Human genetics and genomics a decade after the release of the draft sequence of the human genome

Implementing Whole Genome Sequencing (WGS) in Clinical Practice: Advantages, Challenges, and Future Perspectives

The integration of whole genome sequencing (WGS) into all aspects of modern medicine represents the next step in the evolution of healthcare. Using this technology, scientists and physicians can observe the entire human genome comprehensively, generating a plethora of new sequencing data. Modern computational analysis entails advanced algorithms for variant detection, as well as complex models for classification. Data science and machine learning play a crucial role in the processing and interpretation of results, using enormous databases and statistics to discover new and support current genotype-phenotype correlations. In clinical practice, this technology has greatly enabled the development of personalized medicine, approaching each patient individually and in accordance with their genetic and biochemical profile. The most propulsive areas include rare disease genomics, oncogenomics, pharmacogenomics, neonatal screening, and infectious disease genomics. Another crucial application of WGS lies in the field of multi-omics, working towards the complete integration of human biomolecular data. Further technological development of sequencing technologies has led to the birth of third and fourth-generation sequencing, which include long-read sequencing, single-cell genomics, and nanopore sequencing. These technologies, alongside their continued implementation into medical research and practice, show great promise for the future of the field of medicine.

Identification of potential genetic causal variants for obesity-related traits using statistical fine mapping

BACKGROUND

Obesity is highly influenced by heritability and variant effects. While previous genome-wide association studies (GWASs) have successfully identified numerous genetic loci associated with obesity-related traits [body mass index (BMI) and waist-to-hip ratio (WHR)], most causal variants remain unidentified. The high degree of linkage disequilibrium (LD) throughout the genome makes it extremely difficult to distinguish the GWAS-associated SNPs that exert a true biological effect.

OBJECTIVE

This study was to identify the potential causal variants having a biological effect on obesity-related traits.

METHODS

We used Probabilistic Annotation INTegratOR, a Bayesian fine-mapping method, which incorporated genetic association data (GWAS summary statistics), LD structure, and functional annotations to calculate a posterior probability of causality for SNPs across all loci of interest. Moreover, we performed gene expression analysis using the available public transcriptomic data to validate the corresponding genes of the potential causal SNPs partially.

RESULTS

We identified 96 SNPs for BMI and 43 SNPs for WHR with a high posterior probability of causality (> 99%), including 49 BMI SNPs and 24 WHR SNPs which did not reach genome-wide significance in the original GWAS. Finally, we partially validated some genes corresponding to the potential causal SNPs.

CONCLUSION

Using a statistical fine-mapping approach, we identified a set of potential causal variants to be prioritized for future functional validation and also detected some novel trait-associated variants. These results provided novel insight into our understanding of the genetics of obesity and also demonstrated that fine mapping may improve upon the results identified by the original GWASs.

New Challenges for Anatomists in the Era of Omics

Anatomic studies have traditionally relied on macroscopic, microscopic, and histological techniques to investigate the structure of tissues and organs. Anatomic studies are essential in many fields, including medicine, biology, and veterinary science. Advances in technology, such as imaging techniques and molecular biology, continue to provide new insights into the anatomy of living organisms. Therefore, anatomy remains an active and important area in the scientific field. The consolidation in recent years of some omics technologies such as genomics, transcriptomics, proteomics, and metabolomics allows for a more complete and detailed understanding of the structure and function of cells, tissues, and organs. These have been joined more recently by "omics" such as radiomics, pathomics, and connectomics, supported by computer-assisted technologies such as neural networks, 3D bioprinting, and artificial intelligence. All these new tools, although some are still in the early stages of development, have the potential to strongly contribute to the macroscopic and microscopic characterization in medicine. For anatomists, it is time to hitch a ride and get on board omics technologies to sail to new frontiers and to explore novel scenarios in anatomy.

Long Non-Coding RNAs: The New Frontier into Understanding the Etiology of Alcohol Use Disorder

Alcohol use disorder (AUD) is a complex, chronic, debilitating condition impacting millions worldwide. Genetic, environmental, and epigenetic factors are known to contribute to the development of AUD. Long non-coding RNAs (lncRNAs) are a class of regulatory RNAs, commonly referred to as the “dark matter” of the genome, with little to no protein-coding potential. LncRNAs have been implicated in numerous processes critical for cell survival, suggesting that they play important functional roles in regulating different cell processes. LncRNAs were also shown to display higher tissue specificity than protein-coding genes and have a higher abundance in the brain and central nervous system, demonstrating a possible role in the etiology of psychiatric disorders. Indeed, genetic (e.g., genome-wide association studies (GWAS)), molecular (e.g., expression quantitative trait loci (eQTL)) and epigenetic studies from postmortem brain tissues have identified a growing list of lncRNAs associated with neuropsychiatric and substance use disorders. Given that the expression patterns of lncRNAs have been associated with widespread changes in the transcriptome, including methylation, chromatin architecture, and activation or suppression of translational activity, the regulatory nature of lncRNAs may be ubiquitous and an innate component of gene regulation. In this review, we present a synopsis of the functional impact that lncRNAs may play in the etiology of AUD. We also discuss the classifications of lncRNAs, their known functional roles, and therapeutic advancements in the field of lncRNAs to further clarify the functional relationship between lncRNAs and AUD.

Recent developments in systems biology and genetic engineering toward design of vaccines for TB

Tuberculosis (TB) is one of the most prevalent diseases worldwide. The currently available Bacillus Calmette-Guérin vaccine is not sufficient in protecting against pulmonary TB. Although many vaccines have been evaluated in clinical trials, but none of them yet has proven to be more successful. Thus, new strategies are urgently needed to design more effective TB vaccines. The emergence of new technologies will undoubtedly accelerate the process of vaccine development. This review summarizes the potential and validated applications of emerging technologies, including: systems biology (genomics, proteomics, and transcriptomics), genetic engineering, and other computational tools to discover and develop novel vaccines against TB. It also discussed that the significant implementation of these approaches will play crucial roles in the development of novel vaccines to cure and control TB.

Population differentiation and epidemic tracking of Bursaphelenchus xylophilus in China based on chromosome-level assembly and whole-genome sequencing data

BACKGROUND

Bursaphelenchus xylophilus, the pinewood nematode, kills millions of pine trees worldwide every year, and causes enormous economic and ecological losses. Despite extensive research on population variation, there is little understanding of the population-wide variation spectrum in China.

RESULTS

We sequenced an inbred B. xylophilus strain using Pacbio+Illumina+Bionano+Hi-C and generated a chromosome-level assembly (AH1) with six chromosomes of 77.1 Mb (chromosome N50: 12 Mb). The AH1 assembly shows very high continuity and completeness, and contains novel genes with potentially important functions compared with previous assemblies. Subsequently, we sequenced 181 strains from China and the USA and found ~7.8 million single nucleotide polymorphisms (SNPs). Analysis shows that the B. xylophilus population in China can be divided into geographically bounded subpopulations with severe cross-infection and potential migrations. In addition, distribution of B. xylophilus is dominated by temperature zones while geographically associated SNPs are mainly located on adaptation related GPCR gene families, suggesting the nematode has been evolving to adapt to different temperatures. A machine-learning based epidemic tracking method has been established to predict their geographical origins, which can be applied to any other species.

