Autosomal Short Tandem Repeat Loci Research Articles

A rare case of type II tri-allelic inheritance at vWA, SE33, D8S1179, and D13S317 loci demonstrated by STR analysis in paternity testing.

Short tandem repeat (STR) typing has been regularly used in paternity disputes and forensic human identification linked caseworks. Occasionally, forensic scientists come across aberrant allele patterns during STR typing because of mutations, genetic variations, and other abnormalities. The tri-allelic pattern of STR is rare, particularly, the case where this pattern exists at 4 loci. Here, we report the type II tri-allelic patterns observed at vWA, SE33, D8S1179, and D13S317 loci in the product of conception (POC) sample during the course of our regular paternity case investigation. The DNA extracted from the blood samples and tissue of POC were subjected to STR typing for autosomal and sex STR loci using the commercial QIAGEN's Investigator® IDplex Plus Kit and QIAGEN's Investigator® 24plex QS Kit. Capillary electrophoresis was carried out in 3500 and 3500xL Genetic Analyzer Applied Biosystems and genotyped using GeneMapper ID-X Software v1.5 and v1.6. In this case of paternity inclusion, the POC sample displayed type II tri-allelic patterns at vWA (16, 19, 20), SE33 (19, 28.2, 29.2), D13S317 (16, 19, 20), and D8S1179 (10, 13, 17) loci. In addition, the POC displayed an abnormal genotype with a heterozygous peak imbalance (type II-B) of (1:2) pattern at D3S1358, D21S11, and D16S539 loci, of (2:1) pattern at D1S1656, D12S391, D10S1248, D2S1338, D2S441, D18S317, FGA, CSF1PO, and D5S818 loci, and type II-C allelic pattern (one single peak with triplicate height) at D19S433 and DS7820 loci. Understanding of such anomalous genotypes improves the knowledge about tri-allelic pattern of CODIS loci and helps in the appropriate interpretation of the results in STR typing.

日本人集団において個人を識別するのに必要なSTRとSNPの最小座位数

For this study, we investigated the minimum number of short tandem repeat (STR) and single nucleotide polymorphism (SNP) loci sufficient for personal identification in the Japanese population. A guidance for the data volume that should be treated as personal information was presented here. The uniqueness of individual genotypes was evaluated according to the Scientific Working Group on DNA Analysis Methods interpretation guideline, using the probability that another individual would have the same genotype by chance. In the Japanese population, the threshold of random match probability sufficient for personal identification was 8.15×10－11. In STR, it was considered that when 9 or more of the 21 autosomal STR loci of the GlobalFiler system were combined, they should correspond to personal information. For SNP, a total of 112 loci should be required for identification when cumulating the number of loci at the minor allele frequency interval of 0.01. However, based on the median of allele distribution, a total of 47 loci were necessary to reach below the threshold. Furthermore, we simulated the number of the required loci when the size of the population was variable. Since genome data is already widely used in society, we need to recognize that strict management of genome data are essential from the viewpoint of protecting personal information.

A Tibetan group from Ngawa Tibetan and Qiang Autonomous Prefecture, southwest China, is rich in genetic polymorphisms at 36 autosomal STR loci and shares a complex genetic structure with other Chinese populations

The Tibetan people are ancient and populous, constituting the seventh-largest of the fifty-five ethnic minority groups in China. The Ngawa Tibetan and Qiang Autonomous Prefecture (NTQAP), situated on the border of northwest and southwest China, has its distinct group relationships. Short tandem repeat (STR) is extremely polymorphic and extensively used in the application of forensic medicine and population genetics. However, it is not clear the genetic information including linkage disequilibrium (LD) by 36 autosomal STR (A-STR) markers in the Tibetan group from NTQAP. The Tibetan population from NTQAP of southwest China was examined for 36 A-STR loci in the research. Every marker across the 36 A-STR loci was consistent with Hardy–Weinberg equilibrium (HWE). The results of the calculation revealed that the total discrimination power (TDP) is 1–2.2552 × 10−42 and the cumulative probability of exclusion (CPE) is 1–1.3031 × 10−16. Subsequently, a total of 345 alleles with allelic frequencies ranging from 0.00382 to 0.55343 were identified, and the allelic numbers varied from 5 in both the TH01 and TPOX markers to 28 in the SE33 locus. The Ngawa Tibetan population, along with other Chinese populations, exhibited influences from historical factors and regional distribution, as indicated by the results of population genetics analysis. We thus first explored the genetic characteristics and correlated forensic parameters of the 36 A-STR markers in NTQAP to fill the gap in the Tibetan population. It was discovered that these 36 autosomal STR markers supplemented forensic STR databases and offered extremely valuable polymorphisms for Chinese forensic applications, such as parentage testing and personal identification. Moreover, the study would contribute additional information regarding the substructure and diversity in the Chinese population.

