Understanding genetic variability: exploring large-scale copy number variants through non-invasive prenatal testing in European populations.

Large-scale copy number variants (CNVs) are structural alterations in the genome that involve the duplication or deletion of DNA segments, contributing to genetic diversity and playing a crucial role in the evolution and development of various diseases and disorders, as they can lead to the dosage imbalance of one or more genes. Massively parallel sequencing (MPS) has revolutionized the field of genetic analysis and contributed significantly to routine clinical diagnosis and screening. It offers a precise method for detecting CNVs with exceptional accuracy. In this context, a non-invasive prenatal test (NIPT) based on the sequencing of cell-free DNA (cfDNA) from pregnant women's plasma using a low-coverage whole genome MPS (WGS) approach represents a valuable source for population studies. Here, we analyzed genomic data of 12,732 pregnant women from the Slovak (9,230), Czech (1,583), and Hungarian (1,919) populations. We identified 5,062 CNVs ranging from 200 kbp and described their basic characteristics and differences between the subject populations. Our results suggest that re-analysis of sequencing data from routine WGS assays has the potential to obtain large-scale CNV population frequencies, which are not well known and may provide valuable information to support the classification and interpretation of this type of genetic variation. Furthermore, this could contribute to expanding knowledge about the central European genome without investing in additional laboratory work, as NIPTs are a relatively widely used screening method.

Validated WGS and WES protocols proved saliva-derived gDNA as an equivalent to blood-derived gDNA for clinical and population genomic analyses.

BACKGROUND: Whole exome sequencing (WES) and whole genome sequencing (WGS) have become standard methods in human clinical diagnostics as well as in population genomics (POPGEN). Blood-derived genomic DNA (gDNA) is routinely used in the clinical environment. Conversely, many POPGEN studies and commercial tests benefit from easy saliva sampling. Here, we evaluated the quality of variant call sets and the level of genotype concordance of single nucleotide variants (SNVs) and small insertions and deletions (indels) for WES and WGS using paired blood- and saliva-derived gDNA isolates employing genomic reference-based validated protocols. METHODS: The genomic reference standard Coriell NA12878 was repeatedly analyzed using optimized WES and WGS protocols, and data calls were compared with the truth dataset published by the Genome in a Bottle Consortium. gDNA was extracted from the paired blood and saliva samples of 10 participants and processed using the same protocols. A comparison of paired blood-saliva call sets was performed in the context of WGS and WES genomic reference-based technical validation results. RESULTS: The quality pattern of called variants obtained from genomic-reference-based technical replicates correlates with data calls of paired blood-saliva-derived samples in all levels of tested examinations despite a higher rate of non-human contamination found in the saliva samples. The F1 score of 10 blood-to-saliva-derived comparisons ranged between 0.8030-0.9998 for SNVs and between 0.8883-0.9991 for small-indels in the case of the WGS protocol, and between 0.8643-0.999 for SNVs and between 0.7781-1.000 for small-indels in the case of the WES protocol. CONCLUSION: Saliva may be considered an equivalent material to blood for genetic analysis for both WGS and WES under strict protocol conditions. The accuracy of sequencing metrics and variant-detection accuracy is not affected by choosing saliva as the gDNA source instead of blood but much more significantly by the genomic context, variant types, and the sequencing technology used.

Characterization of bacteriophages infecting multidrug-resistant uropathogenic Escherichia coli strains.

Uropathogenic Escherichia coli (UPEC) is the most common causative agent of urinary tract infections, and strains that are resistant to antibiotics are a major problem in treating these infections. Phage therapy is a promising alternative approach that can be used to treat infections caused by polyresistant bacterial strains. In the present study, 16 bacteriophages isolated from sewage and surface water were investigated. Phage host specificity was tested on a collection of 77 UPEC strains. The phages infected 2-44 strains, and 80% of the strains were infected by at least one phage. The susceptible E. coli strains belonged predominantly to the B2 phylogenetic group, including strains of two clones, CC131 and CC73, that have a worldwide distribution. All of the phages belonged to class Caudoviricetes and were identified as members of the families Straboviridae, Autographiviridae, and Drexlerviridae and the genera Kagunavirus, Justusliebigvirus, and Murrayvirus. A phage cocktail composed of six phages - four members of the family Straboviridae and two members of the family Autographiviridae - was prepared, and its antibacterial activity was tested in liquid medium. Complete suppression of bacterial growth was observed after 5-22 hours of cultivation, followed by partial regrowth. At 24 hours postinfection, the cocktail suppressed bacterial growth to 43-92% of control values. Similar results were obtained when testing the activity of the phage cocktail in LB and in artificial urine medium. The results indicate that our phage cocktail has potential to inhibit bacterial growth during infection, and they will therefore be preserved in the national phage bank, serving as valuable resources for therapeutic applications.