CONCLUSION

Our study provides the community with the first high-quality chromosome-level assembly which includes a comprehensive catalogue of genetic variations. It provides insights into population structure and effective tracking method for this invasive species, which facilitates future studies to address a variety of applied, genomic and evolutionary questions in B. xylophilus as well as related species.

The emerging roles of NGS in clinical oncology and personalized medicine

Next-generation sequencing (NGS) has been increasingly popular in genomics studies over the last decade, as new sequencing technology has been created and improved. Recently, NGS started to be used in clinical oncology to improve cancer therapy through diverse modalities ranging from finding novel and rare cancer mutations, discovering cancer mutation carriers to reaching specific therapeutic approaches known as personalized medicine (PM). PM has the potential to minimize medical expenses by shifting the current traditional medical approach of treating cancer and other diseases to an individualized preventive and predictive approach. Currently, NGS can speed up in the early diagnosis of diseases and discover pharmacogenetic markers that help in personalizing therapies. Despite the tremendous growth in our understanding of genetics, NGS holds the added advantage of providing more comprehensive picture of cancer landscape and uncovering cancer development pathways. In this review, we provided a complete overview of potential NGS applications in scientific and clinical oncology, with a particular emphasis on pharmacogenomics in the direction of precision medicine treatment options.

Role of MicroRNAs and their corresponding ACE2/Apelin signaling pathways in hypertension

Hypertension is controlled via the alteration of microRNAs (miRNAs), their therapeutic targets angiotensin II type I receptor (AT1R) and cross talk of signaling pathways. The stimulation of the Ang II/AT1R pathway by deregulation of miRNAs, has also been linked to cardiac remodeling as well as the pathophysiology of high blood pressure. As miRNAs have been associated to ACE2/Apelin and Mitogen-activated protein kinases (MAPK) signaling, it has revealed an utmost protective impact over hypertension and cardiovascular system. The ACE2-coupled intermodulation between RAAS, Apelin system, MAPK signaling pathways, and miRNAs reveal the practicalities of high blood pressure. The research of miRNAs may ultimately lead to the expansion of an innovative treatment strategy for hypertension, which indicates the need to explore them further at the molecular level. Therefore, here we have focused on the mechanistic importance of miRNAs in hypertension, ACE2/Apelin signaling as well as their biological functions, with a focus on interplay and crosstalk between ACE2/Apelin signaling, miRNAs, and hypertension, and the progress in miRNA-based diagnostic techniques with the goal of facilitating the development of new hypertension-controlling therapeutics.

Emerging Role of microRNAs in Stroke Protection Elicited by Remote Postconditioning

Remote ischemic conditioning (RIC) represents an innovative and attractive neuroprotective approach in brain ischemia. The purpose of this intervention is to activate endogenous tolerance mechanisms by inflicting a subliminal ischemia injury to the limbs, or to another “remote” region, leading to a protective systemic response against ischemic brain injury. Among the multiple candidates that have been proposed as putative mediators of the protective effect generated by the subthreshold peripheral ischemic insult, it has been hypothesized that microRNAs may play a vital role in the infarct-sparing effect of RIC. The effect of miRNAs can be exploited at different levels: (1) as transducers of protective messages to the brain or (2) as effectors of brain protection. The purpose of the present review is to summarize the most recent evidence supporting the involvement of microRNAs in brain protection elicited by remote conditioning, highlighting potential and pitfalls in their exploitation as diagnostic and therapeutic tools. The understanding of these processes could help provide light on the molecular pathways involved in brain protection for the future development of miRNA-based theranostic agents in stroke.

The design, implementation, and effectiveness of intervention strategies aimed at improving genetic referral practices: a systematic review of the literature

Purpose

Despite rapid advancements in genetics and genomics, referral practices remain suboptimal. This systematic review assesses the extent to which approaches from implementation science have been applied to address suboptimal genetic referral practices.

Methods

A search of MEDLINE, EMBASE, and PsycINFO generated 7,794 articles, of which 28 were included. Lay barriers were mapped to the Theoretical Domains Framework (TDF) and interventions mapped to behavior change techniques. Use of implementation and behavior change frameworks was assessed, and the Theory and Techniques Tool used to determine theoretical alignment.

Results

Knowledge was the most frequent retrospectively TDF-coded barrier, followed by environmental context and resources, and skills. Significant referral improvements occurred in 56% of studies. Among these, the most frequent interventions were clinical data review systems, family history collection and referral tools, and embedding genetics staff into nongenetic specialties. Few studies used implementation frameworks or reported implementation outcomes, though some deployed intuitive strategies that aligned with theory.

Conclusion

Genetic referral interventions are rarely informed by implementation and/or behavior change theories, limiting opportunities for learning across contexts. Retrospective coding has provided a suite of theoretically linked strategies, which may be useful for informing future efforts. Incorporating these strategies into clinical guidelines may facilitate operationalization within the system.

The influence of X chromosome variants on trait neuroticism

Autosomal variants have successfully been associated with trait neuroticism in genome-wide analysis of adequately powered samples. But such studies have so far excluded the X chromosome from analysis. Here, we report genetic association analyses of X chromosome and XY pseudoautosomal single nucleotide polymorphisms (SNPs) and trait neuroticism using UK Biobank samples (N = 405,274). Significant association was found with neuroticism on the X chromosome for 204 markers found within three independent loci (a further 783 were suggestive). Most of the lead neuroticism-related X chromosome variants were located in intergenic regions (n = 397). Involvement of HS6ST2, which has been previously associated with sociability behaviour in the dog, was supported by single SNP and gene-based tests. We found that the amino acid and nucleotide sequences are highly conserved between dogs and humans. From the suggestive X chromosome variants, there were 19 nearby genes which could be linked to gene ontology information. Molecular function was primarily related to binding and catalytic activity; notable biological processes were cellular and metabolic, and nucleic acid binding and transcription factor protein classes were most commonly involved. X-variant heritability of neuroticism was estimated at 0.22% (SE = 0.05) from a full dosage compensation model. A polygenic X-variant score created in an independent sample (maximum N ≈ 7,300) did not predict significant variance in neuroticism, psychological distress, or depressive disorder. We conclude that the X chromosome harbours significant variants influencing neuroticism, and might prove important for other quantitative traits and complex disorders.

AGE/RAGE signaling-mediated endoplasmic reticulum stress and future prospects in non-coding RNA therapeutics for diabetic nephropathy

Disturbance of endoplasmic reticulum (ER) homeostasis triggered by the accumulation of unfolded proteins and advanced glycation end-products (AGEs) plays a major role in pathophysiology of diabetic nephropathy. Activation of receptor for AGEs (RAGE) stimulates NADPH oxidase-mediated reactive oxygen species (ROS) production, leading to ER stress, inflammation, glomerular hypertrophy, podocyte injury, and renal fibrosis. A growing body of evidence indicates that non-coding RNAs (ncRNAs) could rescue ER stress and renal inflammation by the epigenetic modification. This review summarizes ncRNA regulation in AGE/RAGE signaling-mediated ER stress, and discusses the opportunities and challenges of ncRNA-loaded extracellular vesicle therapy in diabetic nephropathy.

