X-chromosomal Short Tandem Repeats Research Articles

Population data of eight X-chromosomal STR markers in Ewe individuals from Ghana

The investigation of the X-linked DNA markers are well established in the forensic routine case work. We studied an Ewe population sample from Ghana. The eight X-chromosomal STRs DXS10135, DXS8378, DXS7132, DXS10074, HPRTB, DXS10101, DXS10134 and DXS7423 were analyzed in 182 Ewe individuals (108 females and 74 males) from the region of Sogakofe (Ghana). Allele frequencies and statistical parameter as well as comparison with known data from Germans and with data from an Amharic population (Ethiopia) are presented.

Analysis of 8 STR of the X-chromosome in two Italian regions (Umbria and Sardinia)

Eight X-chromosome STR were investigated in two groups of individuals from two Italian regions, Umbria and Sardinia. These two regions have a very different history. Umbria, situated in the centre of Italy and without defensive natural barriers, in the course of the centuries has been object of many invasions and appropriations by foreign people. On the contrary, Sardinia, an island in the centre of the Mediterranean sea, has endured a minor number of foreign invasions. The ChrX markers were amplified in a pentaplex (DXS6789, DXS7423, DXS6807, DXS101, DXS8377) and a triplex (DXS10074, DXS10075, DXS10079) that represents a haplotype. The DNA was extracted from 200 blood samples using the QIAmp DNA Minikit (Qiagen™). Amplification products were detected on an ABI PRISM 310 Genetic Analyzer (Applied Biosystems), using the same dye labels, run conditions, standard (GeneScan 500 Liz) and matrix file of AmpFlSTRIdentifiler. Statistical analyses for all the loci and intergroup comparisons between the two regional groups of individuals were performed.

Molecular characterization of a null allele at locus DXS8378

Typing of X-chromosomal short tandem repeat (STR) loci in a deficiency paternity case revealed a single Mendelian incompatibility between a female child and her putative grandmother, consisting of an opposite homozygosity at locus DXS8378. The presence of a null allele due to a primer binding site mutation on the child's paternally inherited X chromosome was confirmed by amplification with newly designed DXS8378 external primers. Sequencing analysis showed a point mutation (C > T transition at position 168, according to GenBank accession G08098) in the binding site of the original DXS8378 reverse primer.

Genetic Polymorphisms of four X-STR Loci: DXS6797, DXS6800, HPRTB and GATA172D05 in a Peruvian population sample

The X linked short tandem repeats (STR) markers have proven to be very useful tools for paternity testing when the disputed child is female. The purpose of this study was to describe the genetic polymorphism of four X-chromosomal STR loci (DXS6797, DXS6800, HPRTB and GATA172D05) in a Peruvian population sample and evaluate their efficiency in forensic practice and paternity testing.

Allele distribution of three X-chromosome STR loci in an antioquian population sample

The X-linked short tandem repeats (STR) markers have proven to be very useful tools for paternity testing when the disputed child is female. The aim of this study was to describe the polymorphism of three X-chromosomal STR loci (DXS6797, DXS6800 and HPRTB) in an Antioquian (Colombian) population sample. PCR products were separated in 4% acrylamide-bis-acrylamide denaturing gels followed by silver staining. Allele size determination and genotyping were performed according to recommendations of the DNA Commission of the International Society of Forensic Genetic using the allelic ladder manufactured at home and based on DNA controls including K562 and 9947A (Promega). Gene frequencies were calculated using ARLEQUIN version 3.11. Population genetic data were obtained by analyzing 127–400 unrelated males and 135 unrelated females from Antioquian (Colombian) population. Distribution of the allele frequencies of these systems for Antioquia population is similar to the European populations.

Polymorphism of four X-chromosomal STR loci in Belarusians and Slovaks

We have investigated four X-chromosomal STR loci (a tetranucleotide repeat marker HPRTB, DXS7423 and trinucleotide repeat systems DXS101, DXS8377) in population samples of unrelated Belarusian and Slovak males ( N = 180 and 116, respectively). Markers were amplified in a multiplex PCR reaction with primers labeled with fluorescent dyes 5-FAM and 5-JOE (dye set F). The separation and detection of PCR products were performed by capillary electrophoresis on a 3130 Genetic Analyzer (Applied Biosystems), using positive controls (K562 and NA9947A) and the GeneScan-500 ROX internal lane standard. Allele designation was based on comparison with the constructed allelic ladder. We performed statistical analysis estimating power of discrimination for males (PD male). Our data was compared with European populations from Poland and Germany. The obtained data are useful in forensic practice and they contribute to creation of national X-STR databases in Belarus and Slovakia.

