Autosomal STR Typing Research Articles

Comparative analysis of DNA preservation in permanent and deciduous teeth of adults and non-adults: Implications for archaeological and forensic research

This study investigates the preservation of DNA in different categories of teeth, including permanent and deciduous, fully developed and not fully developed, in both adults and non-adults. Teeth were sampled from a modern-era cemetery in Ljubljana, Slovenia. DNA extraction was performed using a full demineralisation protocol. DNA quantity and quality were assessed using qPCR analyses, and autosomal STR typing was conducted to verify genetic profiles. Results revealed significant differences in DNA preservation among various tooth categories. Fully developed permanent teeth of adults exhibited the highest DNA yields, attributed to their fully developed roots and thicker cementum, which is rich in DNA. Deciduous teeth, with thinner enamel and cementum, showed lower DNA preservation regardless of developmental stage. Non-adult teeth generally yielded less DNA compared to adults, even when considering only fully developed permanent teeth, indicating factors beyond developmental stage. These findings suggest that, in archaeological and forensic contexts, researchers should prioritize fully developed permanent teeth for DNA analysis due to their superior preservation. Additionally, this study underscores the importance of considering tooth type and developmental stage when selecting samples for genetic analysis in cases where petrous bone is unavailable, expanding our understanding of DNA preservation in human remains.

Evaluation of Detection Efficiency for Trio Full Sibling Testing.

To study the detection efficiency of trio full sibling with another known full sibling reference added under different number of autosomal STR typing systems. Based on 43 detection systems consisting of 13 to 55 representative autosomal STR loci, 10 000 true families (full sibling group) and 10 000 false families (unrelated individual group) were randomly simulated. The full sibling index (FSI) was calculated based on the method of family reconstruction. The cumulative sibling relationship index (CFSI) of 0.000 1 and 10 000 were used as the evaluation thresholds, and the detection efficiency parameters were calculated and compared with the identification of the duo full sibling testing. With the increasing number of STR loci, the error rate and inability of judgement rate gradually decreased; the sensitivity, specificity, correct rate of judgment and other parameters gradually increased, and the system efficiency gradually improved. Under the same detection system, trio full sibling testing showed higher sensitivity, specificity, system efficiency and lower inability of judgement rate compared with duo full sibling testing. When the system efficiency was higher than 0.85 and inability of judgement rate was less than 0.01%, at least 20 STRs should be detected for trio full sibling testing, which was less than 29 STRs required by duo full sibling testing. The detection efficiency of trio full sibling testing is superior to that of duo full sibling testing with the same detection system, which is an effective identification scheme for laboratories with inadequate detection systems or for materials with limited conditions.

Kinship analysis of skeletal remains from the Middle Ages

Medieval cemeteries Klisa-Guca Gora, Alihodze and Glavica-Han Bila located in the Travnik area (Travnik, Bosnia and Herzegovina) were archaeologically examined in the period 2011–2014, revealing human skeletal remains of 11 individuals in total. Archaeological skeletal samples, previously deposited in Travnik Homeland Museum (Travnik, Bosnia and Herzegovina) were subjected to genetic analysis. The aim of this research was to test familiar relationship of 11 individuals excavated from three medieval cemeteries and to predict Y-haplogroup for male individuals. In order to perform molecular-genetic characterisation of collected human skeletal remains, two systems of genetic markers were analysed: autosomal and Y-STR loci. Complete or partial data obtained by autosomal STR typing of 11 individuals were subjected to kinship analysis. Male sex was determined in eight samples out of 11. Direct relatives of the "brother-brother" type were detected in one case with high kinship probability (KP) value of 99.99996 %. Complete or nearly complete and usable Y-STR profiles were obtained for six out of eight male individuals. The presence of identical haplotypes at Y-STR loci and results of Y-haplogroup prediction suggest that all male individuals share the same paternal lineage and belong to J2a haplogroup. Overall, this study emphasises the usefulness, efficiency and sensitivity of STR markers in the molecular-genetic characterisation of old skeletal remains as well as the importance of employing additional markers like Y-STRs in archaeogenetic studies, besides traditionally used autosomal STR markers, in order to get a comprehensive information about close and distant relatives, and ancestry.