The Nigerian Bioinformatics and Genomics Network (NBGN): a collaborative platform to advance bioinformatics and genomics in Nigeria

Africa plays a central importance role in the human origins, and disease susceptibility, agriculture and biodiversity conservation. Nigeria as the most populous and most diverse country in Africa, owing to its 250 ethnic groups and over 500 different native languages is imperative to any global genomic initiative. The newly inaugurated Nigerian Bioinformatics and Genomics Network (NBGN) becomes necessary to facilitate research collaborative activities and foster opportunities for skills' development amongst Nigerian bioinformatics and genomics investigators. NBGN aims to advance and sustain the fields of genomics and bioinformatics in Nigeria by serving as a vehicle to foster collaboration, provision of new opportunities for interactions between various interdisciplinary subfields of genomics, computational biology and bioinformatics as this will provide opportunities for early career researchers. To provide the foundation for sustainable collaborations, the network organises conferences, workshops, trainings and create opportunities for collaborative research studies and internships, recognise excellence, openly share information and create opportunities for more Nigerians to develop the necessary skills to exceed in genomics and bioinformatics. NBGN currently has attracted more than 650 members around the world. Research collaborations between Nigeria, Africa and the West will grow and all stakeholders, including funding partners, African scientists, researchers across the globe, physicians and patients will be the eventual winners. The exponential membership growth and diversity of research interests of NBGN just within weeks of its establishment and the unanticipated attendance of its activities suggest the significant importance of the network to bioinformatics and genomics research in Nigeria.

Unbalanced Sample Size Introduces Spurious Correlations to Genome-Wide Heterozygosity Analyses

Excess of heterozygosity (H) is a widely used measure of genetic diversity of a population. As high-throughput sequencing and genotyping data become readily available, it has been applied to investigating the associations of genome-wide genetic diversity with human diseases and traits. However, these studies often report contradictory results. In this paper, we present a meta-analysis of five whole-exome studies to examine the association of H scores with Alzheimer's disease. We show that the mean H score of a group is not associated with the disease status, but ot is associated with the sample size. Across all five studies, the group with more samples has a significantly lower H score than the group with fewer samples. To remove potential confounders in empirical data sets, we perform computer simulations to create artificial genomes controlled for the number of polymorphic loci, the sample size, and the allele frequency. Analyses of these simulated data confirm the negative correlation between the sample size and the H score. Furthermore, we find that genomes with a large number of rare variants also have inflated H scores. These biases altogether can lead to spurious associations between genetic diversity and the phenotype of interest. Based on these findings, we advocate that studies shall balance the sample sizes when using genome-wide H scores to assess genetic diversities of different populations, which helps improve the reproducibility of future research.

The Genetic Architecture of Kidney Disease

The kidney is subject to a wide range of abnormalities, many of which have a significant hereditable component. Next generation sequencing is increasingly bringing the genetic drivers of Mendelian disease into focus at the base pair level, whereas inexpensive genotyping arrays have surveyed hundreds of thousands of individuals to identify common variants that predispose to kidney dysfunction. In this first article in a CJASN series on kidney genomics, we review how both rare and common variants contribute to kidney disease, explore how evolution may influence the genetic variants that affect kidney function, consider how genetic information is and will be used in the clinic, and identify some of the most important future directions for kidney disease research. Forthcoming articles in the series will elaborate on many of these themes.

Factors associated with willingness to provide biospecimens for genetics research among African American cancer survivors

This study evaluated factors associated with willingness to provide biospecimens for cancer genetic research among African American cancer survivors. A total of 200 African American adults diagnosed with breast, colon, and/or prostate cancers completed a self-administered survey. Family history information, beliefs about cancer research, cancer genetics and disparities knowledge, willingness to provide a biospecimen, and demographics were obtained. Chi-square, independent samples t tests, and logistic regression analyses were performed. Overall, 79% of this sample was willing to provide a biospecimen for cancer genetics research. Independent associations of willingness to provide a biospecimen existed among demographics (males (p = 0.041)), those who believed in the importance of genetic causes of cancer (p < 0.001), individuals who believe it is important to participate in genetics research (p < 0.001), and those who indicated they would participate in genetics research to help future generations (p = 0.026). Overall, 12.5-56% of participants demonstrated some level of genetics and cancer disparities. This study identified factors that may be incorporated into future research interventions to engage the African American cancer population in cancer genetics biobanking research.

CytoConverter: a web-based tool to convert karyotypes to genomic coordinates

BACKGROUND

Cytogenetic nomenclature is used to describe chromosomal aberrations (or lack thereof) in a collection of cells, referred to as the cells' karyotype. The nomenclature identifies locations on chromosomes using a system of cytogenetic bands, each with a unique name and region on a chromosome. Each band is microscopically visible after staining, and encompasses a large portion of the chromosome. More modern analyses employ genomic coordinates, which precisely specify a chromosomal location according to its distance from the end of the chromosome. Currently, there is no tool to convert cytogenetic nomenclature into genomic coordinates. Since locations of genes and other genomic features are usually specified by genomic coordinates, a conversion tool will facilitate the identification of the features that are harbored in the regions of chromosomal gain and loss that are implied by a karyotype.

RESULTS

Our tool, termed CytoConverter, takes as input either a single karyotype or a file consisting of multiple karyotypes from several individuals. All net chromosomal gains and losses implied by the karyotype are returned in standard genomic coordinates, along with the numbers of cells harboring each aberration if included in the input. CytoConverter also returns graphical output detailing areas of gains and losses of chromosomes and chromosomal segments.

CONCLUSIONS

CytoConverter is available as a web-based application at https://jxw773.shinyapps.io/Cytogenetic__software/ and as an R script at https://sourceforge.net/projects/cytoconverter/ . Supplemental Material detailing the underlying algorithms is available.

Iranome: A catalog of genomic variations in the Iranian population

Considering the application of human genome variation databases in precision medicine, population-specific genome projects are continuously being developed. However, the Middle Eastern population is underrepresented in current databases. Accordingly, we established Iranome database (www.iranome.com) by performing whole exome sequencing on 800 individuals from eight major Iranian ethnic groups representing the second largest population of Middle East. We identified 1,575,702 variants of which 308,311 were novel (19.6%). Also, by presenting higher frequency for 37,384 novel or known rare variants, Iranome database can improve the power of molecular diagnosis. Moreover, attainable clinical information makes this database a good resource for classifying pathogenicity of rare variants. Principal components analysis indicated that, apart from Iranian-Baluchs, Iranian-Turkmen, and Iranian-Persian Gulf Islanders, who form their own clusters, rest of the population were genetically linked, forming a super-population. Furthermore, only 0.6% of novel variants showed counterparts in "Greater Middle East Variome Project", emphasizing the value of Iranome at national level by releasing a comprehensive catalog of Iranian genomic variations and also filling another gap in the catalog of human genome variations at international level. We introduce Iranome as a resource which may also be applicable in other countries located in neighboring regions historically called Greater Iran (Persia).

