Diagnostic clinical genome and exome sequencing

Chromosome Microarray Analysis and Exome Sequencing: Implementation in Prenatal Diagnosis of Fetuses with Digestive System Malformations

(1) Purpose: Retrospective back-to-back comparisons were performed to evaluate the accuracy, effectiveness, and incremental yield of chromosome microarray analysis (CMA) and exome sequencing (ES) analysis in fetuses with digestive system malformations (DSMs). (2) Methods: In total, 595 women with fetal DSMs who underwent prenatal diagnosis were enrolled. We analyzed the diagnostic yields of CMA and ES and evaluated pregnancy outcomes. Copy number variants (CNVs) were classified according to the American College of Medical Genetics and Genomics guidelines. (3) Results: Pathogenic CNVs were detected in 11/517 (2.12%) fetuses, and variants of unknown significance (VUS) were identified in 69 (13.35%) fetuses using CMA. ES detected 29 pathogenic/likely pathogenic variants in 23/143 (16.08%) fetuses and 26/143 (18.2%) VUS. In those with other ultrasound abnormalities, the detection rate of multiple system structural malformations was 41.2%, followed by skeletal (33.3%), cardiovascular (25.4%), and central nervous system (18.6%) malformations. Of the 391 surviving children, 40 (10.2%) exhibited varying degrees of mental retardation. (4) Conclusion: A correlation exists between DSMs and chromosomal abnormalities. When combined with other systemic abnormalities, the incidence of chromosomal abnormalities increases significantly. Patients with congenital DSM are at risk of developing neurodevelopmental disorders. Combined CMA and ES detection of fetal DSM has good clinical application potential.

Are genetic counselors prepared to counsel active-duty service members? A survey of genetic counselors' self-efficacy, counseling techniques, and knowledge of military policy

Given the expected rise in genomic sequencing projects within the US Military and the increased availability of genetic testing to the United States as a whole, current and prospective active-duty service members (SMs) may undergo genetic counseling services in the civilian sector for pre-test and post-test counseling. The overall goal of this study was to better understand genetic counselors' preparedness to address military-specific policies and psychosocial needs of patients from this underrepresented population. Members of the National Society of Genetic Counselors were asked to complete a four-part survey including demographic information, Likert scale questions to separately rate self-efficacy when working with civilians and SMs, case scenarios with multiple-choice options and open-ended responses to assess knowledge of military policy, and open-ended questions regarding psychosocial scenarios related to military service. Eighty-eight responses were analyzed using Microsoft Office Excel for the qualitive thematic analysis and SPSS/RStudio for the quantitative data. While over 75% (n = 69/88, SD = 0.48) of surveyed genetic counselors scored 4 of 4 on knowledge of military policy and reported similarly high levels of self-efficacy when working with SMs (mean = 26.77 out of 30, SD = 4.15) and the general population (mean = 27.99 out of 30, SD = 4.31), the qualitative data suggested an alternative perspective. Up to 57% (n = 50/88) of responses were scored as expressing low confidence concerning knowledge of military policy. One potential explanation for this uncertainty may be due to participants reporting that they never (69.32% (n = 61/88]) or are unsure if (12.50% (n = 11/88]) they received training related to providing counseling services to SMs. We suggest the establishment of educational initiatives for genetic counselors focusing on how to discuss genetic testing with SMs in relation to their health and safety, well-being, and potential employment implications.

Identification of a novel ANK1 mutation in a Chinese family with hereditary spherocytosis: A case report

The present study describes the clinical profile and ankyrin 1 (ANK1) mutation status of a Chinese family with hereditary spherocytosis (HS). A young male patient (proband) was diagnosed with HS after presenting with anaemia and jaundice. The Coombs test was negative and spherocytes were found in peripheral blood smears. Magnetic resonance imaging showed splenomegaly and splenic iron depositions. The red blood cell osmotic fragility test was positive. The eosin-5'-maleimide binding test showed reduced mean channel fluorescence. Whole-exome sequencing revealed a novel ANK1 mutation (c.4707G>A), resulting in a nonsense mutation (p.Trp1569*). The patient's father, paternal aunt and paternal grandmother exhibited comparable clinical symptoms and Sanger sequencing confirmed the same mutation in these family members. To the best of our knowledge, an HS pedigree with this novel ANK1 nonsense mutation has not been previously reported. At the same time, the unique clinical presentation of this pedigree helps our understanding of the heterogeneity of clinical manifestations of HS.

Precision Medicine through Next-Generation Sequencing in Inherited Eye Diseases in a Korean Cohort

In this study, we investigated medically or surgically actionable genes in inherited eye disease, based on clinical phenotype and genomic data. This retrospective consecutive case series included 149 patients with inherited eye diseases, seen by a single pediatric ophthalmologist, who underwent genetic testing between 1 March 2017 and 28 February 2018. Variants were detected using a target enrichment panel of 429 genes and known deep intronic variants associated with inherited eye disease. Among 149 patients, 38 (25.5%) had a family history, and this cohort includes heterogeneous phenotype including anterior segment dysgenesis, congenital cataract, infantile nystagmus syndrome, optic atrophy, and retinal dystrophy. Overall, 90 patients (60.4%) received a definite molecular diagnosis. Overall, NGS-guided precision care was provided to 8 patients (5.4%). The precision care included cryotherapy to prevent retinal detachment in COL2A1 Stickler syndrome, osteoporosis management in patients with LRP5-associated familial exudative vitreoretinopathy, and avoidance of unnecessary phlebotomy in hyperferritinemia-cataract syndrome. A revision of the initial clinical diagnosis was made in 22 patients (14.8%). Unexpected multi-gene deletions and dual diagnosis were noted in 4 patients (2.7%). We found that precision medical or surgical managements were provided for 8 of 149 patients (5.4%), and multiple locus variants were found in 2.7% of cases. These findings are important because individualized management of inherited eye diseases can be achieved through genetic testing.

Leveraging health systems data to characterize a large effect variant conferring risk for liver disease in Puerto Ricans

The integration of genomic data into health systems offers opportunities to identify genomic factors underlying the continuum of rare and common disease. We applied a population-scale haplotype association approach based on identity-by-descent (IBD) in a large multi-ethnic biobank to a spectrum of disease outcomes derived from electronic health records (EHRs) and uncovered a risk locus for liver disease. We used genome sequencing and in silico approaches to fine-map the signal to a non-coding variant (c.2784-12T>C) in the gene ABCB4. In vitro analysis confirmed the variant disrupted splicing of the ABCB4 pre-mRNA. Four of five homozygotes had evidence of advanced liver disease, and there was a significant association with liver disease among heterozygotes, suggesting the variant is linked to increased risk of liver disease in an allele dose-dependent manner. Population-level screening revealed the variant to be at a carrier rate of 1.95% in Puerto Rican individuals, likely as the result of a Puerto Rican founder effect. This work demonstrates that integrating EHR and genomic data at a population scale can facilitate strategies for understanding the continuum of genomic risk for common diseases, particularly in populations underrepresented in genomic medicine.

Exome variant discrepancies due to reference-genome differences

Despite release of the GRCh38 human reference genome more than seven years ago, GRCh37 remains more widely used by most research and clinical laboratories. To date, no study has quantified the impact of utilizing different reference assemblies for the identification of variants associated with rare and common diseases from large-scale exome-sequencing data. By calling variants on both the GRCh37 and GRCh38 references, we identified single-nucleotide variants (SNVs) and insertion-deletions (indels) in 1,572 exomes from participants with Mendelian diseases and their family members. We found that a total of 1.5% of SNVs and 2.0% of indels were discordant when different references were used. Notably, 76.6% of the discordant variants were clustered within discrete discordant reference patches (DISCREPs) comprising only 0.9% of loci targeted by exome sequencing. These DISCREPs were enriched for genomic elements including segmental duplications, fix patch sequences, and loci known to contain alternate haplotypes. We identified 206 genes significantly enriched for discordant variants, most of which were in DISCREPs and caused by multi-mapped reads on the reference assembly that lacked the variant call. Among these 206 genes, eight are implicated in known Mendelian diseases and 53 are associated with common phenotypes from genome-wide association studies. In addition, variant interpretations could also be influenced by the reference after lifting-over variant loci to another assembly. Overall, we identified genes and genomic loci affected by reference assembly choice, including genes associated with Mendelian disorders and complex human diseases that require careful evaluation in both research and clinical applications.