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.

Intra-bone nuclear DNA variability and STR typing success in Second World War 12th thoracic vertebrae

Bones are an important source of DNA for identification in forensic medicine, especially when the remains are skeletonized, which is the case when dealing with victims of the Second World War. Often the amount of bone available for sampling is limited, and therefore it is crucial to sample the bone segment with the highest adequate DNA quantity for identification. Studies performed on all representative skeletal element types of the human body showed that the amount of DNA obtained from different skeletal elements of different body regions varies greatly. When bones from torso were analyzed, thoracic vertebrae outperformed other vertebrae (cervical and lumbar) and, alongside the first ribs, were among the most appropriate bone elements for identification purposes. It was also shown that the quantity of DNA varies significantly within a single bone type. This study focused on exploring intra-bone DNA variability between five parts of 12th thoracic vertebrae (laminae + spinous process, pedicles + transverse processes, and corpus right, left, and middle). The research was based on the theory that the distribution of body weight and consequently bone remodeling, as well as the ratio between cancellous and cortical bone, contribute to different quantities of DNA in different parts of vertebra sampled. The vertebrae were cleaned and cut into five parts, and each part was completely ground to obtain homogenous bone powder. Half a gram of powder from each part was decalcified using a full demineralization extraction method. The DNA was purified in a Biorobot EZ1 machine (Qiagen). DNA quantity and quality were determined using the PowerQuant System (Promega) and autosomal STR typing success using the GlobalFiler Amplification Kit (Applied Biosystems). Thirty-five 12th thoracic vertebrae were sampled from a single Second World War mass grave. The best results with the highest DNA quantity were found in laminae and the spinous process, and among them all vertebrae analyzed yielded full STR profiles except three, where only a few dropouts occurred. The second-ranked bone part was the pedicles and transverse processes. The comparison of DNA degradation in the vertebral segments analyzed does not show statistically significant differences. Considering our research, when only the torso is available for identification, the 12th thoracic vertebra should be collected and the vertebral arch should be sampled for genetic analyses.

Intra-bone nuclear DNA variability and STR typing success in Second World War first ribs

DNA sampling and typing are used for identifying missing persons or war victims. In recent forensic studies, little focus has been placed on determining intra-bone variability within a single skeletal element. When dealing with aged human bones, complete skeletal remains are rarely present. In cases in which only the torso is available, studies have shown that ribs are one of the most appropriate samples, but intra-bone variability has not yet been studied. A higher degree of remodeling was found to contribute to higher DNA yield in the parts of the skeletal element where the most strain is concentrated. This study explores intra-bone variability in proximal, middle, and distal parts of the first human rib by determining the quantity and quality of DNA using the PowerQuant System (Promega) and autosomal STR typing success using the PowerPlex ESI 17 Fast System (Promega). Thirty first ribs from a single Second World War mass grave were sampled. No variation in DNA degradation was observed across the individual rib. The highest quantity of DNA was measured in the proximal part of the first rib, and in all ribs except three, full or almost full genetic profiles were obtained. Thus, when only the torso is present in archaeological or medico-legal cases, first ribs are recommended to be collected if possible, and the proximal or vertebral ends should be sampled for genetic analysis.

Improved autosomal STR typing of degraded femur samples extracted using a custom demineralization buffer and DNA IQ™

Bone samples are utilized as a source of DNA in disaster victim identification and human remains investigations. However, DNA recovery from bones is time consuming and prone to contamination. A logical approach for postmortem identification is to validate efficient DNA extraction methods requiring less bone material using improved molecular kits with less hands-on time and workflows that facilitate faster turn-around time for processing. In this study, we evaluated DNA yield and amplification efficiency of DNA extracts using a new custom bone demineralization buffer (DMB; Promega) and extracted via manual and automated DNA IQ™ workflows. Including the demineralization step, the bone protocol can be completed in ∼4 h and even less with minimal sample handling when automated. Overall, a rapid and simple DNA extraction with improved allele recovery was validated using degraded bone samples exposed to tropical environments and post-disaster recovery as well as adverse conditions of embalming prior to internment.