Recurrent miscalling of missense variation from short-read genome sequence data

Background

Short-read resequencing of genomes produces abundant information of the genetic variation of individuals. Due to their numerous nature, these variants are rarely exhaustively validated. Furthermore, low levels of undetected variant miscalling will have a systematic and disproportionate impact on the interpretation of individual genome sequence information, especially should these also be carried through into in reference databases of genomic variation.

Results

We find that sequence variation from short-read sequence data is subject to recurrent-yet-intermittent miscalling that occurs in a sequence intrinsic manner and is very sensitive to sequence read length. The miscalls arise from difficulties aligning short reads to redundant genomic regions, where the rate of sequencing error approaches the sequence diversity between redundant regions. We find the resultant miscalled variants to be sensitive to small sequence variations between genomes, and thereby are often intrinsic to an individual, pedigree, strain or human ethnic group. In human exome sequences, we identify 2–300 recurrent false positive variants per individual, almost all of which are present in public databases of human genomic variation. From the exomes of non-reference strains of inbred mice, we identify 3–5000 recurrent false positive variants per mouse – the number of which increasing with greater distance between an individual mouse strain and the reference C57BL6 mouse genome. We show that recurrently miscalled variants may be reproduced for a given genome from repeated simulation rounds of read resampling, realignment and recalling. As such, it is possible to identify more than two-thirds of false positive variation from only ten rounds of simulation.

Conclusion

Identification and removal of recurrent false positive variants from specific individual variant sets will improve overall data quality. Variant miscalls arising are highly sequence intrinsic and are often specific to an individual, pedigree or ethnicity. Further, read length is a strong determinant of whether given false variants will be called for any given genome – which has profound significance for cohort studies that pool datasets collected and sequenced at different points in time.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5863-2) contains supplementary material, which is available to authorized users.

RT States: systematic annotation of the human genome using cell type-specific replication timing programs

MOTIVATION

The replication timing (RT) program has been linked to many key biological processes including cell fate commitment, 3D chromatin organization and transcription regulation. Significant technology progress now allows to characterize the RT program in the entire human genome in a high-throughput and high-resolution fashion. These experiments suggest that RT changes dynamically during development in coordination with gene activity. Since RT is such a fundamental biological process, we believe that an effective quantitative profile of the local RT program from a diverse set of cell types in various developmental stages and lineages can provide crucial biological insights for a genomic locus.

RESULTS

In this study, we explored recurrent and spatially coherent combinatorial profiles from 42 RT programs collected from multiple lineages at diverse differentiation states. We found that a Hidden Markov Model with 15 hidden states provide a good model to describe these genome-wide RT profiling data. Each of the hidden state represents a unique combination of RT profiles across different cell types which we refer to as 'RT states'. To understand the biological properties of these RT states, we inspected their relationship with chromatin states, gene expression, functional annotation and 3D chromosomal organization. We found that the newly defined RT states possess interesting genome-wide functional properties that add complementary information to the existing annotation of the human genome.

AVAILABILITY AND IMPLEMENTATION

R scripts for inferring HMM models and Perl scripts for further analysis are available https://github.com/PouletAxel/script_HMM_Replication_timing.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Metabolomics Analysis of Mesenchymal Stem Cells

Various mesenchymal stem cells as easily accessible and multipotent cells can share different essential signaling pathways related to their stemness ability. Understanding the mechanism of stemness ability can be useful for controlling the stem cells for regenerative medicine targets. In this context, OMICs studies can analyze the mechanism of different stem cell properties or stemness ability via a broad range of current high-throughput techniques. This field is fundamentally directed toward the analysis of whole genome (genomics), mRNAs (transcriptomics), proteins (proteomics) and metabolites (metabolomics) in biological samples. According to several studies, metabolomics is more effective than other OMICs ّfor various system biology concerns. Metabolomics can elucidate the biological mechanisms of various mesenchymal stem cell function by measuring their metabolites such as their secretome components. Analyzing the metabolic alteration of mesenchymal stem cells can be useful to promote their regenerative medicine application.

The genetic basis of disease

Genetics plays a role, to a greater or lesser extent, in all diseases. Variations in our DNA and differences in how that DNA functions (alone or in combinations), alongside the environment (which encompasses lifestyle), contribute to disease processes. This review explores the genetic basis of human disease, including single gene disorders, chromosomal imbalances, epigenetics, cancer and complex disorders, and considers how our understanding and technological advances can be applied to provision of appropriate diagnosis, management and therapy for patients.

The Collaborative African Genomics Network (CAfGEN): Applying Genomic technologies to probe host factors important to the progression of HIV and HIV-tuberculosis infection in sub-Saharan Africa

Background: Here, we describe how the Collaborative African Genomics Network ( CAfGEN) of the Human Heredity and Health in Africa (H3Africa) consortium is using genomics to probe host genetic factors important to the progression of HIV and HIV-tuberculosis (TB) coinfection in sub-Saharan Africa.   The H3Africa was conceived to facilitate the application of genomics technologies to improve health across Africa..          Methods: CAfGEN is an H3Africa collaborative centre comprising expertise from the University of Botswana; Makerere University; Baylor College of Medicine Children's Clinical Centers of Excellence (COEs) in Botswana, Uganda, and Swaziland; as well as Baylor College of Medicine, Texas. The COEs provide clinical expertise for community engagement, participant recruitment and sample collection while the three University settings facilitate processing and management of genomic samples and provide infrastructure and training opportunities to sustain genomics research. Results: The project has focused on utilizing whole-exome sequencing to identify genetic variants contributing to extreme HIV disease progression phenotypes in children, as well as RNA sequencing and integrated genomics to identify host genetic factors associated with TB disease progression among HIV-positive children. These cohorts, developed using the COEs' electronic medical records, are exceptionally well-phenotyped and present an unprecedented opportunity to assess genetic factors in individuals whose HIV was acquired by a different route than their adult counterparts in the context of a unique clinical course and disease pathophysiology. Conclusions: Our approach offers the prospect of developing a critical mass of well-trained, highly-skilled, continent-based African genomic scientists. To ensure long term genomics research sustainability in Africa, CAfGEN contributes to a wide range of genomics capacity and infrastructure development on the continent, has laid a foundation for genomics graduate programs at its institutions, and continues to actively promote genomics research through innovative forms of community engagement brokered by partnerships with governments and academia to support genomics policy formulation.

SeqAcademy: an educational pipeline for RNA-Seq and anchor-Seq analysis

Quantification of gene expression and characterization of gene transcript structures are central problems in molecular biology. RNA sequencing (RNA-Seq) and chromatin immunoprecipitation sequencing (anchor-Seq) are important methods, but can be cumbersome and difficult for beginners to learn. To teach interested students and scientists how to analyze RNA-Seq and anchor-Seq data, we present a start-to-finish tutorial for analyzing RNA-Seq and anchor-Seq data: SeqAcademy ( source code:  https://github.com/NCBI-Hackathons/seqacademy, webpage: http://www.seqacademy.org/). This user-friendly pipeline, fully written in markdown language, emphasizes the use of publicly available RNA-Seq and anchor-Seq data and strings together popular tools that bridge that gap between raw sequencing reads and biological insight. We demonstrate practical and conceptual considerations for various RNA-Seq and anchor-Seq analysis steps with a biological use case - a previously published yeast experiment. This work complements existing sophisticated RNA-Seq and anchor-Seq pipelines designed for advanced users by gently introducing the critical components of RNA-Seq and anchor-Seq analysis to the novice bioinformatician. In conclusion, this well-documented pipeline will introduce state-of-the-art RNA-Seq and anchor-Seq analysis tools to beginning bioinformaticians and help facilitate the analysis of the burgeoning amounts of public RNA-Seq and anchor-Seq data.

