Variation of X-chromosomal microsatellites in Belarus within the context of their genetic diversity in Europe

Allelic and haplotype diversity of 12 X-chromosomal short tandem repeats in Koreans, with an analysis of anomalous profiles

Owing to the unique inheritance pattern of the X chromosome, X-chromosomal short tandem repeat (X-STR) analysis represents a valuable tool in forensic DNA examination-particularly in complex kinship cases, missing person investigations, and disaster victim identification. We analyzed buccal swabs from 429 unrelated Korean males for forensic statistical parameters of 12 X-STRs. Among the 427 individuals analyzed (2 were excluded), DXS10135 was the most informative marker (polymorphism information content [PIC] = 0.9131) and DXS7423 the least informative (PIC = 0.4250). When analyzed based on the four linkage groups (LGs), each individual had unique 12 X-STR haplotypes, with LG1 showing the highest haplotype diversity (0.9968) and the most common haplotype frequency (0.0164). LG1 was also the most informative (PIC = 0.9945), followed by LG3, LG4, and LG2 (with haplotype diversities of 0.9882-0.9968). Our analysis shows that Koreans clustered with East Asians, displayed strong genetic similarity, but differed significantly from Emirati Arabs, Brazilians, Argentinians, and Europeans, forming three distinct clusters influenced by historical and geographical factors. Within the examined X-STR haplotypes, biallelic patterns were identified in two instances: one involved a duplication at DXS10146, as indicated by relative peak height and normalized peak height ratio analysis, and the other encompassed eight loci, where balanced peak heights (72.51 %) and an X peak height imbalance at the amelogenin locus (59.69 %) were indicative of Klinefelter syndrome with sex chromosome aneuploidy. The 12 X-STR loci are informative and discriminatory in the Korean population, providing critical insights for forensic applications and genetic research.

X-chromosomal STRs: Metapopulations and mutation rates

The analysis of STRs located on the X chromosome has been one of the strategies used to address complex kinship cases. Its usefulness is, however, limited by the low availability of population haplotype frequency data and lack of knowledge on the probability of mutations. Due to the large amount of data required to obtain reliable estimates, it is important to investigate the possibility of grouping data from populations with similar profiles when calculating these parameters. To better understand the partition of genetic diversity among human populations for the X-STRs most used in forensics, an analysis was carried out based on data available in the literature and new data (23,949 haplotypes in total; from these 10,445 new) obtained through collaborative exercises within the Spanish and Portuguese Working Group of the International Society for Forensic Genetics. Based on the available population data, a similarity in X-STR profiles was found in European populations, and in East Asian populations, except for some isolates. A greater complexity was found for African, South American, and South and Southeast Asian populations, preventing their grouping into large metapopulations. New segregation data on 2273 father/mother/daughter trios were also obtained, aiming for a more thorough analysis of X-STR mutation rates. After combining our data with published information on father/mother/daughter trios, no mutations were detected in 13 out of 37 loci analyzed. For the remaining loci, mutation rates varied between 2.68 × 10-4 (DXS7133) and 1.07x10-2 (DXS10135), being 5.2 times higher in the male (4.16 ×10-3) than in the female (8.01 ×10-4) germline.

Analysis of 12 X-STRs loci in a population from southeastern Brazil

Short tandem repeat (STR) markers on the X chromosome have a high potential for solving complex kinship analysis and individual identification cases. To achieve such purposes, allele and haplotype frequencies for the specific population are necessary. Nonetheless, such frequencies are not always available. Therefore, we obtained haplotypes from 520 unrelated males from four different geographic regions of Espírito Santo - Brazil, using the Investigator Argus X-12 kit. Forensic parameters for linked groups of four X-STR loci are reported. Genetic distance analyzes suggest that ES population is genetically closer to the Italian population and farther from the Mexican one, among the populations analyzed in this study.

