X-chromosomal Short Tandem Repeats Research Articles

Genetic Polymorphisms and Forensic Parameters of Thirteen X-Chromosome Markers in the Iraqi Kurdish Population.

X-chromosome short tandem repeat (X-STR) tools are crucial in forensic genetics and human population fields. This study presents the development and validation of a multiplex STR system consisting of thirteen X-STR loci and amelogenin specific to the human X chromosome. The system was optimized and tested for species specificity, sensitivity, stability, and DNA mixture using 9947A female and 9948 male control genomic DNA. The amplified products of nine loci were sequenced to determine the correct amplicon length. Allele frequencies, forensic parameters, mean exclusion chance (MEC), linkage disequilibrium (LD), and allelic patterns were investigated using DNA samples from 225 (159 male, 66 female) unrelated Kurdish individuals who live in Sulaymaniyah province in the Kurdistan region of Iraq. The most informative locus in the Kurdish population was GATA172D05, while the least informative locus was DXS10164. The results demonstrated that the 13 X-STR system is highly polymorphic and sensitive for forensic DNA identification. Genetic distance-based clustering, metric multidimensional scaling (MDS), and correlation matrix were analyzed for 19 ethnic groups and populations. The phylogenetic tree showed that populations clustered according to their ethnogeographic relationships. The findings revealed genetic links between the Iraqi Kurds, Caucasians, Iraqi Arabs, United States (U.S.) ethnic groups, and Chinese populations.

Forensic efficiency and genetic polymorphisms of 12 X-chromosomal STR loci in Northeastern Thai populations.

Northeastern Thailand comprises one-third of the country and is home to various populations, with Lao Isan constituting the majority, while others are considered minority groups. Previous studies on forensic short tandem repeats (STRs) in Thailand predominantly focused on autosomal STRs but there was a paucity of X-STRs, exclusively reported from the North and Central regions of the country. In this study, we have newly established a 12 X-STRs from a total of 896 samples from Northeastern Thailand, encompassing Lao Isan as the major group in the region, alongside nine minor populations (Khmer, Mon, Nyahkur, Bru, Kuy, Phutai, Kalueang, Nyaw, and Saek). Across all ten populations, the combined powers of discrimination in both genders were high and the combined mean exclusion chance (MEC) indices calculated for deficiency, normal trio and duo cases were also high (> 0.99999). DXS10148 emerged as the most informative marker, while DXS7423 was identified as the least informative. Genetic comparison based on X-STRs frequency supported genetic distinction of cerain minor groups such as Kuy, Saek and Nyahkur from other northeastern Thai groups as well as genetic differences according to the geographic region of Thai groups (Northeast, North and Central). In sum, the overall results on population genetics are in agreement with earlier reports on other genetic systems, indicating the informativeness of X-STRs for use in anthropological genetics studies. From a forensic perspective, despite the limitations of small sample sizes for minority groups, the present results contribute to filling the gap in the reference X-STRs database of the major group Lao Isan, providing valuable frequency data for forensic applications in Thailand and neighboring countries.

Forensic autosomal and gonosomal short tandem repeat marker reference database for populations in Burkina Faso

Tandem repeat genetic profiles used in forensic applications varies between populations. Despite the diversity and security issues in the Sahel that require the identification of victims (soldiers and civilians), Burkina Faso (BF) remains understudied. To fill this information gap, 396 unrelated individuals from BF were genotyped using a MICROREADER 21 ID System kit. All 20 short tandem repeat (STR) loci tested passed the Hardy–Weinberg equilibrium (HWE) test. The combined powers of exclusion for duos (CPE duos) and trios (CPE trios) for the 20 tested loci were 0.9999998 and 0.9999307, respectively. The probability that two individuals would share the same DNA profiles among the BF population was 9.80898 × 10–26. For the X-chromosome STR analysis, 292 individuals were included in this study using a MICROREADER 19X Direct ID System kit. Among the 19 loci, no significant deviations from HWE test were observed in female samples after Bonferroni correction (p < 0.05/19 = 0.0026), except for loci GATA165B12 and DXS7423. The results showed that the combined power of exclusion (CPE) and the combined power of discrimination in females (CPDF) and males (CPDM) were 0.999999760893, 0.999999999992, and 1, respectively. Comparison with other African sub-populations showed that geographical proximity is a reliable indicator of genetic relatedness.