SeqAcademy: an educational pipeline for RNA-Seq and ChIP-Seq analysis

Quantification of gene expression and characterization of gene transcript structures are central problems in molecular biology. RNA sequencing (RNA-Seq) and chromatin immunoprecipitation sequencing (ChIP-Seq) are important methods, but can be cumbersome and difficult for beginners to learn. To teach interested students and scientists how to analyze RNA-Seq and ChIP-Seq data, we present a start-to-finish tutorial for analyzing RNA-Seq and ChIP-Seq data: SeqAcademy ( source code:  https://github.com/NCBI-Hackathons/seqacademy, webpage: http://www.seqacademy.org/). This user-friendly pipeline, fully written in Jupyter Notebook, emphasizes the use of publicly available RNA-Seq and ChIP-Seq data and strings together popular tools that bridge that gap between raw sequencing reads and biological insight. We demonstrate practical and conceptual considerations for various RNA-Seq and ChIP-Seq analysis steps with a biological use case - a previously published yeast experiment. This work complements existing sophisticated RNA-Seq and ChIP-Seq pipelines designed for advanced users by gently introducing the critical components of RNA-Seq and ChIP-Seq analysis to the novice bioinformatician. In conclusion, this well-documented pipeline will introduce state-of-the-art RNA-Seq and ChIP-Seq analysis tools to beginning bioinformaticians and help facilitate the analysis of the burgeoning amounts of public RNA-Seq and ChIP-Seq data.

SeqAcademy: an educational pipeline for RNA-Seq and ChIP-Seq analysis

Quantification of gene expression and characterization of gene transcript structures are central problems in molecular biology. RNA sequencing (RNA-Seq) and chromatin immunoprecipitation sequencing (ChIP-Seq) are important methods, but can be cumbersome and difficult for beginners to learn. To teach interested students and scientists how to analyze RNA-Seq and ChIP-Seq data, we present a start-to-finish tutorial for analyzing RNA-Seq and ChIP-Seq data: SeqAcademy ( source code:  https://github.com/NCBI-Hackathons/seqacademy, webpage: http://www.seqacademy.org/). This user-friendly pipeline, fully written in markdown language, emphasizes the use of publicly available RNA-Seq and ChIP-Seq data and strings together popular tools that bridge that gap between raw sequencing reads and biological insight. We demonstrate practical and conceptual considerations for various RNA-Seq and ChIP-Seq analysis steps with a biological use case - a previously published yeast experiment. This work complements existing sophisticated RNA-Seq and ChIP-Seq pipelines designed for advanced users by gently introducing the critical components of RNA-Seq and ChIP-Seq analysis to the novice bioinformatician. In conclusion, this well-documented pipeline will introduce state-of-the-art RNA-Seq and ChIP-Seq analysis tools to beginning bioinformaticians and help facilitate the analysis of the burgeoning amounts of public RNA-Seq and ChIP-Seq data.

SeqAcademy: an educational pipeline for RNA-Seq and ChIP-Seq analysis

Quantification of gene expression and characterization of gene transcript structures are central problems in molecular biology. RNA sequencing (RNA-Seq) and chromatin immunoprecipitation sequencing (ChIP-Seq) are important methods, but can be cumbersome and difficult for beginners to learn. To teach interested students and scientists how to analyze RNA-Seq and ChIP-Seq data, we present a start-to-finish tutorial for analyzing RNA-Seq and ChIP-Seq data: SeqAcademy ( source code:  https://github.com/NCBI-Hackathons/seqacademy, webpage: http://www.seqacademy.org/). This user-friendly pipeline, fully written in Jupyter Notebook, emphasizes the use of publicly available RNA-Seq and ChIP-Seq data and strings together popular tools that bridge that gap between raw sequencing reads and biological insight. We demonstrate practical and conceptual considerations for various RNA-Seq and ChIP-Seq analysis steps with a biological use case - a previously published yeast experiment. This work complements existing sophisticated RNA-Seq and ChIP-Seq pipelines designed for advanced users by gently introducing the critical components of RNA-Seq and ChIP-Seq analysis to the novice bioinformatician. In conclusion, this well-documented pipeline will introduce state-of-the-art RNA-Seq and ChIP-Seq analysis tools to beginning bioinformaticians and help facilitate the analysis of the burgeoning amounts of public RNA-Seq and ChIP-Seq data.

Novel functional variants at the GWAS-implicated loci might confer risk to major depressive disorder, bipolar affective disorder and schizophrenia

BACKGROUND

A challenge of understanding the mechanisms underlying cognition including neurodevelopmental and neuropsychiatric disorders is mainly given by the potential severity of cognitive disorders for the quality of life and their prevalence. However, the field has been focused predominantly on protein coding variation until recently. Given the importance of tightly controlled gene expression for normal brain function, the goal of the study was to assess the functional variation including non-coding variation in human genome that is likely to play an important role in cognitive functions. To this end, we organized and utilized available genome-wide datasets from genomic, transcriptomic and association studies into a comprehensive data corpus. We focused on genomic regions that are enriched in regulatory activity-overlapping transcriptional factor binding regions and repurpose our data collection especially for identification of the regulatory SNPs (rSNPs) that showed associations both with allele-specific binding and allele-specific expression. We matched these rSNPs to the nearby and distant targeted genes and then selected the variants that could implicate the etiology of cognitive disorders according to Genome-Wide Association Studies (GWAS). Next, we use DeSeq 2.0 package to test the differences in the expression of the certain targeted genes between the controls and the patients that were diagnosed bipolar affective disorder and schizophrenia. Finally, we assess the potential biological role for identified drivers of cognition using DAVID and GeneMANIA.

RESULTS

As a result, we selected fourteen regulatory SNPs locating within the loci, implicated from GWAS for cognitive disorders with six of the variants unreported previously. Grouping of the targeted genes according to biological functions revealed the involvement of processes such as 'posttranscriptional regulation of gene expression', 'neuron differentiation', 'neuron projection development', 'regulation of cell cycle process' and 'protein catabolic processes'. We identified four rSNP-targeted genes that showed differential expression between patient and control groups depending on brain region: NRAS-in schizophrenia cohort, CDC25B, DDX21 and NUCKS1-in bipolar disorder cohort.

CONCLUSIONS

Overall, our findings are likely to provide the keys for unraveling the mechanisms that underlie cognitive functions including major depressive disorder, bipolar disorder and schizophrenia etiopathogenesis.

