SNP Markers as Additional Information to Resolve Complex Kinship Cases

FLT4 gene polymorphisms influence isolated ventricular septal defect predisposition in a Southwest China population

BACKGROUND

Ventricular septal defect (VSD) is the most common congenital heart disease. Although a small number of genes associated with VSD have been found, the genetic factors of VSD remain unclear. In this study, we evaluated the association of 10 candidate single nucleotide polymorphisms (SNPs) with isolated VSD in a population from Southwest China.

METHODS

Based on the results of 34 congenital heart disease whole-exome sequencing and 1000 Genomes databases, 10 candidate SNPs were selected. A total of 618 samples were collected from the population of Southwest China, including 285 VSD samples and 333 normal samples. Ten SNPs in the case group and the control group were identified by SNaPshot genotyping. The chi-square (χ2) test was used to evaluate the relationship between VSD and each candidate SNP. The SNPs that had significant P value in the initial stage were further analysed using linkage disequilibrium, and haplotypes were assessed in 34 congenital heart disease whole-exome sequencing samples using Haploview software. The bins of SNPs that were in very strong linkage disequilibrium were further used to predict haplotypes by Arlequin software. ViennaRNA v2.5.1 predicted the haplotype mRNA secondary structure. We evaluated the correlation between mRNA secondary structure changes and ventricular septal defects.

RESULTS

The χ2 results showed that the allele frequency of FLT4 rs383985 (P = 0.040) was different between the control group and the case group (P < 0.05). FLT4 rs3736061 (r2 = 1), rs3736062 (r2 = 0.84), rs3736063 (r2 = 0.84) and FLT4 rs383985 were in high linkage disequilibrium (r2 > 0.8). Among them, rs3736061 and rs3736062 SNPs in the FLT4 gene led to synonymous variations of amino acids, but predicting the secondary structure of mRNA might change the secondary structure of mRNA and reduce the free energy.

CONCLUSIONS

These findings suggest a possible molecular pathogenesis associated with isolated VSD, which warrants investigation in future studies.

Evaluation of the usefulness of insertion-null markers in critical skeletal remains

Forensic DNA analysis in compromised skeletal remains may pose challenges due to DNA degradation, often resulting in partial or negative autosomal STRs profiles. To address this issue, alternative approaches such as mitochondrial DNA or SNPs typing may be employed; however, they are labour-intensive and costly. Insertion-null alleles (INNULs), short interspersed nuclear elements, have been suggested as a valuable tool for human identification in challenging samples due to their small amplicon size. A commercial kit including 20 INNULs markers along with amelogenin (InnoTyper® 21) has been developed. This study assesses its utility using degraded skeletal remains, comparing the results obtained (the number of detected alleles, RFU values, PHR, and the number of reportable markers) to those obtained using GlobalFiler™. Subsequently, the random match probability of the two profiles for each sample was determined using Familias version 3 to evaluate the power of discrimination of the results obtained from each kit. In every sample, InnoTyper® 21 yielded more alleles, higher RFU values, and a greater number of reportable loci. However, in most cases, both profiles were similarly informative. In conclusion, InnoTyper® 21 serves as a valuable complement to the analysis of challenging samples in cases where a poor or negative profile was obtained.

Advancing human genotyping: The Infinium HTS iSelect Custom microarray panel (Rita) development study