High DNA yield from metatarsal and metacarpal bones from Slovenian Second World War skeletal remains

DNA yield varies by anatomical region, and the selection of bone types that yield maximum recovery of DNA is important to maximize the success of human identification of skeletal remains. The goal of our study was to explore inter- and intra-individual variation in DNA content by measuring nuclear DNA quantity and quality and autosomal STR typing success to determine the most promising skeletal elements for bone sampling. To exclude the influence of taphonomic issues as much as possible, three complete male skeletons from a single Second World War mass grave were examined and all representative skeletal element types of the human body were analyzed. Forty-eight different types of bones from the head, torso, arm, leg, hand, and foot were sampled from each skeleton, 144 bones altogether. The samples were cleaned, and half a gram of bone powder was decalcified using a full demineralization extraction method. The DNA was purified in a Biorobot EZ1 (Qiagen). DNA content and rates of DNA degradation were determined with the PowerQuant (Promega), and the Investigator ESSplex SE QS (Qiagen) was used for STR typing. The highest-yielding bones mostly produced the most complete STR profiles. Among the skeletal elements containing on average the most DNA and producing the most complete profiles in all three skeletons examined were metacarpals, metatarsals, and the petrous portion of the temporal bone. Metatarsals and metacarpals can easily be sampled without using a saw, thus reducing potential DNA contamination. Skeletons from the Second World War can be used as a model for poorly preserved skeletal remains, and the results of the investigation can be applied for genetic identification of highly degraded skeletal remains in routine forensic casework. Although the research was limited to only three skeletons found in a unique mass grave, the data obtained could contribute to sampling strategies for identifying old skeletal remains. More Second World War skeletons will be analyzed in the future to investigate inter-bone variation in the preservation of DNA.

The genomic ancestry of Jat Sikh population from Northwest India inferred from 15 autosomal STR markers using capillary electrophoresis

Background Autosomal STR typing using capillary electrophoresis is a reliable method for establishing parentage and for deciphering genomic ancestry. Aim This study was planned to show the genetic diversity of the Jat Sikh population, which is a widespread community of the Punjab region, and to assess its genetic relationship with existing Indian populations. Subjects and methods Blood samples of unrelated healthy individuals of the Jat Sikhs (n = 123) were used in this study. Fifteen autosomal STR markers along with the sex determination genetic marker Amelogenin were amplified using AmpFlSTR®Identifiler® Plus kit, and genetic analyser 3100 was used for genotyping. Results A total of 246 alleles were observed with allele frequencies ranging from 0.004 to 0.447. The heterozygosity ranged from 0.659 to 0.886, and all studied loci were in Hardy–Weinberg Equilibrium (HWE). Fibrinogen A alpha (Aα) chain (FGA) was found to be the most polymorphic and also the most discriminating locus in the studied population. Neighbor-joining (NJ) tree, principal component analysis (PCA) plot, and Nei’s Distance matrix revealed genetic affinity with the previously reported Jatt Sikh (Punjab) population and showed the outlier nature of this population compared with other Indian populations. Conclusion The data generated by this study enhance the database of Indian populations to be used in civil and forensic cases and also in other population-based genetic studies.

Determination of DNA yield rates in six different skeletal elements in ancient bones