Next-Generation Sequencing Technologies and Neurogenetic Diseases

Next-generation sequencing (NGS) technology has led to great advances in understanding the causes of Mendelian and complex neurological diseases. Owing to the complexity of genetic diseases, the genetic factors contributing to many rare and common neurological diseases remain poorly understood. Selecting the correct genetic test based on cost-effectiveness, coverage area, and sequencing range can improve diagnosis, treatments, and prevention. Whole-exome sequencing and whole-genome sequencing are suitable methods for finding new mutations, and gene panels are suitable for exploring the roles of specific genes in neurogenetic diseases. Here, we provide an overview of the classifications, applications, advantages, and limitations of NGS in research on neurological diseases. We further provide examples of NGS-based explorations and insights of the genetic causes of neurogenetic diseases, including Charcot-Marie-Tooth disease, spinocerebellar ataxias, epilepsy, and multiple sclerosis. In addition, we focus on issues related to NGS-based analyses, including interpretations of variants of uncertain significance, de novo mutations, congenital genetic diseases with complex phenotypes, and single-molecule real-time approaches.

The Use of Whole Genome and Exome Sequencing for Newborn Screening: Challenges and Opportunities for Population Health

Newborn screening (NBS) is a population-based program with a goal of reducing the burden of disease for conditions with significant clinical impact on neonates. Screening tests were originally developed and implemented one at a time, but newer methods have allowed the use of multiplex technologies to expand additions more rapidly to standard panels. Recent improvements in next-generation sequencing are also evolving rapidly from first focusing on individual genes, then panels, and finally all genes as encompassed by whole exome and genome sequencing. The intersection of these two technologies brings the revolutionary possibility of identifying all genetic disorders in newborns, allowing implementation of therapies at the optimum time regardless of symptoms. This article reviews the history of newborn screening and early studies examining the use of whole genome and exome sequencing as a screening tool. Lessons learned from these studies are discussed, along with technical, ethical, and societal challenges to broad implementation.

Neo-Antigen mRNA Vaccines

The interest in therapeutic cancer vaccines has caught enormous attention in recent years due to several breakthroughs in cancer research, among which the finding that successful checkpoint blockade treatments reinvigorate neo-antigen-specific T cells and that successful adoptive cell therapies are directed towards neo-antigens. Neo-antigens are cancer-specific antigens, which develop from somatic mutations in the cancer cell genome that can be highly immunogenic and are not subjected to central tolerance. As the majority of neo-antigens are unique to each patient's cancer, a vaccine technology that is flexible and potent is required to develop personalized neo-antigen vaccines. In vitro transcribed mRNA is such a technology platform and has been evaluated for delivery of neo-antigens to professional antigen-presenting cells both ex vivo and in vivo. In addition, strategies that support the activity of T cells in the tumor microenvironment have been developed. These represent a unique opportunity to ensure durable T cell activity upon vaccination. Here, we comprehensively review recent progress in mRNA-based neo-antigen vaccines, summarizing critical milestones that made it possible to bring the promise of therapeutic cancer vaccines within reach.

The role of exome sequencing in newborn screening for inborn errors of metabolism

Public health newborn screening (NBS) programs provide population-scale ascertainment of rare, treatable conditions that require urgent intervention. Tandem mass spectrometry (MS/MS) is currently used to screen newborns for a panel of rare inborn errors of metabolism (IEMs)1-4. The NBSeq project evaluated whole-exome sequencing (WES) as an innovative methodology for NBS. We obtained archived residual dried blood spots and data for nearly all IEM cases from the 4.5 million infants born in California between mid-2005 and 2013 and from some infants who screened positive by MS/MS, but were unaffected upon follow-up testing. WES had an overall sensitivity of 88% and specificity of 98.4%, compared to 99.0% and 99.8%, respectively for MS/MS, although effectiveness varied among individual IEMs. Thus, WES alone was insufficiently sensitive or specific to be a primary screen for most NBS IEMs. However, as a secondary test for infants with abnormal MS/MS screens, WES could reduce false-positive results, facilitate timely case resolution and in some instances even suggest more appropriate or specific diagnosis than that initially obtained. This study represents the largest, to date, sequencing effort of an entire population of IEM-affected cases, allowing unbiased assessment of current capabilities of WES as a tool for population screening.

Molecular Biology Approaches to Understanding Spondyloarthritis

New and emerging molecular techniques are expanding understanding of the pathophysiology of spondyloarthritis (SpA). Genome-wide association studies identified novel pathways in antigen processing and presentation as well as helper T cell type 17 (T_H17) immunity associated with SpA. Immune cell profiling techniques have supported T_H17 immune responses and increasingly are revealing intestinal mucosal immune cells as associated with disease. Emerging technologies in epigenetics, transcriptomics, microbiome, and proteomics/metabolomics are adding to these, refining disease pathways and potentially identifying biomarkers for diagnosis and treatment responses. This review describes many of the new molecular techniques that are being utilized to investigate SpA.

Secuenciación de nueva generación (NGS) de ADN: presente y futuro en la práctica clínica

Introducción: el término secuenciación de nueva generación (NGS) hace referencia a las tecnologías diseñadas para analizar gran cantidad de ADN de forma masiva y paralela. Abordamos en esta revisión los conceptos básicos de estas tecnologías, las consideraciones de su uso clínico actual y perspectivas a futuro. Desarrollo: las pruebas basadas en NGS han revolucionado el estudio de los genomas pues permiten la lectura de millones de secuencias de ADN de forma masiva y paralela en un menor lapso de tiempo y a menor costo por base. Estas pruebas incluyen la secuenciación de panel de genes, la secuenciación completa del exoma y la secuenciación completa del genoma. El análisis de sus resultados es complejo y requiere de un proceso bioinformático y clínico exhaustivo para su adecuada interpretación. Las limitaciones de las pruebas NGS incluyen aspectos técnicos como la cobertura, profundidad y longitud de las secuencias, las cuales se pueden solventar implementando buenas prácticas de laboratorio. Conclusiones: las pruebas basadas en la secuenciación por NGS son herramientas diagnósticas que deben partir de una aproximación clínica adecuada para su uso razonado, correcta interpretación y toma de decisiones acertadas. Es de gran trascendencia que los médicos tengan la información básica para poder solicitar e interpretar estas pruebas dada su relevancia clínica actual.

Understanding Participation in Genetic Research Among Patients With Multiple Sclerosis: The Influences of Ethnicity, Gender, Education, and Age

This study examined reasons for participation in a genetic study of risk for multiple sclerosis (MS). Our sample consisted of 101 patients diagnosed with MS who were approached about enrolling in the Multiple Sclerosis Genetic Susceptibility Study. Participants were predominantly Hispanic (80%), female (80%), and well educated (71%), having at least some level of college education. Of these 101 individuals who were approached, 95 agreed to participate and are the focus of this report. Among enrollees, the most frequently cited reasons for participation were to find a cure for MS (56%), having MS (46%), and helping future generations (37%). Regression models comparing ethnic groups, Hispanics endorsed having MS as a reason to participate significantly more frequently than non-Hispanics (HI 52%, non-HI 19%, p = 0.015) while non-Hispanics endorsed finding new and better treatments significantly more frequently than Hispanics (Hispanic 17%, non-Hispanic 50%, p = 0.003). Among our three age groups, younger individuals endorsed finding a cure for MS significantly more frequently (74% of 18-35-year olds vs. 56% of 36-55 year olds vs. 39% of >55 year olds). Our results suggest that motivations for participation in genetic research vary by ethnicity, and that these influences need to be considered in developing more inclusive programs of disease-related genetic research. Future efforts should focus on development of standard methods for understanding participation in genetic and genomic research, especially among underrepresented groups as a catalyst for engaging all populations.

