Cleaning protocols in forensic genetic laboratories.

It is pivotal to avoid cross-sample contamination in forensic genetic laboratories and optimal cleaning protocols for the removal of DNA are essential. A survey was performed, and ten forensic genetic laboratories shared their cleaning protocols in pre-PCR and post-PCR laboratories. The cleaning frequencies on different surface areas were somewhat similar, whereas none of the laboratories used the same cleaning reagents. Therefore, the efficiencies of the cleaning protocol utilised were tested and compared. The results showed that freshly made household bleach and Virkon® removed all amplifiable DNA from the surfaces, whereas DNA AWAY™ and the disinfection reagents ethanol, isopropanol, and ChemGene HLD4L did not.

The transcriptome of hand eczema assessed by tape stripping.

BACKGROUND: No biomarkers have been identified that can classify subtypes of hand eczema (HE). Although skin biopsies represent the gold standard for investigations of the skin, the invasive technique is not favorable when investigating skin from sensitive areas. Recent advances in the use of skin-tape strips for molecular investigations enable noninvasive investigations of HE. OBJECTIVE: By using whole transcriptome sequencing (WTS), the molecular profile of HE according to different localizations on the hands, etiologies, and clinical/morphological subtypes was investigated. METHODS: Thirty adult, Danish HE patients, 12 with and 18 without concurrent atopic dermatitis (AD), as well as 16 controls were included. Tape strip samples were collected from lesional, nonlesional, and healthy skin. Total RNA was extracted and WTS was performed. RESULTS: The largest molecular difference of HE patients with and without AD was found in nonlesional skin areas and included a downregulation of CXCL8 for HE patients without AD. Differences between allergic and irritant contact dermatitis included epidermal biomarkers such as EPHA1. CONCLUSION: Skin tape strip samples could be used to assess the gene expression profile of HE on different localizations of the hands. The skin tape strip method identified new molecular markers that showed promising result for the identification of HE subtypes.

[DGPPN pilot study on the implementation of the S3 guideline "Prevention of coercion: prevention and therapy of aggressive behavior in adults"]. / DGPPN-Pilotstudie zur Implementierung der S3-Leitlinie "Verhinderung von Zwang: Prävention und Therapie aggressiven Verhaltens bei Erwachsenen".

OBJECTIVE: To investigate whether implementation recommendations derived from the German guidelines "Prevention of coercion" can be implemented on acute psychiatric wards by means of implementation consultants into ward work and if this contributes to an increased level of adherence to guideline intervention recommendations approved by the DGPPN (Deutsche Gesellschaft für Psychiatrie und Psychotherapie, Psychosomatik und Nervenheilkunde)? MATERIAL AND METHODS: Two medical or nursing experts advised ward teams on the implementation of three individually selected recommendations from the guidelines in a structured consulting process over 6 months. The degree of implementation of the recommendations was assessed before and after the intervention by the ward teams together with the implementation consultants using a tool developed for this purpose (PreVCo rating tool). RESULTS: A total of five wards responsible for compulsorily admitted patients took part in the pilot study; three of them completed the intervention. On all three wards, implementation of the guideline recommendations improved for both selected and unselected recommendations. The strategy of using implementation consultants as well as the application of the PreVCo rating tool were well accepted and considered feasible by both the treatment teams and the implementation consultants. CONCLUSION: This pilot study showed that an implementation of recommendations on psychiatric wards derived from the German guidelines "Prevention of coercion" supported by implementation consultants is feasible, well acceptable among treatment teams and can lead to positive changes. The sample of five wards with diverse patient profiles was convincing. The efficacy in terms of reduction of coercive measures is currently being investigated in a randomized controlled trial on 55 psychiatric wards in different parts of Germany, with an intervention based on this pilot study.

Gene expressions in cerebral palsy subjects reveal structural and functional changes in the gastrocnemius muscle that are closely associated with passive muscle stiffness.

