Elevated germline mutation rate in teenage fathers.

Men age and die, while cells in their germline are programmed to be immortal. To elucidate how germ cells maintain viable DNA despite increasing parental age, we analysed DNA from 24 097 parents and their children, from Europe, the Middle East and Africa. We chose repetitive microsatellite DNA that mutates (unlike point mutations) only as a result of cellular replication, providing us with a natural 'cell-cycle counter'. We observe, as expected, that the overall mutation rate for fathers is seven times higher than for mothers. Also as expected, mothers have a low and lifelong constant DNA mutation rate. Surprisingly, however, we discover that (i) teenage fathers already set out from a much higher mutation rate than teenage mothers (potentially equivalent to 77-196 male germline cell divisions by puberty); and (ii) ageing men maintain sperm DNA quality similar to that of teenagers, presumably by using fresh batches of stem cells known as 'A-dark spermatogonia'.

Evaluation of the VISAGE basic tool for appearance and ancestry inference using ForenSeq® chemistry on the MiSeq FGx® system.

The possibility of providing investigative leads when conventional DNA identification methods fail to solve a case can be of extreme relevance to law enforcement. Therefore, the forensic genetics community has focused research towards the broadened use of DNA, particularly for prediction of appearance traits, bio-geographical ancestry and age. The VISible Attributes through GEnomics (VISAGE) Consortium expanded the use of DNA phenotyping by developing new molecular and statistical tools for appearance, age and ancestry prediction. The VISAGE basic tool for appearance (EVC) and ancestry (BGA) prediction was initially developed using Ampliseq chemistry, but here is being evaluated using ForenSeq chemistry. The VISAGE basic tool offers a total of 41 EVC and 115 BGA SNPs and thus provides more predictions, i.e., skin color, than achieved with the ForenSeq DNA Signature Prep kit that is based on 24 EVC and 56 BGA SNPs. Five VISAGE laboratories participated in collaborative experiments to provide foreground for developmental validation of the assay. Assessment of assay performance and quality metrics, reproducibility, sensitivity, inhibitor tolerance and species specificity are described. Furthermore, the assay was tested using challenging samples such as mock casework samples and artificially degraded DNA. Two different analysis strategies were applied for this study and output on genotype calls and read depth was compared. Overall, inter-laboratory, inter-method and concordance with publicly available data were analysed and compared. Finally, the results showed a reliable and robust tool, which can be easily applied for laboratories already using a MiSeq FGx with ForenSeq reagents.

Haplotype-assisted characterization of germline mutations at short tandem repeat loci.

In this study, 98 families with 101 mutations were analyzed in depth in which a mutation had been observed at one of the four loci D3S1358, FGA, ACTBP2, and VWA. To determine the origin (male/female) of the mutation, five to seven polymorphic flanking markers were selected for each locus concerned and used to construct family-specific haplotypes. Additionally, all alleles of the STR system concerned were sequenced. With this duplicate approach, it was possible to identify the mutated structure and/or mutation event in the vast majority of cases. The ratio of one-step to two-step mutations was 100:1. The ratio of paternal to maternal mutations was 76:8. The ratio of gains to losses was 47:50. Also, the mutation rates in two systems, ACTBP2 and VWA, were clearly higher than those given in the literature.

Sex chromosome changes after sex-mismatched allogeneic bone marrow transplantation can mislead the chimerism analysis.

A 12-year-old male with pre-B-cell acute lymphoblastic leukemia with cryptic BCR/ABL rearrangement underwent sex-mismatched allogeneic bone marrow transplantation (allo-BMT). Contradictory results were provided by various chimerism analyses 3 months later. Y-chromosome-specific quantitative polymerase chain reaction and sex chromosome-specific interphase fluorescence in situ hybridization (i-FISH) showed complete donor chimerism. Analysis of autosomal short tandem repeats (A-STR), BCR/ABL i-FISH test, and X-STR haplotype indicated relapse. Metaphase-FISH and combined BCR/ABL and sex chromosome-specific i-FISH patterns revealed loss of the Y-chromosome and duplication of the X-chromosome in the host cells. Sex chromosome changes after allo-BMT can cause significant difficulties in chimerism analysis.