Refinement of evolutionary medicine predictions based on clinical evidence for the manifestations of Mendelian diseases

Prediction methods have become an integral part of biomedical and biotechnological research. However, their clinical interpretations are largely based on biochemical or molecular data, but not clinical data. Here, we focus on improving the reliability and clinical applicability of prediction algorithms. We assembled and curated two large non-overlapping large databases of clinical phenotypes. These phenotypes were caused by missense variations in 44 and 63 genes associated with Mendelian diseases. We used these databases to establish and validate the model, allowing us to improve the predictions obtained from EVmutation, SNAP2 and PoPMuSiC 2.1. The predictions of clinical effects suffered from a lack of specificity, which appears to be the common constraint of all recently used prediction methods, although predictions mediated by these methods are associated with nearly absolute sensitivity. We introduced evidence-based tailoring of the default settings of the prediction methods; this tailoring substantially improved the prediction outcomes. Additionally, the comparisons of the clinically observed and theoretical variations led to the identification of large previously unreported pools of variations that were under negative selection during molecular evolution. The evolutionary variation analysis approach described here is the first to enable the highly specific identification of likely disease-causing missense variations that have not yet been associated with any clinical phenotype.

The current and future impact of genome-wide sequencing on fetal precision medicine

Next-generation sequencing and other genomic technologies are transforming prenatal and reproductive screening and testing for fetal genetic disorders at an unprecedented pace. Original approaches of screening and testing for fetal genetic and genomic disorders were focused on a few more prevalent conditions that were easily diagnosable with pre-genomic era diagnostic tools. First, chromosomal microarray analysis and then next-generation sequencing brought technology capable of more detailed genomic evaluation to prenatal genetic screening and diagnosis. This has facilitated parallel introduction of a variety of new tests on maternal blood samples, including expanded carrier screening and cell-free DNA-based non-invasive screening for fetal aneuploidy, selected copy number variants, and single-gene disorders. Genomic tests on fetal DNA samples, obtained primarily through amniocentesis or chorionic villus sampling, include chromosomal microarray analysis and gene panel and exome sequencing. All these form the diagnostic pillar of the emerging field of fetal precision medicine, but their implementation is associated with ethical, counseling and healthcare resource utilization challenges. We discuss where in the reproductive and prenatal care continuum these exciting new technologies are integrated, along with associated challenges. We propose areas of priority for research to gain the data in support of their responsible implementation into clinical reproductive and prenatal care.

Application of mass spectrometry-based MHC immunopeptidome profiling in neoantigen identification for tumor immunotherapy

One of the challenges for cancer vaccine and adoptive T-cell-based immunotherapy is to identify the major histocompatibility complex (MHC)-associated non-self neoantigens recognized by T cells. T cell epitope in silico prediction algorithms have been widely used for neoantigen prediction; nonetheless, this platform lacks the experimental evidence of directly identification of the presented epitopes on cell surface. Currently, mass spectrometry (MS)-based proteomics is an advanced analytical technology for large-scale peptide sequencing, which has become a powerful tool for directly profiling the immunopeptidome presented by MHC molecules. Integrating with next-generation sequencing, proteogenomic analysis provides the "gold standard" for neoantigen identification at protein level. This method discovers the tumor-specific neoantigens derived from somatic mutations, proteasome splicing, noncoding RNA, and post-translational modified antigens. Herein, we review basis of antigen processing and presentation, tumor antigen classification, existing approaches for neoantigen discovery, quantitative proteomics, epitope prediction programs, and advantages and drawbacks of proteomics workflow for MHC immunopeptidome profiling. Furthermore, we summarize 40 recently published reports addressing the fundamental theory, breakthrough and most advanced updates for the mass spectrometry-based neoantigen discovery for cancer immunotherapy.

Identification of Polycystic Kidney Disease 1 Like 1 Gene Variants in Children With Biliary Atresia Splenic Malformation Syndrome

Biliary atresia (BA) is the most common cause of end-stage liver disease in children and the primary indication for pediatric liver transplantation, yet underlying etiologies remain unknown. Approximately 10% of infants affected by BA exhibit various laterality defects (heterotaxy) including splenic abnormalities and complex cardiac malformations-a distinctive subgroup commonly referred to as the biliary atresia splenic malformation (BASM) syndrome. We hypothesized that genetic factors linking laterality features with the etiopathogenesis of BA in BASM patients could be identified through whole-exome sequencing (WES) of an affected cohort. DNA specimens from 67 BASM subjects, including 58 patient-parent trios, from the National Institute of Diabetes and Digestive and Kidney Diseases-supported Childhood Liver Disease Research Network (ChiLDReN) underwent WES. Candidate gene variants derived from a prespecified set of 2,016 genes associated with ciliary dysgenesis and/or dysfunction or cholestasis were prioritized according to pathogenicity, population frequency, and mode of inheritance. Five BASM subjects harbored rare and potentially deleterious biallelic variants in polycystic kidney disease 1 like 1 (PKD1L1), a gene associated with ciliary calcium signaling and embryonic laterality determination in fish, mice, and humans. Heterozygous PKD1L1 variants were found in 3 additional subjects. Immunohistochemical analysis of liver from the one BASM subject available revealed decreased PKD1L1 expression in bile duct epithelium when compared to normal livers and livers affected by other noncholestatic diseases. Conclusion: WES identified biallelic and heterozygous PKD1L1 variants of interest in 8 BASM subjects from the ChiLDReN data set; the dual roles for PKD1L1 in laterality determination and ciliary function suggest that PKD1L1 is a biologically plausible, cholangiocyte-expressed candidate gene for the BASM syndrome.

Motivations for Participation in Parkinson Disease Genetic Research Among Hispanics versus Non-Hispanics

Involvement of participants from different racial and ethnic groups in genomic research is vital to reducing health disparities in the precision medicine era. Racial and ethnically diverse populations are underrepresented in current genomic research, creating bias in result interpretation. Limited information is available to support motivations or barriers of these groups to participate in genomic research for late-onset, neurodegenerative disorders. To evaluate willingness for research participation, we compared motivations for participation in genetic studies among 113 Parkinson disease (PD) patients and 49 caregivers visiting the Movement Disorders clinic at the University of Miami. Hispanics and non-Hispanics were equally motivated to participate in genetic research for PD. However, Hispanic patients were less likely to be influenced by the promise of scientific advancements (N = 0.01). This lack of scientific interest, but not other motivations, was found to be likely confounded by lower levels of obtained education (N = 0.001). Overall, these results suggest that underrepresentation of Hispanics in genetic research may be partly due to reduced invitations to these studies.

Analyzing and Reanalyzing the Genome: Findings from the MedSeq Project

Although genome sequencing is increasingly available in clinical and research settings, many questions remain about the interpretation of sequencing data. In the MedSeq Project, we explored how much effort is required to evaluate and report on more than 4,500 genes reportedly associated with monogenic conditions, as well as pharmacogenomic (PGx) markers, blood antigen serotyping, and polygenic risk scores in 100 individuals (50 with cardiomyopathy and 50 healthy) randomized to the sequencing arm. We defined the quality thresholds for determining the need for Sanger confirmation. Finally, we examined the effort needed and new findings revealed by reanalyzing each genome (6-23 months after initial analysis; mean 13 months). Monogenic disease risk and carrier status were reported in 21% and 94% of participants, respectively. Only two participants had no monogenic disease risk or carrier status identified. For the PGx results (18 genotypes in six genes for five drugs), the identified diplotypes prompted recommendation for non-standard dosing of at least one of the analyzed drugs in 95% of participants. For blood antigen studies, we found that 31% of participants had a rare blood antigen genotype. In the cardiomyopathy cohort, an explanation for disease was identified in 48% of individuals. Over the course of the study, 14 variants were reclassified and, upon reanalysis, 18 new variants met criteria for reporting. These findings highlight the quantity of medically relevant findings from a broad analysis of genomic sequencing data as well as the need for periodic reinterpretation and reanalysis of data for both diagnostic indications and secondary findings.