Copy number variations in malignant melanoma: genomic regions, biomarkers, and therapeutic targets.

Malignant melanoma is a skin tumor arising from melanocytes, occurring mostly in predisposed individuals. Melanomas are frequently present with copy number variations (CNVs), i.e., gains or losses of specific DNA regions that have provided immense potential for disease diagnosis and classification. The methodology of CNV detection has revolutionized in past decades, and current high throughput technologies enable us to analyze the entire spectrum of CNV alterations at the whole genome scale. Thus, identifying novel CNV biomarkers and evaluating their applicability in biomedicine are becoming increasingly important. The aim of this review was to summarize copy number changes occurring in malignant melanomas. We made an overview of specific genes and chromosomal locations affected in sporadic and familial melanoma and also of known germline alterations in melanoma-prone families. We summarized genomic regions aberrant in malignant melanoma and highlighted those frequently discussed in the literature, suggesting 7q, 11q, 12q, 9p, and 1q, but also others, as the most affected ones.

Evaluation and limitations of different approaches among COVID-19 fatal cases using whole-exome sequencing data.

BACKGROUND: COVID-19 caused by the SARS-CoV-2 infection may result in various disease symptoms and severity, ranging from asymptomatic, through mildly symptomatic, up to very severe and even fatal cases. Although environmental, clinical, and social factors play important roles in both susceptibility to the SARS-CoV-2 infection and progress of COVID-19 disease, it is becoming evident that both pathogen and host genetic factors are important too. In this study, we report findings from whole-exome sequencing (WES) of 27 individuals who died due to COVID-19, especially focusing on frequencies of DNA variants in genes previously associated with the SARS-CoV-2 infection and the severity of COVID-19. RESULTS: We selected the risk DNA variants/alleles or target genes using four different approaches: 1) aggregated GWAS results from the GWAS Catalog; 2) selected publications from PubMed; 3) the aggregated results of the Host Genetics Initiative database; and 4) a commercial DNA variant annotation/interpretation tool providing its own knowledgebase. We divided these variants/genes into those reported to influence the susceptibility to the SARS-CoV-2 infection and those influencing the severity of COVID-19. Based on the above, we compared the frequencies of alleles found in the fatal COVID-19 cases to the frequencies identified in two population control datasets (non-Finnish European population from the gnomAD database and genomic frequencies specific for the Slovak population from our own database). When compared to both control population datasets, our analyses indicated a trend of higher frequencies of severe COVID-19 associated risk alleles among fatal COVID-19 cases. This trend reached statistical significance specifically when using the HGI-derived variant list. We also analysed other approaches to WES data evaluation, demonstrating its utility as well as limitations. CONCLUSIONS: Although our results proved the likely involvement of host genetic factors pointed out by previous studies looking into severity of COVID-19 disease, careful considerations of the molecular-testing strategies and the evaluated genomic positions may have a strong impact on the utility of genomic testing.

Extracellular vesicles derived from dental mesenchymal stem/stromal cells with gemcitabine as a cargo have an inhibitory effect on the growth of pancreatic carcinoma cell lines in vitro.

Extracellular vesicles (EVs) are nowadays a target of interest in cancer therapy as a successful drug delivering tool. Based on their many beneficial biocompatible properties are designed to transport nucleic acids, proteins, various nanomaterials or chemotherapeutics. Extracellular vesicles derived from mesenchymal stem/stromal cells (MSCs) possess their tumor-homing abilities. This inspired us to engineer the MSC's EVs to be packed with chemotherapeutic agents and deliver it as a Trojan horse directly into tumor cells. In our study, human dental pulp MSCs (DP-MSCs) were cultivated with gemcitabine (GCB), which led to its absorption by the cells and subsequent secretion of the drug out into conditioned media in EVs. Concentrated conditioned media containing small EVs (potentially exosomes) significantly inhibited the cell growth of pancreatic carcinoma cell lines in vitro. DP-MSCs were simultaneously engineered to express a suicide gene fused yeast cytosinedeaminase:uracilphosphoribosyltransferase (yCD::UPRT). The product of the suicide gene converts non-toxic prodrug 5-fluorocytosine (5-FC) to highly cytotoxic chemotherapeutic drug 5-fluorouracil (5-FU) in the recipient cancer cells. Conversion of 5-FC to 5-FU had an additional effect on cancer cell's growth inhibition. Our results showed a therapeutic potential for DP-MSC-EVs to be designed for successful delivering of chemotherapeutic drugs, together with prodrug suicide gene therapy system.

