A genetic study of 12 X-STR loci in the Hungarian population

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.

Extended population genetic analysis of 12 X-STRs - Exemplified using a Norwegian population sample

The use of X-chromosomal markers to resolve questions of relatedness has experienced a significant increase during the last years in forensic genetics. Perhaps primarily due to the emergence of commercial kits, but equally important due to an increased awareness of the utility of those markers. The X-chromosomal inheritance pattern entails that some cases, for instance paternal half-sisters, can potentially be resolved using a few X-chromosomal markers alone. For the statistical assessment in kinship cases it is of importance to have relevant population frequency data. In the present study 631 unrelated males from a Norwegian population sample are analyzed. The resulting haplotypes are compared to previously studied population samples and a deeper analysis of the linkage disequilibrium (LD) structure is conducted. We demonstrate that the power to detect LD will be low when few males, say below 300, are analyzed. We use entropy to describe the degree of LD between multiallelic loci and describe how this measure varies between different studied populations. Large population frequency databases have been recommended when using X-chromosomal markers, and we show that by combining reference databases from genetically similar populations, more precise haplotype frequency estimates can be obtained for rare haplotypes which improves the statistical assessment of the weight of evidence. In addition, we promote the use of simulations to assess the utility of STR markers in contrast to standard forensic parameters. Specifically we perform extensive simulations on cases where X-chromosomal markers are important and illustrate how the results can be used to infer the information gained from these markers.

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.

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.

Investigator Argus X-12 study on the population of northern Croatia

X chromosome STR typing has emerged recently as a powerful tool, complementary to autosomal STR typing, in solving complex forensic and missing person cases. Investigator® Argus X-12 is a commercial product that allows co-amplification of 12 X chromosomal markers belonging to four linkage groups (LGs). In this study, we analyzed by capillary electrophoresis blood samples from 100 females and 102 males from a population of northern Croatia. Statistical analysis included calculation of allele and haplotype frequencies, as well as forensic parameters. The most informative marker for the northern Croatia population was DXS10135 with PIC=0.9211 and a total of 27 alleles. The least polymorphic marker was DXS8378 with 6 alleles. The proportion of observed haplotypes from the number of possible haplotypes varied from 2.74-8.57% across all LGs, with LG1 being the most informative. Of the 11 tested world populations compared to the population of northern Croatia, significant differences in genetic distance (FST) were found for Greenlandic and all non-European populations. We found that all tested markers are in HWE and can thus be used for match probability calculation. Because of high combined power of discrimination in both men and women, Investigator® Argus X-12 is applicable for the northern Croatia population in routine forensic casework.

Analysis of 12 X-chromosomal markers in the population of central Croatia

Investigator® Argus X-12 Kit is a commercially available set that allows simultaneous PCR amplification of 12 X-STR markers belonging to four linkage groups (LG). To assess the forensic efficiency of these markers for the population of central Croatia and consequent applicability in routine forensic casework, DNA from 200 blood samples of unrelated donors (100 female and 100 male) was amplified by Investigator® Argus X-12 Kit and analyzed by capillary electrophoresis. Statistical computations based on allele and haplotype frequencies for LG1 - LG4 were performed using Arlequin 3.5 software and on-line tool available at ChrX-STR.org. In female samples, all X-STR markers were in Hardy-Weinberg equilibrium (HWE). The most informative marker for central Croatia population was DXS10135 with polymorphism information content (PIC) 0.9296. The least polymorphic locus was DXS8378 (PIC=0.6363). Power of discrimination (PD) varied from 0.6968 to 0.9336 in male and from 0.8476 to 0.9916 in female samples. Combined PD exceeded 0.999999999 in both men and women. In male samples, linkage disequilibrium (LD) test revealed significant association (P=0.0000) of one marker pair in LG4 and two marker pairs in LG3. Portion of observed haplotypes in the number of possible haplotypes varied from 2.86% to 7.47% across all LGs. LG1 was the most informative with haplotype diversity (H) 0.9972. High PD of all analyzed markers exhibited for central Croatia population confirms suitability of Investigator® Argus X-12 for forensic pertinence. Moreover, results of this study will be included in establishing a national reference X-STR database based on 12 X-STR loci, which is necessary for the correct interpretation of the forensic casework results.

Complex X chromosome rearrangement associated with multiorgan autoimmunity

BACKGROUND

Turner syndrome, a congenital condition that affects 1/2,500 births, results from absence or structural alteration of the second sex chromosome. Turner syndrome is usually associated with short stature, gonadal dysgenesis and variable dysmorphic features. The classical 45,X karyotype accounts approximately for half of all patients, the remainder exhibit mosaicism or structural abnormalities of the X chromosome. However, complex intra-X chromosomal rearrangements involving more than three breakpoints are extremely rare.

RESULTS

We present a unique case of a novel complex X chromosome rearrangement in a young female patient presenting successively a wide range of autoimmune diseases including insulin dependent diabetes mellitus, Hashimoto's thyroiditis, celiac disease, anaemia perniciosa, possible inner ear disease and severe hair loss. For the genetic evaluation, conventional cytogenetic analysis and FISH with different X specific probes were initially performed. The complexity of these results and the variety of autoimmune problems of the patient prompted us to identify the exact composition and breakpoints of the rearranged X as well as methylation status of the X chromosomes. The high resolution array-CGH (assembly GRCh37/hg19) detected single copy for the whole chromosome X short arm. Two different sized segments of Xq arm were present in three copies: one large size of 80,3 Mb from Xq11.1 to Xq27.3 region and another smaller (11,1 Mb) from Xq27.3 to Xq28 region. An 1,6 Mb Xq27.3 region of the long arm was present in two copies. Southern blot analysis identified a skewed X inactivation with ≈ 70:30 % ratios of methylated/unmethylated fragments. The G-band and FISH patterns of the rearranged X suggested the aspect of a restructured i(Xq) chromosome which was shattered and fortuitously repaired. The X-STR genotype analysis of the family detected that the patient inherited intact maternal X chromosome and a rearranged paternal X chromosome. The multiple Xq breakages and fusions as well as inverted duplication would have been expected to cause a severe Turner phenotype. However, the patient lacks many of the classic somatic features of Turner syndrome, instead she presented multiorgan autoimmune diseases.

CONCLUSIONS

The clinical data of the presented patient suggest that fragmentation of the i(Xq) chromosome elevates the risk of autoimmune diseases.