An X-STRs analysis of the Iraqi Sorani Kurds

A database for the Iraqi Sorani Kurds, specifically focused on the 12 X-short tandem repeat (STR) loci, has been developed to fascilitate forensic and population genetics investigations. The present study involved genotyping 117 unrelated individuals from the Sorani Kurds ethnic group using the Investigator Argus X-12 QS kit. The analysis revealed that the DXS10135 locus exhibited the highest degree of polymorphism, as indicated by a polymorphism information content (PIC) value of 0.94565 and a gene diversity (GD) value of 0.95623. Conversely, the DXS8378 locus displayed the lowest level of polymorphism, with a PIC value of 0.61026 and a GD value of 0.68170. Notably, two individuals were found to possess a rare allele (allele = 6) at the DXS8378 locus, which was not included in the allelic ladder of the kit. Furthermore, a significant linkage disequilibrium (LD) (p < 0.05/117) was observed between the DXS10103 and DXS10101 loci on linkage group 3 (LG3). The ancestral composition of the five primary geographic regions, namely Africa, Middle East, East Asia, Europe, and South America, was determined through the utilization of the [Formula: see text] ratio. The findings of this analysis revealed that the Middle Eastern populations exhibited the lowest [Formula: see text] ratio, measuring at 0.23243, indicating a relatively lower ancestral diversity. Conversely, the European populations showcased the highest [Formula: see text] ratio, measuring at 0.27122, indicative of a greater ancestral diversity within this region. Additionally, the allelic richness indicators, namely distinctive and private alleles, indicated that Africa and the Middle East displayed the highest levels, while Far East Asia exhibited the lowest. This analysis supports the hypothesis of repeated founder effects during outward migrations, as evidenced by both the ancestry variability and the allelic richness. Consequently, the findings of this study have important implications for forensic genetics and population genetics research, particularly in relation to the consideration of genetic predispositions within specific ethnic groups.

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.

Population genetic analysis of 12 X-chromosomal STRs in a Swiss sample

X-chromosomal STRs are a powerful tool to assess a broad variety of complex kinship scenarios. We introduce herewith the first Swiss X-STR dataset based on 1198 individuals (592 female, 606 male), characterized with the Qiagen Investigator® Argus X-12 QS multiplex kit. Anomalous allele patterns, allele and haplotype frequencies, and forensic and population genetic parameters are presented. We detected linkage disequilibrium within three out of the four designated linkage groups and no apparent intra-national population substructure. We compared the dataset to a global panel of X-STR datasets and it fits well in the European context, as expected.

Paternal and maternal mutations in X-STRs: A GHEP-ISFG collaborative study

The GHEP-ISFG organized a collaborative study to estimate mutation rates for the markers included in the Investigator Argus X-12 QS kit Qiagen. A total of 16 laboratories gathered data from 1,612 father/mother/daughter trios, which were used to estimate both maternal and paternal mutation rates, when pooled together with other already published data. Data on fathers and mothers' age at the time of birth of the daughter were also available for ∼93 % of the cases. Population analyses were computed considering the genetic information of a subset of 1,327 unrelated daughters, corresponding to 2,654 haplotypes from residents in several regions of five countries: Argentina, Brazil, Ecuador, Portugal and Spain. Genetic differentiation analyses between the population samples from the same country did not reveal signs of significant stratification, although results from Hardy-Weinberg and linkage disequilibrium tests indicated the need of larger studies for Ecuador and Brazilian populations. The high genetic diversity of the markers resulted in a large number of haplotype combinations, showing the need of huge databases for reliable estimates of their frequencies. It should also be noted the high number of new alleles found, many of them not included in the allelic ladders provided with the kit, as very diverse populations were analyzed. The overall estimates for locus specific average mutation rates varied between 7.5E-04 (for DXS7423) and 1.1E-02 (for DXS10135), the latter being a troublesome figure for kinship analyses. Most of the found mutations (∼92 %) are compatible with the gain or loss of a single repeat. Paternal mutation rates showed to be 5.2 times higher than maternal ones. We also found that older fathers were more prone to transmit mutated alleles, having this trend not been observed in the case of the mothers.