The Collaborative African Genomics Network (CAfGEN): Applying Genomic technologies to probe host factors important to the progression of HIV and HIV-tuberculosis infection in sub-Saharan Africa

Background: The Human Heredity and Health in Africa consortium (H3Africa) was conceived to facilitate the application of genomics technologies to improve health across Africa. Here, we describe how the Collaborative African Genomics Network (CAfGEN) of the H3Africa consortium is using genomics to probe host genetic factors important to the progression of HIV and HIV-tuberculosis (TB) coinfection in sub-Saharan Africa.          Methods: CAfGEN is an H3Africa collaborative centre comprising expertise from the University of Botswana; Makerere University; Baylor College of Medicine Children’s Clinical Centers of Excellence (COEs) in Botswana, Uganda, and Swaziland; as well as Baylor College of Medicine, Texas. The COEs provide clinical expertise for community engagement, participant recruitment and sample collection while the three University settings facilitate processing and management of genomic samples and provide infrastructure and training opportunities to sustain genomics research. Results: The project has focused on utilizing whole-exome sequencing to identify genetic variants contributing to extreme HIV disease progression phenotypes in children, as well as RNA sequencing and integrated genomics to identify host genetic factors associated with TB disease progression among HIV-positive children. These cohorts, developed using the COEs’ electronic medical records, are exceptionally well-phenotyped and present an unprecedented opportunity to assess genetic factors in individuals whose HIV was acquired by a different route than their adult counterparts in the context of a unique clinical course and disease pathophysiology. Conclusions: Our approach offers the prospect of developing a critical mass of well-trained, highly-skilled, continent-based African genomic scientists. To ensure long term genomics research sustainability in Africa, CAfGEN contributes to a wide range of genomics capacity and infrastructure development on the continent, has laid a foundation for genomics graduate programs at its institutions, and continues to actively promote genomics research through innovative forms of community engagement brokered by partnerships with governments and academia to support genomics policy formulation.

The Epstein-Barr Virus Episome Maneuvers between Nuclear Chromatin Compartments during Reactivation

The human genome is structurally organized in three-dimensional space to facilitate functional partitioning of transcription. We learned that the latent episome of the human Epstein-Barr virus (EBV) preferentially associates with gene-poor chromosomes and avoids gene-rich chromosomes. Kaposi's sarcoma-associated herpesvirus behaves similarly, but human papillomavirus does not. Contacts on the EBV side localize to OriP, the latent origin of replication. This genetic element and the EBNA1 protein that binds there are sufficient to reconstitute chromosome association preferences of the entire episome. Contacts on the human side localize to gene-poor and AT-rich regions of chromatin distant from transcription start sites. Upon reactivation from latency, however, the episome moves away from repressive heterochromatin and toward active euchromatin. Our work adds three-dimensional relocalization to the molecular events that occur during reactivation. Involvement of myriad interchromosomal associations also suggests a role for this type of long-range association in gene regulation.

IMPORTANCE The human genome is structurally organized in three-dimensional space, and this structure functionally affects transcriptional activity. We set out to investigate whether a double-stranded DNA virus, Epstein-Barr virus (EBV), uses mechanisms similar to those of the human genome to regulate transcription. We found that the EBV genome associates with repressive compartments of the nucleus during latency and with active compartments during reactivation. This study advances our knowledge of the EBV life cycle, adding three-dimensional relocalization as a novel component to the molecular events that occur during reactivation. Furthermore, the data add to our understanding of nuclear compartments, showing that disperse interchromosomal interactions may be important for regulating transcription.

Patterns of biomarkers for three phenotype profiles of persisting specific learning disabilities during middle childhood and early adolescence: A preliminary study

Students without specific learning disabilities [SLDs] [n=18] and with one of three persisting SLDs in written language despite early and current specialized instruction-Dysgraphia [n=21], Dyslexia [n=40], or oral and written language learning disability OWL LD [n=14]- in grades 4 to 9 [N=56 boys, 38 girls] completed behavioral phenotyping assessment and gave a small blood or saliva sample. Molecular analyses informed by current cross-site research on gene candidates for learning disabilities identified associations between molecular genetic markers and the two defining behavioral phenotypes for each SLDs-WL; dysgraphia [impaired writing alphabet from memory for rs3743204 and sentence copying in best handwriting for rs79382 both in DYX1C1], dyslexia [impaired silent word reading/decoding rate for rs4535189 in DCDC2 and impaired spelling/encoding for rs374205 in DYX1C1], and OWL LD [impaired aural syntax comprehension for rs807701 and oral syntax construction for rs807701 both in DYX1C1]. Implications of these identified associations between molecular markers for alleles for different sites within two gene candidates [and mostly one] and hallmark phenotypes are discussed for translation science [application to practice] and neuroimaging that has identified contrasting brain bases for each of the three SLDs.

Next generation sequencing: clinical applications in solid tumours

Next generation sequencing (NGS) has unravelled the genetic alterations that underlie the pathogenesis of cancer. It is now becoming integrated into routine clinical diagnostics of malignant tumours. NGS supports diagnosis, identifies therapeutic targets, reveals resistance mechanisms and facilitates disease monitoring. It takes a central function in the implementation of cancer therapies adapted to the molecular alterations of tumours.

Contribution of Next-Generation Sequencing to Aquatic and Fish Virology

The recent technological advances in nucleic acid sequencing, called next-generation sequencing (NGS), have revolutionized the field of genomics and have also influenced viral research. Aquatic viruses, and especially those infecting fish, have also greatly benefited from NGS technologies, which provide a huge amount of molecular information at a low cost in a relatively short period of time. Here, we review the use of the current high-throughput sequencing platforms with a special focus on the associated challenges (regarding sample preparation and bioinformatics) in their applications to the field of aquatic virology, especially for: (i) discovering novel viruses that may be associated with fish mortalities, (ii) elucidating the mechanisms of pathogenesis, and finally (iii) studying the molecular epidemiology of these pathogens.

The association of insertions/deletions (INDELs) and variable number tandem repeats (VNTRs) with obesity and its related traits and complications

BACKGROUND

Despite the fact that insertions/deletions (INDELs) are the second most common type of genetic variations and variable number tandem repeats (VNTRs) represent a large portion of the human genome, they have received far less attention than single nucleotide polymorphisms (SNPs) and larger forms of structural variation like copy number variations (CNVs), especially in genome-wide association studies (GWAS) of complex diseases like polygenic obesity. This is exemplified by the vast amount of review papers on the role of SNPs and CNVs in obesity, its related traits (like anthropometric measurements, biochemical variables, and eating behavior), and its related complications (like hypertension, hypertriglyceridemia, hypercholesterolemia, and insulin resistance-collectively known as metabolic syndrome). Hence, this paper reviews the types of INDELs and VNTRs that have been studied for association with obesity and its related traits and complications. These INDELs and VNTRs could be found in the obesity loci or genes from the earliest GWAS and candidate gene association studies, like FTO, genes in the leptin-proopiomelanocortin pathway, and UCP2/3. Given the important role of the brain serotonergic and dopaminergic reward system in obesity susceptibility, the association of INDELs and VNTRs in these neurotransmitters' metabolism and transport genes with obesity is also reviewed. Next, the role of INS VNTR in obesity and its related traits is questionable, since recent large-scale studies failed to replicate the earlier positive associations. As obesity results in chronic low-grade inflammation of the adipose tissue, the proinflammatory cytokine gene IL1RA and anti-inflammatory cytokine gene IL4 have VNTRs that are implicated in obesity. A systemic proinflammatory state in combination with activation of the renin-angiotensin system and decreased nitric oxide bioavailability as found in obesity leads to endothelial dysfunction. This explains why VNTR and INDEL in eNOS and ACE, respectively, could be predisposing factors of obesity. Finally, two novel genes, DOCK5 and PER3, which are involved in the regulation of the Akt/MAPK pathway and circadian rhythm, respectively, have VNTRs and INDEL that might be associated with obesity.