Cerebral palsy (CP) is a non-progressive motor disorder that affects posture and gait due to contracture development. The purpose of this study is to analyze a possible relation between muscle stiffness and gene expression levels in muscle tissue of children with CP. Next-generation sequencing (NGS) of gene transcripts was carried out in muscle biopsies from gastrocnemius muscle (n = 13 children with CP and n = 13 typical developed (TD) children). Passive stiffness of the ankle plantarflexors was measured. Structural changes of the basement membranes and the sarcomere length were measured. Twelve pre-defined gene target sub-categories of muscle function, structure and metabolism showed significant differences between muscle tissue of CP and TD children. Passive stiffness was significantly correlated to gene expression levels of HSPG2 (p = 0.02; R2 = 0.67), PRELP (p = 0.002; R2 = 0.84), RYR3 (p = 0.04; R2 = 0.66), C COL5A3 (p = 0.0007; R2 = 0.88), ASPH (p = 0.002; R2 = 0.82) and COL4A6 (p = 0.03; R2 = 0.97). Morphological differences in the basement membrane were observed between children with CP and TD children. The sarcomere length was significantly increased in children with CP when compared with TD (p = 0.04). These findings show that gene targets in the categories: calcium handling, basement membrane and collagens, were significantly correlated to passive muscle stiffness. A Reactome pathway analysis showed that pathways involved in DNA repair, ECM proteoglycans and ion homeostasis were amongst the most upregulated pathways in CP, while pathways involved in collagen fibril crosslinking, collagen fibril assembly and collagen turnover were amongst the most downregulated pathways when compared with TD children. These results underline that contracture formation and motor impairment in CP is an interplay between multiple factors.

Differential Methylation in the GSTT1 Regulatory Region in Sudden Unexplained Death and Sudden Unexpected Death in Epilepsy.

Sudden cardiac death (SCD) is a diagnostic challenge in forensic medicine. In a relatively large proportion of the SCDs, the deaths remain unexplained after autopsy. This challenge is likely caused by unknown disease mechanisms. Changes in DNA methylation have been associated with several heart diseases, but the role of DNA methylation in SCD is unknown. In this study, we investigated DNA methylation in two SCD subtypes, sudden unexplained death (SUD) and sudden unexpected death in epilepsy (SUDEP). We assessed DNA methylation of more than 850,000 positions in cardiac tissue from nine SUD and 14 SUDEP cases using the Illumina Infinium MethylationEPIC BeadChip. In total, six differently methylated regions (DMRs) between the SUD and SUDEP cases were identified. The DMRs were located in proximity to or overlapping genes encoding proteins that are a part of the glutathione S-transferase (GST) superfamily. Whole genome sequencing (WGS) showed that the DNA methylation alterations were not caused by genetic changes, while whole transcriptome sequencing (WTS) showed that DNA methylation was associated with expression levels of the GSTT1 gene. In conclusion, our results indicate that cardiac DNA methylation is similar in SUD and SUDEP, but with regional differential methylation in proximity to GST genes.

Whole genome and transcriptome sequencing of post-mortem cardiac tissues from sudden cardiac death victims identifies a gene regulatory variant in NEXN.

BACKGROUND: Sudden cardiac death (SCD) is a major public health problem and constitutes a diagnostic and preventive challenge in forensic pathology, especially for cases with structural normal hearts at autopsy, so-called sudden arrhythmic death syndrome (SADS). The identification of new genetic risk factors that predispose to SADS is important, because they may contribute to establish the diagnosis and increase the understanding of disease pathways underlying SADS. Pathogenic mutations in the protein coding regions of cardiac genes were found in relation to SADS. However, much remains unknown about variants in non-coding regions of the genome. METHODS AND RESULTS: In this study, we explored the potential of whole genome sequencing (WGS) and whole transcriptome sequencing (WTS) to find DNA variants in SCD victims with structural normal hearts. With focus on the non-coding regulatory regions, we re-examined a cohort of 13 SADS and sudden unexplained death in infancy (SUDI) victims without disease causing DNA variants in recognized cardiac genes. The genetic re-examination of DNA was carried out using frozen tissue samples and WTS was carried out using five distinct formalin fixed and paraffin embedded (FFPE) cardiac tissue samples from each individual, including anterior and posterior walls of the left ventricle, ventricular papillary muscle, septum, and the right ventricle. We identified 23 candidate variants in regulatory sequences of cardiac genes, including a variant in the promotor region of NEXN, c.-194A>G, that was found to be statistically significantly (p < 0.05) associated with decreased expression of NEXN and cardiac hypertrophy. CONCLUSION: With the use of post-mortem FFPE tissues, we highlight the potential of using WTS investigations and compare gene expression levels with DNA variation in regulatory non-coding regions of the genome for a better understanding of the genetics of cardiac diseases leading to SCD.