Haplotypes and haplotype stability within a 126.6 kb region at Xq28

This study continues earlier attempts to establish linked locus STR clusters at several ChrX areas for usage in kinship testing. The three polymorphic X-chromosomal STR markers DXS10146, DXS10134 and DXS10147 are already known as linkage group within a 79.1 kb region in Xq28. Additionally, the closely linked STR DXS7423 was included into the study of the Xq28 cluster spanning a region of 126.6 kb. Allele and haplotype frequencies of a German and Ethiopian population were reported and compared. Typing this cluster in a German population of 404 males 311 different haplotypes were found. Genotyping of 102 men from Ethiopian population revealed the presence of 96 haplotypes. Recombination analysis was performed in 109 father–daughter–grandson trios in which two crossing over events were observed located in the 65.8 kb region between DXS10134 and DXS10146. Using this STR complex for haplotyping in kinship testing further genetic analyses are required to establish an exact recombination rate.

Results of the 2007 Paternity Testing Workshop of the English Speaking Working Group of the International Society for Forensic Genetics

We present the results of the 2007 Paternity Testing Workshop of the English Speaking Working Group of the International Society for Forensic Genetics. The exercise included paternity testing of blood samples from a mother, a child and an alleged father. The laboratories were encouraged to answer questions concerning their laboratory routines and a paper challenge was distributed in order to compare statistical calculations. A total of 69 laboratories participated. The laboratories used a total of 41 autosomal STRs and PCR-investigated VNTRs, 22 Y-chromosomal STRs, 11 X-chromosomal STRs and 7 VNTR systems investigated with RFLP. The rate of typing and reporting errors was 0.2%.

Population data for 8 X-chromosome STR loci in a population sample from Northern Italy and from the Sardinia island

To establish a database for DXS8378, HPRTB, DXS7423, DXS7132, DXS10134, DXS10074, DXS10101, DXS10135 loci in an Italian population sample from Brescia (Northern Italy) and from the Sardinia island, 131 unrelated individuals were typed. DNA was amplified in a multiplex reaction with subsequent automatic detection using capillary electrophoresis. The obtained data give a contribution to the definition of Italian population STR allele frequencies for the eight analysed loci.

Population data for six X-chromosome STR loci in a Rio de Janeiro (Brazil) sample: Usefulness in forensic casework

This study presents data for the X-chromosome STR loci DXS7133, DXS7424, DXS8378, DXS6807, DXS7423 and DXS8377. In order to establish a database, unrelated individuals (males and females) from Rio de Janeiro were typed for the above loci. No significant differences were observed between allele frequencies in male and female samples (non-differentiation exact P values ≥ 0.156). Hardy–Weinberg equilibrium was tested in the female sample and no significant deviations were found. All six markers have shown to be highly polymorphic in our sample with gene diversities varying between 0.6797 for DXS7133, and 0.9260 for DXS8377. Pairwise linkage disequilibrium analysis did not allow discharging a possible association between DXS7133 and DXS7424 alleles in Rio de Janeiro population. Parameters of forensic interest, like PD M, PD F, Het obs, Het exp, were calculated for each locus. The high discrimination power estimated in both males and females, as well as mean exclusion chance in father/daughter duos and in father/mother/daughter trios, demonstrates the usefulness of these six markers in forensic investigation.