Single Nucleotide Polymorphisms (SNPs), as the most prevalent type of variation in the human genome, play a pivotal role in influencing human traits. They are extensively utilized in diverse fields such as population genetics, forensic science, and genetic medicine. This study focuses on the 'Rita' BeadChip, a custom SNP microarray panel developed using Illumina Infinium HTS technology. Designed for high-throughput genotyping, the panel facilitates the analysis of over 4000 markers efficiently and cost-effectively. After careful clustering performed on a set of 1000 samples, an evaluation of the Rita panel was undertaken, assessing its sensitivity, repeatability, reproducibility, precision, accuracy, and resistance to contamination. The panel's performance was evaluated in various scenarios, including sex estimation and parental relationship assessment, using GenomeStudio data analysis software. Findings show that over 95 % of the custom BeadChip assay markers were successful, with better performance of transitions over other mutations, and a considerably lower success rate for Y chromosome loci. An exceptional call rate exceeding 99 % was demonstrated for control samples, even with DNA input as low as 0.781 ng. Call rates above 80 % were still obtained with DNA quantities under 0.1 ng, indicating high sensitivity and suitability for forensic applications where DNA quantity is often limited. Repeatability, reproducibility, and precision studies revealed consistency of the panel's performance across different batches and operators, with no significant deviations in call rates or genotyping results. Accuracy assessments, involving comparison with multiple available genetic databases, including the 1000 Genome Project and HapMap, denoted over 99 % concordance, establishing the Rita panel's reliability in genotyping. The contamination study revealed insights into background noise and allowed the definition of thresholds for sample quality evaluation. Multiple metrics for differentiating between negative controls and true samples were highlighted, increasing the reliability of the obtained results. The sex estimation tool in GenomeStudio proved highly effective, correctly assigning sex in all samples with autosomal loci call rates above 97 %. The parental relationship assessment of family trios highlighted the utility of GenomeStudio in identifying genotyping errors or potential Mendelian inconsistencies, promoting the application of arrays such as Rita in kinship testing. Overall, this evaluation confirms the Rita microarray as a robust, high-throughput genotyping tool, underscoring its potential in genetic research and forensic applications. With its custom content and adaptable design, it not only meets current genotyping demands but also opens avenues for further research and application expansion in the field of genetic analysis.

Association study of FLT4 and HYDIN single nucleotide polymorphisms with atrial septal defect susceptibility in the Han Chinese population of Southwest China

BACKGROUND

Atrial septal defect (ASD) is a common form of congenital heart disease. Although several genes related to ASD have been found, the genetic factors of ASD remain unclear. This study aimed to evaluate the correlation between 10 candidate single nucleotide polymorphisms (SNPs) and sporadic atrial septal defects.

METHODS

Based on the results of 34 individual whole exome sequences, 10 candidate SNPs were selected. In total, 489 ASD samples and 420 normal samples were collected. The 10 SNPs in the case group and the control group were identified through Snapshot genotyping technology. The χ2-test and unconditional regression model were used to evaluate the relationship between ASD and each candidate SNP. Haploview software was used to perform linkage disequilibrium and haplotype analysis.

RESULTS

The χ2 results showed that the FLT4 rs383985 (P = 0.003, OR = 1.115-1.773), HYDIN rs7198975 (P = 0.04621, OR = 1.003-1.461), and HYDIN rs1774266 (P = 0.04621, OR = 1.003-1.461) alleles were significantly different between the control group and the case group (P < 0.05). Only the association with the FLT4 polymorphism was statistically significant after adjustment for multiple comparisons.

CONCLUSION

These findings suggest that a possible molecular pathogenesis associated with sporadic ASD is worth exploring in future studies.

The use of vitreous humour as a potential source of DNA for postmortem identification in forensic science

Vitreous humour (VH) is routinely collected for toxicological analyses. However, only a few studies have examined its possible use in genotyping. Because of its isolation from the rest of the body, later onset of postmortem changes, and availability, VH could be a potential source of DNA for postmortem identification and other molecular analyses in forensic genetics. During forensic autopsies, samples of different VH volumes (5 ml, 4 ml, 3 ml, 2 ml, 1 ml, and 0.5 ml) were taken from 66 cadavers 24-48 h after death. DNA was also isolated from the samples immediately after collection and after a specific time of storage (1, 2, and 6 months). DNA was isolated using phenol‒chloroform‒isoamyl alcohol (PCI), and the yield and purity of the obtained DNA were determined spectrophotometrically using a FastGene NanoView Photometer. The integrity of the isolated DNA molecule was determined by PCR amplification of the hTERT (113 bp) gene. The results showed that VH could be a reliable source of genetic material for forensic analysis, and the method used for DNA extraction was effective. The yield of the isolated DNA ranged from 6.20 to 609.5 ng/µl, and the purity of the samples was 1.24-2.34. The isolated DNA concentration and integrity depend on the sample volume, but the DNA purity does not. It is also shown that DNA can be extracted from VH samples that have been stored for up to 6 months at - 20 °C. Therefore, using VH can be a valuable material for DNA identification.