Processing biological samples from simulated radiological terrorist events using Rapid DNA instruments

Two commercially available portable Rapid DNA instruments were evaluated for their ability to process 1 µL and 10 µL saliva samples deposited on metal and plastic surfaces and contaminated with surrogates of cesium (Cs)-137, strontium (Sr)-90 and cobalt (Co)-60; radioactive materials potentially released during a nuclear weapon accident or a radiological dispersal device detonation. A comparable success rate was noted for both Rapid DNA instruments when considering the number of complete and balanced DNA profiles, the number of profiles with a minimum of 10 autosomal STR loci (out of 23 [FlexPlex™ 27] or 21 [GlobalFiler™ Express]), and the possibility to search a national DNA database in Canada and the United States. Cobalt had an adverse impact on the quality of the megaplex short tandem repeat (STR) DNA profiles derived on each instrument for two of the three contamination levels tested in this study, i.e., 0.05 M and 0.1 M as reflected by a reduced number of detected alleles and decreased profile peak heights. Strontium exhibited some adverse effect on the Rapid DNA results when used at the highest contamination level (0.1 M) whereas cesium had none. No new artifacts were observed in the Rapid DNA profiles of samples spiked with the non-radiogenic surrogates. Importantly, in the context of a radiological/nuclear (RN) event, the ANDE™ 6C offers the possibility to dispose of all radioactive materials associated with contaminated samples quickly using a chip on which all steps of the Rapid DNA process are performed whereas the RapidHIT™ ID accumulates radioactive materials for many days before disposal. An individual handling 25 samples in a week (5 per day) on the RapidHIT™ ID at a 30.5 cm distance with a 5 min exposure to the radioactive source estimated at every run would exceed the 0.042 µSv/5 min limit with gamma dose rates for Cs at 0.13 mSv and for Co at 3.8 mSv. Beta dose rates calculated for the surrogate isotopes at the three concentrations tested were also above the recommended radiation exposure limit of 1 mSv/yr (0.042 µSv/5 min). Various potential mechanisms of action behind the interference noted for Sr and Co at high concentrations are presented. These elements may play a role in the steps prior to PCR (at the DNA molecule by binding to bases or to phosphate groups), during PCR (at the DNA polymerase as cofactors for catalytic sites), or even during amplified DNA fragment detection (as fluorescence quenchers).

Determination of allele frequencies in 15 autosomal short tandem repeat (STR) loci of Arab residents in Iraq

Determination of allele frequencies in 15 autosomal short tandem repeat (STR) loci of Arab residents in Iraq

Developmental validation of a novel multiple genotyping assay with 24 Canine STR loci

Canine individual identification and parentage testing are essential in various fields, including forensics and breeding programs. This study aimed to develop and validate the Canine 25 A kit, a multiplex polymerase chain reaction (PCR) system designed to address these critical requirements. This novel system enables the simultaneous amplification of 24 canine autosomal short tandem repeat (STR) loci and one sex-determining marker. Validation of the Canine 25 A kit was conducted following the Scientific Working Group on DNA Analysis Methods (SWGDAM) guidelines, demonstrating significant sensitivity, high inhibitor tolerance, canine specificity within a mixture, species specificity, and precision in genotype determination. The Canine 25 A kit was crucial in resolving several forensic cases, such as casework samples from a dog attack incident and parentage determination. Its effectiveness in genotyping these samples highlights its significance in forensic applications. Population genetic parameter analysis revealed a high discriminatory power, as indicated by the calculated combined discrimination power (CDP) values for each breed exceeding 0.999 999 999 999, while the combined power of exclusion (CPE) surpassed 0.9999. Overall, the Canine 25 A kit offers a precise and dependable tool for canine individual identification and parentage determination.

