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Driven by technological advances, an ever-increasing number of genes and mutations are implicated in neuromuscular diseases. This has led to revised classifications of neuromuscular diseases and expanding phenotypic spectra related to single genes. As a result, gene-targeted therapies are emerging. Combined with the reduction in costs of genome sequencing, genetic testing plays an increasingly important role in the diagnostic process of neuromuscular diseases. Nevertheless, caution is warranted since results of genome sequencing can be challenging regarding the interpretation of the results. Here we discuss general principles that aid the efficient use of genetic testing that may improve the interpretation of results (see Table 7.1).
In places where multiple related taxa are invasive and known to hybridize, it is important to have correct identifications to enable an appropriate legal, ecological, and management understanding of each kind of invader. Invasive knotweeds in the genus Reynoutria Houtt. are noxious weeds in Europe, North America, Africa, and Oceania, where they disrupt native plant communities and negatively impact human activities. Two species (R. japonica Houtt., R. sachalinensis (F.Schmidt) Nakai) and their hybrid (known as R. × bohemica Chrtek & Chrtková) have similar invasive tendencies, although there are some noted differences among them in their reproduction potential, ecological tolerance, and effect on native communities. Prior studies demonstrated that there is not only one kind of interspecific hybrid, but in fact at least four kinds that differ in the sequence variants they possess from each parent. Thus, in addition to identifying plants as hybrids, it may become important to distinguish each kind of hybrid when considering control or treatment strategies. In the current study, we expand the available genetic information for invasive knotweeds by providing expanded DNA sequence data for the low-copy nuclear gene LEAFY, which has become important for characterizing hybrids. Our methods recover the same LEAFY genotypes that were identified previously for the commonly sequenced second intron, and we also provide sequence data for the first intron and second exon of the gene.
New data on the complete mitochondrial genome of Azygia robusta (Azygiidae) were obtained by the next-generation sequencing (NGS) approach. The mitochondrial DNA (mtDNA) of A. robusta had a length of 13 857 bp and included 12 protein-coding genes, two ribosomal genes, 22 transfer RNA genes, and two non-coding regions. The nucleotide sequences of the complete mitochondrial genomes of two A. robusta specimens differed from each other by 0.12 ± 0.03%. Six of 12 protein-coding genes demonstrated intraspecific variation. The difference between the nucleotide sequences of the complete mitochondrial genomes of A. robusta and Azygia hwangtsiyui was 26.95 ± 0.35%; the interspecific variation of protein-coding genes between A. robusta and A. hwangtsiyui ranged from 20.5 ± 0.9% (cox1) to 30.7 ± 1.2% (nad5). The observed gene arrangement in the mtDNA sequence of A. robusta was identical to that of A. hwangtsiyui. Codon usage and amino acid frequencies were highly similar between A. robusta and A. hwangtsiyui. The results of phylogenetic analyses based on mtDNA protein-coding regions showed that A. robusta is closely related to A. hwangtsiyui (belonging to the same suborder, Azygiida) that formed a distinct early-diverging branch relative to all other Digenea. A preliminary morphological analysis of paratypes of the two azygiid specimens studied showed visible morphological differences between them. The specimen extracted from Sakhalin taimen (Parahucho perryi) was most similar to A. robusta. Thus, we here provide the first record of a new definitive host, P. perryi, for A. robusta and also molecular characteristics of the trematode specimens.
Chapter 6 outlines the range of methods used to isolate, purify and analyse nucleic acids. Methods to quantify DNA and RNA, and labelling of nucleic acids using radioactive and fluorographic precursors and a range of enzymatic methods, are described. The use of gel electrophoresis to separate DNA fragments is discussed. The principles of first-generation DNA sequencing are outlined, and the Sanger dideoxy method described for manual and automated methods. Next-generation methods for DNA sequencing are covered, to illustrate the range of advanced techniques that have enabled large-scale genome sequencing to become a routine laboratory procedure that is both rapid and cost-effective. Techniques for massively parallel and single-molecule real-time sequencing are described.