X-chromosomal STRs in aDNA kinship analysis.

The analysis of ancient DNA (aDNA) from human skeletal remains can provide useful insights when investigating archaeological finds. One popular application of aDNA is to examine genealogical relationships between individuals recovered at the same archaeological site. For the reconstruction of genealogical relationships, several genetic markers are commonly used: autosomal STRs, mitochondrial lineages (based on SNP-analysis) and Y-chromosomal haplotypes (based on Y-STR-analysis). In this paper, we present the additional opportunities that X-STRs provide in aDNA kinship reconstruction, especially in deficiency cases and for the examination of father-daughter relationships. Possible applications are demonstrated on a range of different kinship reconstructions: confirmation of half-siblingship in the Lichtenstein cave (Germany), exclusion of two potential father-daughter relationships in Goslar (Germany), investigation of three siblingships in Boilstädt (Germany) as well as the confirmation of a father-daughter relationship in Stolpe (Germany). This study shows that the analysis of X-STRs can contribute to the investigation of relationship constellations otherwise difficult to approach (e.g. father-daughter relationships) and that X-STRs are useful to support and complement autosomal STRs, mtDNA and Y-STR data.

Population genetic analyses of Eastern Chinese Han nationality using ForenSeq™ DNA Signature Prep Kit.

Currently, the most commonly used method for human identification and kinship analysis in forensic genetics is the detection of length polymorphism in short tandem repeats (STRs) using polymerase chain reaction (PCR) and capillary electrophoresis (CE). However, numerous studies have shown that considerable sequence variations exist in the repeat and flanking regions of the STR loci, which cannot be identified by CE detection. Comparatively, massively parallel sequencing (MPS) technology can capture these sequence differences, thereby enhancing the identification capability of certain STRs. In this study, we used the ForenSeq™ DNA Signature Prep Kit to sequence 58 STRs and 94 individual identification SNPs (iiSNPs) in a sample of 220 unrelated individuals from the Eastern Chinese Han population. Our aim is to obtain MPS-based STR and SNP data, providing further evidence for the study of population genetics and forensic applications. The results showed that the MPS method, utilizing sequence information, identified a total of 486 alleles on autosomal STRs (A-STRs), 97 alleles on X-chromosome STRs (X-STRs), and 218 alleles on Y-chromosome STRs (Y-STRs). Compared with length polymorphism, we observed an increase of 260 alleles (157, 31, and 72 alleles on A-STRs, X-STRs, and Y-STRs, respectively) across 36 STRs. The most substantial increments were observed in DYF387S1 and DYS389II, with increases of 287.5% and 250%, respectively. The most increment in the number of alleles was found at DYF387S1 and DYS389II (287.5% and 250%, respectively). The length-based (LB) and sequence-based (SB) combined random match probability (RMP) of 27 A-STRs were 6.05E-31 and 1.53E-34, respectively. Furthermore, other forensic parameters such as total discrimination power (TDP), cumulative probability of exclusion of trios (CPEtrio), and duos (CPEduo) were significantly improved when using the SB data, and informative data were obtained for the 94 iiSNPs. Collectively, these findings highlight the advantages of MPS technology in forensic genetics, and the Eastern Chinese Han genetic data generated in this study could be used as a valuable reference for future research in this field.