Developmental validation of a 381 Y-chromosome SNP panel for haplogroup analysis in the Chinese populations

Y-chromosome single nucleotide polymorphism (Y-SNP) shows great variation in geographical distribution and population heterogeneity and can be used to map population genetics around the world. Massive parallel sequencing (MPS) methodology enables high-resolution Y-SNP haplogrouping for a certain male and is widely used in forensic genetics and evolutionary studies. In this present study, we used MPS to develop a customized 381 Y-SNP panel (SifaMPS 381 Y-SNP panel) to investigate the basic structure and subbranches of the haplogroup tree of the Chinese populations. The SifaMPS 381 Y-SNP panel covers all the Y-SNPs from our previously designed 183 Y-SNP panel and additional SNPs under the predominant haplogroups in the Chinese populations based on certain criteria. We also evaluated the sequencing matrix, concordance, sensitivity, repeatability of this panel and the ability to analyze mixed and case-type samples based on the Illumina MiSeq System. The results demonstrated that the novel MPS Y-SNP panel possessed good sequencing performance and generated accurate Y-SNP genotyping results. Although the recommended DNA input was greater than 1.25 ng, we observed that a lower DNA amount could still be used to analyze haplogroups correctly. In addition, this panel could handle mixed samples and common case-type samples and had higher resolution among Chinese Han males than previously reported. In conclusion, the SifaMPS 381 Y-SNP panel showed an overall good performance and offers a better choice for Y-SNP haplogrouping of the Chinese population, thereby facilitating paternal lineage classification, familial searching and other forensic applications.

CRISPR-CasB technology in forensic DNA analysis: challenges and solutions

CRISPR-Cas technology has revolutionized the field of biotechnology with its precise therapeutic use from genetic as well as infectious diseases point of view. This technology is rapidly evolving to single tool enabling site-directed cut in the genome and highly specific activation or inhibition of gene expression or the exchange of single bases. Besides clinical applications, CRISPR-Cas technology has also shown promising use in the field of forensic DNA analysis. Enrichment of targeted genetic marker for identification followed by sequencing and non-PCR-dependent technique ensures the use of CRISPR-Cas technology in challenging forensic biological samples. The use of this advanced technology is also deemed helpful in mixed profile attribution, mostly in LCN contributors and the generation of a useful DNA profile in degraded samples. Besides its useful applications in forensic DNA analysis, CRISPR-Cas technology poses a huge threat from the generation of ghost DNA profiles by modification/alteration of target genetic markers. Forensic DNA analysts should carry out analysis of additional markers such as non-CODIS markers, Y-, X-chromosome markers, and mitochondrial DNA sequencing in a suspected ghost DNA profile case. KEY POINTS: • CRISPR-Cas9 technique is useful in analyzing LCN, mixed and degraded samples • Alteration of DNA using this technique can lead to generation of ghost DNA profiles • Alternative genetic markers and methylation pattern may detect a ghost DNA profile.

Pairwise kinship analysis of 17 pedigrees using massively parallel sequencing

With the tremendous development of massively parallel sequencing (MPS) in the last decade, it has been widely applied in basic science, clinical diagnostics, microbial genomics, as well as forensic genetics. MPS has lots of advantages that may facilitate the kinship analysis. In this study, 243 Chinese Han individuals from 17 families were involved and sequenced using the ForenSeq™ DNA Signature Prep Kit (Verogen, Inc., San Diego, USA), which provided the sequence information of 27 autosomal STRs (A-STRs), 7 X chromosomal STRs (X-STRs), 24 Y chromosomal STRs (Y-STRs) and 94 identity-informative SNPs (iSNPs). A total of 275 pairs of parent-child, 123 pairs of full siblings, 1 pair of twins, 1 pair of half siblings, 158 pairs of grandparent-grandchild, 222 pairs of uncle/aunt-nephew/niece and 121 pairs of first cousins, as well as 701 pairs of unrelated individuals were identified. Using both likelihood ratio (LR) and identical by state (IBS) methods, the kinship analysis was conducted among these relative and non-relative pairs based on the A-STRs and SNPs. As a result, the ForenSeq Signature Kit could solve the analysis of parent-child (t1 = -4, t2 = 4), full siblings (t1 = -2, t2 = 2) and most second-degree kinships (t1 = -1, t2 = 1) using the LR method. When the IBS method was applied, 123 full sibling pairs had a higher average IBS value than other kinship groups in this study. And the IBS method could play a role in the testing of parent-child and full siblings.