Evaluation of the VISAGE Basic Tool for Appearance and Ancestry Prediction Using PowerSeq Chemistry on the MiSeq FGx System.

The study of DNA to predict externally visible characteristics (EVCs) and the biogeographical ancestry (BGA) from unknown samples is gaining relevance in forensic genetics. Technical developments in Massively Parallel Sequencing (MPS) enable the simultaneous analysis of hundreds of DNA markers, which improves successful Forensic DNA Phenotyping (FDP). The EU-funded VISAGE (VISible Attributes through GEnomics) Consortium has developed various targeted MPS-based lab tools to apply FDP in routine forensic analyses. Here, we present an evaluation of the VISAGE Basic tool for appearance and ancestry prediction based on PowerSeq chemistry (Promega) on a MiSeq FGx System (Illumina). The panel consists of 153 single nucleotide polymorphisms (SNPs) that provide information about EVCs (41 SNPs for eye, hair and skin color from HIrisPlex-S) and continental BGA (115 SNPs; three overlap with the EVCs SNP set). The assay was evaluated for sensitivity, repeatability and genotyping concordance, as well as its performance with casework-type samples. This targeted MPS assay provided complete genotypes at all 153 SNPs down to 125 pg of input DNA and 99.67% correct genotypes at 50 pg. It was robust in terms of repeatability and concordance and provided useful results with casework-type samples. The results suggest that this MPS assay is a useful tool for basic appearance and ancestry prediction in forensic genetics for users interested in applying PowerSeq chemistry and MiSeq for this purpose.

Development and validation of the VISAGE AmpliSeq basic tool to predict appearance and ancestry from DNA.

Forensic DNA phenotyping is gaining interest as the number of applications increases within the forensic genetics community. The possibility of providing investigative leads in addition to conventional DNA profiling for human identification provides new insights into otherwise "cold" police investigations. The ability of reporting on the bio-geographical ancestry (BGA), appearance characteristics and age based on DNA obtained from a crime scene sample of an unknown donor makes the exploration of such markers and the development of new methods meaningful for criminal investigations. The VISible Attributes through GEnomics (VISAGE) Consortium aims to disseminate and broaden the use of predictive markers and develop fully optimized and validated prototypes for forensic casework implementation. Here, the first VISAGE appearance and ancestry tool development, performance and validation is reported. A total of 153 SNPs (96.84 % assay conversion rate) were successfully incorporated into a single multiplex reaction using the AmpliSeq™ design pipeline, and applied for massively parallel sequencing with the Ion S5 platform. A collaborative effort involving six VISAGE laboratory partners was devised to perform all validation tests. An extensive validation plan was carefully organized to explore the assay's overall performance with optimum and low-input samples, as well as with challenging and casework mock samples. In addition, forensic validation studies such as concordance and mixture tests recurring to the Coriell sample set with known genotypes were performed. Finally, inhibitor tolerance and specificity were also evaluated. Results showed a robust, highly sensitive assay with good overall concordance between laboratories.

Meiosis study in a population sample from Nigeria: allele frequencies and mutation rates of 16 STR loci.

Allele frequencies for the 16 short tandem repeat (STR) loci D2S1338, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D19S433, D21S11, ACTBP2, CSF1PO, FGA, TH01, TPOX and VWA were determined for 337 immigrants from Nigeria. All loci were in Hardy-Weinberg equilibrium. More than 6,000 meiotic transfers were investigated and ten mutations were observed. Single mutations were observed in the STR systems D2S1338, D3S1358, D7S820, D8S1179, D16S539 and FGA, whereas two mutations were observed in the systems D21S11 and VWA.

Ultrasound-accelerated formalin fixation improves the preservation of nucleic acids extraction in histological sections.