Non-invasive prenatal paternity testing using a standard forensic genetic massively parallel sequencing assay for amplification of human identification SNPs.

Prenatal paternity testing often relies on invasive procedures that cause risk to both the mother and the foetus. Non-invasive, prenatal paternity testing by investigating paternally inherited single nucleotide polymorphisms (SNPs) in cell-free foetal DNA (cffDNA) in maternal plasma was performed at consecutive time points during early gestation. Plasma from 15 pregnant women was investigated at consecutive time points from gestational weeks (GWs) 4-20. The Precision ID Identity Panel and an Ion S5 Sequencer was used to analyse the cffDNA. Paternally inherited foetal SNP alleles were detected from GW7. The median foetal fractions were 0%, 3.9%, 5.1%, 5.2%, and 4.7% at GWs 4, 7, 12, 16, and 20, respectively. The corresponding median numbers of detected paternally inherited foetal autosomal SNP alleles were 0, 3, 9, 10, and 12, respectively. The typical (i.e. geometric mean) paternity indices at GW12 and GW20 were 24 (range 0.0035-8389) and 199 (range 5.1-30,137), respectively. The method is very promising. However, the method can be improved by shortening the lengths of the PCR amplicons and increasing the number of SNPs. To our knowledge, this is the first study to successfully identify paternally inherited foetal SNP alleles at consecutive time points in early gestation independently of the foetal gender.

ISO 17025 validation of a next-generation sequencing assay for relationship testing.

The HID-Ion AmpliSeq™ Identity Panel is a next-generation sequencing assay with 90 autosomal and 34 Y-chromosome SNPs that are amplified in one PCR step and subsequently sequenced using the Ion Personal Genome Machine (Ion PGM™) System. This assay was validated for relationship testing in our ISO 17025 accredited laboratory in 2015. Here, the essential parts of the validation report submitted to the Danish Accreditation Fund are presented. A total of 100 unrelated Danes were typed in duplicates and the locus balance, heterozygote balance (Hb) and noise levels were analysed in detail. Two loci were disregarded for casework because genotyping was uncertain. Hb for rs7520386 was skewed and high levels of noise were observed in rs576261. Three general acceptance criteria for analysis of single-source samples were defined: (i) sequencing depth > 200 reads, (ii) noise level < 3% and (iii) Hb > 0.3. A Python script named SNPonPGM was developed to assist the analyst by highlighting loci that do not fulfil the general acceptance criteria. Furthermore, SNPonPGM has functions that reduce the hands-on time of the reporting officer to a few minutes per case. Mixtures with DNA from two individuals in a 1:24 ratio were readily identified using the three criteria and the SNPonPGM script.

Identification of individuals from low template blood samples using whole transcriptome shotgun sequencing.

Biological trace samples consisting of very few cells pose a challenge to conventional forensic genetic DNA analysis. RNA may be an alternative to DNA when handling low template samples. Whereas each cell only contains two copies of an autosomal DNA segment, the transcriptome retains much of the genomic variation replicated in abundant RNA fragments. In this study, we describe the development of a prototype RNA-based SNP selection set for forensic human identification from low template samples (50 pg gDNA). Whole blood from a subset of the Danish population (41 individuals) and blood stains subjected to degradation at room temperature for up to two weeks were analysed by whole transcriptome shotgun sequencing. Concordance was determined by DNA genotyping with the Infinium Omni5-4 SNP chip. In the 100 protein-coding genes with the most reads, 5214 bi-allelic SNPs with gnomAD minor allele frequencies > 0.1 in the African/African American, East Asian, and (non-Finnish) European populations were identified. Of these, 24 SNPs in 21 genes passed screening in whole blood and degraded blood stains, with a resulting mean match probability of 4.5 ∙ 10-9. Additionally, ancestry informative SNPs and SNPs in genes useful for body fluid identification were identified in the transcriptome. Consequently, shotgun sequencing of RNA from low template samples may be used for a vast host of forensic genetics purposes, including simultaneous human and body fluid identification, leading to direct donor identification in the identified body fluid.