Comparison of single nucleotide polymorphisms and short tandem repeats as markers for differentiating between donors and recipients in solid organ transplantation

Background

Methods

Results

Conclusions

A newly devised multiplex assay of novel polymorphic non-CODIS STRs as a valuable tool for forensic application

DNA profiling that relies on sets of highly polymorphic autosomal STR markers is widely used in the forensic field for human identification and paternity testing. However, the number of markers that are included in the STR kits that are currently available is insufficient to conclusively prove or disprove a relationship between individuals, especially when complex family scenarios are suspected or indirect analyses are required. In these cases, it becomes necessary to increase the number of loci under analysis to reach an adequate likelihood ratio (LR). In this study, we discovered 18 new autosomal non-CODIS STR loci (D1S1616, D1S1608, D2S437, D3S2457, D4S2406, D4S3249, D5S2843, D5S2501, D6S1010, D8S1039, D12S1301, D14S586, D15S815, SHGC-145653, CHLC.GATA14D12, D1S1603, HUMUT7148, and CHLC.GATA84D07) by web scanning and experimental screening. On the basis of this discovery, we developed a novel multiplex typing system named the "SiFaSTR 21plex_NCII Typing System" comprising 1) the 18 non-CODIS autosomal STRs mentioned above, 2) a CODIS locus of D2S1338, and 3) Amelogenin and DYS391. A forensic developmental validation, including sensitivity, species specificity, concordance, reproducibility, sample suitability, testing stability, and mixture testing, was performed following SWGDAM. The results of the validation studies indicated that this system is accurate, reliable and suitable for human DNA profiling. The sensitivity study of the system demonstrated that a full profile was obtainable with DNA as low as 125 pg. Species specificity was proven by the lack of cross-reactivity with a series of common animal species. The stability study demonstrated that 1 ng of control DNA could be fully genotyped with concentrations of haematin ≤ 150 μM, indigotin ≤ 5000 ng/μl, urea ≤ 16000 ng/μl, nigrosine ≤ 100 ng/μl and humic acid ≤ 20 ng/μl. In the mixture test, all of the minor alleles could be called at mixed ratios of 1:1, 1:3 and 3:1. We also investigated the allelic frequencies and forensic parameters of the included markers in 259 Chinese Han individuals. The forensic efficiency parameters, including the total power of discrimination (TDP) and the combined exclusion power in duos (CPE_duos) and in trios (CPE_trios) of the system were calculated to be greater than 0.9999999, 0.9997347 and 0.9999997, respectively. This result proved that the system is suitable for human identification and paternity testing. The 18 newly discovered non-CODIS STRs and the developed system will be a valuable supplementary tool for the forensic community and will help solve complex paternity cases, evolutionary studies and population investigations.

Sequenced-based French population data from 169 unrelated individuals with Verogen's ForenSeq DNA signature prep kit

Massively Parallel Sequencing (MPS) applied to forensic genetics allows the simultaneous analysis of hundreds of genetic markers and the access to full amplicon sequences which help to increase available allele diversity. Meanwhile, sequence variation within the repeat regions represents the majority of the allele diversity, flanking regions adjacent to the repeat core provide an additional degree of variation. The forensic genetics community needs access to population data, from relevant parts of the world that contain this new sequence diversity in order to perform statistical calculations. In this study, we report sequence-based Short Tandem Repeat (STR) and identity Single Nucleotide Polymorphism (iSNPs) allele data for 169 French individuals across 58 STRs and 92 SNPs included in the Verogen ForenSeq DNA Signature Prep kit. 42 STRs out of 58 showed an increased number of alleles due to sequence variation in the repeat motif and/or the flanking regions. D9S1122 showed the largest overall gain with an increase of observed heterozygosities of almost 25 %. The combined match probability combining 27 autosomal STRs and 91 identity SNPs was 1.11E-69. Sequence-based allele frequencies included in this publication will help forensic laboratories to increase the power of discrimination for identification, kinship analysis and mixture interpretation.