The aim of the present study was to examine an ultrasound-accelerated fixation technique that reduces the exposure time of the tissue to formaldehyde with respect to the analysis of nucleic acids. We extracted and analysed DNA and RNA from three series of autopsy specimens from five routine cases. Two series were shortly fixed in 4% buffered formalin (15 and 30 min, respectively) whilst being irradiated with high-frequency, high-intensity ultrasound. The last series (control) was routinely fixed in 4% buffered formalin for 24-48 h without irradiation. Although sufficient amounts of DNA of good quality could be extracted and amplified from all three series, the peak heights obtained from conventional fixation were smaller and allele dropout occurred more often, especially for the longer amplicons. RNA yield depended on the fixation procedure, i.e. the shortest fixation time led to the highest RNA yield and quality. No differences were observed with regard to the quality of the histological slides both with conventional and immunohistochemical staining methods. Keeping in mind the increasing need for molecular diagnosis, this fixation technique can be useful to ensure stable quality of nucleic acids in archived autopsy specimens.

Identification of the microdeletion breakpoint in a GLRA1null allele of Turkish hyperekplexia patients.

Hyperekplexia (startle disease) is a hereditary motor disease caused by mutations within the GLRA1 gene (Chr. 5q33.1), which encodes the alpha1 subunit of the inhibitory glycine receptor (GlyR). While most patients are diagnosed with dominant hyperekplexia associated with point mutations within or adjacent to the channel pore, recessive hyperekplexia is less frequent. Here, we report five new pedigrees of recessive hyperekplexia in apparently unrelated families of Kurdish origin associated with a deletion of exons 1-7 of the GLRA1 gene. The deletion was identical in all families, encompassing 329 Kb of genomic sequence. No other known functional genes were involved, indicating that the GLRA1null allele is distinct from the 5q syndrome. Analysis of the DNA sequence flanking the proximal and distal breakpoint revealed no significant homology of sequences immediately adjacent to the breaks. Consensus sites for Toposiomerase II were detected close to the breakpoint compatible with an illegitimate recombination event. No heterozygous carriers of the deletion allele were detected by screening of 500 individuals from the southeastern Mediterranean region belonging to four different ethnic groups. Hence, the identical nature of the breakpoint junction in all patients and carriers suggests a founder mutation in an ethnic population originating from Turkey.

A collaborative study of the EDNAP group regarding Y-chromosome binary polymorphism analysis.

A collaborative study was carried out by the European DNA Profiling Group (EDNAP) in order to evaluate the performance of Y-chromosome binary polymorphism analysis in different European laboratories. Four blood samples were sent to the laboratories, to be analysed for 11 Y-chromosome single nucleotide polymorphisms (SNPs): SRY-1532, M40, M35, M213, M9, 92R7, M17, P25, M18, M153 and M167. All the labs were also asked to submit a population study including these markers. All participating laboratories reported the same results, indicating the reproducibility and robustness of Y-chromosome SNP typing. A total of 535 samples from six different European populations were also analysed. In Galicia (NW Spain) and Belgium, the most frequent haplogroup was R1b*(xR1b1,R1b3df). Haplogroup F*(xK) is one of the most frequent in Austria and Denmark, while the lowest frequency appear in Belgium. Haplogroup frequencies found in this collaborative study were compared with previously published European Y-chromosome haplogroup data.

Allele frequencies of 13 short tandem repeat (STR) loci in the Romanian population.

A population study on 13 tetra- and pentameric STR loci (D3S1358, VWA, D8S1179, D21S11, D18S51, D16S539, D2S1338, D19S433, THO1, FGA, ACTBP2 (SE33), Penta D and Penta E) was performed with Romanians from the Bucharest area.

STR analysis of artificially degraded DNA-results of a collaborative European exercise.