Genetic diversity and forensic statistical support for the 12 X-STR markers in the Malaysian Indian population using Qiagen Investigator® Argus X-12 QS kit

X-chromosome short tandem repeats (X-STRs) are useful for human identification, especially in complex kinship scenarios. Since forensic statistical parameters vary among populations and the X-STRs population data for the diverse population of Peninsular Malaysia's are unavailable, this attempt for Indians (n = 201) appears forensically relevant to support the 12 X-STRs markers' evidential value for human identification in Malaysia. The Qiagen Investigator® Argus X-12 QS kit showed that DXS10135 was the most polymorphic locus with high genetic diversity, polymorphism information richness, heterozygosity, and exclusion power. Based on allele frequencies, the strength of discrimination and mean exclusion chance (MECKrüger, MECKishida, MECDesmarais, and MECDesmaraisDuo) values for the Malaysian Indians were ≥0.999997790686228. As for haplotype frequencies, the overall discrimination power and mean exclusion probability (MECKrüger, MECKishida, MECDesmarais, and MECDesmaraisDuo) were ≥0.9999984801951. The genetic distance, neighbor-joining phylogenetic tree, and principal component analysis also supported the evidential value of the 12 X-STRs markers for forensic practical caseworks in Malaysia.

Application of the Investigator Argus X-12 QS Kit and the Famlinkx Software for Solving Complex Kinship Forensic Genetics Cases in Colombia: Case Report

X-chromosome short tandem repeats (X-STRs) genotyping is a powerful ¬tool in forensic genetics for resolving intricate kinship cases due to its distinctive inheritance pattern. It proves particularly valuable in scenarios where the application of autosomal (A-STR) and Y-chromosomal STR (Y-STR) markers falls short in addressing such cases, especially those involving complex situations and kinship analyses encompassing extensive and incomplete pedigrees. The recent advancement and implementation of the Argus X-12 QS kit along with the FamilinkX software for X-STR analysis have facilitated the resolution of forensic cases that were formerly inconclusive or not received by the laboratory due to their high complexity. This article delineates seven intricate cases of kinship and identification conducted at the Forensic Genetics Laboratory of the National Institute of Legal Medicine and Forensic Sciences in Bogotá, Colombia, in instances where autosomal STRs yielded non-conclusive or weak likelihood ratio (LR) values, the combination of the Argus X-12 QS kit and the FamilinkX software proved instrumental in elucidating and enhancing LR values, thereby leading to conclusive outcomes. The article details a case involving the confirmation of the identity of a body retrieved from water, which was subsequently returned to the institute by its relatives for identification. It also encompasses cases involving maternal half-siblings, complex pedigrees with paternal half-aunts, and others. In each scenario, the total LR was estimated by combining the LR of autosomal STRs (LR AS-STR) with the LR of X-STRs (LR X-STR), utilizing the population frequency database specific to Colombia. Additionally, the LRs of X-STRs obtained using population frequency data from Colombia were compared with those from Mexico. The data derived from both the Mexican and Colombian populations exhibited a high degree of similarity. The collective LR values substantiate the efficacy of X-STR markers, particularly in resolving cases of maternal half-siblings. The analysis underscores the robust informativeness of the 12 X-STR loci examined in the context of forensic testing

Features and Prospects of the Use of X-chromosomal Tandem Repeats in Forensic Molecular Genetic Examination

When conducting molecular genetic examinations, biological specialists in Ukraine usually use kits for autosomal STR repeats and Y-chromosome repeats and do not use kits for X-chromosomal STR repeats at all. The research paper’s purpose is to analyze the literature data to determine the characteristics of the X chromosome, the possibilities of using X chromosome typing kits, and their implementation in the forensic practice of experts in molecular genetic examinations. The criteria for searching and STR loci are defined, the characteristics of commercial kits (in particular, Argus X-8 PCR Amplification Kit from Biotype AG and Investigator Argus X-12 QS Kit (Germany), X19 X-STRs amplification kit from AGCU ScienTech Inc. and 19X Direct ID system (China)) the directions of their use are considered. The data of scientific and methodological literature on the frequency of mutations, the prevalence of alleles in populations, and the prospects for creating a common database of X-STR repeats are studied. To achieve this goal, general and special methods were used, among which the main one is the structural genetic analysis and synthesis of X-chromosome research data from the standpoint of forensic genetics. The methods of formalizing the characteristics of commercial X-STR repeat kits and their comparative analysis, systematizing possible areas of STR repeat use taking into account the peculiarities of X chromosome inheritance, and generalizing population studies conducted in European countries were also used.