SHORT CONCLUSION

In conclusion, INDELs and VNTRs could have important functional consequences in the pathophysiology of obesity, and research on them should be continued to facilitate obesity prediction, prevention, and treatment.

Pharmacogenomics in Asia: a systematic review on current trends and novel discoveries

While early pharmacogenomic studies have primarily been carried out in Western populations, there has been a notable increase in the number of Asian studies over the past decade. We systematically reviewed all pharmacogenomic studies conducted in Asia published before 2016 to highlight trends and identify research gaps in Asia. We observed that pharmacogenomic research in Asia was dominated by larger developed countries, notably Japan and Korea, and mainly driven by local researchers. Studies were focused on drugs acting on the CNS, chemotherapeutics and anticoagulants. Significantly, several novel pharmacogenomic associations have emerged from Asian studies. These developments are highly encouraging for the strength of regional scientific and clinical community and propound the importance of discovery studies in different populations.

Advantages of genome sequencing by long-read sequencer using SMRT technology in medical area

PacBio RS II is the first commercialized third-generation DNA sequencer able to sequence a single molecule DNA in real-time without amplification. PacBio RS II's sequencing technology is novel and unique, enabling the direct observation of DNA synthesis by DNA polymerase. PacBio RS II confers four major advantages compared to other sequencing technologies: long read lengths, high consensus accuracy, a low degree of bias, and simultaneous capability of epigenetic characterization. These advantages surmount the obstacle of sequencing genomic regions such as high/low G+C, tandem repeat, and interspersed repeat regions. Moreover, PacBio RS II is ideal for whole genome sequencing, targeted sequencing, complex population analysis, RNA sequencing, and epigenetics characterization. With PacBio RS II, we have sequenced and analyzed the genomes of many species, from viruses to humans. Herein, we summarize and review some of our key genome sequencing projects, including full-length viral sequencing, complete bacterial genome and almost-complete plant genome assemblies, and long amplicon sequencing of a disease-associated gene region. We believe that PacBio RS II is not only an effective tool for use in the basic biological sciences but also in the medical/clinical setting.

Fast detection of deletion breakpoints using quantitative PCR

The routine detection of large and medium copy number variants (CNVs) is well established. Hemizygotic deletions or duplications in the large Duchenne muscular dystrophy DMD gene responsible for Duchenne and Becker muscular dystrophies are routinely identified using multiple ligation probe amplification and array-based comparative genomic hybridization. These methods only map deleted or duplicated exons, without providing the exact location of breakpoints. Commonly used methods for the detection of CNV breakpoints include long-range PCR and primer walking, their success being limited by the deletion size, GC content and presence of DNA repeats. Here, we present a strategy for detecting the breakpoints of medium and large CNVs regardless of their size. The hemizygous deletion of exons 45-50 in the DMD gene and the large autosomal heterozygous PARK2 deletion were used to demonstrate the workflow that relies on real-time quantitative PCR to narrow down the deletion region and Sanger sequencing for breakpoint confirmation. The strategy is fast, reliable and cost-efficient, making it amenable to widespread use in genetic laboratories.

An 'Omics' Perspective on Cardiomyopathies and Heart Failure

Pathological enlargement of the heart, represented by hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM), occurs in response to many genetic and non-genetic factors. The clinical course of cardiac hypertrophy is remarkably variable, ranging from lifelong absence of symptoms to rapidly declining heart function and sudden cardiac death (SCD). Unbiased omics studies have begun to provide a glimpse into the molecular framework underpinning altered mechanotransduction, mitochondrial energetics, oxidative stress, and extracellular matrix in the heart undergoing physiological and pathological hypertrophy. Omics analyses indicate that post-transcriptional regulation of gene expression plays an overriding role in the normal and diseased heart. Studies to date highlight a need for more effective bioinformatics to better integrate patient omics data with their comprehensive clinical histories.

Systems Genetic Validation of the SNP-Metabolite Association in Rice Via Metabolite-Pathway-Based Phenome-Wide Association Scans

In the post-GWAS (Genome-Wide Association Scan) era, the interpretation of GWAS results is crucial to screen for highly relevant phenotype-genotype association pairs. Based on the single genotype-phenotype association test and a pathway enrichment analysis, we propose a Metabolite-pathway-based Phenome-Wide Association Scan (M-PheWAS) to analyze the key metabolite-SNP pairs in rice and determine the regulatory relationship by assessing similarities in the changes of enzymes and downstream products in a pathway. Two SNPs, sf0315305925 and sf0315308337, were selected using this approach, and their molecular function and regulatory relationship with Enzyme EC:5.5.1.6 and with flavonoids, a significant downstream regulatory metabolite product, were demonstrated. Moreover, a total of 105 crucial SNPs were screened using M-PheWAS, which may be important for metabolite associations.

Evolving Roles for Physicians and Genetic Counselors in Managing Complex Genetic Disorders

Proponents of personalized medicine predict that genetic information will provide pivotal perspectives for the prevention and management of complex disorders. Personalized medicine differs from traditional Western medicine, in that it focuses on more complex disorders that require mechanistic disease modeling and outcome simulation by integrating genomic risk, environmental stressors, and biomarkers as indicators of disease state. This information could be useful to guide targeted therapy and prevent pathologic outcomes. However, gaps exist in the process of linking the pieces together; currently, genetic data are seldom used to assist physicians in clinical decision making. With rapid growth in genetic data and the requirements for new paradigms for complex disorders comes the need to train professionals to understand and manage the impact of genetic information on patients within these clinical settings. Here we describe the challenges, controversies, and opportunities for genetics and genetic counselors in managing complex disorders and discuss the rationale for modifications in genetic counselor training and function. We conclude that a major paradigm shift is underway and a compelling functional, ethical, and financial argument can be made for employing properly trained genetic counselors to be strategically positioned within the health-care industries that are responsible for managing complex disorders.

Genomic medicine in gastroenterology: A new approach or a new specialty?