Performance evaluation of pathogenicity-computation methods for missense variants

With expanding applications of next-generation sequencing in medical genetics, increasing computational methods are being developed to predict the pathogenicity of missense variants. Selecting optimal methods can accelerate the identification of candidate genes. However, the performances of different computational methods under various conditions have not been completely evaluated. Here, we compared 12 performance measures of 23 methods based on three independent benchmark datasets: (i) clinical variants from the ClinVar database related to genetic diseases, (ii) somatic variants from the IARC TP53 and ICGC databases related to human cancers and (iii) experimentally evaluated PPARG variants. Some methods showed different performances under different conditions, suggesting that they were not always applicable for different conditions. Furthermore, the specificities were lower than the sensitivities for most methods (especially, for the experimentally evaluated benchmark datasets), suggesting that more rigorous cutoff values are necessary to distinguish pathogenic variants. Furthermore, REVEL, VEST3 and the combination of both methods (i.e. ReVe) showed the best overall performances with all the benchmark data. Finally, we evaluated the performances of these methods with de novo mutations, finding that ReVe consistently showed the best performance. We have summarized the performances of different methods under various conditions, providing tentative guidance for optimal tool selection.

PEDIA: prioritization of exome data by image analysis

Purpose

Phenotype information is crucial for the interpretation of genomic variants. So far it has only been accessible for bioinformatics workflows after encoding into clinical terms by expert dysmorphologists.

Methods

Here, we introduce an approach driven by artificial intelligence that uses portrait photographs for the interpretation of clinical exome data. We measured the value added by computer-assisted image analysis to the diagnostic yield on a cohort consisting of 679 individuals with 105 different monogenic disorders. For each case in the cohort we compiled frontal photos, clinical features, and the disease-causing variants, and simulated multiple exomes of different ethnic backgrounds.

Results

The additional use of similarity scores from computer-assisted analysis of frontal photos improved the top 1 accuracy rate by more than 20–89% and the top 10 accuracy rate by more than 5–99% for the disease-causing gene.

Conclusion

Image analysis by deep-learning algorithms can be used to quantify the phenotypic similarity (PP4 criterion of the American College of Medical Genetics and Genomics guidelines) and to advance the performance of bioinformatics pipelines for exome analysis.

A novel mutation in SPTA1 identified by whole exome sequencing in a Chinese family for hereditary elliptocytosis presenting with hyperbilirubinemia: A case report

RATIONALE

Hereditary elliptocytosis is an inherited disorder characterized by the elliptical red blood cells (RBCs) on the peripheral blood smear and related hemolysis, mainly results from a heterozygous mutation in the genes that encode protein 4.1, α-spectrin, β-spectrin. Mutations of SPTA1 are the most common.

PATIENT CONCERNS

A 21-year-old female presented with left epigastric pain and jaundice with numerous elliptical RBCs on blood film. The family history review discovered jaundice in her sibling.

DIAGNOSIS

A novel heterozygous mutation of SPTA1 was detected in the proband, her brother and father, c.7220_7221del:p.Tyr2407* in exon 52. Bioinformatics analysis indicated that this mutation was likely pathogenic and results in early termination of transcription and production of defective protein.

INTERVENTIONS

The proband underwent splenectomy and cholecystectomy due to symptomatic splenomegaly and gallstone.

OUTCOMES

After surgery, the bilirubin levels decreased to normal (i.e., total bilirubin 16.4 μmol/L; indirect bilirubin 12.3 μmol/L), and the pain and uncomfortableness in the upper abdomen relieved completely.

LESSONS

We suggest that simultaneous whole exome sequencing of causative genes of all family members is a useful strategy to identify pathogenetic mutations for hereditary RBC membrane disorders, mainly in cases with an ambiguous phenotype.

Functional characterization of 3D protein structures informed by human genetic diversity

Sequence variation data of the human proteome can be used to analyze 3D protein structures to derive functional insights. We used genetic variant data from nearly 140,000 individuals to analyze 3D positional conservation in 4,715 proteins and 3,951 homology models using 860,292 missense and 465,886 synonymous variants. Sixty percent of protein structures harbor at least one intolerant 3D site as defined by significant depletion of observed over expected missense variation. Structural intolerance data correlated with deep mutational scanning functional readouts for PPARG, MAPK1/ERK2, UBE2I, SUMO1, PTEN, CALM1, CALM2, and TPK1 and with shallow mutagenesis data for 1,026 proteins. The 3D structural intolerance analysis revealed different features for ligand binding pockets and orthosteric and allosteric sites. Large-scale data on human genetic variation support a definition of functional 3D sites proteome-wide.

Wiedemann-Steiner syndrome with a novel pathogenic variant in KMT2A: a case report

Case Description:

We report the case of a one-year-old girl who was diagnosed with Wiedemann-Steiner Syndrome based on the identification of a novel de novo frameshift mutation in the KMT2A gene by whole exome sequencing and supported by her clinical features.

Clinical Findings:

KMT2A mutations cause Wiedemann-Steiner Syndrome, a very rare genetic disorder characterized by congenital hypertrichosis, short stature, intellectual disability, and distinct facial features.

Treatment and Outcome:

Whole exome sequencing identified a novel frameshift variant: c. 4177dupA (p.Ile1393Asnfs * 14) in KMT2A; this change generates an alteration of the specific binding to non-methylated CpG motifs of the DNA to the protein. The genotype and phenotype of the patient were compared with those of earlier reported patients in the literature.

Clinical Relevance:

In diseases with low frequency, it is necessary to establish a genotype-phenotype correlation that allows the establishment of therapeutic and follow-up goals. The phenotype comparation with other reported cases did not show differences attributable to sex or age among patients with Wiedemann-Steiner Syndrome. Whole exome sequencing allows identifying causality in conditions with high clinical and genetic heterogeneity like hypertrichosis.

Haack T, M. Strom T, Kortüm F, Meitinger T, C. Muntau A, Santer R, Kubisch C, Lessel D, Denecke* J, Hempel* M. Exome Sequencing in Children

BACKGROUND

In developed countries, global developmental disorders are encounter- ed in approximately 1% of all children. The causes are manifold, and no exogenous cause can be identified in about half of the affected children. The parallel investi- gation of the coding sequences of all genes of the affected individual (whole exome sequencing, WES) has developed into a successful diagnostic method for identify- ing the cause of the problem. It is not yet clear, however, when WES should best be used in routine clinical practice in order to exploit the potential of this method to the fullest.

METHODS

In an interdisciplinary study, we carried out standardized clinical pheno- typing and a systematic genetic analysis (WES of the index patient and his or her parents, so-called trio WES) in 50 children with developmental disturbances of unclear etiology and with nonspecific neurological manifestations.

RESULTS

In 21 children (42% of the collective), we were able to identify the cause of the disorder by demonstrating a mutation in a gene known to be associated with disease. Three of these children subsequently underwent specific treatment. In 22 other children (44%), we detected possibly etiological changes in candidate genes not currently known to be associated with human disease.

CONCLUSION

Our detection rate of at least 42% is high in comparison with the results obtained in other studies from Germany and other countries to date and implies that WES can be used to good effect as a differential diagnostic tool in pediatric neurol- ogy. WES should be carried out in both the index patient and his or her parents (trio- WES) and accompanied by close interdisciplinary collaboration of human geneti- cists and pediatricians, by comprehensive and targeted phenotyping (also after the diagnosis is established), and by the meticulous evaluation of all gene variants.

Copy Number Variants Account for a Tiny Fraction of Undiagnosed Myopathic Patients

Next-generation sequencing (NGS) technologies have led to an increase in the diagnosis of heterogeneous genetic conditions. However, over 50% of patients with a genetically inherited disease are still without a diagnosis. In these cases, different hypotheses are usually postulated, including variants in novel genes or elusive mutations. Although the impact of copy number variants (CNVs) in neuromuscular disorders has been largely ignored to date, missed CNVs are predicted to have a major role in disease causation as some very large genes, such as the dystrophin gene, have prone-to-deletion regions. Since muscle tissues express several large disease genes, the presence of elusive CNVs needs to be comprehensively assessed following an accurate and systematic approach. In this multicenter cohort study, we analyzed 234 undiagnosed myopathy patients using a custom array comparative genomic hybridization (CGH) that covers all muscle disease genes at high resolution. Twenty-two patients (9.4%) showed non-polymorphic CNVs. In 12 patients (5.1%), the identified CNVs were considered responsible for the observed phenotype. An additional ten patients (4.3%) presented candidate CNVs not yet proven to be causative. Our study indicates that deletions and duplications may account for 5⁻9% of genetically unsolved patients. This strongly suggests that other mechanisms of disease are yet to be discovered.