Collaborative exercise: analysis of age estimation using a QIAGEN protocol and the PyroMark Q48 platform.

Human age estimation from trace samples may give important leads early in a police investigation by contributing to the description of the perpetrator. Several molecular biomarkers are available for the estimation of chronological age, and currently, DNA methylation patterns are the most promising. In this study, a QIAGEN age protocol for age estimation was tested by five forensic genetic laboratories. The assay comprised bisulfite treatment of the extracted DNA, amplification of five CpG loci (in the genes of ELOVL2, C1orf132, TRIM59, KLF14, and FHL2), and sequencing of the amplicons using the PyroMark Q48 platform. Blood samples from 49 individuals with ages ranging from 18 to 64 years as well as negative and methylation controls were analyzed. An existing age estimation model was applied to display a mean absolute deviation of 3.62 years within the reference data set. Key points: Age determination as an intelligence tool during investigations can be a powerful tool in forensic genetics.In this study, five laboratories ran 49 samples and obtained a mean absolute deviation of 3.62 years.Five markers were analyzed on a PyroMark Q48 platform.

Mitochondrial genome diversity and population structure of the giant squid Architeuthis: genetics sheds new light on one of the most enigmatic marine species.

Despite its charismatic appeal to both scientists and the general public, remarkably little is known about the giant squid Architeuthis, one of the largest of the invertebrates. Although specimens of Architeuthis are becoming more readily available owing to the advancement of deep-sea fishing techniques, considerable controversy exists with regard to topics as varied as their taxonomy, biology and even behaviour. In this study, we have characterized the mitochondrial genome (mitogenome) diversity of 43 Architeuthis samples collected from across the range of the species, in order to use genetic information to provide new and otherwise difficult to obtain insights into the life of this animal. The results show no detectable phylogenetic structure at the mitochondrial level and, furthermore, that the level of nucleotide diversity is exceptionally low. These observations are consistent with the hypotheses that there is only one global species of giant squid, Architeuthis dux (Steenstrup, 1857), and that it is highly vagile, possibly dispersing through both a drifting paralarval stage and migration of larger individuals. Demographic history analyses of the genetic data suggest that there has been a recent population expansion or selective sweep, which may explain the low level of genetic diversity.

Tracking niche variation over millennial timescales in sympatric killer whale lineages.

Niche variation owing to individual differences in ecology has been hypothesized to be an early stage of sympatric speciation. Yet to date, no study has tracked niche width over more than a few generations. In this study, we show the presence of isotopic niche variation over millennial timescales and investigate the evolutionary outcomes. Isotopic ratios were measured from tissue samples of sympatric killer whale Orcinus orca lineages from the North Sea, spanning over 10 000 years. Isotopic ratios spanned a range similar to the difference in isotopic values of two known prey items, herring Clupea harengus and harbour seal Phoca vitulina. Two proxies of the stage of speciation, lineage sorting of mitogenomes and genotypic clustering, were both weak to intermediate indicating that speciation has made little progress. Thus, our study confirms that even with the necessary ecological conditions, i.e. among-individual variation in ecology, it is difficult for sympatric speciation to progress in the face of gene flow. In contrast to some theoretical models, our empirical results suggest that sympatric speciation driven by among-individual differences in ecological niche is a slow process and may not reach completion. We argue that sympatric speciation is constrained in this system owing to the plastic nature of the behavioural traits under selection when hunting either mammals or fish.

Genetic diversity among pandemic 2009 influenza viruses isolated from a transmission chain.