Throughout history, many medical milestones have been achieved to prevent and treat human diseases. Man's early conception of illness was naturally holistic or integrative. However, scientific knowledge was atomized into quantitative and qualitative research. In the field of medicine, the main trade-off was the creation of many medical specialties that commonly treat patients in advanced stages of disease. However, now that we are immersed in the post-genomic era, how should we reevaluate medicine? Genomic medicine has evoked a medical paradigm shift based on the plausibility to predict the genetic susceptibility to disease. Additionally, the development of chronic diseases should be viewed as a continuum of interactions between the individual's genetic make-up and environmental factors such as diet, physical activity, and emotions. Thus, personalized medicine is aimed at preventing or reversing clinical symptoms, and providing a better quality of life by integrating the genetic, environmental and cultural factors of diseases. Whether using genomic medicine in the field of gastroenterology is a new approach or a new medical specialty remains an open question. To address this issue, it will require the mutual work of educational and governmental authorities with public health professionals, with the goal of translating genomic medicine into better health policies.

Chromosome territory repositioning induced by PHA-activation of lymphocytes: A 2D and 3D appraisal

Background

Genomes and by extension chromosome territories (CTs) in a variety of organisms exhibit nonrandom organization within interphase nuclei. CTs are susceptible to movement upon induction by a variety of stimuli, including: cell differentiation, growth factors, genotoxic agents, proliferating status, and stimulants that induce novel transcription profiles. These findings suggest nuclear architecture can undergo reorganization, providing support for a functional significance of CT organization. The effect of the initiation of transcription on global scale chromatin architecture has been underexplored. This study investigates the organization of all 24 human chromosomes in lymphocytes from two individuals in resting and phytohaemagglutinin activated lymphocytes using 2D and 3D approaches.

Results

The radial organization of CTs in lymphocytes in both resting and activated lymphocytes follows a gene-density pattern. However, CT organization in activated nuclei appears less constrained exhibiting a more random organization. We report differences in the spatial relationship between homologous and heterologous CTs in activated nuclei. In addition, a reproducible radial hierarchy of CTs was identified and evidence of a CT repositioning was observed in activated nuclei using both 2D and 3D approaches.

Conclusions

Alterations between resting and activated lymphocytes could be adaptation of CTs to the new transcription profile and possibly the formation of new neighborhoods of interest or interaction of CTs with nuclear landmarks. The increased distances between homologous and heterologous CTs in activated lymphocytes could be a reflection of a defensive mechanism to reduce potential interaction to prevent any structural chromosome abnormalities (e.g. translocations) as a result of DNA damage that increases during lymphocyte activation.

Spatial positioning of all 24 chromosomes in the lymphocytes of six subjects: evidence of reproducible positioning and spatial repositioning following DNA damage with hydrogen peroxide and ultraviolet B

The higher-order organization of chromatin is well-established, with chromosomes occupying distinct positions within the interphase nucleus. Chromatin is susceptible to, and constantly assaulted by both endogenous and exogenous threats. However, the effects of DNA damage on the spatial topology of chromosomes are hitherto, poorly understood. This study investigates the organization of all 24 human chromosomes in lymphocytes from six individuals prior to- and following in-vitro exposure to genotoxic agents: hydrogen peroxide and ultraviolet B. This study is the first to report reproducible distinct hierarchical radial organization of chromosomes with little inter-individual differences between subjects. Perturbed nuclear organization was observed following genotoxic exposure for both agents; however a greater effect was observed for hydrogen peroxide including: 1) More peripheral radial organization; 2) Alterations in the global distribution of chromosomes; and 3) More events of chromosome repositioning (18 events involving 10 chromosomes vs. 11 events involving 9 chromosomes for hydrogen peroxide and ultraviolet B respectively). Evidence is provided of chromosome repositioning and altered nuclear organization following in-vitro exposure to genotoxic agents, with notable differences observed between the two investigated agents. Repositioning of chromosomes following genotoxicity involved recurrent chromosomes and is most likely part of the genomes inherent response to DNA damage. The variances in nuclear organization observed between the two agents likely reflects differences in mobility and/or decondensation of chromatin as a result of differences in the type of DNA damage induced, chromatin regions targeted, and DNA repair mechanisms.

Obesity and genomics: role of technology in unraveling the complex genetic architecture of obesity

Obesity is a complex and multifactorial disease that occurs as a result of the interaction between "obesogenic" environmental factors and genetic components. Although the genetic component of obesity is clear from the heritability studies, the genetic basis remains largely elusive. Successes have been achieved in identifying the causal genes for monogenic obesity using animal models and linkage studies, but these approaches are not fruitful for polygenic obesity. The developments of genome-wide association approach have brought breakthrough discovery of genetic variants for polygenic obesity where tens of new susceptibility loci were identified. However, the common SNPs only accounted for a proportion of heritability. The arrival of NGS technologies and completion of 1000 Genomes Project have brought other new methods to dissect the genetic architecture of obesity, for example, the use of exome genotyping arrays and deep sequencing of candidate loci identified from GWAS to study rare variants. In this review, we summarize and discuss the developments of these genetic approaches in human obesity.

Genome-wide association study of metabolic syndrome in koreans

Metabolic syndrome (METS) is a disorder of energy utilization and storage and increases the risk of developing cardiovascular disease and diabetes. To identify the genetic risk factors of METS, we carried out a genome-wide association study (GWAS) for 2,657 cases and 5,917 controls in Korean populations. As a result, we could identify 2 single nucleotide polymorphisms (SNPs) with genome-wide significance level p-values (<5 × 10^-8), 8 SNPs with genome-wide suggestive p-values (5 × 10^-8 ≤ p < 1 × 10^-5), and 2 SNPs of more functional variants with borderline p-values (5 × 10^-5 ≤ p < 1 × 10^-4). On the other hand, the multiple correction criteria of conventional GWASs exclude false-positive loci, but simultaneously, they discard many true-positive loci. To reconsider the discarded true-positive loci, we attempted to include the functional variants (nonsynonymous SNPs [nsSNPs] and expression quantitative trait loci [eQTL]) among the top 5,000 SNPs based on the proportion of phenotypic variance explained by genotypic variance. In total, 159 eQTLs and 18 nsSNPs were presented in the top 5,000 SNPs. Although they should be replicated in other independent populations, 6 eQTLs and 2 nsSNP loci were located in the molecular pathways of LPL, APOA5, and CHRM2, which were the significant or suggestive loci in the METS GWAS. Conclusively, our approach using the conventional GWAS, reconsidering functional variants and pathway-based interpretation, suggests a useful method to understand the GWAS results of complex traits and can be expanded in other genomewide association studies.

A systematic review of factors that act as barriers to patient referral to genetic services

Patients who might benefit from genetic services may be denied access through failure to be referred. To investigate the evidence on barriers to referral to genetic services, we conducted a systematic review of empirical evidence on this topic. Nine studies were included in the review. Barriers related to non-genetic healthcare professionals were: lack of awareness of patient risk factors, failure to obtain adequate family history, lack of knowledge of genetics and genetic conditions, lack of awareness of genetic services, inadequate coordination of referral and lack of genetics workforce. Those related to individuals affected by or at risk of a genetic condition were: lack of awareness of personal risk, lack of knowledge and/or awareness of medical history of family members and lack of knowledge of genetic services. Research on access to genetic services is heterogeneous; stronger empirical evidence is needed on factors that are barriers, and further research is needed to develop 'targeted interventions' for equitable access to genetic services in a range of populations.