Large-scale identification of human bone remains via SNP microarray analysis with reference SNP database

Single nucleotide polymorphisms (SNPs) are valuable markers complementary to conventional forensic short tandem repeat (STR) markers in genetic typing, with potential advantages in challenging forensic casework. With the advent of high-throughput technologies, such as microarrays and massively parallel sequencing, the use of SNP typing has now expanded to large-scale forensic applications. Herein, a forensic case is presented to demonstrate the usefulness of SNP typing in identifying large-scale human bone remains with reference database construction. A total of 402 bone remains were recovered from an island in the Jeju Province of Korea where a massive disaster occurred in 1948. The first phase of the identification process was accomplished via conventional DNA typing methods including autosomal and Y-chromosomal STR typing, and mitochondrial DNA sequencing, which resulted in the identification of 74 of 402 remains. The second phase of the identification involved the remaining 327 unidentified remains using SNP typing as a supplementary tool based on Affymetrix resequencing array. The SNP markers of 782 family members were also analyzed and a reference database was constructed for comparison. An additional 51 bone remains were identified in the second phase. SNP data obtained from the supplementary genotyping yielded additional genetic information as well as contributed to kinship testing to determine the second degrees of relationship. In addition SNPs are useful in discriminating ambiguous relationship when only STR data are available. A software program developed for SNP typing system enabled efficient kinship analysis for large-scale forensic identification. The results and the casework are described and discussed.

A microhap panel for kinship analysis through massively parallel sequencing technology

It is widely recognized that microhaps are powerful markers for different forensic purposes, mainly due to their advantages of both short tandem repeats and single nucleotide polymorphisms, including multiple alleles, low mutation rate, and absence of stutter peaks. In the present study, a panel of 60 microhap loci was developed and utilized in forensic kinship analysis as a preliminary study. Genotyping of microhap was performed by massively parallel sequencing and haplotypes were directly achieved from sequence reads of 73 samples from Chinese Han population. We observed that 49 out of 60 loci have effective number of alleles greater than 3.0 and 10 out of 60 have values above 4.0, with an average value of 3.5598. The heterozygosity values were in a range from 0.5840 to 0.8546 with an average of 0.7268 and the cumulative power of exclusion value of the 60 loci is equal to 1-4.78 × 10^-18 . Moreover, we demonstrated the applicability of this method by different relationship inference problems, including identification of single parent-offspring, full-sibling, and second-degree relative. The results indicated that the assembled microhap panel provided more power for relationship inference, than commonly used short tandem repeats or single nucleotide polymorphism system.

Forensic Genetics and Genotyping

Forensic genetics represents a combination of molecular and population genetics. Personal identification and kinship analysis (e.g. paternity testing) are the two main subjects of forensic DNA analysis. Biological specimens from which DNA is isolated are blood, semen, saliva, tissues, bones, teeth, hairs. Genotyping has become a basis in the characterization of forensic biological evidence. It is performed using a variety of genetic markers, which are divided into two large groups: bi-allelic (single-nucleotide polymorphisms, SNP) and multi-allelic polymorphisms (variable number of tandem repeats, VNTR and short tandem repeats, STR). This review describes the purpose of genetic markers in forensic investigation and their limitations. The STR loci are currently the most informative genetic markers for identity testing, but in cases without a suspect SNP can predict offender’s ancestry and phenotype traits such as skin, eyes and hair color. Nowadays, many countries worldwide have established forensic DNA databases based on autosomal short tandem repeats and other markers. In order for DNA profile database to be useful at a national or international level, it is essential to standardize genetic markers used in laboratories.