Current sampling strategy for laboratories typing bones for human identification include samples obtained from femur, tooth and temporal bone. Latest studies suggest that the small bones of the hands and feet were very similar or even better in DNA yield. These bones can be easily sampled with a disposable scalpel and thus reduce potential DNA contamination. The aim of our study was to determine the suitability of metatarsals, metacarpals and phalanges for genetic identification. 48 bone samples from 8 different skeletons (six from 18th century and two from 3rd century) were obtained from 5 archaeological sites in Slovenia. In each skeleton, 6 different skeletal elements were sampled (temporal bone, molar, femur, metacarpal bone, metatarsal bone and proximal phalanx of the hand), and strict precautions followed to prevent contamination. Half of gram of bone powder was decalcified using full demineralization extraction method. The DNA was purified in a Biorobot EZ1 (Qiagen), DNA content determined with the PowerQuant kit (Promega), and autosomal STR typing performed with the Investigator ESSplex Plus kit (Qiagen). Up to 8.75 ng DNA/g of powder was obtained from samples analyzed. The highest yields were detected in temporal bone and the lowest in femur. The success rate of STR typing was evaluated according to the number of successfully typed loci and a strong correlation between the success rate of STR typing and the amount of extracted DNA was confirmed. For all eight skeletons full consensus genetic profiles were determined from skeletal elements analyzed. Our findings suggest it would be suitable to include metatarsal and metacarpal bones in sampling strategy for human identification although further research is needed to substantiate the findings of this study.

Different skeletal elements as a source of DNA for genetic identification of Second World War victims

To this day process of identification of missing persons from skeletonized human remains with help of forensic genetics proves to be complex and challenging. The success rate of genetic identification in bones strongly depends on a combination of various factors, most importantly environmental factors and post-mortem interval. Furthermore, there are individual-specific factors that affect DNA preservation, such as race, gender, age and type of skeletal elements. The goal of our study was to optimize sampling process through determining which skeletal elements are superior in their preservation of DNA in 70-yearold skeletons belonging to victims of Second World War. We sampled different types of bones and teeth from three such skeletons found in Slovenian hidden mass grave Huda jama, 56 elements from each respective skeleton, together 168 elements. With the help of parameters, such as quantity of DNA, degradation rate and typing success, we tried to find the best types of elements to identify the victims. Prior to powdering bones and teeth, we removed contaminants. We decalcified 0.5 g bone and tooth powder followed by extraction and purification of DNA using Biorobot EZ1 (Qiagen). Quantification of obtained nuclear DNA was carried out using PowerQuant kit (Promega) and autosomal STR typing using ESSplex SE QS kit (Qiagen). Best parameters to assess skeletal elements that are superior in their DNA preservation were quantity of DNA and number of successfully typed STR loci. Metacarpal and metatarsal bones proved to be the best, followed by intermediate cuneiform, first distal foot phalanx, talus, petrous bone and tibia. We also created elimination database for persons involved in exhumation, anthropological and genetic analyses and exclude potential contamination.

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.

Comparing different post-mortem human samples as DNA sources for downstream genotyping and identification

The capability of DNA laboratories to perform genotyping procedures from post-mortem remains, including those that had undergone putrefaction, continues to be a challenge in the Philippines, a country characterized by very humid and warm conditions all year round. These environmental conditions accelerate the decomposition of human remains that were recovered after a disaster and those that were left abandoned after a crime. When considerable tissue decomposition of human remains has taken place, there is no other option but to extract DNA from bone and/or teeth samples. Routinely, femur shafts are obtained from recovered bodies for human identification because the calcium matrix protects the DNA contained in the osteocytes. In the Philippines, there is difficulty in collecting femur samples after natural disasters or even human-made disasters, because these events are usually characterized by a large number of fatalities. Identification of casualties is further delayed by limitation in human and material resources. Hence, it is imperative to test other types of biological samples that are easier to collect, transport, process and store.We analyzed DNA that were obtained from body fluid, bone marrow, muscle tissue, clavicle, femur, metatarsal, patella, rib and vertebral samples from five recently deceased untreated male cadavers and seven male human remains that were embalmed, buried for ∼1 month and then exhumed. The bodies had undergone different environmental conditions and were in various stages of putrefaction. A DNA extraction method utilizing a detergent-washing step followed by an organic procedure was used. The utility of bone marrow and vitreous fluid including bone marrow and vitreous fluid that was transferred on FTA® cards and subjected to autosomal STR and Y-STR DNA typing were also evaluated. DNA yield was measured and the presence or absence of PCR inhibitors in DNA extracts was assessed using Plexor®HY. All samples were amplified using PowerPlex®21 and PowerPlexY®23 systems and analyzed using the AB3500 Genetic Analyzer and the GeneMapper® ID-X v.1.2 software.PCR inhibitors were consistently detected in bone marrow, muscle tissue, rib and vertebra samples. Amplifiable DNA was obtained in a majority of the samples analyzed. DNA recovery from 0.1g biological material was adequate for successful genotyping of most of the non-bone and bone samples. Complete DNA profiles were generated from bone marrow, femur, metatarsal and patella with 0.1ng DNA template. Using 0.5ng DNA template resulted in increased allele recovery and improved intra- and inter-locus peak balance.