Genetic profile characterization and segregation analysis of 10 X-STRs in a sample from Santander, Colombia

Ten X-chromosome short tandem repeats (X-STRs: DXS8378, DXS7132, DXS9898, DXS6809, DXS6789, DXS101, GATA172D05, HPRTB, DXS8377, and DXS7423) were analyzed in a sample of unrelated individuals (108 males and 110 females) from the Santander Department in Colombia. In this sample, gene diversities varied between 63.56%, for DXS8378, and 91.41%, for DXS8377. For this set of 10 X-STRs, a high discrimination power was obtained for both male (1 in 3 x 10(6)) and female (1 in 9 x 10(10)) samples and a high mean exclusion chance in father/daughter duos (99.993%) and in father/mother/daughter trios (99.9999%), demonstrating the usefulness of this set of markers in forensic and kinship analysis. Hardy-Weinberg equilibrium was tested in the female sample and no significant deviations were found. Pairwise analysis showed significant differences in the comparison with samples from Spain, Peru, and Argentina and with African American and Hispanic samples from New York. This same set of X-STRs was also typed in 51 mother/father/daughter trios, 43 mother/son duos, and in a single father/daughter pair. In total, four mutations were observed; one at DXS7132 and at DXS6809, and two at DXS8377. Two mutations were paternal and one maternal; and to a fourth mutation, it was not possible to define its origin.

Development of a five ChX STRs loci typing system

We investigated the polymorphism of five X-chromosomal short tandem repeat markers (ChrX STRs) loci (DXS7132, DXS981, DXS6803, DXS6809, and DXS6789) and their value for forensic applications. A fluorescent multiplex polymerase chain reaction (PCR) for amplifying five ChrX STRs loci in the same PCR reaction was set up. A total of 827 unrelated individuals of the Han nationality in China were tested. The results show that the five loci in the multiplex system provide high polymorphism information for forensic identification and paternity testing, particularly for difficult paternity-deficient cases.

Five X-chromosome short tandem repeats in a Western Mexican population

X-linked microsatellites represent an efficient complement of autosomal and Y-chromosomal markers in forensic and kinship analysis. DXS337 (n=208), DXS101 (n=208), HPRTB (n=206), DXS8377 (n=220), and DXS7423 (n=213) were genotyped in male and female samples from a Western Mexican Mestizo population using singleplex systems and polyacrylamide gel electrophoresis. Genotype distributions did not deviate from Hardy-Weinberg expectations, and pairwise allele combination analysis was consistent with independent segregation for every marker (p>0.05). Allele frequencies were not different by gender. Differences in allele distribution with respect to Caucasian population data (DXS101, HPRTB, DXS8377, DXS7423) seem attributable to the native Mexican component. For the set of five markers, the combined power of discrimination and the probability of exclusion in paternity tests in trios were greater than 0.999. The present data reveal that the panel of five X-short tandem repeats analyzed is highly informative in forensic identity and parentage studies in Western Mexico.

WITHDRAWN: Population data for eight X-Chromosome STR loci in a population sample from Northern Italy and from the Sardinia island

WITHDRAWN: Population data for eight X-Chromosome STR loci in a population sample from Northern Italy and from the Sardinia island

Population genetic evaluation of eight X-chromosomal short tandem repeat loci using Mentype Argus X-8 PCR amplification kit

The evaluation of four pairs of X-chromosomal short tandem repeats (STRs), i.e. DXS10135–DXS8378, DXS7132–DXS10074, HPRTB-DXS10101 and DXS7423–DXS10134 was carried out using the Argus X-8 Multiplex amplification kit. These eight STRs are distributed as four closely linked pairs over the entire X-chromosome (ChrX), and for practical reasons they are assigned to four linkage groups 1–4. The genetic distance within the STR pairs is assumed to be <1 cM, whereas the pair to pair space is about 50 cM or more. Here, we present single STR allele frequencies, haplotype frequencies of the respective STR pairs and further population genetic parameters of forensic interest. Most data refer to a German population, however small samples from Ghana and Japan were also investigated. Furthermore, sequencing of all STR loci displayed the presence of microvariant alleles and variations in the repeat flanking region. A total of 350 meioses investigated here revealed only one sperm DXS7132 mutation. For analysis of linkages within the STR pairs a study involving 104 female meiosis with respect to recombination events was performed. The STR panel presented here provides a powerful tool for solving complex kinship in the case that X-chromosomal lineages can be taken under investigation.