Repression of a large number of genes requires interplay between homologous recombination and HIRA.

During homologous recombination, Dbl2 protein is required for localisation of Fbh1, an F-box helicase that efficiently dismantles Rad51-DNA filaments. RNA-seq analysis of dbl2Δ transcriptome showed that the dbl2 deletion results in upregulation of more than 500 loci in Schizosaccharomyces pombe. Compared with the loci with no change in expression, the misregulated loci in dbl2Δ are closer to long terminal and long tandem repeats. Furthermore, the misregulated loci overlap with antisense transcripts, retrotransposons, meiotic genes and genes located in subtelomeric regions. A comparison of the expression profiles revealed that Dbl2 represses the same type of genes as the HIRA histone chaperone complex. Although dbl2 deletion does not alleviate centromeric or telomeric silencing, it suppresses the silencing defect at the outer centromere caused by deletion of hip1 and slm9 genes encoding subunits of the HIRA complex. Moreover, our analyses revealed that cells lacking dbl2 show a slight increase of nucleosomes at transcription start sites and increased levels of methylated histone H3 (H3K9me2) at centromeres, subtelomeres, rDNA regions and long terminal repeats. Finally, we show that other proteins involved in homologous recombination, such as Fbh1, Rad51, Mus81 and Rad54, participate in the same gene repression pathway.

Cross-Kingdom Interaction of miRNAs and Gut Microbiota with Non-Invasive Diagnostic and Therapeutic Implications in Colorectal Cancer.

Colorectal cancer (CRC) has one of the highest incidences among all types of malignant diseases, affecting millions of people worldwide. It shows slow progression, making it preventable. However, this is not the case due to shortcomings in its diagnostic and management procedure and a lack of effective non-invasive biomarkers for screening. Here, we discuss CRC-associated microRNAs (miRNAs) and gut microbial species with potential as CRC diagnostic and therapy biomarkers. We provide rich evidence of cross-kingdom miRNA-mediated interactions between the host and gut microbiome. miRNAs have emerged with the ability to shape the composition and dynamics of gut microbiota. Intestinal microbes can uptake miRNAs, which in turn influence microbial growth and provide the ability to regulate the abundance of various microbial species. In the context of CRC, targeting miRNAs could aid in manipulating the balance of the microbiota. Our findings suggest the need for correlation analysis between the composition of the gut microbiome and the miRNA expression profile.

APOC3 and ABCA1 variants in unusual combined hypolipidaemia showing premature peripheral vascular disease.

BACKGROUND: Familial combined hypolipidaemia is a condition characterised by very low concentrations of circulating very-low-density lipoprotein (VLDL), low-density lipoprotein cholesterol (LDL), and high-density lipoprotein cholesterol (HDL). It is thought that low LDL/combined hypolipidaemia can protect from cardiovascular disease (CVD), but this is not what we found in a case we present. OBJECTIVE: We report on a 57-years-old male patient with combined hypolipidaemia who presented with premature peripheral vascular disease. We investigated also his two sons, 32- and 27-years-old, who manifested a tendency to low lipid levels. METHODS AND RESULTS: We used Illumina exome analysis in all three individuals and in all of them we could exclude the major effect of the variants within the genes most frequently mutated in hypolipidaemia, including recently reported LIPC gene variant. Instead, in all three individuals we identified a novel ABCA1 variant, possibly responsible for the decreased HDL levels. The proband and one of his sons also share the splicing APOC3 variant rs138326449, known to be associated with decreased TG levels. CONCLUSION: The heterogeneous nature and the risk of atherosclerosis in combined hypolipidaemia seems to be variable, based on an interplay between low HDL and LDL levels, and it depends on the combination of variants that cause it (Tab. 2, Ref. 38).

Non-intuitive trends of fetal fraction development related to gestational age and fetal gender, and their practical implications for non-invasive prenatal testing.