Expanded Croatian 12 X-STR loci database with an overview of anomalous profiles

In order to implement X-chromosome short tandem repeat (X-STR) typing into routine forensic practice, reference database of a given population should be established. Therefore we extended already published data with additional 397 blood samples from unrelated Croatian citizens, and analyzed the total of 995 samples (549 male and 446 female) typed by Investigator^® Argus X-12 Kit. To test genetic homogeneity of consecutively processed five historic-cultural regions covering the entire national territory, we calculated pairwise Fst genetic distances between regions based on allele and full haplotype frequencies. Since the comparison did not yield any statistically significant difference, we integrated STR profile information from all regions and used the whole data set to calculate forensic parameters. The most informative marker is DXS10135 (polymorphism information content (PIC = 0.929) and the most informative linkage group (LG) is LG1 (PIC = 0.996). We confirmed linkage disequilibrium (LD) for seven marker pairs belonging to LG2, LG3 and LG4. By including LD information, we calculated cumulative power of discrimination that amounted to 0.999999999997 in females and 0.999999005 in males. We also compared Croatia with 13 European populations based on haplotype frequencies and detected no statistically significant Fst values after Bonferroni correction in any LG. Multi-dimensional scaling plot revealed tight grouping of four Croatian regions amongst populations of southern, central and northern Europe, with the exception of northern Croatia. In this study we gave the first extensive overview of aberrant profiles encountered during Investigator^® Argus X-12 typing. We found ten profiles consistent with single locus duplication followed by tetranucleotide tract length polymorphism. Locus DXS10079 is by far the most frequently affected one, presumably mutated in eight samples. We also found four profiles consistent with X-chromosome aneuploidy (three profiles with XXX pattern and one profile with XXY pattern). In conclusion, we established integral forensic Croatian X-chromosome database, proved forensic pertinence of Investigator^® Argus X-12 Kit for the entire Croatian population and identified locus DXS10079 as a potential duplication hotspot.

Investigation of 12 X-STR loci in Mongolian and Eastern Han populations of China with comparison to other populations

Due to the unique inheritance pattern, X-chromosomal short tandem repeats (X-STRs) have several advantages in complex kinship cases, such as deficiency cases or grandparent-grandchild and half-sisters testing. In our study, 541 unrelated individuals gathered from Mongolian and Eastern Chinese Han populations were successfully genotyped using the Investigator Argus X-12 kit. We calculated allele/haplotype frequencies and other forensic parameters of the two populations and further explored their genetic distance with already published Chinese populations and six global populations. Our results showed that the 12 X-STR markers were highly informative in the two populations when compared with nine other Chinese populations: significant differences were found at several loci. Geographically neighboring populations or different ethnic groups within the same area appeared to have closer evolutionary relationships. We also analyzed population genetic structure by performing clustering with the STRUCTURE program and Principal Coordinate Analysis (PCoA), and we found that the Chinese and other populations enrolled in this study could be distinguished. Furthermore, Mongolian males were distinguishable from the other studied males by a moderate genetic distance. Our study also expanded the X-STR database, which could facilitate the appropriate application of the 12 X-STR markers in the forensic field in China.

Establishment of 11 linked X-STR loci within 1.1 Mb to assist with kinship testing

This report identifies and characterizes 10 novel short tandem repeat (STR) loci on the human X chromosome, all of which are within a range of 1.1 Mb. These newly characterized loci were developed to aid in kinship assignment when the X chromosome is specifically required. The repeat DNA sequences were identified initially using data in GenBank and are located immediately upstream and downstream from the previously described locus DXS6807. Only those loci with seven or more observed alleles were used for further study resulting in the identification of 10 new loci. The distance between each pair of loci ranged from 24,998 to 244,701 bp with an average of approximately 110.8 kb. The number of observed alleles ranged from 7 to 30 for these 10 loci with a polymorphic information content ranging from 0.593 to 0.930. The LOD score from a pairwise linkage study ranged from 4.40 to 23.73, indicating that these 11 loci were highly linked, as expected. In line with standard forensic practice, all 11 loci can be amplified in one multiplex reaction, and comprehensive allelic ladders for all the loci have been constructed. These newly established 11 linked STR loci on the human X chromosome were found to be highly polymorphic and have the potential to aid in kinship testing where the X chromosome loci currently plays a role.