Short Tandem Repeat (STR) Profiling of Earwax DNA Obtained from Healthy Volunteers.

The present study aimed to establish human earwax as a potential source of DNA evidence that could be effectively used in human identification. Sixty earwax samples were obtained from 15 healthy male and female Saudi volunteers living in Riyadh, Saudi Arabia. Four consecutive earwax swab samples were obtained from each volunteer and stored for 1, 15, 30 and 60 days. Earwax samples were stored at room temperature (20-22 °C). Reference oral swab was also taken from each volunteer. DNA was extracted by QIAamp DNA Mini kit and quantified by real-time polymerase chain reaction (RT-PCR) on 7500 Thermal Cycler. Autosomal STR loci were amplified using AmpFLSTR™ Identifiler™ Plus PCR Amplification Kit (Thermo Fisher Scientific, Carlsbad, CA, USA). Amplified fragments were size separated and analyzed on a 3500 Genetic Analyzer. Complete autosomal STR profiles were obtained from the earwax swabs of all the volunteers stored up to 30 days after the collection. Some STR profiles were partially obtained 60 days after the earwax collection. Allelic drop-out, allelic drop-in, and stutters were seen in earwax samples analyzed 60 days after the collection. The results have shown that human earwax can be a potential source of DNA evidence for human identification up to 30 days after the earwax collection. It is recommended to quickly analyze earwax samples or store them at room temperature or at -10 °C after their recovery from the crime scene.

Sequence-based allelic variations and frequencies for 22 autosomal STR loci in the Lebanese population

This is the first study that characterizes the sequence-based allelic variations of 22 autosomal Short Tandem Repeat (aSTR) loci in a population dataset collected from Lebanon. Genomic DNA extracts from 195 unrelated Lebanese individuals were amplified with PowerSeq 46GY System Prototype. Targeted amplicons were subjected to DNA library preparation and sequenced on the Verogen MiSeq FGx Sequencing System. Raw FASTQ data files were processed by STRait Razor v3. Sequence strings were annotated according to the considerations of the DNA Commission of the International Society for Forensic Genetics (ISFG) and tabulated herein with their respective allelic frequencies and GeneBank accession and version numbers. The sequenced Lebanese dataset resulted in 429 distinct allelic sequences as compared to the 236 alleles identified by length only. The increase in the number of alleles was observed at 18 out of 22 aSTR loci and was attributed to the sequence variations residing in both the STR repeat motifs and flanking regions. The study uncovered 25 novel aSTR allelic sequences across 12 loci for which GenBank records did not previously exist in the STRSeq BioProject, PRJNA380127. For a concordance check, the length-based allelic calls derived from the full sequences were compared to those genotyped using capillary electrophoresis (CE) methods. Population genetic parameters relevant to the evaluation of forensic DNA evidence were assessed for the sequence-based data and compared to the parameters generated from the length-based information. Using the sequence-based data, Analysis of MOlecular VAriance (AMOVA), genetic distances, and population genetic structure were evaluated for 1231 individuals sampled from the Lebanese and four U.S. populations (African American, Asian, Caucasian, and Hispanic). The results were tabulated and visualized in a population tree, multidimensional scaling scatter plots, and bar plots. This newly established sequence-based database for the Lebanese population can be beneficial for extending NGS applicability to casework or paternity testing and assessing the strength of evidence for NGS-STR profiles. The described novel sequence variants at certain loci can further help in the effort to characterize the sequence diversity of STR markers from different populations around the world.

A genetic Study of the Ghanaian Population Using 15 Autosomal STR Loci.