Optimization and Development of an Efficient 13 X-STRs Multiplex PCR System for Paternity Testing

X-chromosomal short tandem repeats (X-STRs) markers complement autosomal STR identification systems and valuable tools in complex kinship cases. Objective: To develop a multiplex PCR system that consists of 13 X-chromosome STR markers, including GATA172D05, DXS8378, DXS6801, DXS6793, DXS6810, DXS7132, GATA31E08, DXS9902, HPRTB, DXS6789, DXS7423, DXS8377, DXS981 and sex-determining locus Amelogenin. Methods: Primer sequences of all X-STR markers were acquired from the Genome databases, and the original sequences for HPRTB, DXS6789, DXS7423, DXS8377 and DXS981 were modified to eliminate primer-dimer formation and optimize melting temperatures to increase annealing efficiency. All primer pairs were labelled with fluorescent dyes to support amplification in a multiplex PCR, and the cycling conditions for multiplex PCR were optimized. Alleles for each locus were bi-directionally sequenced to determine the exact repeat size, and alleles generated in multiplex reactions were undistinguishable from alleles produced in a single marker PCR reaction. Results: The combined power of discrimination of 13 X-STRs was 2.96 x 10-13 and 2.58 x10-8 in females and males, respectively. Conclusions: In conclusion, we have developed a 14-plex PCR system that can potentially be used for parentage testing and forensic casework studies.

Genetic polymorphism and variability in the Guangdong Hakka, Teochew, and Cantonese groups: A comprehensive analysis of 19 X-STRs.

X chromosomeshort tandem repeat (X-STR) loci are playing an increasingly important role inforensic work, identifying female traces in male contamination and explainingcomplex kinship analyses. In this study, we analyzed thegenetic polymorphism of 19 X-STR loci in the Guangdong Hakka, Teochew and Cantonese groups, respectively, aswell as in the Guangdong Hakka, Teochew andCantonese pooled Han. The genetic diversity and forensic characteristics of the19 X-STRs and 7 linkage groups were investigated, respectively. The experiments showed that the genetic diversity (GD) and polymorphism information content (PIC) in the pooledGuangdong Han ranged from 0.5320 to 0.9234 and 0.4369 to 0.9171, respectively, and the cumulative power of discrimination for males (PDM), power of discrimination for females (PDF) and mean paternity exclusion chance (MEC) were higher than 0.9999999, indicating that the 19 X-STRs had high geneticpolymorphism and discriminatory power. Genetic differences among Chinese Hansubgroups and among different Chinese populations were investigated byphylogenetic reconstruction and principal component analysis (PCA), respectively. Genetic analyses based on neighbor-joining (NJ) tree and principal component analysis plot showed that Cantonese, Teochew and Hakka were closely genetically related, and different populations with closer linguistic components had more genetic affinity. This study adds to the forensic X-STR database and demonstrates the forensic efficiency of 19 X-STRs for the Hakka, Teochewand Cantonese populations in Guangdong, and the pooled Han of Hakka, Teochewand Cantonese people in Guangdong.

DNA Fingerprinting: A Revolution in the Field of Forensic Sciences

DNA profiling, commonly called DNA fingerprinting or DNA testing, has a wide range of uses, including assisting in criminal cases and wildlife conservation. The firm tissues of the teeth are resistant to external events such as decomposition, bruise, and incineration. Pulp tissue provides a rich DNA source. The review focuses on the various DNA Collection Procedures, the different techniques employed in DNA isolation and amplification. There are a numerous DNA Profiling or Typing systems such as Mitochondrial DNA (mtDNA) analysis, Restriction Fragment Length Polymorphism, Y chromosome analysis, Single Nucleotide Polymorphism (SNP) typing , Short Tandem Repeat (STR) typing, Gender typing, X-chromosome STR Typing. DNA fingerprinting has been applied to solve many cases. Although present DNA analysis techniques are fairly specialized, several upcoming simplifications may increase their simplicity of use.