Discovery of fetal cell-free DNA fragments in maternal blood revolutionized prenatal diagnostics. Although non-invasive prenatal testing (NIPT) is already a matured screening test with high specificity and sensitivity, the accurate estimation of the proportion of fetal fragments, called fetal fraction, is crucial to avoid false-negative results. In this study, we collected 6999 samples from women undergoing NIPT testing with a single male fetus to demonstrate the influence of fetal fraction by the maternal and fetal characteristics. We show several fetal fraction discrepancies that contradict the generally presented conventional view. At first, the fetal fraction is not consistently rising with the maturity of the fetus due to a drop in 15 weeks of maturation. Secondly, the male samples have a lower fetal fraction than female fetuses, arguably due to the smaller gonosomal chromosomes. Finally, we discuss not only the possible reasons why this inconsistency exists but we also outline why these differences have not yet been identified and published. We demonstrate two non-intuitive trends to better comprehend the fetal fraction development and more precise selection of patients with sufficient fetal fraction for accurate testing.

Mitochondrial DNA copy number changes, heteroplasmy, and mutations in plasma-derived exosomes and brain tissue of glioblastoma patients.

Glioblastoma is the most common malignant tumor of the central nervous system (CNS) in adults. Glioblastoma cells show increased glucose consumption associated with poor prognosis. Since mitochondria play a crucial role in energy metabolism, mutations and copy number changes of mitochondrial DNA may serve as biomarkers. As the brain is difficult to access, analysis of mitochondria directly from the brain tissue represents a challenge. Exosome analysis is an alternative (still poorly explored) approach to investigate molecular changes in CNS tumors. We analyzed brain tissue DNA and plasma-derived exosomal DNA (exoDNA) of 44 glioblastoma patients and 40 control individuals. Quantitative real-time PCR was performed to determine mtDNA copy numbers and the Kruskal-Wallis and Mann-Whitney U test were used for statistical analysis of data. Subsequently, sequencing libraries were prepared and sequenced on the MiSeq platform to identify mtDNA point mutations. Tissue mtDNA copy number was different among controls and patients in multiple comparisons. A similar tendency was detected in exosomes. Based on NGS analysis, several mtDNA point mutations showed slightly different frequencies between cases and controls, but the clinical relevance of these observations is difficult to assess and likely less than that of overall mtDNA copy number changes. Allele frequencies of variants were used to determine the level of heteroplasmy (found to be higher in exo-mtDNA of control individuals). Despite the suggested potential, the use of such biomarkers for the screening and/or diagnosis of glioblastomas is still limited, thus further studies are needed.

Liquid Biopsy as a Source of Nucleic Acid Biomarkers in the Diagnosis and Management of Lynch Syndrome.

Lynch syndrome (LS) is an autosomal dominant inherited cancer predisposition disorder, which may manifest as colorectal cancer (CRC), endometrial cancer (EC) or other malignancies of the gastrointestinal and genitourinary tract as well as the skin and brain. Its genetic cause is a defect in one of the four key DNA mismatch repair (MMR) loci. Testing of patients at risk is currently based on the absence of MMR protein staining and detection of mutations in cancer tissue and the germline, microsatellite instability (MSI) and the hypermethylated state of the MLH1 promoter. If LS is shown to have caused CRC, lifetime follow-up with regular screening (most importantly, colonoscopy) is required. In recent years, DNA and RNA markers extracted from liquid biopsies have found some use in the clinical diagnosis of LS. They have the potential to greatly enhance the efficiency of the follow-up process by making it minimally invasive, reproducible, and time effective. Here, we review markers reported in the literature and their current clinical applications, and we comment on possible future directions.

Alzheimer's Disease-Associated SNP rs708727 in SLC41A1 May Increase Risk for Parkinson's Disease: Report from Enlarged Slovak Study.

SLC41A1 (A1) SNPs rs11240569 and rs823156 are associated with altered risk for Parkinson's disease (PD), predominantly in Asian populations, and rs708727 has been linked to Alzheimer's disease (AD). In this study, we have examined a potential association of the three aforementioned SNPs and of rs9438393, rs56152218, and rs61822602 (all three lying in the A1 promoter region) with PD in the Slovak population. Out of the six tested SNPs, we have identified only rs708727 as being associated with an increased risk for PD onset in Slovaks. The minor allele (A) in rs708727 is associated with PD in dominant and completely over-dominant genetic models (ORD = 1.36 (1.05-1.77), p = 0.02, and ORCOD = 1.34 (1.04-1.72), p = 0.02). Furthermore, the genotypic triplet GG(rs708727) + AG(rs823156) + CC(rs61822602) might be clinically relevant despite showing a medium (h ≥ 0.5) size difference (h = 0.522) between the PD and the control populations. RandomForest modeling has identified the power of the tested SNPs for discriminating between PD-patients and the controls to be essentially zero. The identified association of rs708727 with PD in the Slovak population leads us to hypothesize that this A1 polymorphism, which is involved in the epigenetic regulation of the expression of the AD-linked gene PM20D1, is also involved in the pathoetiology of PD (or universally in neurodegeneration) through the same or similar mechanism as in AD.