OpenEHR modeling for genomics in clinical practice

PURPOSE

The increasing usage of high throughput sequencing in personalized medicine brings new challenges to the realm of healthcare informatics. Patient records need to accommodate data of unprecedented size and complexity as well as keep track of their production process. In this work we present a solution for integrating genomic data into electronic health records via openEHR archetypes.

METHODS

We use the popular Variant Call Format as the base format to represent genetic test results within openEHR. We evaluate existing openEHR archetypes to determine what can be extended or specialized and what needs to be developed ex novo.

RESULTS

Eleven new archetypes have been developed, while an existing one has been specialized to represent genomic data. We show their applicability to rare genetic diseases and compare our approach to HL7 FHIR.

CONCLUSION

The proposed model allows to represent genetic test results in health records in a structured format. It supports different levels of abstraction, allowing both automated processing and clinical decision support. It is extensible via external references, allowing to keep track of data provenance and adapt to future domain changes.

Clinical cancer genomic profiling by three-platform sequencing of whole genome, whole exome and transcriptome

To evaluate the potential of an integrated clinical test to detect diverse classes of somatic and germline mutations relevant to pediatric oncology, we performed three-platform whole-genome (WGS), whole exome (WES) and transcriptome (RNA-Seq) sequencing of tumors and normal tissue from 78 pediatric cancer patients in a CLIA-certified, CAP-accredited laboratory. Our analysis pipeline achieves high accuracy by cross-validating variants between sequencing types, thereby removing the need for confirmatory testing, and facilitates comprehensive reporting in a clinically-relevant timeframe. Three-platform sequencing has a positive predictive value of 97–99, 99, and 91% for somatic SNVs, indels and structural variations, respectively, based on independent experimental verification of 15,225 variants. We report 240 pathogenic variants across all cases, including 84 of 86 known from previous diagnostic testing (98% sensitivity). Combined WES and RNA-Seq, the current standard for precision oncology, achieved only 78% sensitivity. These results emphasize the critical need for incorporating WGS in pediatric oncology testing.

Clinical oncology is rapidly adopting next-generation sequencing technology for nucleotide variant and indel detection. Here the authors present a three-platform approach (whole-genome, whole-exome, and whole-transcriptome) in pediatric patients for the detection of diverse types of germline and somatic variants.

A Comparison of Whole Genome Sequencing to Multigene Panel Testing in Hypertrophic Cardiomyopathy Patients

BACKGROUND

As DNA sequencing costs decline, genetic testing options have expanded. Whole exome sequencing and whole genome sequencing (WGS) are entering clinical use, posing questions about their incremental value compared with disease-specific multigene panels that have been the cornerstone of genetic testing.

METHODS AND RESULTS

Forty-one patients with hypertrophic cardiomyopathy who had undergone targeted hypertrophic cardiomyopathy genetic testing (either multigene panel or familial variant test) were recruited into the MedSeq Project, a clinical trial of WGS. Results from panel genetic testing and WGS were compared. In 20 of 41 participants, panel genetic testing identified variants classified as pathogenic, likely pathogenic, or uncertain significance. WGS identified 19 of these 20 variants, but the variant detection algorithm missed a pathogenic 18 bp duplication in myosin binding protein C (MYBPC3) because of low coverage. In 3 individuals, WGS identified variants in genes implicated in cardiomyopathy but not included in prior panel testing: a pathogenic protein tyrosine phosphatase, non-receptor type 11 (PTPN11) variant and variants of uncertain significance in integrin-linked kinase (ILK) and filamin-C (FLNC). WGS also identified 84 secondary findings (mean=2 per person, range=0-6), which mostly defined carrier status for recessive conditions.

CONCLUSIONS

WGS detected nearly all variants identified on panel testing, provided 1 new diagnostic finding, and allowed interrogation of posited disease genes. Several variants of uncertain clinical use and numerous secondary genetic findings were also identified. Whereas panel testing and WGS provided similar diagnostic yield, WGS offers the advantage of reanalysis over time to incorporate advances in knowledge, but requires expertise in genomic interpretation to appropriately incorporate WGS into clinical care.

CLINICAL TRIAL REGISTRATION

URL: https://clinicaltrials.gov. Unique identifier: NCT01736566.

Increasing Role of Titin Mutations in Neuromuscular Disorders

The TTN gene with 363 coding exons encodes titin, a giant muscle protein spanning from the Z-disk to the M-band within the sarcomere. Mutations in the TTN gene have been associated with different genetic disorders, including hypertrophic and dilated cardiomyopathy and several skeletal muscle diseases.

Before the introduction of next generation sequencing (NGS) methods, the molecular analysis of TTN has been laborious, expensive and not widely used, resulting in a limited number of mutations identified. Recent studies however, based on the use of NGS strategies, give evidence of an increasing number of rare and unique TTN variants. The interpretation of these rare variants of uncertain significance (VOUS) represents a challenge for clinicians and researchers.

The main aim of this review is to describe the wide spectrum of muscle diseases caused by TTN mutations so far determined, summarizing the molecular findings as well as the clinical data, and to highlight the importance of joint efforts to respond to the challenges arising from the use of NGS. An international collaboration through a clinical and research consortium and the development of a single accessible database listing variants in the TTN gene, identified by high throughput approaches, may be the key to a better assessment of titinopathies and to systematic genotype– phenotype correlation studies.

GENETICS IN ENDOCRINOLOGY: Genetic counseling for congenital hypogonadotropic hypogonadism and Kallmann syndrome: new challenges in the era of oligogenism and next-generation sequencing

Congenital hypogonadotropic hypogonadism (CHH) and Kallmann syndrome (KS) are rare, related diseases that prevent normal pubertal development and cause infertility in affected men and women. However, the infertility carries a good prognosis as increasing numbers of patients with CHH/KS are now able to have children through medically assisted procreation. These are genetic diseases that can be transmitted to patients' offspring. Importantly, patients and their families should be informed of this risk and given genetic counseling. CHH and KS are phenotypically and genetically heterogeneous diseases in which the risk of transmission largely depends on the gene(s) responsible(s). Inheritance may be classically Mendelian yet more complex; oligogenic modes of transmission have also been described. The prevalence of oligogenicity has risen dramatically since the advent of massively parallel next-generation sequencing (NGS) in which tens, hundreds or thousands of genes are sequenced at the same time. NGS is medically and economically more efficient and more rapid than traditional Sanger sequencing and is increasingly being used in medical practice. Thus, it seems plausible that oligogenic forms of CHH/KS will be increasingly identified making genetic counseling even more complex. In this context, the main challenge will be to differentiate true oligogenism from situations when several rare variants that do not have a clear phenotypic effect are identified by chance. This review aims to summarize the genetics of CHH/KS and to discuss the challenges of oligogenic transmission and also its role in incomplete penetrance and variable expressivity in a perspective of genetic counseling.

A phenotype centric benchmark of variant prioritisation tools

Next generation sequencing is a standard tool used in clinical diagnostics. In Mendelian diseases the challenge is to discover the single etiological variant among thousands of benign or functionally unrelated variants. After calling variants from aligned sequencing reads, variant prioritisation tools are used to examine the conservation or potential functional consequences of variants. We hypothesised that the performance of variant prioritisation tools may vary by disease phenotype. To test this we created benchmark data sets for variants associated with different disease phenotypes. We found that performance of 24 tested tools is highly variable and differs by disease phenotype. The task of identifying a causative variant amongst a large number of benign variants is challenging for all tools, highlighting the need for further development in the field. Based on our observations, we recommend use of five top performers found in this study (FATHMM, M-CAP, MetaLR, MetaSVM and VEST3). In addition we provide tables indicating which analytical approach works best in which disease context. Variant prioritisation tools are best suited to investigate variants associated with well-studied genetic diseases, as these variants are more readily available during algorithm development than variants associated with rare diseases. We anticipate that further development into disease focussed tools will lead to significant improvements.