In naming the dead: Autosomal and Y-chromosomal STR typing on human skeletal remains from an 18th/19th century aristocratic crypt in Gallspach, Upper Austria.

Ancient DNA analyses have shown to be a powerful tool in the joint transdisciplinary assessment of archaeological records involving human remains. In this study we set out to identify single inhumations by synoptically evaluating the historical, archaeological, anthropological and molecular records on human remains from the crypt of the aristocratic family of Hoheneck (or: Hohenegg) dating to the 18(th) and 19(th) century AD. A total of 11 individuals were under investigation, yielding complete autosomal and Y-chromosomal STR profiles for 5 persons clearly showing a family group. DNA results, anthropological data and archaeological records taken together resulted in (almost) unambiguous correlation to historical records on the persons entombed in the crypt.

The genetic polymorphisms and mutation rates of 24 Y-STR loci in Guangdong Han population

Objective: To investigate the polymorphisms and mutation phenomenon of 24 Y-STR loci from GFS 24Y system in Guangdong Han population. Methods: Blood samples of 800 father-son duos which had been confirmed parentage with autosomal STR typing were collected to observe mutation phenomenon, in which the samples from fathers were regarded as unrelated individuals to observe genetic polymorphisms. Samples were genotyped with GFS 24Y fluorescent multiplex system. The statistical analysis was also performed for the typing results. Results: 794 different haplotypes were identified from 800 unrelated Guangdong Han male individuals, among which 788 were unique. The overall haplotype diversity (HD) and discrimination capacity (DC) were 0.999 98 and 0.992 5 respectively. Totally, 296 alleles were observed at 24 Y-STR loci. The value of gene diversity (GD) was varied from 0.552 1 (DYS531) to 0.960 9 (DYS385a/b). Among 19 219 allele transfers at 24 Y-STR loci, 42 mutation events were observed in 41 father-son duos. The total mutation rate was 2.185 310 (95% CI: 1.575 410 ∼ 2.952 810). Conclusion: The 24 Y-STR loci included in GFS 24Y system are highly polymorphic in Guangdong Han population and show great application value for forensic personal identification and patrilineal kinship testing.

Y-haplotype Screening of Local Patrilineages Followed by Autosomal STR Typing Can Detect Likely Perpetrators in Some Populations

The male-specific, human Y-chromosomal short tandem repeats (Y-STRs) are very useful in forensic analysis and human evolution studies. The authors report two sexual crime cases in which the perpetrators were successfully traced using Y-haplotype screening of local patrilineages followed by autosomal STR typing. First, several main local patrilineages from local cases were investigated using Y-STR haplotyping, aimed to find the pedigrees whose haplotypes were identical or similar to those of the crime scene samples. Then, several key suspects were defined from the screened pedigrees, and autosomal STR typing was performed to identify the perpetrator of the crime. The application of Y-haplotype screening of local patrilineages followed by autosomal STR typing in these two cases demonstrates its usefulness for solving sexually related crimes in certain populations.

