and old individuals. In women, we assessed their associations with reported and observed numbers of children. We found no statistically significant associations of these SNPs with survival between the three age groups nor with women's reported and observed fertility. Population stratification was unlikely to explain these results. Apart from a lack of power, we hypothesise that genetic heterogeneity of complex phenotypes and gene-environment interactions prevent the identification of genetic variants explaining variation in survival and fertility in humans.

A SNP panel and online tool for checking genotype concordance through comparing QR codes

In the current precision medicine era, more and more samples get genotyped and sequenced. Both researchers and commercial companies expend significant time and resources to reduce the error rate. However, it has been reported that there is a sample mix-up rate of between 0.1% and 1%, not to mention the possibly higher mix-up rate during the down-stream genetic reporting processes. Even on the low end of this estimate, this translates to a significant number of mislabeled samples, especially over the projected one billion people that will be sequenced within the next decade. Here, we first describe a method to identify a small set of Single nucleotide polymorphisms (SNPs) that can uniquely identify a personal genome, which utilizes allele frequencies of five major continental populations reported in the 1000 genomes project and the ExAC Consortium. To make this panel more informative, we added four SNPs that are commonly used to predict ABO blood type, and another two SNPs that are capable of predicting sex. We then implement a web interface (http://qrcme.tech), nicknamed QRC (forQR code based Concordance check), which is capable of extracting the relevant ID SNPs from a raw genetic data, coding its genotype as a quick response (QR) code, and comparing QR codes to report the concordance of underlying genetic datasets. The resulting 80 fingerprinting SNPs represent a significant decrease in complexity and the number of markers used for genetic data labelling and tracking. Our method and web tool is easily accessible to both researchers and the general public who consider the accuracy of complex genetic data as a prerequisite towards precision medicine.

Comparison of Two Massively Parallel Sequencing Platforms using 83 Single Nucleotide Polymorphisms for Human Identification

The potential of Massively Parallel Sequencing (MPS) technology to vastly expand the capabilities of human identification led to the emergence of different MPS platforms that use forensically relevant genetic markers. Two of the MPS platforms that are currently available are the MiSeq^® FGx™ Forensic Genomics System (Illumina) and the HID-Ion Personal Genome Machine (PGM)™ (Thermo Fisher Scientific). These are coupled with the ForenSeq™ DNA Signature Prep kit (Illumina) and the HID-Ion AmpliSeq™ Identity Panel (Thermo Fisher Scientific), respectively. In this study, we compared the genotyping performance of the two MPS systems based on 83 SNP markers that are present in both MPS marker panels. Results show that MiSeq^® FGx™ has greater sample-to-sample variation than the HID-Ion PGM™ in terms of read counts for all the 83 SNP markers. Allele coverage ratio (ACR) values show generally balanced heterozygous reads for both platforms. Two and four SNP markers from the MiSeq^® FGx™ and HID-Ion PGM™, respectively, have average ACR values lower than the recommended value of 0.67. Comparison of genotype calls showed 99.7% concordance between the two platforms.

Allele frequencies and other forensic parameters of the HID-Ion AmpliSeq™ Identity Panel markers in Basques using the Ion Torrent PGM™ platform

The HID-Ion AmpliSeq™ Identity Panel amplifies 90 autosomal SNPs and 34 Y- SNPs with massively parallel sequencing (MPS) using the Ion Torrent PGM™ platform. In the present study, 105 Basques were analyzed to assess this panel. All loci were in Hardy-Weinberg equilibrium and no association between them was detected. Forensic parameters were calculated as 5.74×10^-36 for combined match probability and 99.99998% for combined power of exclusion. In conclusion, the HID Identity panel and the use of this new MPS technology are very promising tools for paternity testing and human identification in routine casework in the forensic field.

Genome-wide screening for highly discriminative SNPs for personal identification and their assessment in world populations

The applications of DNA profiling aim to identify perpetrators, missing family members and disaster victims in forensic investigations. Single nucleotide polymorphisms (SNPs) based forensic applications are emerging rapidly with a potential to replace short tandem repeats (STRs) based panels which are now being used widely, and there is a need for a well-designed SNP panel to meet such challenge for this transition. Here we present a panel of 175 SNP markers (referred to as Fudan ID Panel or FID), selected from ∼3.6 million SNPs, for the application of personal identification. We optimized and validated FID panel using 729 Chinese individuals using a next generation sequencing (NGS) technology. We showed that the SNPs in the panel possess very high heterozygosity as well as low within- and among-continent differentiations, enabling FID panel exhibit discrimination power in both regional and worldwide populations, with the average match probabilities ranging from 4.77×10^-71 to 1.06×10^-64 across 54 world populations. With the advent of biomedical research, the SNPs connecting physical anthropological, physiological, behavioral and phenotypic traits will be eventually added to the forensic panels that will revolutionize criminal investigation.