During the last two decades, the world has witnessed the emergence and re-emergence of arthropod-borne viruses, better known as arboviruses. The close contact between sylvatic, rural and peri-urban vector species and humans has been mainly determined by the environment-modifying human activity. The resulting interactions have led to multiple dead-end host infections and have allowed sylvatic arboviruses to eventually adapt to new vectors and hosts, contributing to the establishment of urban transmission cycles of some viruses with enormous epidemiologic impact. The metagenomic next-generation sequencing (NGS) approach has allowed obtaining unbiased sequence information of millions of DNA and RNA molecules from clinical and environmental samples. Robust bioinformatics tools have enabled the assembly of individual sequence reads into contigs and scaffolds partially or completely representing the genomes of the microorganisms and viruses being present in biological samples of clinical relevance. In this review, we describe the different ecological scenarios for the emergence of viral diseases, the virus adaptation process required for the establishment of a new transmission cycle and the usefulness of NGS and computational methods for the discovery and routine genomic surveillance of mosquito-borne viruses in their ecosystems.
Forensic DNA analysis plays a central role in the judicial system. A DNA sample can change the course of an investigation with immense consequences. Because DNA typing is recognized as the epitome of forensic science, increasing public awareness in this area is vital. Through several cases, examples and illustrations, this book explains the basic principles of forensic DNA typing, and how it integrates with law enforcement investigations and legal decisions. Written for a general readership, Understanding Forensic DNA explains both the power and the limitations of DNA analysis. This book dispels common misunderstandings regarding DNA analysis and shows how astounding match probabilities such as one-in-a-trillion are calculated, what they really mean, and why DNA alone never solves a case.
Although immune checkpoint inhibitors (ICIs) have produced remarkable responses in non-small cell lung cancer (NSCLC) patients, receivers still have a relatively low response rate. Initial response assessment by conventional imaging and evaluation criteria is often unable to identify whether patients can achieve durable clinical benefit from ICIs. Overall, there are sparse effective biomarkers identified to screen NSCLC patients responding to this therapy. A lot of studies have reported that patients with specific gene mutations may benefit from or resist to immunotherapy. However, the single gene mutation may be not effective enough to predict the benefit from immunotherapy for patients. With the advancement in sequencing technology, further studies indicate that many mutations often co-occur and suggest a drastic transformation of tumour microenvironment phenotype. Moreover, co-mutation events have been reported to synergise to activate or suppress signalling pathways of anti-tumour immune response, which also indicates a potential target for combining intervention. Thus, the different mutation profile (especially co-mutation) of patients may be an important concern for predicting or promoting the efficacy of ICIs. However, there is a lack of comprehensive knowledge of this field until now. Therefore, in this study, we reviewed and elaborated the value of cancer mutation profile in predicting the efficacy of immunotherapy and analysed the underlying mechanisms, to provide an alternative way for screening dominant groups, and thereby, optimising individualised therapy for NSCLC patients.
Blood parasites comprise some of the most prevalent pathogens in nature, and their detection and identification are major objectives in varied fields such as ecology and biomedicine. Two approaches were compared, one based on Sanger sequencing and the other next-generation sequencing (NGS) based, in terms of their performance in detecting avian blood parasites across tropical Southeast Asian birds. Across a panel of 528 bird individuals, 43 birds were ascertained to be infected with avian haemosporidians using a polymerase chain reaction-based detection method. Among these samples, NGS-based barcoding confirmed co-infections by multiple blood parasites in all eight cases where Sanger sequencing produced double peaks. Importantly however, the NGS-based method produced another five diagnoses of co-infections (62.5%) in which Sanger-based barcoding remained equivocal. In contrast to Sanger sequencing, the NGS-based method was able to identify co-infecting haemosporidian lineages via their barcodes. The accuracy of avian haemosporidian lineage identification was not compromised by the shorter length of NGS sequences, with ~94% of NGS barcodes producing matches identical to those of the Sanger barcodes. The application of NGS-based barcoding methods promises to enhance parasite identification and reduce erroneous inferences based on artefacts.
