Applying Genomic Analysis to Newborn Screening

Mass spectrometry for metabolomics analysis: Applications in neonatal and cancer screening

Chemical analysis by analytical instrumentation has played a major role in disease diagnosis, which is a necessary step for disease treatment. While the treatment process often targets specific organs or compounds, the diagnostic step can occur through various means, including physical or chemical examination. Chemically, the genome may be evaluated to give information about potential genetic outcomes, the transcriptome to provide information about expression actively occurring, the proteome to offer insight on functions causing metabolite expression, or the metabolome to provide a picture of both past and ongoing physiological function in the body. Mass spectrometry (MS) has been elevated among other analytical instrumentation because it can be used to evaluate all four biological machineries of the body. In addition, MS provides enhanced sensitivity, selectivity, versatility, and speed for rapid turnaround time, qualities that are important for instance in clinical procedures involving the diagnosis of a pediatric patient in intensive care or a cancer patient undergoing surgery. In this review, we provide a summary of the use of MS to evaluate biomarkers for newborn screening and cancer diagnosis. As many reviews have recently appeared focusing on MS methods and instrumentation for metabolite analysis, we sought to describe the biological basis for many metabolomic and additional omics biomarkers used in newborn screening and how tandem MS methods have recently been applied, in comparison to traditional methods. Similar comparison is done for cancer screening, with emphasis on emerging MS approaches that allow biological fluids, tissues, and breath to be analyzed for the presence of diagnostic metabolites yielding insight for treatment options based on the understanding of prior and current physiological functions of the body.

Principles of Genomic Newborn Screening Programs: A Systematic Review

IMPORTANCE

Genomic newborn screening (gNBS) may optimize the health and well-being of children and families. Screening programs are required to be evidence based, acceptable, and beneficial.

OBJECTIVES

To identify what has been discovered following the reporting of the first gNBS pilot projects and to provide a summary of key points for the design of gNBS.

EVIDENCE REVIEW

A systematic literature review was performed on April 14, 2021, identifying 36 articles that addressed the following questions: (1) what is the interest in and what would be the uptake of gNBS? (2) what diseases and genes should be included? (3) what is the validity and utility of gNBS? and (4) what are the ethical, legal, and social implications? Articles were only included if they generated new evidence; all opinion pieces were excluded.

FINDINGS

In the 36 articles included, there was high concordance, except for gene disease inclusion, which was highly variable. Key findings were the need for equitable access, appropriate educational materials, and informed and flexible consent. The process for selecting genes for testing should be transparent and reflect that parents value the certainty of prediction over actionability. Data should be analyzed in a way that minimizes uncertainty and incidental findings. The expansion of traditional newborn screening (tNBS) to identify more life-threatening and treatable diseases needs to be balanced against the complexity of consenting parents of newborns for genomic testing as well as the risk that overall uptake of tNBS may decline. The literature reflected that the right of a child to self-determination should be valued more than the possibility of the whole family benefiting from a newborn genomic test.

CONCLUSIONS AND RELEVANCE

The findings of this systematic review suggest that implementing gNBS will require a nuanced approach. There are gaps in our knowledge, such as the views of diverse populations, the capabilities of health systems, and health economic implications. It will be essential to rigorously evaluate outcomes and ensure programs can evolve to maximize benefit.

Simple Test, Complex System: Multifaceted Views of Newborn Screening Science, Technology, and Policy

Newborn screening (NBS) is a public health service provided for all babies born in the United States and in most countries of the developed world. A series of tests are applied to the blood taken from newborn babies to detect genetic and metabolic disorders that can be treated if identified early. With early treatment and therapy, the affected babies can usually live a normal, healthy life. Timing for sampling, testing, and reporting is vital for NBS to function as an effective system. In order to be an effective system, the evolution of science, technology, and policy gradually had to come into a synchronous partnership, where the discovery of new genetic disorders led to timely development of technology for screening, which is supported by policy and implemented into practice. The timely "dance" of these partnerships in an era of personalized health and medicine forms the integrated approach supporting NBS. This review will include a brief history of scientific development, policymaking, and the economic consideration in the expansion of the NBS.

Justifying the Expansion of Neonatal Screening: Two Cases

During the last two decades, neonatal screening in Europe and North America has expanded substantially. This article examines two recent suggestions for expanding neonatal screening: severe combined immunodeficiency (SCID) and X-linked adrenoleukodystrophy (X-ALD). With reference to well-established risk-benefit based rationales for screening, it is argued that the case for introducing SCID in neonatal screening is considerably stronger than for introducing X-ALD. For instance, the majority of those screened for X-ALD most likely have a negative risk-benefit ratio of screening: they develop milder symptoms or perhaps no symptoms at all, while still being monitored for a long time. This argument is used as a vehicle for making some general points regarding justified expansions of neonatal screening. First, when considering the expansion of neonatal screening, we should look at a condition specific case-by-case basis. Moreover, future expansions of neonatal screening should stick to the well-established rationales for screening while avoiding risk-benefit slippage. Otherwise, more strict procedures of informed consent are warranted in neonatal screening, procedures that, in the end, risk undermining the benefits of current neonatal screening programmes.