Molecularly confirmed pontocerebellar hypoplasia in a large family from Slovakia with four severely affected children.

BACKGROUND: Pontocerebellar hypoplasia type 1 (PCH1) is characterized by a central and peripheral motor dysfunction associated with anterior horn cell degeneration, similar to spinal muscular atrophy (SMA). OBJECTIVES: We analysed three probands (later discovered to be siblings) suspected to have severe SMA, however, not confirmed by genetic test. METHODS: Clinical-exome analysis (Illumina) was performed to identify causative variants, followed by Sanger sequencing confirmation in probands and other 10 family members. RESULTS: Homozygous pathogenic variant c.92G>C (p.(Gly31Ala)) in the Exosome Component 3 (EXOSC3) gene was found in all 3 probands, thus confirming the diagnosis of a severe form of PCH1B. The parents and six siblings were carriers, while one sibling was homozygous for a reference allele. This variant is frequent in the Czech Roma population, where it is considered a founder mutation. Haplotype analysis in this largest reported PCH1B family showed that our patients inherited from their father (of Roma origin) a haplotype identical to that found in the Czech Roma population, thus indicating these alleles have a common origin. CONCLUSION: This EXOSC3 variant is rare among the general population but most likely frequent also among Roma people in Slovakia. PCH1B should be considered for a differential diagnosis in infants manifesting SMA-like phenotype, especially if of Roma origin (Tab. 1, Fig. 1, Ref. 22). Text in PDF www.elis.sk Keywords: pontocerebellar hypoplasia, PCH1B, EXOSC3, SMA plus syndromes, pathogenic sequence variant.

Privacy-preserving storage of sequenced genomic data.

BACKGROUND: The current and future applications of genomic data may raise ethical and privacy concerns. Processing and storing of this data introduce a risk of abuse by potential offenders since the human genome contains sensitive personal information. For this reason, we have developed a privacy-preserving method, named Varlock providing secure storage of sequenced genomic data. We used a public set of population allele frequencies to mask the personal alleles detected in genomic reads. Each personal allele described by the public set is masked by a randomly selected population allele with respect to its frequency. Masked alleles are preserved in an encrypted confidential file that can be shared in whole or in part using public-key cryptography. RESULTS: Our method masked the personal variants and introduced new variants detected in a personal masked genome. Alternative alleles with lower population frequency were masked and introduced more often. We performed a joint PCA analysis of personal and masked VCFs, showing that the VCFs between the two groups cannot be trivially mapped. Moreover, the method is reversible and personal alleles in specific genomic regions can be unmasked on demand. CONCLUSION: Our method masks personal alleles within genomic reads while preserving valuable non-sensitive properties of sequenced DNA fragments for further research. Personal alleles in the desired genomic regions may be restored and shared with patients, clinics, and researchers. We suggest that the method can provide an additional security layer for storing and sharing of the raw aligned reads.

The Role of Exosomes in Cancer Progression.

Early detection, characterization and monitoring of cancer are possible by using extracellular vesicles (EVs) isolated from non-invasively obtained liquid biopsy samples. They play a role in intercellular communication contributing to cell growth, differentiation and survival, thereby affecting the formation of tumor microenvironments and causing metastases. EVs were discovered more than seventy years ago. They have been tested recently as tools of drug delivery to treat cancer. Here we give a brief review on extracellular vesicles, exosomes, microvesicles and apoptotic bodies. Exosomes play an important role by carrying extracellular nucleic acids (DNA, RNA) in cell-to-cell communication causing tumor and metastasis development. We discuss the role of extracellular vesicles in the pathogenesis of cancer and their practical application in the early diagnosis, follow up, and next-generation treatment of cancer patients.

Dante: genotyping of known complex and expanded short tandem repeats.