BACKGROUND: Influenza viruses such as swine-origin influenza A(H1N1) virus (A(H1N1)pdm09) generate genetic diversity due to the high error rate of their RNA polymerase, often resulting in mixed genotype populations (intra-host variants) within a single infection. This variation helps influenza to rapidly respond to selection pressures, such as those imposed by the immunological host response and antiviral therapy. We have applied deep sequencing to characterize influenza intra-host variation in a transmission chain consisting of three cases due to oseltamivir-sensitive viruses, and one derived oseltamivir-resistant case. METHODS: Following detection of the A(H1N1)pdm09 infections, we deep-sequenced the complete NA gene from two of the oseltamivir-sensitive virus-infected cases, and all eight gene segments of the viruses causing the remaining two cases. RESULTS: No evidence for the resistance-causing mutation (resulting in NA H275Y substitution) was observed in the oseltamivir-sensitive cases. Furthermore, deep sequencing revealed a subpopulation of oseltamivir-sensitive viruses in the case carrying resistant viruses. We detected higher levels of intra-host variation in the case carrying oseltamivir-resistant viruses than in those infected with oseltamivir-sensitive viruses. CONCLUSIONS: Oseltamivir-resistance was only detected after prophylaxis with oseltamivir, suggesting that the mutation was selected for as a result of antiviral intervention. The persisting oseltamivir-sensitive virus population in the case carrying resistant viruses suggests either that a small proportion survive the treatment, or that the oseltamivir-sensitive virus rapidly re-establishes itself in the virus population after the bottleneck. Moreover, the increased intra-host variation in the oseltamivir-resistant case is consistent with the hypothesis that the population diversity of a RNA virus can increase rapidly following a population bottleneck.

Prediction of chronological age and its applications in forensic casework: methods, current practices, and future perspectives.

Estimating an individual's age can be relevant in several areas primarily related to the clinical and forensic fields. In the latter, estimation of an individual's chronological age from biological material left by the perpetrator at a crime scene may provide helpful information for police investigation. Estimation of age is also beneficial in immigration cases, where age can affect the person's protection status under the law, or in disaster victim identification to narrow the list of potential missing persons. In the last decade, research has focused on establishing new approaches for age prediction in the forensic field. From the first forensic age estimations based on morphological inspections of macroscopic changes in bone and teeth, the focus has shifted to molecular methods for age estimation. These methods allow the use of samples from human biological material that does not contain morphological age features and can, in theory, be investigated in traces containing only small amounts of biological material. Molecular methods involving DNA analyses are the primary choice and estimation of DNA methylation levels at specific sites in the genome is the most promising tool. This review aims to provide an overview of the status of forensic age prediction using molecular methods, with particular focus in DNA methylation. The frequent challenges that impact forensic age prediction model development will be addressed, together with the importance of validation efforts within the forensic community.

Longitudinal changes and variation in human DNA methylation analysed with the Illumina MethylationEPIC BeadChip assay and their implications on forensic age prediction.

DNA methylation, a pivotal epigenetic modification, plays a crucial role in regulating gene expression and is known to undergo dynamic changes with age. The present study investigated epigenome-wide methylation profiles in 64 individuals over two time points, 15 years apart, using the Illumina EPIC850k arrays. A mixed-effects model identified 2821 age-associated differentially methylated CpG positions (aDMPs) with a median rate of change of 0.18% per year, consistent with a 10-15% change during a human lifespan. Significant variation in the baseline DNA methylation levels between individuals of similar ages as well as inconsistent direction of change with time across individuals were observed for all the aDMPs. Twenty-three of the 2821 aDMPs were previously incorporated into forensic age prediction models. These markers displayed larger changes in DNA methylation with age compared to all the aDMPs and less variation among individuals. Nevertheless, the forensic aDMPs also showed inter-individual variations in the direction of DNA methylation changes. Only cg16867657 in ELOVL2 exhibited a uniform direction of the age-related change among the investigated individuals, which supports the current knowledge that CpG sites in ELOVL2 are the best markers for age prediction.

DNA quality evaluation of formalin-fixed paraffin-embedded heart tissue for DNA methylation array analysis.