Integrating Functional Analysis in the Next-Generation Sequencing Diagnostic Pipeline of RASopathies

RASopathies are a group of heterogeneous conditions caused by germline mutations in RAS/MAPK signalling pathway genes. With next-generation sequencing (NGS), sequencing capacity is no longer a limitation to molecular diagnosis. Instead, the rising number of variants of unknown significance (VUSs) poses challenges to clinical interpretation and genetic counselling. We investigated the potential of an integrated pipeline combining NGS and the functional assessment of variants for the diagnosis of RASopathies. We included 63 Chinese patients with RASopathies that had previously tested negative for PTPN11 and HRAS mutations. In these patients, we performed a genetic analysis of genes associated with RASopathies using a multigene NGS panel and Sanger sequencing. For the VUSs, we evaluated evidence from genetic, bioinformatic and functional data. Twenty disease-causing mutations were identified in the 63 patients, providing a primary diagnostic yield of 31.7%. Four VUSs were identified in five patients. The functional assessment supported the pathogenicity of the RAF1 and RIT1 VUSs, while the significance of two VUSs in A2ML1 remained unclear. In summary, functional analysis improved the diagnostic yield from 31.7% to 36.5%. Although technically demanding and time-consuming, a functional genetic diagnostic analysis can ease the clinical translation of these findings to aid bedside interpretation.

PhenoDis: a comprehensive database for phenotypic characterization of rare cardiac diseases

Background

Thoroughly annotated data resources are a key requirement in phenotype dependent analysis and diagnosis of diseases in the area of precision medicine. Recent work has shown that curation and systematic annotation of human phenome data can significantly improve the quality and selectivity for the interpretation of inherited diseases. We have therefore developed PhenoDis, a comprehensive, manually annotated database providing symptomatic, genetic and imprinting information about rare cardiac diseases.

Results

PhenoDis includes 214 rare cardiac diseases from Orphanet and 94 more from OMIM. For phenotypic characterization of the diseases, we performed manual annotation of diseases with articles from the biomedical literature. Detailed description of disease symptoms required the use of 2247 different terms from the Human Phenotype Ontology (HPO). Diseases listed in PhenoDis frequently cover a broad spectrum of symptoms with 28% from the branch of ‘cardiovascular abnormality’ and others from areas such as neurological (11.5%) and metabolism (6%). We collected extensive information on the frequency of symptoms in respective diseases as well as on disease-associated genes and imprinting data. The analysis of the abundance of symptoms in patient studies revealed that most of the annotated symptoms (71%) are found in less than half of the patients of a particular disease. Comprehensive and systematic characterization of symptoms including their frequency is a pivotal prerequisite for computer based prediction of diseases and disease causing genetic variants. To this end, PhenoDis provides in-depth annotation for a complete group of rare diseases, including information on pathogenic and likely pathogenic genetic variants for 206 diseases as listed in ClinVar. We integrated all results in an online database (http://mips.helmholtz-muenchen.de/phenodis/) with multiple search options and provide the complete dataset for download.

Conclusion

PhenoDis provides a comprehensive set of manually annotated rare cardiac diseases that enables computational approaches for disease prediction via decision support systems and phenotype-driven strategies for the identification of disease causing genes.

Characterizing reduced coverage regions through comparison of exome and genome sequencing data across 10 centers

PURPOSE:

As massively parallel sequencing is increasingly being used for clinical decision-making, it has become critical to understand parameters that affect sequencing quality and to establish methods for measuring and reporting clinical sequencing standards. In this report, we propose a definition for reduced coverage regions and have established a set of standards for variant calling in clinical sequencing applications.

METHODS:

To enable sequencing centers to assess the regions of poor sequencing quality in their own data, we optimized and used a tool (ExCid) to identify reduced coverage loci within genes or regions of particular interest. We used this framework to examine sequencing data from 500 patients generated in ten projects from sequencing centers in the NHGRI/NCI Clinical Sequencing Exploratory Research (CSER) Consortium.

RESULTS:

This approach identified reduced coverage regions in clinically relevant genes, including known clinically relevant loci that were uniquely missed at individual centers, in multiple centers, and in all centers.

CONCLUSIONS:

This report provides a process roadmap for clinical sequencing centers looking to perform similar analyses on their data.

Peripheral Arterial Disease Genetics: Progress to Date and Challenges Ahead

PURPOSE OF REVIEW

In this paper, we review the progress made thus far in research related to the genetics of peripheral arterial disease (PAD) by detailing efforts to date in heritability, linkage analyses, and candidate gene studies. We further summarize more contemporary genome-wide association studies (GWAS) and epigenetic studies of PAD. Finally, we review current challenges and future avenues of advanced research in PAD genetics including whole genome sequencing studies.

RECENT FINDINGS

Studies have estimated the heritability of PAD to be moderate, though the contribution to this heritability that is independent of traditional cardiovascular risk factors remains unclear. Recent efforts have identified SNPs associated with PAD in GWAS analyses, but these have yet to be replicated in independent studies. Much remains to be discovered in the field of PAD genetics. An improved understanding of the genetic foundation for PAD will allow for earlier diagnosis of disease and a more complete pathophysiological understanding of the mechanisms of the disease leading to novel therapeutic interventions. Future avenues for success will likely arise from very large-scale GWAS, whole genome sequencing, and epigenetic studies involving very well-characterized cohorts.

A Comparison of Whole Genome Sequencing to Multigene Panel Testing in Hypertrophic Cardiomyopathy Patients

BACKGROUND

As DNA sequencing costs decline, genetic testing options have expanded. Whole exome sequencing and whole genome sequencing (WGS) are entering clinical use, posing questions about their incremental value compared with disease-specific multigene panels that have been the cornerstone of genetic testing.

METHODS AND RESULTS

Forty-one patients with hypertrophic cardiomyopathy who had undergone targeted hypertrophic cardiomyopathy genetic testing (either multigene panel or familial variant test) were recruited into the MedSeq Project, a clinical trial of WGS. Results from panel genetic testing and WGS were compared. In 20 of 41 participants, panel genetic testing identified variants classified as pathogenic, likely pathogenic, or uncertain significance. WGS identified 19 of these 20 variants, but the variant detection algorithm missed a pathogenic 18 bp duplication in myosin binding protein C (MYBPC3) because of low coverage. In 3 individuals, WGS identified variants in genes implicated in cardiomyopathy but not included in prior panel testing: a pathogenic protein tyrosine phosphatase, non-receptor type 11 (PTPN11) variant and variants of uncertain significance in integrin-linked kinase (ILK) and filamin-C (FLNC). WGS also identified 84 secondary findings (mean=2 per person, range=0-6), which mostly defined carrier status for recessive conditions.

CONCLUSIONS

WGS detected nearly all variants identified on panel testing, provided 1 new diagnostic finding, and allowed interrogation of posited disease genes. Several variants of uncertain clinical use and numerous secondary genetic findings were also identified. Whereas panel testing and WGS provided similar diagnostic yield, WGS offers the advantage of reanalysis over time to incorporate advances in knowledge, but requires expertise in genomic interpretation to appropriately incorporate WGS into clinical care.

CLINICAL TRIAL REGISTRATION

URL: https://clinicaltrials.gov. Unique identifier: NCT01736566.

A three-caller pipeline for variant analysis of cancer whole-exome sequencing data

Rapid advancements in next generation sequencing (NGS) technologies, coupled with the dramatic decrease in cost, have made NGS one of the leading approaches applied in cancer research. In addition, it is increasingly used in clinical practice for cancer diagnosis and treatment. Somatic (cancer‑only) single nucleotide variants and small insertions and deletions (indels) are the simplest classes of mutation, however, their identification in whole exome sequencing data is complicated by germline polymorphisms, tumor heterogeneity and errors in sequencing and analysis. An increasing number of software and methodological guidelines are being published for the analysis of sequencing data. Usually, the algorithms of MuTect, VarScan and Genome Analysis Toolkit are applied to identify the variants. However, one of these algorithms alone results in incomplete genomic information. To address this issue, the present study developed a systematic pipeline for analyzing the whole exome sequencing data of hepatocellular carcinoma (HCC) using a combination of the three algorithms, named the three‑caller pipeline. Application of the three‑caller pipeline to the whole exome data of HCC, improved the detection of true positive mutations and a total of 75 tumor‑specific somatic variants were identified. Functional enrichment analysis revealed the mutations in the genes encoding cell adhesion and regulation of Ras GTPase activity. This pipeline provides an effective approach to identify variants from NGS data for subsequent functional analyses.