Massively parallel sequencing of 231 autosomal SNPs with a custom panel: a SNP typing assay developed for human identification with Ion Torrent PGM

The custom-designed single nucleotide polymorphism (SNP) panel amplified 231 autosomal SNPs in one PCR reaction and subsequently sequenced with massively parallel sequencing (MPS) technology and Ion Torrent personal genome machine (PGM). SNPs were chosen from SNPforID, IISNP, HapMap, dbSNP, and related published literatures. Full concordance was obtained between available MPS calling and Sanger sequencing with 9947A and 9948 controls. Ten SNPs (rs4606077, rs334355, rs430046, rs2920816, rs4530059, rs1478829, rs1498553, rs7141285, rs12714757 and rs2189011) with low coverage or heterozygote imbalance should be optimized or excluded from the panel. Sequence data had sufficiently high coverage and gave reliable SNP calling for the remaining 221 loci with the custom MPS–SNP panel. A default DNA input amount of 10 ng per reaction was recommended by Ampliseq technology but sensitivity testing revealed positive results from as little as 1 ng input DNA. Mixture testing with this panel is possible through analysis of the F_MAR (frequency of major allele reads) values at most loci with enough high coverage depth and low level of sequencing noise. These results indicate the potential advantage of the custom MPS–SNP assays and Ion Torrent PGM platform for forensic study.

Developmental validation of the MiSeq FGx Forensic Genomics System for Targeted Next Generation Sequencing in Forensic DNA Casework and Database Laboratories

Human DNA profiling using PCR at polymorphic short tandem repeat (STR) loci followed by capillary electrophoresis (CE) size separation and length-based allele typing has been the standard in the forensic community for over 20 years. Over the last decade, Next-Generation Sequencing (NGS) matured rapidly, bringing modern advantages to forensic DNA analysis. The MiSeq FGx™ Forensic Genomics System, comprised of the ForenSeq™ DNA Signature Prep Kit, MiSeq FGx™ Reagent Kit, MiSeq FGx™ instrument and ForenSeq™ Universal Analysis Software, uses PCR to simultaneously amplify up to 231 forensic loci in a single multiplex reaction. Targeted loci include Amelogenin, 27 common, forensic autosomal STRs, 24 Y-STRs, 7 X-STRs and three classes of single nucleotide polymorphisms (SNPs). The ForenSeq™ kit includes two primer sets: Amelogenin, 58 STRs and 94 identity informative SNPs (iiSNPs) are amplified using DNA Primer Set A (DPMA; 153 loci); if a laboratory chooses to generate investigative leads using DNA Primer Set B, amplification is targeted to the 153 loci in DPMA plus 22 phenotypic informative (piSNPs) and 56 biogeographical ancestry SNPs (aiSNPs). High-resolution genotypes, including detection of intra-STR sequence variants, are semi-automatically generated with the ForenSeq™ software. This system was subjected to developmental validation studies according to the 2012 Revised SWGDAM Validation Guidelines. A two-step PCR first amplifies the target forensic STR and SNP loci (PCR1); unique, sample-specific indexed adapters or "barcodes" are attached in PCR2. Approximately 1736 ForenSeq™ reactions were analyzed. Studies include DNA substrate testing (cotton swabs, FTA cards, filter paper), species studies from a range of nonhuman organisms, DNA input sensitivity studies from 1ng down to 7.8pg, two-person human DNA mixture testing with three genotype combinations, stability analysis of partially degraded DNA, and effects of five commonly encountered PCR inhibitors. Calculations from ForenSeq™ STR and SNP repeatability and reproducibility studies (1ng template) indicate 100.0% accuracy of the MiSeq FGx™ System in allele calling relative to CE for STRs (1260 samples), and >99.1% accuracy relative to bead array typing for SNPs (1260 samples for iiSNPs, 310 samples for aiSNPs and piSNPs), with >99.0% and >97.8% precision, respectively. Call rates of >99.0% were observed for all STRs and SNPs amplified with both ForenSeq™ primer mixes. Limitations of the MiSeq FGx™ System are discussed. Results described here demonstrate that the MiSeq FGx™ System meets forensic DNA quality assurance guidelines with robust, reliable, and reproducible performance on samples of various quantities and qualities.

Microhaplotype identified and performed in genetic investigation using PCR-SSCP

The recently introduced concept of microhaplotype loci has attracted attention in forensics. Previous studies estimated the allele frequencies generally through obtaining genotypic data on the individual SNPs from a larger set of unrelated individuals then phasing microhaplotypes by statistical and computational techniques. Determining phase for a single new individual requires the larger set of individuals to have been genotyped previously. Rare microhaplotypes possessed only by the target individual or microhaplotypes private to a specific population not previously studied are unlikely to be accurately phased using data sets of SNPs. Thus, there is a demand for an approach that could directly determine a gain single individual's precise microhaplotype information. In the present study, we introduced potential approaches of single chain sequencing based Massively Parallel Sequencing Technology (MiSeq) and PCR based Single Strand Conformational Polymorphism (SSCP) technology which was simple, accurate, and cost-effective. The results indicated that microhaplotypes contain much more polymorphic information than divided SNPs per locus (average heterozygosity of microhaplotype 0.61 VS SNPs 0.41). When microhaplotype allele frequencies were compared among five Chinese ethnic populations, significantly different distributions were found between the Han and Uyghur populations. Further analysis of pairwise Fst values and analysis of molecular variance (AMOVA), showed significant population differentiation between the Uyghur and other populations.