Autosomal short tandem repeat (STR) population data collected from a well characterized population are needed to correctly assigning the weight of DNA profiles in the courtroom and widely used for ancestral analyses. In this study, allele frequencies for the 15 autosomal short tandem repeat (STR) loci included in the AmpFlSTR® Identifiler® plus kit (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, VWA, TPOX, D18S51, D5S818, FGA) were obtained by genotyping 332 unrelated individuals of Ghanaian origin. Statistical tests on STR genotype data showed no significant departure from Hardy-Weinberg equilibrium (HWE). The overall match probability, combined power of exclusion and combined power of discrimination for these loci were 1 in 3.85 × 1017, 0.99999893 and 0.99999998, respectively. Polymorphic information content (PIC) greater than 0.70 was observed for all loci except TH01 and D13S317. These statistical parameters confirm that this combination of loci is valuable for forensic identification and parentage analysis. Our results were also compared with those for 20 other human populations analyzed for the same set of markers. We observed that the Ghanaian population grouped with other African populations in two-dimensional principal coordinate (PCO) and a neighbor-joining (N-J) data mapping and placed closest to Nigerians. This observation reflects cultural similarities and geographical factors, coupled with the long history of migration and trading activities between Ghana and Nigeria. Our report provides what we believe to be the first published autosomal STR data for the general Ghanaian population using 15 loci genotyped using the AmpFlSTR® Identifiler® plus kit methodology. Our data show that the loci tested have sufficient power to be used reliably for DNA profiling in forensic casework and help to elucidate the genetic history of people living in the country.

DNA Polymorphism of 13 Autosomal Short Tandem Repeats (STR) Loci in Mentawai Populations.

<b>Background and Objective:</b> Indonesia consists of various ethnic groups with diverse cultures. However, research on allele frequencies and genetic variations of each ethnic group in Indonesia has not been well established. Therefore, a study was conducted on 13 STR loci panels to analyze the mentawai population as an enhancement of the Indonesian population's genetic data library and genetic variation. Mentawai is one of the Indonesian tribes who live on Mentawai Island, West Sumatera. <b>Materials and Methods:</b> The PrepFiler kit to extract DNA from blood and the GlobalFiler kit for amplifying the 13 loci were used. The genetic analyzer ABI PRISM 3500 was used to detect PCR products. Data were processed and analyzed by EasyDNA and FORSTAT software. <b>Results:</b> The allele frequency data for 13 autosomal loci in Mentawai populations were obtained. Expected heterozygosity was found with a minimum of 0.607 for TPOX and a maximum of 0.866 for FGA. Power of discrimination (PD) values ranges from TPOX (0.792) to FGA (0.968). Polymorphic information content (PIC) values for all loci were high, ranging from 0.642 for TPOX to 0.921 for vWA. Three off-ladder alleles in these findings were detected. Allele 6.3 at the TH01 loci and allele 14.2 at the D18S51 loci are exquisite. The mean expected heterozygosity and mean power of discrimination value across the 13 loci were 75.9 and 90.1%, indicating striking gene diversity. <b>Conclusion:</b> These 13 STR loci can be used for population genetic studies and forensic identification.

Unveiling genetic diversity and forensic utility of SureID® human DNA identification kits: a comprehensive analysis of 44 autosomal STR loci in English and Irish populations

Background: Human identification and kinship testing in forensic science rely on Short Tandem Repeat (STR) multiplex kits, typically containing loci recommended by standard sets. However, complementary kits with additional STR loci can be valuable in complex cases. Allele frequency databases specific to the population are essential for accurate forensic analysis. Aim: This study aimed to generate allele frequencies and population genetic data for 44 autosomal STR loci from SureID® PanGlobal and 27comp kits in English and Irish populations for forensic casework, human identification, and kinship testing. Subjects and methods: Buccal swab samples from 645 White Caucasians (365 English, 280 Irish) were collected. DNA was extracted and amplified using the mentioned kits. Quality control, statistical analysis, and genetic distance calculations were performed. Results: Both kits demonstrated robustness with no significant deviations from Hardy-Weinberg Equilibrium (HWE). Variant alleles and minor discordances between kits were observed. Syntenic STR pairs were identified but showed no significant linkage. A close genetic relationship was found between English and Irish populations, allowing for combined databases. Conclusions: The SureID® PanGlobal and 27comp kits showed high discriminatory power and reliability in the English and Irish populations. Care is needed when handling variant alleles, discordances, and syntenic loci. Combining data from both populations is feasible for a comprehensive database. Further studies are required to explore their effectiveness in diverse populations.