Classification of Genes: Standardized Clinical Validity Assessment of Gene-Disease Associations Aids Diagnostic Exome Analysis and Reclassifications

Ascertaining a diagnosis through exome sequencing can provide potential benefits to patients, insurance companies, and the healthcare system. Yet, as diagnostic sequencing is increasingly employed, vast amounts of human genetic data are produced that need careful curation. We discuss methods for accurately assessing the clinical validity of gene-disease relationships to interpret new research findings in a clinical context and increase the diagnostic rate. The specifics of a gene-disease scoring system adapted for use in a clinical laboratory are described. In turn, clinical validity scoring of gene-disease relationships can inform exome reporting for the identification of new or the upgrade of previous, clinically relevant gene findings. Our retrospective analysis of all reclassification reports from the first 4 years of diagnostic exome sequencing showed that 78% were due to new gene-disease discoveries published in the literature. Among all exome positive/likely positive findings in characterized genes, 32% were in genetic etiologies that were discovered after 2010. Our data underscore the importance and benefits of active and up-to-date curation of a gene-disease database combined with critical clinical validity scoring and proactive reanalysis in the clinical genomics era.

Exome sequencing covers >98% of mutations identified on targeted next generation sequencing panels

Background

With the expanded availability of next generation sequencing (NGS)-based clinical genetic tests, clinicians seeking to test patients with Mendelian diseases must weigh the superior coverage of targeted gene panels with the greater number of genes included in whole exome sequencing (WES) when considering their first-tier testing approach. Here, we use an in silico analysis to predict the analytic sensitivity of WES using pathogenic variants identified on targeted NGS panels as a reference.

Methods

Corresponding nucleotide positions for 1533 different alterations classified as pathogenic or likely pathogenic identified on targeted NGS multi-gene panel tests in our laboratory were interrogated in data from 100 randomly-selected clinical WES samples to quantify the sequence coverage at each position. Pathogenic variants represented 91 genes implicated in hereditary cancer, X-linked intellectual disability, primary ciliary dyskinesia, Marfan syndrome/aortic aneurysms, cardiomyopathies and arrhythmias.

Results

When assessing coverage among 100 individual WES samples for each pathogenic variant (153,300 individual assessments), 99.7% (n = 152,798) would likely have been detected on WES. All pathogenic variants had at least some coverage on exome sequencing, with a total of 97.3% (n = 1491) detectable across all 100 individuals. For the remaining 42 pathogenic variants, the number of WES samples with adequate coverage ranged from 35 to 99. Factors such as location in GC-rich, repetitive, or homologous regions likely explain why some of these alterations were not detected across all samples. To validate study findings, a similar analysis was performed against coverage data from 60,706 exomes available through the Exome Aggregation Consortium (ExAC). Results from this validation confirmed that 98.6% (91,743,296/93,062,298) of pathogenic variants demonstrated adequate depth for detection.

Conclusions

Results from this in silico analysis suggest that exome sequencing may achieve a diagnostic yield similar to panel-based testing for Mendelian diseases.

When bins blur: Patient perspectives on categories of results from clinical whole genome sequencing

BACKGROUND

Clinical genome and exome sequencing (CGES) is being used in an expanding range of clinical settings. Most approaches to offering patients choices about learning CGES results classify results according to expert definitions of clinical actionability. Little is known about how patients conceptualize different categories of CGES results.

METHODS

The MedSeq Project is a randomized controlled trial studying the use of whole-genome sequencing (WGS) in primary care and cardiology. We surveyed 202 patient-participants about different kinds of WGS results and conducted qualitative interviews with 49 of these participants. Interview data were analyzed both inductively and deductively using thematic content analysis.

RESULTS

Participants demonstrated high levels of study understanding and genetic literacy. A small majority of participants wanted to learn all of their WGS results (n = 123, 61%). Qualitative data provided a deeper understanding of participants' perspectives about different types of WGS results. Participants did not have the same views about which WGS results would be actionable or upsetting to learn. They conceptualized variants of uncertain significance (VUS) in a variety of different ways. Many participants expressed optimism that the uncertainty associated with VUS results could be reduced over time.

CONCLUSIONS

Proposals to determine which WGS/CGES results to disclose by soliciting patient preferences may fail to appreciate the complex ways patients think about disease and the information WGS/CGES can produce. Our findings challenge prevailing methods of facilitating patient choice and assessing the benefits and harms related to the return of WGS/CGES results, which mostly rely on expert definitions of clinical utility to categorize the kinds of results patients can learn.

Precision medicine for advanced prostate cancer

PURPOSE OF REVIEW

Precision cancer medicine, the use of genomic profiling of patient tumors at the point-of-care to inform treatment decisions, is rapidly changing treatment strategies across cancer types. Precision medicine for advanced prostate cancer may identify new treatment strategies and change clinical practice. In this review, we discuss the potential and challenges of precision medicine in advanced prostate cancer.

RECENT FINDINGS

Although primary prostate cancers do not harbor highly recurrent targetable genomic alterations, recent reports on the genomics of metastatic castration-resistant prostate cancer has shown multiple targetable alterations in castration-resistant prostate cancer metastatic biopsies. Therapeutic implications include targeting prevalent DNA repair pathway alterations with PARP-1 inhibition in genomically defined subsets of patients, among other genomically stratified targets. In addition, multiple recent efforts have demonstrated the promise of liquid tumor profiling (e.g., profiling circulating tumor cells or cell-free tumor DNA) and highlighted the necessary steps to scale these approaches in prostate cancer.

SUMMARY

Although still in the initial phase of precision medicine for prostate cancer, there is extraordinary potential for clinical impact. Efforts to overcome current scientific and clinical barriers will enable widespread use of precision medicine approaches for advanced prostate cancer patients.

TECRL, a new life-threatening inherited arrhythmia gene associated with overlapping clinical features of both LQTS and CPVT

Genetic causes of many familial arrhythmia syndromes remain elusive. In this study, whole‐exome sequencing (WES) was carried out on patients from three different families that presented with life‐threatening arrhythmias and high risk of sudden cardiac death (SCD). Two French Canadian probands carried identical homozygous rare variant in TECRL gene (p.Arg196Gln), which encodes the trans‐2,3‐enoyl‐CoA reductase‐like protein. Both patients had cardiac arrest, stress‐induced atrial and ventricular tachycardia, and QT prolongation on adrenergic stimulation. A third patient from a consanguineous Sudanese family diagnosed with catecholaminergic polymorphic ventricular tachycardia (CPVT) had a homozygous splice site mutation (c.331+1G>A) in TECRL. Analysis of intracellular calcium ([Ca²⁺]_i) dynamics in human induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs) generated from this individual (TECRL_Hom‐hiPSCs), his heterozygous but clinically asymptomatic father (TECRL_Het‐hiPSCs), and a healthy individual (CTRL‐hiPSCs) from the same Sudanese family, revealed smaller [Ca²⁺]_i transient amplitudes as well as elevated diastolic [Ca²⁺]_i in TECRL_Hom‐hiPSC‐CMs compared with CTRL‐hiPSC‐CMs. The [Ca²⁺]_i transient also rose markedly slower and contained lower sarcoplasmic reticulum (SR) calcium stores, evidenced by the decreased magnitude of caffeine‐induced [Ca²⁺]_i transients. In addition, the decay phase of the [Ca²⁺]_i transient was slower in TECRL_Hom‐hiPSC‐CMs due to decreased SERCA and NCX activities. Furthermore, TECRL_Hom‐hiPSC‐CMs showed prolonged action potentials (APs) compared with CTRL‐hiPSC‐CMs. TECRL knockdown in control human embryonic stem cell‐derived CMs (hESC‐CMs) also resulted in significantly longer APs. Moreover, stimulation by noradrenaline (NA) significantly increased the propensity for triggered activity based on delayed afterdepolarizations (DADs) in TECRL_Hom‐hiPSC‐CMs and treatment with flecainide, a class Ic antiarrhythmic drug, significantly reduced the triggered activity in these cells. In summary, we report that mutations in TECRL are associated with inherited arrhythmias characterized by clinical features of both LQTS and CPVT. Patient‐specific hiPSC‐CMs recapitulated salient features of the clinical phenotype and provide a platform for drug screening evidenced by initial identification of flecainide as a potential therapeutic. These findings have implications for diagnosis and treatment of inherited cardiac arrhythmias.