Archived formalin-fixed and paraffin-embedded (FFPE) heart tissue from autopsied individuals represents an important resource for investigating the DNA methylation of heart tissue of deceased individuals. The DNA quality of FFPE tissue from autopsies may be decreased, affecting the DNA methylation measurements. Therefore, inexpensive screening methods for estimating DNA quality are valuable. We investigated the correlation between the DNA quality of archived FFPE heart tissue examined with the Illumina Infinium HD FFPE QC assay (Infinium QC) and Thermo Fisher's Quantifiler Trio DNA Quantification kit (QuantifilerTrio), respectively, and the amount of usable DNA methylation data as measured by the probe detection rate (probe DR) obtained with the Illumina Infinium MethylationEPIC array. We observed a high correlation (r2 = 0.75; p < 10-11) between the QuantifilerTrio degradation index, DI, and the amount of usable DNA methylation data analysed with SeSAMe, whereas a much weaker correlation was observed between the Infinium QC and SeSAMe probe DR (r2 = 0.17; p < 0.05). Based on the results, QuantifilerTrio DI seems to predict the proportion of usable DNA methylation data analysed with the Illumina Infinium MethylationEPIC array and SeSAMe by a linear model: SeSAMe probe DR = 0.80-log10(DI) × 0.25.

Implementation of guidelines on prevention of coercion and violence (PreVCo) in psychiatry: a multicentre randomised controlled trial.

Background: Interventions to prevent the use of coercion in psychiatric hospitals have been summarized in the 2018 German Association for Psychiatry, Psychotherapy, and Psychosomatic's comprehensive guidelines. Twelve recommendations for implementation of these guideline on psychiatric wards have been deducted and their feasibility has been tested in a pilot study, using external implementation consultants as facilitators. The objective of the PreVCo study was to test their effect in a randomised clinical trial. Methods: Fifty-four psychiatric wards in Germany treating voluntary and involuntary patients were randomly allocated to either an intervention or to a waiting list condition. The intervention consisted of the implementation of three out of 12 suggested recommendations as selected by the ward teams, supported by external study workers. As the primary outcome measure, the number of coercive measures used per bed and month in the final 3 months of the intervention period was determined. Secondary outcomes were the cumulative duration of coercive measures used per bed and months and assaults per bed and month. Achieved guideline adherence was measured by a fidelity scale developed for this purpose during a pilot study for the PreVCo Rating Tool. After a 3-month baseline collection period under routine conditions, randomisation was done after matching wards pairwise according to frequency of coercive measures used and scores on the PreVCo Rating Tool at baseline. The duration of the intervention period was 12 months; control wards received only an initial workshop presentation of the study and completed their PreVCo ratings. We used the Wilcoxon signed rank test and the paired t-test and conducted sensitivity analyses for different periods of observation. Findings: Neither the number of coercive measures used per month and bed nor their cumulative duration nor the number of assaults per bed and months differed significantly between the 27 intervention wards and the 27 control wards in the final 3 months of the intervention period. The median number of coercive measures used decreased by 45% (median 0.96 (IQR 1.34)-0.53 (IQR 0.59) from baseline until the end of the intervention period on the intervention wards and by 28% (median 0.98 (IQR 1.71)-0.71 (IQR 1.08) on waiting list wards. The PreVCo Rating Tool showed a significant improvement in intervention wards compared to control wards, indicating a successful implementation. Interpretation: The study demonstrated that guideline adherence could be significantly improved by the intervention. However, there was no evidence for an effect on the frequency or duration of coercive measures used. Spill-over effects and the impact of the COVID-19 pandemic on in-patient care might have limited the effect of the intervention. Further research from robust randomised controlled trials are necessary to identify effective interventions to reduce the use of coercion in psychiatric hospitals. Funding: The study was funded by the German Innovationsfonds beim Gemeinsamen Bundesausschuss (project no. 01VSF19037). The funder had no role in study design or data collection.

Altered gene expression levels of genes related to muscle function in adults with cerebral palsy.