High-resolution genotyping of 58 STRs in 635 Northern Han Chinese with MiSeq FGx ® Forensic Genomics System

Sequence polymorphisms were characterized at 27 autosomal STRs (A-STRs), 7 X chromosomal STRs (X-STRs), and 24 Y chromosomal STRs (Y-STRs) in 635 Northern Han Chinese with the ForenSeq DNA Signature Prep Kit on the MiSeq FGx Forensic Genomics System. Since repeat region (RR) and flanking region (FR) variation can be detected by massively parallel sequencing (MPS), the increase in the number of unique alleles and the average of gene diversity was 78.18% and 3.51% between sequence and length, respectively. A total of 74 novel RR variants were identified at 33 STRs compared with STRSeq and previous studies, and 13 FR variants (rs1770275883, rs2053373277, rs2082557941, rs1925525766, rs1926380862, rs1569322793, rs2051848492, rs2051848696, rs2016239814, rs2053269960, rs2044518192, rs2044536444, and rs2089968964) were first submitted to dbSNP. Also, 99.94% of alleles were concordant between the ForenSeq DNA Signature Prep Kit and commercial CE kits. Discordance resulted from the low performance at D22S1045 and occasionally at DYS392, flanking region deletions at D7S820 and DXS10074, and the strict alignment algorithm at DXS7132. Null alleles at DYS505 and DYS448 and multialleles at DYS387S1a/b, DYS385a/b, DYS448, DYS505, DXS7132, and HPRTB were validated with other MPS and CE kits. Thus, a high-resolution sequence-based (SB) and length-based (LB) allele frequencies dataset from Northern Han Chinese has been established already. As expected, forensic parameters increased significantly on combined power of discrimination (PD) and combined power of exclusion (PE) at A-STRs, mildly on combined PD and combined mean exclusion chance (MEC) at X-STRs, and barely on discrimination capacity (DC) at Y-STRs. Additionally, MiSeq FGx quality metrics and MPS performance were evaluated in this study, which presented the high-quality of the dataset at 20 consecutive runs, such as ≥ 60% bases with a quality score of 20 or higher (%≥ Q20), > 60% of effective reads, > 2000 × of depth of coverage (DoC), ≥ 60% of allele coverage ratio (ACR) or heterozygote balance, ≥ 70% of inter-locus balance, and ≤ 0.4 of the absolute value of observed minus expected heterozygosity (|Hexp – Hobs|). In conclusion, MiSeq FGx can help us generate a high-resolution and high-quality dataset for human identification and population genetic studies.

Applications of X-Chromosome Short Tandem Repeats for Human Identification: A Review

The forensic DNA profiling technique has tremendously contributed to forensic human identification, an important aspect in forensic investigations. In instances whereby comparison samples are unavailable, utilization of short tandem repeats of X chromosome (X-STRs) may prove useful to resolve complex kinship investigations involving missing persons and mass disasters. Despite such evidential values, the use of X-STRs during investigations remains scarce in many Southeast Asian countries including Malaysia, requiring concerted efforts for establishing forensic statistical support for its diverse populations (especially the admixture populations), standardizing core loci and procedure, improving the knowledge among practitioners as well as developing suitable standard operating procedure for incorporating X-STRs analysis in the overall DNA profiling framework. Hence, this review paper aims to highlight the developments, applications and population data of X-STRs, as well as its challenges and future insights for forensic casework.

Forensic characterisation and polymorphism analysis of 16 X-chromosomal STRs in the Jining Han population in Eastern China

Background X-chromosomal short tandem repeats (X-STRs) are a useful supplementary approach to analysing autosomal markers in forensics and kinship studies; such markers are not well-characterised in many populations. Aim To investigate population genetic polymorphism and forensic characterisation of 16 X-STRs in the Jining Han population, and analyse genetic relationships with other Chinese populations. Subjects and methods Allele frequencies for 16 X-STR loci were obtained from a sample set of 527 unrelated individuals from the Jining Han population. Population genetic analyses of Jining Han and another 10 reference populations were conducted using phylogenetic tree, principal component analysis and multidimensional scaling. Results We detected 149 alleles, with frequencies ranging from 0.0013 to 0.8242. The combined powers of discrimination in males and females were 0.999999997194774 and 0.999999999999995, respectively. The combined mean exclusion change (MEC)Krüger, MECKishida, MECDesmarais, and MECDesmarais Duos values were 0.999974632649096, 0.999999976997582, 0.999999977013201, and 0.999993755768423, respectively. We detected relatively high genetic homogeneity in populations with similar ethnic or geographic origins, and a close relationship between the Jining Han and Beijing Han populations. Conclusions The present findings indicate that the 16 X-STR loci examined are highly polymorphic in the Han population of Jining, providing useful information for forensic science and population genetics studies.