Southeast Asian diversity: first insights into the complex mtDNA structure of Laos

BackgroundVast migrations and subsequent assimilation processes have shaped the genetic composition of Southeast Asia, an area of close contact between several major ethnic groups. To better characterize the genetic variation of this region, we analyzed the entire mtDNA control region of 214 unrelated donors from Laos according to highest forensic quality standards. To detail the phylogeny, we inspected selected SNPs from the mtDNA coding region. For a posteriori data quality control, quasi-median network constructions and autosomal STR typing were performed. In order to describe the mtDNA setup of Laos more thoroughly, the data were subjected to population genetic comparisons with 16 East Asian groups.ResultsThe Laos sample exhibited ample mtDNA diversity, reflecting the huge number of ethnic groups listed. We found several new, so far undescribed mtDNA lineages in this dataset and surrounding populations. The Laos population was characteristic in terms of haplotype composition and genetic structure, however, genetic comparisons with other Southeast Asian populations revealed limited, but significant genetic differentiation. Notable differences in the maternal relationship to the major indigenous Southeast Asian ethnolinguistic groups were detected.ConclusionsIn this study, we portray the great mtDNA variety of Laos for the first time. Our findings will contribute to clarify the migration history of the region. They encourage setting up regional and subpopulation databases, especially for forensic applications. The Laotian sequences will be incorporated into the collaborative EMPOP mtDNA database http://www.empop.org upon publication and will be available as the first mtDNA reference data for this country.

Efficiency evaluation of a DNA extraction and purification protocol on archival formalin-fixed and paraffin-embedded tissue

Formalin-fixed and paraffin-embedded tissue (FF-PET) is an invaluable resource for retrospective molecular genetic studies, but the extraction of high-quality genomic DNA from FF-PET is still a problematic issue. Despite the range of DNA extraction methods currently in use, the association of phenol–chloroform extraction and silica-based purification protocols, reported in ancient DNA studies on archaeological bones, has, to our knowledge, not been used for DNA extraction from FF-PET yet. The present study compared the efficiency of three DNA extraction and purification protocols from two different FF-PET substrates, heart and liver, by using quantitative PCR and multiplex amplification. We showed that the method, using phenol–chloroform and the QIAamp DNA mini ® Kit (Qiagen), was the most effective DNA extraction and purification method and that the DNA quantity extracted from liver is statistically more important than that extracted from heart. Autosomal STR typing by multiplex amplifications gave partial allelic profiles with only small size products (less than 300 bases) amplified, suggesting that DNA extracted from FF-PET was degraded. In conclusion, the protocol presented here, previously described in studies on ancient bones, should find application in different molecular studies involving FF-PET material.

Cell line DNA typing in forensic genetics—the necessity of reliable standards

The incorporation of reference DNA is crucial to the validation of any DNA typing protocol. This paper aims to provide a panel of reference DNAs for actual forensic profiling strategies, i.e. autosomal and gonosomal STR typing as well as mtDNA sequencing. We have characterised three human lymphoid cell lines, GM9947, GM9948 and GM3657, and considered 58 autosomal and gonosomal microsatellites as well as the mitochondrial control region sequence. Well-established markers and STRs recently developed for forensic use were involved. K562 DNA samples which we purchased from two different suppliers were also analysed. They revealed conflicting results with regard to the ChrX STR marker genotype. Hence, we suggest that K562 is no longer used for the calibration of profiling techniques. Our investigation establishes a panel of one female and two male DNA samples as an STR allelic ladder calibration tool and offers information on six alleles of each autosome (AS) marker, three alleles of each X chromosome (ChrX) marker and two alleles of each ChrY marker. In addition, sequences of the mitochondrial control region of the three DNAs are communicated in order to provide sequencing quality control.

Y-STR typing in forensic analysis

We reinvestigated 20 cases of rape/sexual maltreatment from the years 2000/2001 (i.e. 61 different samples) that had already been investigated by STR typing (using Profiler Plus and mentype kit). In 10 cases, male DNA has been detected in stains or vaginal swabs, samples from the other 10 cases did not show any traces of male DNA. Ten Y-specific loci were amplified in two multiplex PCRs, mpI: DYS393, DYS19, DYS392, DYS385; mpII: DYS390, DYS391, DYS389I and II. Even though amplification of Y-specific loci was not more sensitive and did not lead to any other conclusions than autosomal STR typing alone, in specific cases Y-STR determination gave important information, e.g. when the male suspect was unknown or when mixed stains from more than one male person had to be investigated.