Magnetic bead-based separation of sperm cells from semen-vaginal fluid mixed stains using an anti-ACRBP antibody.

Forensic DNA analysis of semen-vaginal fluid mixed stains is essential and necessary in sexual assault cases. Here, we used a magnetic bead conjugated acrosin binding protein (ACRBP) antibody to separate and enrich sperm cells from mixed stains. Previously, western blotting indicated that ACRBP was specifically expressed in sperm cells, but not in female blood and epithelial cells, while immunofluorescence data showed ACRBP was localized to the acrosome in sperm cells. In our study, sperm were separated from mixed samples at three sperm cell/female buccal epithelial cell ratios (103:103; 103:104; and 103:105) using a magnetic bead conjugated ACRBP antibody. Subsequently, 23 autosomal short tandem repeat (STR) loci were amplified using the Huaxia™ Platinum PCR Amplification System and genotyped using capillary electrophoresis. The genotyping success rate for STR loci was 90% when the sperm to female buccal epithelial cell ratio was > 1:100 in mixed samples. Our results suggest that the magnetic bead conjugated ACRBP antibody is effective for isolating sperm cells in sexual assault cases.

Genetic diversity of 15 STR loci in Yunnan Va ethnic minority and the phylogenetic relationships with 26 other populations

Background The Va (also called “Wa”) people are an ethnic minority living mainly in the southwest of Yunnan Province Aim This study was conducted to obtain the genetic information and forensic statistical parameters of 15 autosomal short tandem repeat (STR) loci included in the AmpFlSTR®Identifiler™ kit (Applied Biosystems, Foster City, CA) in the Yunnan Va population, with a view to enriching the genetic databases of the Chinese Va population. Subjects and methods A total of 508 unrelated Chinese Va individuals were genotyped with this 15 STR kit, the genetic polymorphisms and associated forensic parameters were calculated. The genetic relationships between Chinese Va and 26 other Chinese populations were also evaluated. Results All of the STR loci reached the Hardy–Weinberg equilibrium after Bonferroni correction. A total of 159 alleles were observed with allele frequencies ranging from 0.000984 to 0.606299. The combined discrimination power (CDP) and the cumulative probability of excluding (CPE) of the 15 STR loci were 0.999 999 999 999 999 988 126 and 0.999 995 734, respectively. Our results indicated that the geographically adjacent or ethnically close populations showed a higher genetic affinity. Conclusions The results of this study will enrich the forensic databases of the Chinese Va population and could be applied in forensic analysis.

Allele frequencies of 31 autosomal short tandem repeat (auSTR) loci obtained using the Precision ID GlobalFiler™ NGS STR Panel v2 in 322 individuals from the Japanese population

In human identification methods that target short tandem repeats (STRs), massively parallel sequencing (MPS) technology has made it possible to genotype at the level of the specific sequence itself. This allows for the detection of repeat unit variants and single nucleotide polymorphisms (SNPs) adjacent to the STRs. Using the GlobalFiler™ NGS STR Panel v2, Ion S5, and Converge software, this study constructed a Japanese database of 31 autosomal STRs (auSTRs) and two sex markers from 322 individuals. After excluding some sequence errors and stutters, a total of 31 novel alleles were identified. Additionally, using the allele frequencies of 31 auSTR loci, the match probabilities for the length-based and sequence-based data were calculated to be 1.433 × 10−34 and 9.163 × 10−38, respectively. These values are at least nine orders of magnitude higher than that obtained from 21 auSTR loci in the Japanese population using the conventional capillary electrophoresis method. The database generated in this study is expected to be implemented in forensic practice and used to solve difficult casework.