Genetic polymorphisms of 19 X-STRs in populations of Hubei Han and Guangxi Zhuang and their comparisons with 13 other Chinese populations

Background A prerequisite for applying short tandem repeat (STR) kits is obtaining population allele and/or haplotype frequencies and forensic parameters. Aim Firstly, we aimed to investigate the population data of 19 X-chromosomal STRs (X-STRs) included in the AGCU X19 STR kit in the Han people residing in Hubei Province, Central China, and the Zhuang people residing in the Guangxi Zhuang Autonomous Region of South China. Furthermore, we compared these population data with those for other Chinese populations. Subjects and methods In total, 509 unrelated Han males and 266 unrelated Zhuang males were genotyped using the AGCU X19 STR kit. Allele frequencies, haplotype frequencies, and forensic parameters were computed, and genetic differences among 15 Chinese populations were analysed. Results The 19 X-STRs showed a high power of discrimination and high mean chance of exclusion, whether calculated using allele or haplotype frequencies. Major differences were found between Han and Oroqen, Uyghur, Mongolian, Tibetan, Li, and Yi populations. Aberrant biallelic patterns at DXS10159, DXS10134, and DXS10079 and allelic dropouts at DXS10164 were observed. Conclusion The 19 X-STRs were highly polymorphic in the Hubei Han and Guangxi Zhuang populations, and the AGCU X19 STR kit was shown to be suitable for forensic casework.

Population genetic analysis of 12 X-STR markers in Slovakia

Background: During the last 20 years, X-chromosomal STR markers have become widely used in forensic genetics and paternity testing. Nevertheless, to exploit their full potential in any given population, a reliable reference dataset needs to be established. Since no relevant studies concerning these markers have been performed on the Slovak population so far, we decided to analyse several commonly used markers in this population. Aim: To create an informative set of Slovak population data concerning X-STR markers. Subjects and methods: We genotyped 378 individuals and analysed 12 loci (DXS10148, DX10135, DXS8378, DXS7132, DXS10079, DXS10074, DXS10103, HPRTB, DXS10101, DXS10146, DXS10134 and DXS742) localised in four distinct linkage groups. Results: Our analysis showed that the most informative marker is DXS10135 (PIC = 0,927) and the most informative linkage group (LG) is LG1 with 149 different haplotypes. This analysis also confirmed linkage disequilibrium for two pairs of markers (DX10101-DX10103 and DX10101-HPRTB) within LG3 in female samples. No statistically significant departure from HWE was observed for any locus. Moreover, the interpopulation comparison of 8 European populations based on haplotype frequencies showed no statistically significant FST values in any LG, except for LG2 in comparison with the German population. Conclusion: We created a haplotype database for forensic analyses and kinship testing in Slovakia, as well as the CE dataset which can be used to further increase the decision power in similar analyses in the future.

Forensic Applications of Markers Present on the X Chromosome.

Microsatellite genetic markers are the gold standard for human genetic identification. Forensic analyses around the world are carried out through protocols using the analysis of STR markers in autosomal chromosomes and in the Y chromosome to solve crimes. However, these analyses do not allow for the resolution of all cases, such as rape situations with suspicion of incest, paternity without a maternal sample for comparison, and biological traces with DNA mixture where the profile sought is female, among other situations. In these complex cases, the study of X-chromosome STR markers significantly increases the probability of identification by complementing the data obtained for autosomal and Y-chromosome markers, due to the unique structure of the X chromosome and its exclusive method of inheritance. However, there are currently no validated Brazilian protocols for this purpose, nor are there any population data necessary for statistical analyses that must be included in the issuance of expert reports. Thus, the aim of this article is to provide a literary review of the applications of X-chromosomal markers in population genetics.