Characterisation of the STR markers DXS10146, DXS10134 and DXS10147 located within a 79.1 kb region at Xq28

Three polymorphic X-chromosomal STR markers within a 79 kb region at Xq28 were studied and registered in the GDB as DXS10146, DXS10134 and DXS10147. These markers were molecular characterised and evaluated for their forensic usage. As a result DXS10134 was recently integrated in the commercial available test kit Mentype Argus X-8. At locus DXS10146 we found 23 alleles with PIC and HET values of 0.878 and 0.887. Locus DXS10134 showed 17 alleles with PIC and HET values of 0.844 and 0.858. At locus DXS10147 only 5 alleles with some lower PIC and HET values of 0.636 and 0.692 were found. Additionally, the already known and closely linked STR DXS7423 was included into the haplotyping and recombination studies. Testing this cluster a German population of 404 males revealed the presence of 311 haplotypes. Recombination analysis was performed in 109 father–daughter–grandson trios in which two crossing over events were observed located in the 65.8 kb region between DXS10146 and DXS10134. By using this STR complex for haplotyping in kinship testing further genetic analyses are required to establish an exact recombination rate.

Allele frequencies for 10 X-STR loci in Nu population of Yunnan, China

More recently, forensic interest has focused on X-chromosomal markers and which are especially useful in paternity cases with daughters. Genetic polymorphism studies at 10 short tandem repeat (STR) loci on the X-chromosome (DXS6804, DXS6799, DXS8378, DXS7130, DXS7132, HPRTB, DXS7133, DXS7423, DXS101 and DXS6789) were carried out in Yunnan Nu population of China. We aimed at increase in pool of forensically relevant data for allele distribution and frequency of X-chromosomal STRs. Statistical analysis and forensic efficiency data show no deviations from Hardy–Weinberg equilibrium.

Resolving Paternity Relationships Using X‐Chromosome STRs and Bayesian Networks

X-chromosomal short tandem repeats (X-STRs) are very useful in complex paternity cases because they are inherited by male and female offspring in different ways. They complement autosomal STRs (as-STRs) allowing higher paternity probabilities to be attained. These probabilities are expressed in a likelihood ratio (LR). The formulae needed to calculate LR depend on the genotype combinations of suspected pedigrees. LR can also be obtained by the use of Bayesian networks (BNs). These are graphical representations of real situations that can be used to easily calculate complex probabilities. In the present work, two BNs are presented, which are designed to derive LRs for half-sisters/half-sisters and mother/daughter/paternal grandmother relationships. These networks were validated against known formulae and show themselves to be useful in other suspect pedigree situations than those for which they were developed. The BNs were applied in two paternity cases. The application of the mother/daughter/paternal grandmother BN highlighted the complementary value of X-STRs to as-STRs. The same case evaluated without the mother underlined that missing information tends to be conservative if the alleged father is the biological father and otherwise nonconservative. The half-sisters case shows a limitation of statistical interpretations in regard to high allelic frequencies.

Development and forensic validation of a new multiplex PCR assay with 12 X-chromosomal short tandem repeats

One multiplex system for the co-amplification of 12 X-chromosomal short tandem repeats (STRs) DXS7132, DXS8378, DXS6809, DXS7133, DXS6789, DXS7424, GATA172D05, HPRTB, DXS7423, GATA31E08, DXS101, DXS6807 and amelogenin was analysed in a sample of 200 (100 males and 100 females) unrelated healthy individuals living in Northern Italy. The χ 2-test for genotype distribution of the X-chromosomal STRs showed no significant deviation from the Hardy–Weinberg equilibrium (HWE). Allele frequencies between female and male samples were not significantly different in all examined markers. In the kinship cases involving 40 family trios with daughter and 10 father/daughter duos, no mutation was detected. The combined power of discrimination (PDc) of the 12 X-STRs for both females and males was PDc > 0.999999.

X-chromosomal polymorphism data for the ethnic minority of Polish Tatars and the religious minority of Old Believers residing in northeastern Poland

Population samples of 420 unrelated individuals of the ethnic minority of Polish Tatars and the religious minority of Old Believers residing in northeastern Poland were tested for four X-chromosomal STR frequencies by multiplex PCR and subsequent automated fluorescent detection (ABI 310) using a commercially available kit Mentype Argus X-UL. Kinship tests revealed a typical X-linked inheritance with no mutation. Significant differences in allele frequency distributions confirm previous findings regarding genetic variation among ethnic groups residing in northeastern Poland.