Evaluation of genetic polymorphisms at 21 autosomal STR loci in Ramgharia Sikh population of Punjab, India

Background STR (Short Tandem Repeat) markers are highly polymorphic markers, which are widely used in forensics DNA analysis and aid to ascertain unique genotype profiles of individuals and determine the genetic diversity of the given population. Aim In the present study, an attempt has been made to evaluate the population genetic diversity of the Ramgharia Sikh population of Punjab, India, using 21 autosomal STR loci (D3S1358, vWA, D16S539, CSF1PO, TPOX, D8S1179, D21S11, D18S51, D2S441, D19S433, TH01, FGA, D22S1045, D5S818, D13S317, D7S820, SE33, D10S1248, D1S1656, D12S391, and D2S1338) to augment the emerging forensic database related to the indigenous population of India. Subjects and methods For generation of the database, 200 (blood on FTA card) samples were obtained from genetically unrelated Ramgharia Sikhs residing in the state of Punjab. Twenty-one autosomal STR markers were analysed using the Globalfiler® PCR amplification kit. Results With the help of various statistical tools, a total of 232 alleles were observed and 11.048 ± 1.284 (mean ± standard deviation) alleles per locus were recorded. No locus deviated from Hardy Weinberg Equilibrium. SE33 locus was found to be the most polymorphic and exhibited the highest discrimination power, that is, 0.99. Moreover, results further indicated that Ramgharia Sikhs of Punjab showed a high affinity with Bhils of Madhya Pradesh (India). Thus, the studied population showed genetic proximity with the geographically close populations of India and showed significant genetic variations with distant populations, which was evident from the UPGMA tree and Principal Component Analysis plot. Conclusion Overall, the 21 autosomal STRs were found to be polymorphic in the Ramgharia population and suitable for forensic casework and studies on population genetics.

Genetic polymorphism and forensic application of 23 autosomal STR loci in the Han population of Panjin City, Liaoning Province, Northeastern China

Background Short tandem repeats (STRs) are consecutive repetition of a repeat motif and widely used in forensic medicine and human genetics because of their high polymorphism. Subjects and methods In the current study, 23 autosomal STR loci were genotyped from 1263 unrelated healthy individuals living in Panjin City, Liaoning Province, Northeastern China using the VeriFilerTM Express PCR Amplification Kit. The population comparison was performed between the Panjin Han population and the other relevant groups to further explore the structure of Panjin Han and its relationship with the other groups. Results The results found 316 alleles across the 23 STRs and the corresponding allelic frequencies ranged from 0.5198 to 0.0004. Except for D3S1358, TPOX, TH01, and D3S1358, all STR loci were highly polymorphic (PIC > 0.7), with the Penta E locus having the highest degree of polymorphism (0.9147). For population comparison, the exact test of population differentiation found that no significant difference was observed between the Panjin Han and the other Han populations, except for Guangdong Han and Jiangxi Han. Conclusion The Panjin Han population showed significant differences with the other ethnic groups in China (Bouyei, Dong, Hui, Miao, Tibetan, and Uygur) and the foreign ethnic groups.

Allelic frequencies distribution and forensic parameters of 23 autosomal short tandem repeats in the population of the State of Pernambuco, Brazil