Population genomics meet Lagrangian simulations: Oceanographic patterns and long larval duration ensure connectivity among Paracentrotus lividus populations in the Adriatic and Ionian seas

Connectivity between populations influences both their dynamics and the genetic structuring of species. In this study, we explored connectivity patterns of a marine species with long-distance dispersal, the edible common sea urchin Paracentrotus lividus, focusing mainly on the Adriatic-Ionian basins (Central Mediterranean). We applied a multidisciplinary approach integrating population genomics, based on 1,122 single nucleotide polymorphisms (SNPs) obtained from 2b-RAD in 275 samples, with Lagrangian simulations performed with a biophysical model of larval dispersal. We detected genetic homogeneity among eight population samples collected in the focal Adriatic-Ionian area, whereas weak but significant differentiation was found with respect to two samples from the Western Mediterranean (France and Tunisia). This result was not affected by the few putative outlier loci identified in our dataset. Lagrangian simulations found a significant potential for larval exchange among the eight Adriatic-Ionian locations, supporting the hypothesis of connectivity of P. lividus populations in this area. A peculiar pattern emerged from the comparison of our results with those obtained from published P. lividus cytochrome b (cytb) sequences, the latter revealing genetic differentiation in the same geographic area despite a smaller sample size and a lower power to detect differences. The comparison with studies conducted using nuclear markers on other species with similar pelagic larval durations in the same Adriatic-Ionian locations indicates species-specific differences in genetic connectivity patterns and warns against generalizing single-species results to the entire community of rocky shore habitats.

Kinship Testing Based on SNPs Using Microarray System

BACKGROUND

Kinship testing using biallelic SNP markers has been demonstrated to be a promising approach as a supplement to standard STR typing, and several systems, such as pyrosequencing and microarray, have been introduced and utilized in real forensic cases. The Affymetrix microarray containing 169 autosomal SNPs developed for forensic application was applied to our practical case for kinship analysis that had remained inconclusive due to partial STR profiles of degraded DNA and possibility of inbreeding within the population.

CASE REPORT

169 autosomal SNPs were typed on array with severely degraded DNA of two bone samples, and the kinship compared to genotypes in a reference database of their putative family members.

RESULTS

Two bone samples remained unidentified through traditional STR typing with partial profiles of 10 or 14 of 16 alleles. Because these samples originated from a geographically isolated population, a cautious approach was required when analyzing and declaring true paternity only based on PI values. In a supplementary SNP typing, 106 and 78 SNPs were obtained, and the match candidates were found in each case with improved PI values than using only STRs and with no discrepant SNPs in comparison.

CONCLUSION

Our case showed that the utility of multiple SNPs on array is expected in practical forensic caseworks with an establishment of reference database.

Pairwise Kinship Analysis by the Index of Chromosome Sharing Using High-Density Single Nucleotide Polymorphisms

We developed a new approach for pairwise kinship analysis in forensic genetics based on chromosomal sharing between two individuals. Here, we defined "index of chromosome sharing" (ICS) calculated using 174,254 single nucleotide polymorphism (SNP) loci typed by SNP microarray and genetic length of the shared segments from the genotypes of two individuals. To investigate the expected ICS distributions from first- to fifth-degree relatives and unrelated pairs, we used computationally generated genotypes to consider the effect of linkage disequilibrium and recombination. The distributions were used for probabilistic evaluation of the pairwise kinship analysis, such as likelihood ratio (LR) or posterior probability, without allele frequencies and haplotype frequencies. Using our method, all actual sample pairs from volunteers showed significantly high LR values (i.e., ≥ 108); therefore, we can distinguish distant relationships (up to the fifth-degree) from unrelated pairs based on LR. Moreover, we can determine accurate degrees of kinship in up to third-degree relationships with a probability of > 80% using the criterion of posterior probability ≥ 0.90, even if the kinship of the pair is totally unpredictable. This approach greatly improves pairwise kinship analysis of distant relationships, specifically in cases involving identification of disaster victims or missing persons.