Degradation of human DNA extracted from forensic stains is, in most cases, the result of a natural process due to the exposure of the stain samples to the environment. Experiences with degraded DNA from casework samples show that every sample may exhibit different properties in this respect, and that it is difficult to systematically assess the performance of routinely used typing systems for the analysis of degraded DNA samples. Using a batch of artificially degraded DNA with an average fragment size of approx. 200 bp a collaborative exercise was carried out among 38 forensic laboratories from 17 European countries. The results were assessed according to correct allele detection, peak height and balance as well as the occurrence of artefacts. A number of common problems were identified based on these results such as strong peak imbalance in heterozygous genotypes for the larger short tandem repeat (STR) fragments after increased PCR cycle numbers, artefact signals and allelic drop-out. Based on the observations, strategies are discussed to overcome these problems. The strategies include careful balancing of the amount of template DNA and the PCR cycle numbers, the reaction volume and the amount of Taq polymerase. Furthermore, a careful evaluation of the results of the fragment analysis and of automated allele calling is necessary to identify the correct alleles and avoid artefacts.

Analysis of 15 short tandem repeats reveals significant differences between the Arabian populations from Morocco and Syria.

The short tandem repeat (STR) systems D3S1358, TH01, D21S11, D18S51, Penta E, D5S818, D13S317, D7S820, D16S539, CSF1PO, Penta D, vWA, D8S1179, TPOX and FGA were studied in Arabian population samples from Morocco and Syria. No significant deviation from Hardy-Weinberg equilibrium could be observed in either preparation. Comparing the Moroccan and Syrian populations using the program RxC, no similarity could be observed at all 15 loci. In the Moroccan and Syrian populations the matching probability is 1 in 1.4 x 10(17) and 1 in 2.6 x 10(17), respectively. Thus, the combination of these 15 STR loci is powerful tool for forensic identification in Arabian populations.

Identification of DYS385 allele variants by using shorter amplicons and Northern Thai haplotype data.

Primers currently used for amplification of locus DYS385 on the Y chromosome give quite long amplicons that are difficult to resolve on native polyacrylamide gels. We therefore designed new primers that give much shorter products for easy separation. With this system, two allele variants that were characterized by sequencing as 14.1 (GAAA --> GAAAA) and 14.2 (GA insertion), were identified in two unrelated Northern Thai men due to their decreased mobility. Interestingly, initial capillary electrophoresis mistyped the 14.1 variant amplified with the traditional primers as allele 14. Forty different haplotypes were found in 147 Northern Thais with a haplotype diversity of 0.9430. Haplotype 13-18 (frequency 0.136) is the most frequent one: for comparison: haplotype 14-18 (frequency 0.074) was found to be the most common in a population from Bangkok (n = 95) in an earlier study. This striking difference within Thailand's population probably results from genetic differences in the founding populations.

An economical mtDNA SNP assay detecting different mitochondrial haplogroups in identical HVR 1 samples of Caucasian ancestry.

BACKGROUND: We had sequenced 329 Caucasian samples in Hypervariable Region 1 (HVR 1) and found that they belong to eleven different mitochondrial DNA (mtDNA) haplotypes. The sample set was further analysed by an mtDNA assay examining 32 single nucleotide polymorphisms (SNPs) for haplogroup discrimination. In a validation study on 160 samples of different origin it was shown that these SNPs were able to discriminate between the evolved superhaplogroups worldwide (L, M and N) and between the nine most common Caucasian haplogroups (H, I, J, K, T, U, V, W and X). RESULTS: The 32 mtDNA SNPs comprised 42 different SNP haplotypes instead of only eleven haplotypes after HVR 1 sequencing. The assay provided stable results in a range of 5ng genomic DNA down to virtually no genomic DNA per reaction. It was possible to detect samples of African, Asian and Eurasian ancestry, respectively. DISCUSSION: The 32 mtDNA SNP assay is a helpful adjunct to further distinguish between identical HVR 1 sequences of Caucasian origin. Our results suggest that haplogroup prediction using HVR 1 sequencing provides instable results. The use of coding region SNPs for haplogroup assignment is more suited than using HVR 1 haplotypes.