Communicating microarray results of uncertain clinical significance in consultation summary letters and implications for practice

Letter-writing is an integral practice for genetic health professionals. In Victoria, Australia, patients with a chromosomal variant of uncertain clinical significance (VUS) referred to a clinical geneticist (CG) for evaluation receive consultation summary letters. While communication of uncertainty has been explored in research to some extent, little has focused on how uncertainty is communicated within consultation letters. We aimed to develop a multi-layered understanding of the ways in which CGs communicate diagnostic uncertainty in consultation summary letters. We used theme-oriented discourse analysis of 49 consultation summary letters and thematic analysis of a focus group involving eight CGs. Results showed that CGs have become more confident in their description of VUS as 'contributing factors' to patients' clinical features, but remain hesitant to assign definitive causality. CGs displayed strong epistemic stance when discussing future technological improvements to provide hope and minimise potentially disappointing outcomes for patients and families. CGs reported feeling overwhelmed by their workload associated with increasing numbers of patients with VUS, and this has led to a reduction in the number of review appointments offered over time. This study provides a rich description of the content and process of summary letters discussing VUS. Our findings have implications for letter-writing and workforce management. Furthermore, these findings may be of relevance to VUS identified by genomic sequencing in clinical practice.

A first-line diagnostic assay for limb-girdle muscular dystrophy and other myopathies

Background

Fifty random genetically unstudied families (limb-girdle muscular dystrophy (LGMD)/myopathy) were screened with a gene panel incorporating 759 OMIM genes associated with neurological disorders. Average coverage of the CDS and 10 bp flanking regions of genes was 99 %. All families were referred to the Neurosciences Clinic of King Faisal Specialist Hospital and Research Centre, Saudi Arabia. Patients presented with muscle weakness affecting the pelvic and shoulder girdle. Muscle biopsy in all cases showed dystrophic or myopathic changes. Our main objective was to evaluate a neurological gene panel as a first-line diagnostic test for LGMD/myopathies.

Results

Our panel identified the mutation in 76 % of families (38/50; 11 novel). Thirty-four families had mutations in LGMD-related genes with four others having variants not typically associated with LGMD. The majority of cases had recessive inheritance with homoallelic pathogenic variants (97.4 %, 37/38), as expected considering the high rate of consanguinity in the study population. In one case, we detected a heterozygous mutation in DNAJB responsible for LGMD-1E. Our cohort included seven different subtypes of LGMD2. Mutations of DYSF were the most commonly identified cause of disease followed by that in CAPN3 and FKRP. Non-LGMD myopathies were due to mutations in genes associated with congenital disorder of glycosylation (ALG2), rigid spine muscular dystrophy 1 (SEPN1), inclusion body myopathy2/Nonaka myopathy (GNE), and neuropathy (WNK1). Whole exome sequencing (WES) of patients who remained undiagnosed with the neurological panel did not improve our diagnostic yield.

Conclusions

Our neurological panel achieved a high clinical sensitivity (76 %) and is an effective first-line laboratory test in patients with LGMD and other myopathies. This sensitive, cost-effective, and rapid assay significantly assists clinical practice especially in these phenotypically and genetically heterogeneous disorders. Moreover, the application of the American College of Medical Genetics (ACMG) and Association for Molecular Pathology (AMP) guidelines applied in the classification of variant pathogenecity provides a clear interpretation for physicians on the relevance of such findings.

Electronic supplementary material

The online version of this article (doi:10.1186/s40246-016-0089-8) contains supplementary material, which is available to authorized users.

Genetics of Tinnitus: An Emerging Area for Molecular Diagnosis and Drug Development

Subjective tinnitus is the perception of sound in the absence of external or bodily-generated sounds. Chronic tinnitus is a highly prevalent condition affecting over 70 million people in Europe. A wide variety of comorbidities, including hearing loss, psychiatric disorders, neurodegenerative disorders, and temporomandibular joint (TMJ) dysfunction, have been suggested to contribute to the onset or progression of tinnitus; however, the precise molecular mechanisms of tinnitus are not well understood and the contribution of genetic and epigenetic factors remains unknown. Human genetic studies could enable the identification of novel molecular therapeutic targets, possibly leading to the development of novel pharmaceutical therapeutics. In this article, we briefly discuss the available evidence for a role of genetics in tinnitus and consider potential hurdles in designing genetic studies for tinnitus. Since multiple diseases have tinnitus as a symptom and the supporting genetic evidence is sparse, we propose various strategies to investigate the genetic underpinnings of tinnitus, first by showing evidence of heritability using concordance studies in twins, and second by improving patient selection according to phenotype and/or etiology in order to control potential biases and optimize genetic data output. The increased knowledge resulting from this endeavor could ultimately improve the drug development process and lead to the preventive or curative treatment of tinnitus.

Comparison of genome sequencing and clinical genotyping for pharmacogenes

We compared whole exome sequencing (WES, n = 176 patients) and whole genome sequencing (WGS, n = 68) and clinical genotyping (DMET array-based approach) for interrogating 13 genes with Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines. We focused on 127 CPIC important variants: 103 single nucleotide variations (SNV), 21 insertion/deletions (Indel), HLA-B alleles, and two CYP2D6 structural variations. WES and WGS provided interrogation of nonoverlapping sets of 115 SNV/Indels with call rate >98%. Among 68 loci interrogated by both WES and DMET, 64 loci (94.1%, confidence interval [CI]: 85.6-98.4%) showed no discrepant genotyping calls. Among 66 loci interrogated by both WGS and DMET, 63 loci (95.5%, CI: 87.2-99.0%) showed no discrepant genotyping calls. In conclusion, even without optimization to interrogate pharmacogenetic variants, WES and WGS displayed potential to provide reliable interrogation of most pharmacogenes and further validation of genome sequencing in a clinical lab setting is warranted.

A comparative assessment of clinical whole exome and transcriptome profiling across sequencing centers: implications for precision cancer medicine

Advances in next generation sequencing technologies provide approaches to comprehensively determine genomic alterations within a tumor that occur as a cause or consequence of neoplastic growth. Though providers offering various cancer genomics assays have multiplied, the level of reproducibility in terms of the technical sensitivity and the conclusions resulting from the data analyses have not been assessed.We sought to determine the reproducibility of ascertaining tumor genome aberrations using whole exome sequencing (WES) and RNAseq. Samples of the same metastatic tumors were independently processed and subjected to WES of tumor and constitutional DNA, and RNAseq of RNA, at two sequencing centers. Overall, the sequencing results were highly comparable. Concordant mutation calls ranged from 88% to 93% of all variants including 100% agreement across 154 cancer-associated genes. Regions of copy losses and gains were uniformly identified and called by each sequencing center and chromosomal plots showed nearly identical patterns. Transcript abundance levels also exhibited a high degree of concordance (r2 ≥ 0.78;Pearson). Biologically-relevant gene fusion events were concordantly called. Exome sequencing of germline DNA samples provided a minimum of 30X coverage depth across 56 genes where incidental findings are recommended to be reported. One possible pathogenic variant in the APC gene was identified by both sequencing centers.The findings from this study demonstrate that results of somatic and germline sequencing are highly concordant across sequencing centers that have substantial experience in the technological requirements for preparing, sequencing and annotating DNA and RNA from human biospecimens.