Nosocomial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks among health care workers have been scarcely reported so far. This report presents the results of an epidemiologic and molecular investigation of a SARS-CoV-2 outbreak among laundromat facility workers in a large tertiary centre in Israel. Following the first three reported cases of SARS-CoV-2 among laundromat workers, all 49 laundromat personnel were screened by qRT-PCR tests using naso- and oropharingeal swabs. Epidemiologic investigations included questionnaires, interviews and observations of the laundromat facility. Eleven viral RNA samples were then sequenced, and a phylogenetic analysis was performed using MEGAX.
The integrated investigation defined three genetic clusters and helped identify the index cases and the assumed routes of transmission. It was then deduced that shared commute and public showers played a role in SARS-CoV-2 transmission in this outbreak, in addition to improper PPE use and social gatherings (such as social eating and drinking). In this study, we present an integrated epidemiologic and molecular investigation may help detect the routes of SARS-CoV-2 transmission, emphasising such routes that are less frequently discussed. Our work reinforces the notion that person-to-person transmission is more likely to cause infections than environmental contamination (e.g. from handling dirty laundry).
We report a familial cluster of 24 individuals infected with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The index case had a travel history and spent 24 days in the house before being tested and was asymptomatic. Physical overcrowding in the house provided a favourable environment for intra-cluster infection transmission. Restriction of movement of family members due to countrywide lockdown limited the spread in community. Among the infected, only four individuals developed symptoms. The complete genome sequences of SARS-CoV-2 was retrieved using next-generation sequencing from eight clinical samples which demonstrated a 99.99% similarity with reference to Wuhan strain and the phylogenetic analysis demonstrated a distinct cluster, lying in the B.6.6 pangolin lineage.
Microbiome, the study of microbial communities in specific environments, has developed significantly since the Human Microbiome Project began. Microbiomes have been associated with changes within environmental niches and the development of various diseases. The development of high-throughput technology such as next-generation sequencing has also allowed us to perform transcriptome studies, which provide accurate functional profiling data. Metabolome studies, which analyse the metabolites found in the environment, are the most direct environmental condition indicator. Although each dataset provides valuable information on its own, the integration of multiple datasets provides a deeper understanding of the relationship between the host, agent and environment. Therefore, network analysis using multiple datasets might give a clearer understanding of disease pathogenesis.
The finding of conjoined oocytes is a rare occurrence that accounts for only 0.3% of all human retrieved oocytes. This phenomenon is quite different from that of a traditional single oocyte emanating from one follicle, and may result in dizygotic twins and mosaicism. Given the insufficient evidence on how to approach conjoined oocytes, their fate is variable among different in vitro fertilization (IVF) centres. In this observational report, we propose a new protocol for the use of these conjoined oocytes using intracytoplasmic sperm injection (ICSI), laser-cutting technique and next-generation sequencing (NGS). The first case report demonstrates that conjoined oocytes can penetrate their shared zona pellucida (ZP) at Day 6. The second case is that of a 25-year-old female patient who underwent a successful embryo transfer cycle after removal of one oocyte in which a pair of conjoined human oocytes underwent ICSI, laser-cutting separation and NGS testing. The patient achieved pregnancy and gave birth to single healthy female originally derived from conjoined oocytes. This case provided a means through which normal pregnancy may be achieved from conjoined oocytes using laser-cutting separation techniques. The protocol described may be especially beneficial to patients with a limited number of oocytes.
The few Antarctic studies to date to have applied metabarcoding in Antarctica have primarily focused on microorganisms. In this study, for the first time, we apply high-throughput sequencing of environmental DNA to investigate the diversity of Embryophyta (Viridiplantae) DNA present in soil samples from two contrasting locations on Deception Island. The first was a relatively undisturbed site within an Antarctic Specially Protected Area at Crater Lake, and the second was a heavily human-impacted site in Whalers Bay. In samples obtained at Crater Lake, 84% of DNA reads represented fungi, 14% represented Chlorophyta and 2% represented Streptophyta, while at Whalers Bay, 79% of reads represented fungi, 20% represented Chlorophyta and < 1% represented Streptophyta, with ~1% of reads being unassigned. Among the Embryophyta we found 16 plant operational taxonomic units from three Divisions, including one Marchantiophyta, eight Bryophyta and seven Magnoliophyta. Sequences of six taxa were detected at both sampling sites, eight only at Whalers Bay and two only at Crater Lake. All of the Magnoliophyta sequences (flowering plants) represent species that are exotic to Antarctica, with most being plausibly linked to human food sources originating from local national research operator and tourism facilities.