Analysis of 12 X-STR loci in the population of south Croatia

The aim of the study was to assess forensic pertinence of 12 short tandem repeats (STRs) on X-chromosome in south Croatia population. Investigator^® Argus X-12 kit was used to co-amplify 12 STR loci belonging to four linkage groups (LGs) on X-chromosome in 99 male and 98 female DNA samples of unrelated donors. PCR products were analyzed by capillary electrophoresis. Population genetic and forensic parameters were calculated by the Arlequin and POPTREE2 software, and an on-line tool available at ChrX-STR.org. Hardy-Weinberg equilibrium was confirmed for all X-STR markers in female samples. Biallelic patterns at DXS10079 locus were detected in four male samples. Polymorphism information content for the most (DXS10135) and the least (DXS8378) informative markers was 0.9212 and 0.6347, respectively. In both male and female samples, combined power of discrimination exceeded 0.999999999. As confirmed by linkage disequilibrium test, significant association of marker pair DXS10074-DXS10079 (P = 0.0004) within LG2 and marker pair DXS10101-DXS10103 (P = 0.0003) within LG3 was found only in male samples. Number of observed haplotypes in our sample pool amounted 3.01, 7.53, 5 and 3.25% of the number of possible haplotypes for LG1, LG2, LG3 and LG4, respectively. According to haplotype diversity value of 0.9981, LG1 was the most informative. In comparison of south Croatia with 26 world populations, pair-wise [Formula: see text] values increase in parallel with geographical distance. Overall statistical assessment confirmed suitability of Investigator^® Argus X-12 kit for forensic casework in both identification and familial testing in the population of south Croatia.

STR Profiling for Discrimination between Wild and Domestic Swine Specimens and between Main Breeds of Domestic Pigs Reared in Belarus

A panel comprising 16 short tandem repeats (STRs) and a gender-specific amelogenin marker was worked out and tested for robustness in discrimination between wild and domestic swine subspecies encountered in Europe, between regional populations of wild boars and between main breeds of domestic pigs reared in Belarus. The STR dataset comprised 310 wild boars, inhabiting all administrative regions of Belarus, and 313 domestic pigs, representing three local and three cosmopolitan lines. Additionally, a total of 835 wild boars were genotyped for the presence of melanocortin 1 receptor (MC1R) alleles specific for domestic pigs. Correctness of assignment of STR profiles to appropriate populations was measured by log-likelihood ratios (log-LRs). All samples were correctly identified as wild boars or domestic pigs with average log-LR of 42.4 (LR = 2.6×10¹⁸). On the other hand, as many as 50 out of 835 (6.0%) genotyped wild boars from Belarus possessed MC1R alleles specific to domestic pigs, demonstrating supremacy of our STR profiling system over traditional differentiation between wild boars and domestic pigs, based on single binary markers. Mean log-LRs for allocation of wild boars to their regions of origin and of domestic pigs to appropriate breeds were 2.3 (LR = 9.7) and 13.4 (LR = 6.6×10⁵), respectively. Our results demonstrate the developed STR profiling system to be a highly efficient tool for differentiation between wild and domestic swine subspecies and between diverse breeds of domestic pigs as well as for verification of genetic identity of porcine specimens for the purpose of forensic investigations of wildlife crimes, assurance of veterinary public health, parentage control in animal husbandry, food safety management and traceability of livestock products.