Genetic analysis of X-chromosomal short tandem repeat (X-STR) frequencies in Arab Iraqi male population

BackgroundThe X-chromosome short tandem repeat (STR) polymorphisms are a particular tool in the fields of human population genetics and personal identification. It was necessary in investigating complex kinship or deficiency cases in conditions where information on mitochondrial DNA (mtDNA) or Y chromosome polymorphisms have been used to explore their direct paternal line. This study aimed to investigate the allele frequency of (12X-STR) of 200 unrelated males from different region of Baghdad City to serve as a reference data base for individual identification in Iraqi population. ResultsTwelve X-STR loci (DXS7424, HPRTB, DXS8377, GATA31E08, DXS7423, DXS8378, DXS9895, DXS10074, DXS6809, DXS7133, DXS101, DXS6807) were successfully amplified by multiplex PCR and divided into four groups. According to measures of allele frequency, the higher alleles frequency were 16, 11, 46, 11, 14, 10, 15, 15.2, 35, 11, 25, and 11 while the lowest alleles frequency were 11, 9, 52,53, 7, 17, 14, 13, 12.2,17, 36, 15, 16, 22, 29, and 17 that observed at the 12 loci respectively. Forensic efficiency parameter for DXS8377 locus in the first group showed highest polymorphic allele in the Iraqi Arab population with the frequencies ranging from 0.005 to 0.16%. The power of discrimination (PD) value ranged from 0.663 for DXS7423 locus and 0.9066 for DXS8377 locus. In addition, the polymorphism information content (PIC) value ranged from 0.602974 for DXS7423 locus to 0.899206 for DXS8377 locus. ConclusionsOverall the X-STR markers become used as an important source of information beside the autosomal and Y-STR markers, especially for kinship testing and haplotype analysis.

DNA in forensic odontology: An overview

Human remains are tremendously damaged and degraded in forensic cases and the identification becomes very difficult, in those cases teeth and bones are often the only reliable sources of DNA for identification. Advances in DNA extraction techniques and short-amplicon DNA typing have greatly increased our potential to identify human remains which were previously considered to be too compromised for genetic analysis. As the teeth are largely protected within the jawbones and remains protected from the environmental conditions and prevent these tissues from postmortem decomposition and DNA decay. DNA profile tests which are performed nowadays are totally reliable and give details about an individual’s physical characteristics, ethnicity, place of origin and sex. These tests are also accepted as legal proofs in courts. These tests are: Restriction Fragment Length Polymorphism Typing, STRs Typing, Mitochondrial DNA Analysis, Y-Chromosome Analysis, X-Chromosome STR, Single Nucleotide Polymorphism. The aim of this review is to provide a better understanding and knowledge about the latest techniques in DNA for human identification in the field of forensic odontology.

Investigation of X-STR haplotype diversity in the Australian Aboriginal population

ABSTRACT X-chromosome short tandem repeat (X-STR) analysis complements autosomal and Y-chromosome STR typing for complex kinship analysis and screening of candidate lists in familial searches. To statistically evaluate X-STR profiling results, Australian forensic laboratories require X-STR haplotype frequency databases for relevant populations. Our study is the first to report haplotype data for the Australian Aboriginal population. X-STR haplotypes were generated for 298 self-declared male Aboriginals using the Investigator® Argus X-12 Kit. Haplotype frequencies and parameters of forensic interest are presented. The discrimination power of a full haplotype was 98.7% and the cumulative power of discrimination was 0.9999999988 for males and 0.999999999999999 for females. MDS plots of pairwise FST genetic distances and STRUCTURE histograms identified some segregation of X-STR haplotypes between individuals from the Desert and Eyre regions as compared to the Spencer, Riverine and urban Adelaide regions. Comparison of Australian Aboriginal X-STR haplotypes to those of other global populations showed the most similarity to Europeans and least similarity with Asian populations. Ancestral X-STR haplotypes appeared most conserved in the outback Desert and Eyre regions where assimilation with Europeans is lower. Overall genetic structure was minimal and a single X-STR haplotype database combining all regions is considered appropriate for likelihood ratio calculation.