Paediatric cardiomyopathy is a progressive, often lethal disorder and the most common cause of heart failure in children. Despite its severe outcomes, the genetic aetiology is still poorly characterised. High-throughput sequencing offers a great opportunity for a better understanding of the genetic causes of cardiomyopathy.
Aim:
The current study aimed to elucidate the genetic background of cardiomyopathy in Egyptian children.
Methods:
This hospital-based study involved 68 patients; 58 idiopathic primary dilated cardiomyopathy and 10 left ventricular noncompaction cardiomyopathy. Cardiomyopathy-associated genes were investigated using targeted next-generation sequencing.
Results:
Consanguinity was positive in 53 and 70% of dilated cardiomyopathy and left ventricular noncompaction cardiomyopathy patients, respectively. Positive family history of cardiomyopathy was present in 28% of dilated cardiomyopathy and 10% of the left ventricular noncompaction cardiomyopathy patients. In 25 patients, 29 rare variants were detected; 2 likely pathogenic variants in TNNI3 and TTN and 27 variants of uncertain significance explaining 2.9% of patients.
Conclusions:
The low genetic detection rate suggests that novel genes or variants might underlie paediatric cardiomyopathy in Egypt, especially with the high burden of consanguinity. Being the first national and regional report, our study could be a reference for future genetic testing in Egyptian cardiomyopathy children. Genome-wide tests (whole exome/genome sequencing) might be more suitable than the targeted sequencing to investigate the primary cardiomyopathy patients. Molecular characterisation of cardiomyopathies in different ethnicities will allow for global comparative studies that could result in understanding the pathophysiology and heterogeneity of cardiomyopathies.
The myxozoan Tetracapsuloides bryosalmonae is a widely spread endoparasite that causes proliferative kidney disease (PKD) in salmonid fish. We developed an in silico pipeline to separate transcripts of T. bryosalmonae from the kidney tissue of its natural vertebrate host, brown trout (Salmo trutta). After stringent filtering, we constructed a partial transcriptome assembly T. bryosalmonae, comprising 3427 transcripts. Based on homology-restricted searches of the assembled parasite transcriptome and Atlantic salmon (Salmo salar) proteome, we identified four protein targets (Endoglycoceramidase, Legumain-like protease, Carbonic anhydrase 2, Pancreatic lipase-related protein 2) for the development of anti-parasitic drugs against T. bryosalmonae. Earlier work of these proteins on parasitic protists and helminths suggests that the identified anti-parasitic drug targets represent promising chemotherapeutic candidates also against T. bryosalmonae, and strengthen the view that the known inhibitors can be effective in evolutionarily distant organisms. In addition, we identified differentially expressed T. bryosalmonae genes between moderately and severely infected fish, indicating an increased abundance of T. bryosalmonae sporogonic stages in fish with low parasite load. In conclusion, this study paves the way for future genomic research in T. bryosalmonae and represents an important step towards the development of effective drugs against PKD.
Paediatric cardiomyopathy is a progressive and often lethal disorder and the most common cause of heart failure in children. Despite their severe outcomes, their genetic etiology is still poorly characterised. The current study aimed at uncovering the genetic background of idiopathic primary hypertrophic cardiomyopathy in a cohort of Egyptian children using targeted next-generation sequencing. The study included 24 patients (15 males and 9 females) presented to the cardiomyopathy clinic of Cairo University Children’s Hospital with a median age of 2.75 (0.5–14) years. Consanguinity was positive in 62.5% of patients. A family history of hypertrophic cardiomyopathy was present in 20.8% of patients. Ten rare variants were detected in eight patients; two pathogenic variants (8.3%) in MBPC3 and MYH7, and eight variants of uncertain significance in MYBPC3, TTN, VCL, MYL2, CSRP3, and RBM20.