MOTIVATION: Short tandem repeats (STRs) are stretches of repetitive DNA in which short sequences, typically made of 2-6 nucleotides, are repeated several times. Since STRs have many important biological roles and also belong to the most polymorphic parts of the human genome, they became utilized in several molecular-genetic applications. Precise genotyping of STR alleles, therefore, was of high relevance during the last decades. Despite this, massively parallel sequencing (MPS) still lacks the analysis methods to fully utilize the information value of STRs in genome scale assays. RESULTS: We propose an alignment-free algorithm, called Dante, for genotyping and characterization of STR alleles at user-specified known loci based on sequence reads originating from STR loci of interest. The method accounts for natural deviations from the expected sequence, such as variation in the repeat count, sequencing errors, ambiguous bases and complex loci containing several different motifs. In addition, we implemented a correction for copy number defects caused by the polymerase induced stutter effect as well as a prediction of STR expansions that, according to the conventional view, cannot be fully captured by inherently short MPS reads. We tested Dante on simulated datasets and on datasets obtained by targeted sequencing of protein coding parts of thousands of selected clinically relevant genes. In both these datasets, Dante outperformed HipSTR and GATK genotyping tools. Furthermore, Dante was able to predict allele expansions in all tested clinical cases. AVAILABILITY AND IMPLEMENTATION: Dante is open source software, freely available for download at https://github.com/jbudis/dante. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Combining count- and length-based z-scores leads to improved predictions in non-invasive prenatal testing.

MOTIVATION: Non-invasive prenatal testing or NIPT is currently among the top researched topic in obstetric care. While the performance of the current state-of-the-art NIPT solutions achieve high sensitivity and specificity, they still struggle with a considerable number of samples that cannot be concluded with certainty. Such uninformative results are often subject to repeated blood sampling and re-analysis, usually after two weeks, and this period may cause a stress to the future mothers as well as increase the overall cost of the test. RESULTS: We propose a supplementary method to traditional z-scores to reduce the number of such uninformative calls. The method is based on a novel analysis of the length profile of circulating cell free DNA which compares the change in such profiles when random-based and length-based elimination of some fragments is performed. The proposed method is not as accurate as the standard z-score; however, our results suggest that combination of these two independent methods correctly resolves a substantial portion of healthy samples with an uninformative result. Additionally, we discuss how the proposed method can be used to identify maternal aberrations, thus reducing the risk of false positive and false negative calls. AVAILABILITY AND IMPLEMENTATION: The open-source code of the proposed methods, together with test data, is freely available for non-commercial users at github web page https://github.com/jbudis/lambda. SUPPLEMENTARY INFORMATION: Supplementary materials are available at Bioinformatics online.

Circulating Cell-Free Nucleic Acids: Main Characteristics and Clinical Application.

Liquid biopsy recently became a very promising diagnostic method that has several advantages over conventional invasive methods. Liquid biopsy may serve as a source of several important biomarkers including cell-free nucleic acids (cf-NAs). Cf-DNA is widely used in prenatal testing in order to characterize fetal genetic disorders. Analysis of cf-DNA may provide information about the mutation profile of tumor cells, while cell-free non-coding RNAs are promising biomarker candidates in the diagnosis and prognosis of cancer. Many of these markers have the potential to help clinicians in therapy selection and in the follow-up of patients. Thus, cf-NA-based diagnostics represent a new path in personalized medicine. Although several reviews are available in the field, most of them focus on a limited number of cf-NA types. In this review, we give an overview about all known cf-NAs including cf-DNA, cf-mtDNA and cell-free non-coding RNA (miRNA, lncRNA, circRNA, piRNA, YRNA, and vtRNA) by discussing their biogenesis, biological function and potential as biomarker candidates in liquid biopsy. We also outline possible future directions in the field.

Technical and Methodological Aspects of Cell-Free Nucleic Acids Analyzes.

Analyzes of cell-free nucleic acids (cfNAs) have shown huge potential in many biomedical applications, gradually entering several fields of research and everyday clinical care. Many biological properties of cfNAs can be informative to gain deeper insights into the function of the organism, such as their different types (DNA, RNAs) and subtypes (gDNA, mtDNA, bacterial DNA, miRNAs, etc.), forms (naked or vesicle bound NAs), fragmentation profiles, sequence composition, epigenetic modifications, and many others. On the other hand, the workflows of their analyzes comprise many important steps, from sample collection, storage and transportation, through extraction and laboratory analysis, up to bioinformatic analyzes and statistical evaluations, where each of these steps has the potential to affect the outcome and informational value of the performed analyzes. There are, however, no universal or standard protocols on how to exactly proceed when analyzing different cfNAs for different applications, at least according to our best knowledge. We decided therefore to prepare an overview of the available literature and products commercialized for cfNAs processing, in an attempt to summarize the benefits and limitations of the currently available approaches, devices, consumables, and protocols, together with various factors influencing the workflow, its processes, and outcomes.