Cerebral palsy (CP) is the most common cause of movement disorders in children. Next generation sequencing (NGS) studies have previously shown that expression levels are fundamentally different in children with CP compared to typically developing (TD). However, given that children are in full development, we might expect gene expression levels to change once maturity is reached. Therefore, the main purpose of this study was to investigate gene expression levels of 93 target genes in adults with CP using NGS on muscle biopsies of the gastrocnemius, taken from 22 participants (n = 12 adults with CP; n = 10 TD adults). Subsequently, we carried out NGS of the mitochondrial genome to identify mtDNA variants, and additionally we studied the mitochondrial content using transmission electron microscopy images of the gastrocnemius muscle. Finally, we compared systemic ion levels between TD adults and adults with CP. Differential gene expression levels were found in genes involved in muscle contraction (MYH1 and MYBPC2), mitochondrial function kATP5J, CYCS and NDUFB6), calcium handling (CAMK2B and ATP2A), metabolism (LPL), muscle signaling (MYC, CREB1, ACVR2B, LMNA and TRIM54), and ECM (TNC). There was no statistical significant difference between CP and TD for mtDNA variant frequencies and mitochondrial content. The ion levels of Ca2+, Na+ and K+ were statistically significantly reduced while the Cl- levels were significant increased in adults with CP compared to TD adults. These results highlight that most transcriptional differences are related to muscle function in adults with CP and that mitochondrial function might be altered but not mitochondrial content.

Reproducibility of the Infinium methylationEPIC BeadChip assay using low DNA amounts.

The Infinium MethylationEPIC BeadChip (EPIC) is a reliable method for measuring the DNA methylation of more than 850,000 CpG positions. In clinical and forensic settings, it is critical to be able to work with low DNA amounts without risking reduced reproducibility. We evaluated the EPIC for a range of DNA amounts using two-fold serial dilutions investigated on two different days. While the ß-value distributions were generally unaffected by decreasing DNA amounts, the median squared Pearson's correlation coefficient (R2) of between-days ß-value comparisons decreased from 0.994 (500 ng DNA) to 0.957 (16 ng DNA). The median standard deviation of the ß-values was 0.005 and up to 0.017 (median of medians: 0.014) for ß-values around 0.6-0.7. With decreasing amounts of DNA from 500 ng to 16 ng, the percentage of probes with standard deviations ≤ 0.1 decreased from 99.9% to 99.4%. This study showed that high reproducibility results are obtained with DNA amounts in the range 125-500 ng DNA, while DNA amounts equal to 63 ng or below gave less reproducible results.

The stratum corneum transcriptome in atopic dermatitis can be assessed by tape stripping.

BACKGROUND: Skin biopsies represent a gold standard in skin immunology and pathology but can cause pain and induce scarring. Non-invasive techniques will facilitate study recruitment of e.g. patients with paediatric atopic dermatitis (AD), hand eczema or facial dermatitis. OBJECTIVE: By RNA sequencing, we examined whether the stratum corneum transcriptome in AD skin can be assessed by tape stripping, as compared to the epidermal transcriptome of AD in skin biopsies. To make the procedure clinically relevant tape strips were stored and shipped at room temperature for up to 3 days. METHODS: Nine adult Caucasian AD patients and three healthy volunteers were included. Tape samples were collected from non-lesional and lesional skin. Biopsies were collected from lesional skin and were split into epidermis and dermis. Total RNA was extracted, and shotgun sequencing was performed. RESULTS: Shotgun sequencing could be performed on skin cells obtained from two consecutive tape strips which had been stored and shipped at room temperature for up to three days. The most prominent differences between the tape strip and biopsy derived transcriptome were due to structural genes, while established molecular markers of AD, including CCL17, CCL22, IL17A and S100A7-S100A9, were also identified in tape strip samples. Furthermore, the tape strip derived transcriptome showed promise in also analysing the skin microbiome. CONCLUSION: Our study shows that the stratum corneum (SC) transcriptome of AD can be assessed by tape stripping the skin, supporting that this method may be central in future skin biomarker research. NCBI GEO data accession: GSE160501.