Here, we report on the first national study in Egypt that analysed sarcomeric and non-sarcomeric variants in a cohort of idiopathic paediatric hypertrophic cardiomyopathy patients using next-generation sequencing. The current pilot study suggests that paediatric hypertrophic cardiomyopathy in Egypt might have a particular genetic background, especially with the high burden of consanguinity. Including the genetic testing in the routine diagnostic service is important for a better understanding of the pathophysiology of the disease, proper patient management, and at-risk detection. Genome-wide tests (whole exome/genome sequencing) might be better than the targeted sequencing approach to test primary hypertrophic cardiomyopathy patients in addition to its ability for the identification of novel genetic causes.
Non-invasive prenatal testing (NIPT) using cell-free foetal DNA has been widely accepted in recent years for detecting common foetal chromosome aneuploidies, such as trisomies 13, 18 and 21, and sex chromosome aneuploidies. In this study, the practical clinical performance of our foetal DNA testing was evaluated for analysing all chromosome aberrations among 7113 pregnancies in Italy.
Methods
This study was a retrospective analysis of collected NIPT data from the Ion S5 next-generation sequencing platform obtained from Altamedica Medical Centre in Rome, Italy.
Results
In this study, NIPT showed 100% sensitivity and 99.9% specificity for trisomies 13, 18 and 21. Out of the 7113 samples analysed, 74 cases (1%) were positive by NIPT testing; foetal karyotyping and follow-up results validated 2 trisomy 13 cases, 5 trisomy 18 cases, 58 trisomy 21 cases and 10 sex chromosome aneuploidy cases. There were no false-negative results.
Conclusion
In our hands, NIPT had high sensitivity and specificity for common chromosomal aneuploidies such as trisomies 13, 18 and 21.
Influenza A virus is a serious human pathogen that assembles enveloped virions on the plasma membrane of the host cell. The pleiomorphic morphology of influenza A virus, represented by spherical, elongated, or filamentous particles, is important for the spread of the virus in nature. Using fixative protocols for sample preparation and negative staining electron microscopy, we found that the recombinant A/WSN/33 (H1N1) (rWSN) virus, a strain considered to be strictly spherical, may produce filamentous particles when amplified in the allantoic cavity of chicken embryos. In contrast, the laboratory WSN strain and the rWSN virus amplified in Madin–Darby canine kidney cells exhibited a spherical morphology. Next-generation sequencing (NGS) suggested a rare Ser126Cys substitution in the M1 protein of rWSN, which was confirmed by the mass spectrometric analysis. No structurally relevant substitutions were found by NGS in other proteins of rWSN. Bioinformatics algorithms predicted a neutral structural effect of the Ser126Cys mutation. The mrWSN_M1_126S virus generated after the introduction of the reverse Cys126Ser substitution exhibited a similar host-dependent partially filamentous phenotype. We hypothesize that a shortage of some as-yet-undefined cellular components involved in virion budding and membrane scission may result in the appearance of filamentous particles in the case of usually “nonfilamentous” virus strains.
Epilepsy is a common neurological condition that shows a marked genetic predisposition. The advent of next-generation sequencing (NGS) has transformed clinical genetic testing by allowing the rapid screen for causative variants in multiple genes. There are currently no NGS-based multigene panel diagnostic tests available for epilepsy as a licensed clinical diagnostic test in Ontario, Canada. Eligible patient samples are sent out of country for testing by commercial laboratories, which incurs significant cost to the public healthcare system.
Objective:
An expert Working Group of medical geneticists, pediatric neurologists/epileptologists, biochemical geneticists, and clinical molecular geneticists from Ontario was formed by the Laboratories and Genetics Branch of the Ontario Ministry of Health and Long-Term Care to develop a programmatic approach to implementing epilepsy panel testing as a provincial service.
Results:
The Working Group made several recommendations for testing to support the clinical delivery of care in Ontario. First, an extension of community healthcare outcomes-based program should be incorporated to inform and educate ordering providers when requesting and interpreting a genetic panel test. Second, any gene panel testing must be “evidence-based” and takes into account varied clinical indications to reduce the chance of uncertain and secondary results. Finally, an ongoing evaluative process was recommended to ensure continued test improvement for the future.
Conclusion:
This epilepsy panel testing implementation plan will be a model for genetic care directed toward a specific set of conditions in the province and serve as a prototype for genetic testing for other genetically heterogeneous diseases.