Development of a SNP-based panel for human identification for Indian populations

The widely employed short tandem repeat (STR)-based panels for forensic human identification (HID) have limitations while dealing with challenging forensic samples involving DNA degradation, resulting in dropping-out of higher molecular weight alleles/loci. To address this issue, bialleic markers like single nucleotide polymorphisms (SNPs) and insertion-deletions (indels), which can be scored even when the template DNA is heavily degraded (<100bp), have been suggested as alternative markers for HID testing. Recent studies have highlighted their utility in forensic HID and several panels based on biallelic markers have been described for worldwide populations. However, there has been very little information about the behavior of such DNA markers in Indian populations, which is known to possess great genetic diversity. This study describes a two-step approach for designing a SNP-based panel consisting of 70 SNPs for HID testing in Indian populations. In the first step, candidate SNPs were shortlisted from public databases by screening them for several criteria including allelic distribution, genomic location, potential phenotypic expression or functionality and species specificity. The second step involved genotyping the shortlisted SNPs in various Indian populations followed by shortlisting of the best performers for identity-testing. Starting with 592,652 SNPs listed in Human660W-Quad Beadchip (Illumina Inc.), we shortlisted 275 candidate SNPs for identity-testing and genotyped them in 462 unrelated individuals from different population groups in India. Post genotyping and statistical analyses based on biogeographic regions, 206 SNPs demonstrated desired allelic distribution (Heterozygosity≥0.4 and F_ST≤0.02), from which 2-4 widely separated (>20 Mb apart) SNPs from each chromosome were finally selected to construct a panel of 70 SNPs. This panel on average possessed match probability 10e-29 and probability of paternity of 0.99999997, which was orders of magnitude higher than most of the currently employed STR-based chemistries and SNP-based panels that were proposed previously for HID testing. For comparison purpose, genotyping previously reported SNPs for HID in our samples led us to conclude that the panel developed in this study is much more efficient and robust and better suited for the Indian populations.

Evaluation of the impact of genetic linkage in forensic identity and relationship testing for expanded DNA marker sets

Advances in massively parallel sequencing technology have enabled the combination of a much-expanded number of DNA markers (notably STRs and SNPs in one or combined multiplexes), with the aim of increasing the weight of evidence in forensic casework. However, when data from multiple loci on the same chromosome are used, genetic linkage can affect the final likelihood calculation. In order to study the effect of linkage for different sets of markers we developed the biostatistical tool ILIR, (Impact of Linkage on forensic markers for Identity and Relationship tests). The ILIR tool can be used to study the overall impact of genetic linkage for an arbitrary set of markers used in forensic testing. Application of ILIR can be useful during marker selection and design of new marker panels, as well as being highly relevant for existing marker sets as a way to properly evaluate the effects of linkage on a case-by-case basis. ILIR, implemented via the open source platform R, includes variation and genomic position reference data for over 40 STRs and 140 SNPs, combined with the ability to include additional forensic markers of interest. The use of the software is demonstrated with examples from several different established marker sets (such as the expanded CODIS core loci) including a review of the interpretation of linked genetic data.

An Algorithm Measuring Donor Cell-Free DNA in Plasma of Cellular and Solid Organ Transplant Recipients That Does Not Require Donor or Recipient Genotyping

Cell-free DNA (cfDNA) has significant potential in the diagnosis and monitoring of clinical conditions. However, accurately and easily distinguishing the relative proportion of DNA molecules in a mixture derived from two different sources (i.e., donor and recipient tissues after transplantation) is challenging. In human cellular transplantation, there is currently no useable method to detect in vivo engraftment, and blood-based non-invasive tests for allograft rejection in solid organ transplantation are either non-specific or absent. Elevated levels of donor cfDNA have been shown to correlate with solid organ rejection, but complex methodology limits implementation of this promising biomarker. We describe a cost-effective method to quantify donor cfDNA in recipient plasma using a panel of high-frequency single nucleotide polymorphisms, next-generation (semiconductor) sequencing, and a novel mixture model algorithm. In vitro, our method accurately and rapidly determined donor:recipient DNA admixture. For in vivo testing, donor cfDNA was serially quantified in an infant with a urea cycle disorder after receiving six daily infusions of donor liver cells. Donor cfDNA isolated from 1 to 2 ml of recipient plasma was detected as late as 24 weeks after infusion suggesting engraftment. The percentage of circulating donor cfDNA was also assessed in pediatric and adult heart transplant recipients undergoing routine endomyocardial biopsy with levels observed to be stable over time and generally measuring <1% in cases without moderate or severe cellular rejection. Unlike existing non-invasive methods used to define the proportion of donor cfDNA in solid organ transplant patients, our assay does not require sex mismatch, donor genotyping, or whole-genome sequencing and potentially has broad application to detect cellular engraftment or allograft injury after transplantation.