Mitochondrial control region sequences from a Vietnamese population sample.

Entire mitochondrial control region data were generated for 187 individuals from Vietnam. These samples have been previously typed for 16 autosomal short-tandem repeats (STRs) [1].

Novel transcript profiling of diffuse alveolar damage induced by hyperoxia exposure in mice: normalization by glyceraldehyde 3-phosphate dehydrogenase.

Under mechanical ventilation with high-inspired oxygen concentration, diffuse alveolar damage was found to take place in some patients. To clarify the molecular pathophysiology of this condition, we investigated the time course of gene expression changes induced by hyperoxia exposure in mouse lung using real-time quantitative polymerase chain reaction (qPCR). Our results normalized by glyceraldehyde 3-phosphate dehydrogenase showed that mRNA levels of cysteine rich protein 61 (CYR61) and connective tissue growth factor (CTGF) were significantly upregulated, while those of surfactant-associated protein C (SFTPC), cytochrome P450, 2F2 (CYP2F2), Claudin 1, (CLDN1), membrane-associated zonula occludens protein-1 (ZO-1), lysozyme (LYZS), and P lysozyme structural (LZP-S) were significantly downregulated. Increasing level of mRNAs, each encoding CYR61 and CTGF, suggests a serious risk of fibrosing alveolitis. Decrease in levels of mRNAs for SFTPC, CYP2F2, CLDN1, ZO-1, LYZS, and LZP-S suggests alveolar dysfunction and disruption of the immune system. Moreover, we confirmed apoptotic conditions, such as significant upregulations of mRNA levels in Myc and Galectin-3. Hyperoxic condition probably yielded reactive oxygen species (ROS), which resulted in a malignant cycle of ROS production by Myc overexpression.

Identification of West Eurasian mitochondrial haplogroups by mtDNA SNP screening: results of the 2006-2007 EDNAP collaborative exercise.

The European DNA Profiling (EDNAP) Group performed a collaborative exercise on a mitochondrial (mt) DNA screening assay that targeted 16 nucleotide positions in the coding region and allowed for the discrimination of major west Eurasian mtDNA haplogroups. The purpose of the exercise was to evaluate the stability and reproducibility of the self-developed multiplex-PCR and multiplex-single base extension kit by blind-testing saliva and hair shaft samples provided by the organizing laboratory. The overall success rate in obtaining useful results was high given that some of the participating laboratories had no previous experience with the technology and/or mtDNA analysis. The results of this collaborative exercise stimulate the expansion of screening methods in forensic laboratories to increase efficiency and performance of mtDNA typing, and thus demonstrates that mtDNA SNP typing is a powerful tool for forensic casework analysis.

Y-chromosomal microsatellite mutation rates in a population sample from northwestern Germany.

To estimate Y-chromosomal short tandem repeat (Y-STR) mutation rates, 15 loci (i.e., DYS19, DYS389 I/II, DYS390, and DYS393; DYS437, DYS438, DYS439, and DYS385; DYS391, DYS392, YCA II, and DXYS156) were analyzed in a sample of 1,029 father/son pairs from Westphalia, northwestern Germany. Among 15,435 meiotic allele transfers, 32 mutations were observed; thus, the mutation rate across all 15 Y-STR loci was 2.1 x 10(-3) per locus (95% C.I.: 1.5-3.0 x 10(-3)). With the exception of a three-repeat mutation at DYS385, all remaining mutations were single repeat mutations. Repeat losses were more frequent than gains (20:12), and the mutation rate appeared to increase with age. The Y haplogroups that were detected in the individuals showing a mutation reflect the haplogroup distribution in the Westphalian population. Additionally, the correlation of surnames and haplotypes was tested: Only 49 surnames occurred more than once, and only two men with the same rare surname shared the same haplotype. All other men with identical surnames carried different haplotypes.