Located in the Northeast Region, the Pernambuco State is one of the 27 federative units of Brazil. Here, we determined populational data for 23 short tandem repeat (STR) markers – CSF1PO, FGA, TH01, TPOX, vWA, D1S1656, D2S1338, D2S441, D3S1358, D5S818, D7S820, D8S1179, D10S1248, D12S391, D13S317, D16S539, D18S51, D19S433, D21S11, D22S1045, PENTA D, PENTA E and SE33 — of the Pernambuco population. The sample consisted of 767 healthy, adult, unrelated individuals (437 males, 330 females) born and resident in the State of Pernambuco. STRs were amplified using three multiplex kits, according to the availability: PowerPlex® Fusion 6C System (Promega Corporation), PowerPlex® Fusion System (Promega Corporation) and GlobalFiler™ Express (Thermo Fisher Scientific). Allelic frequencies, forensic parameters and Hardy-Weinberg equilibrium determinations were estimated for all the 23 loci. No deviations from the Hardy-Weinberg equilibrium were observed for any of the markers, after Bonferroni correction. We observed that the most and less informative markers were SE33 and TPOX, respectively. The combined power of discrimination (CPD) was 0.99999999999999999999999999999, and the combined power of exclusion (CPE) was 0.99999999997. The cumulative typical paternity index was 37,919,301,869.3021. Interpopulation analyses (Nei’s genetic distance) based on the expanded CODIS core loci was performed between the Pernambuco sample and other global populations. Pernambuco was the closest Brazilian population to African group and stayed distant from the Native American group. This work contributed to show that a panel of 23 autosomal STR loci is very informative, being able for forensic applications related in this population.

An Application of ITO Analysis in Secondary Kinship Identification.

Objective As the methods of the paternity and kinship testing have been developed, the second-degree and more distant relationships remain challenging in forensic science. Currently, the ITO method is the mainstream method to clarify the kinship between two individuals. Methods In this study, the ITO algorithm was used to calculate the uncle-nephew index based on 55 autosomal short tandem repeats (STRs) loci that were universally used for forensic identification. 19 STRs loci in Y chromosome were used for verification of the kinship. Results The cumulative uncle-nephew index between A and B was calculated to 0.993 by the analysis of the genotyping results of 21 STRs. When genotyping results of the other 34 STRs were added to the calculation algorithm, the cumulative uncle-nephew index between A and B was promoted to 227.928. Meanwhile, genotyping results of 17 Y-STRs loci showed that A and B shared the same Y-STRs haplotype that was in accord with the paternal inheritance law. Conclusion The biological uncle-nephew relationship between A and B are identified by applying the statistical principles and genetic technologies.

Validation of the AGCU Expressmarker 20 + 20Y kit: A 6-dye multiplex assay for forensic application

The AGCU Expressmarker 20 + 20Y Kit is a newly devised short tandem repeat (STR) multiplex system that simultaneously analyses a set of 19 autosomal STR loci, 20 Y chromosomal STR loci and the amelogenin locus with six-dye fluorescent labelling. Here, the AGCU Expressmarker 20 + 20Y system was validated following the guidelines published by the Scientific Working Group on DNA Analysis Methods (SWGDAM), including PCR-condition, sensitivity, mixtures, species specificity, models of inhibition, precision, stutter percentage, concordance, population genetic studies, performance on three kinds of degraded DNA and a type of casework samples. The results indicated that the kit had high sensitivity when there was a small amount of DNA (0.0625 ng), more than one male (minor: major=1:19), or a mixture of males and females (male: female=1:32), models of inhibition (250 μM hematin, 1500 ng/μL humic acid and more than 100 ng/μL tannic acid) and degraded samples. The kit showed high precision level with standard deviation of allele size no more than 0.0930. Furthermore, this system was also tested in 444 random male samples of Chinese Han and Hui population, showing its high discrimination capability in Han and Hui population. Meanwhile, the system was applicable to the case of the AMELY abnormality. In short, the kit was verified and proved to be a robust, reliable and suitable tool for human identification and casework samples.

Mutation rate evaluation at 21 autosomal STR loci: Paternity testing experience

The short tandem repeats (STRs) or microsatellites are used for paternity testing and these sequences mutate more rapidlythanbulkDNAsequences. A total of 746 paternity cases were analysed to understand the mutation rate of 21 autosomal STR loci. We identified 41 mutations in 11 STR Loci with a maximum at SE33. No mutations occurred in the remaining 10 STR loci. The overall average mutation rate was estimated as 0.004523 and the estimated locus-specific mutation rate varied between 0.001214 and 0.016990. Among these 90.24% was accounted for single-step mutation, 2.44% for two steps, and 7.32 % for three or muti steps. The obtained data is crucial and could be helpful for ensuring the accuracy of DNA testing and interpretation.