New tools and approaches to newborn screening: ready to open Pandora's box?

The landscape of newborn screening (NBS) is changing as new tools are developed. We must acknowledge that NBS is a very important and extraordinarily positive initiative especially for rare and serious inherited disorders; however, lessons learned from current NBS should guide the future of NBS as we enter the era of “omics” that will expand NBS for many other genetic disorders. In this article, I will first discuss new tools such as genomics and metabolomics for NBS. I will then turn to assessing how best to take advantage of new technical developments while considering the best interests of patients and the success of newborn screening.

Content Analysis of Informed Consent for Whole Genome Sequencing Offered by Direct-to-Consumer Genetic Testing Companies

Whole exome sequencing (WES) and whole genome sequencing (WGS) have become increasingly available in the research and clinical settings and are now also being offered by direct-to-consumer (DTC) genetic testing (GT) companies. This offer can be perceived as amplifying the already identified concerns regarding adequacy of informed consent (IC) for both WES/WGS and the DTC GT context. We performed a qualitative content analysis of Websites of four companies offering WES/WGS DTC regarding the following elements of IC: pre-test counseling, benefits and risks, and incidental findings (IFs). The analysis revealed concerns, including the potential lack of pre-test counseling in three of the companies studied, missing relevant information in the risks and benefits sections, and potentially misleading information for consumers. Regarding IFs, only one company, which provides opportunistic screening, provides basic information about their management. In conclusion, some of the information (and related practices) present on the companies' Web pages salient to the consent process are not adequate in reference to recommendations for IC for WGS or WES in the clinical context. Requisite resources should be allocated to ensure that commercial companies are offering high-throughput sequencing under responsible conditions, including an adequate consent process.

Exome screening to identify loss-of-function mutations in the rhesus macaque for development of preclinical models of human disease

Background

Exome sequencing has been utilized to identify genetic variants associated with disease in humans. Identification of loss-of-function mutations with exome sequencing in rhesus macaques (Macaca mulatta) could lead to valuable animal models of genetic disease. Attempts have been made to identify variants in rhesus macaques by aligning exome data against the rheMac2 draft genome. However, such efforts have been impaired due to the incompleteness and annotation errors associated with rheMac2. We wished to determine whether aligning exome reads against our new, improved rhesus genome, MacaM, could be used to identify high impact, loss-of-function mutations in rhesus macaques that would be relevant to human disease.

Results

We compared alignments of exome reads from four rhesus macaques, the reference animal and three unrelated animals, against rheMac2 and MacaM. Substantially more reads aligned against MacaM than rheMac2. We followed the Broad Institute’s Best Practice guidelines for variant discovery which utilizes the Genome Analysis Toolkit to identify high impact mutations. When rheMac2 was used as the reference genome, a large number of apparent false positives were identified. When MacaM was used as the reference genome, the number of false positives was greatly reduced. After examining the variant analyses conducted with MacaM as reference genome, we identified two putative loss-of-function mutations, in the heterozygous state, in genes related to human health. Sanger sequencing confirmed the presence of these mutations. We followed the transmission of one of these mutations (in the butyrylthiocholine gene) through three generations of rhesus macaques. Further, we demonstrated a functional decrease in butyrylthiocholinesterase activity similar to that observed in human heterozygotes with loss-of-function mutations in the same gene.

Conclusions

The new MacaM genome can be effectively utilized to identify loss-of-function mutations in rhesus macaques without generating a high level of false positives. In some cases, heterozygotes may be immediately useful as models of human disease. For diseases where homozygous mutants are needed, directed breeding of loss-of-function heterozygous animals could be used to create rhesus macaque models of human genetic disease. The approach we describe here could be applied to other mammals, but only if their genomes have been improved beyond draft status.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2509-5) contains supplementary material, which is available to authorized users.

Can we afford to sequence every newborn baby's genome?

Whole-exome sequencing and whole-genome sequencing are gradually entering into the clinical arena. Drops in sequencing prices have led some to suggest that these analyses could be extended to the screening of whole populations or subsets thereof. Herein, we argue that this optimism is presently still unfounded. While cost estimates take into account the generation of sequence data, they fail to properly evaluate both the price of accurate and efficient interpretation and of the proper return of genomic information to the consulting individuals. Thus, short of inventing new, cost-effective ways of achieving these goals, the latter are likely to ruin our healthcare systems. We posit that due to lack of available resources, generalization of this practice remains, for the time being, unrealistic.

Challenges of using next generation sequencing in newborn screening

Whole-genome and whole-exome sequencing for clinical applications is now an integral part of medical genetics practice. The term newborn screening refers to public health programs designed to screen newborns for various treatable metabolic conditions, by measuring levels of circulating blood metabolites. The availability and significant decrease in sequencing costs has raised the question of whether metabolic newborn screening should be replaced by whole-genome or whole-exome sequencing. While newborn genome sequencing can potentially increase the number of disorders identified by newborn screening, the generalization of its practice raises a number of important ethical issues. This short article argues that there are medical, psychological, ethical and economic reasons why widespread dissemination of newborn screening is still premature.

Expectations and values about expanded newborn screening: a public engagement study

OBJECTIVES

Newborn bloodspot screening (NBS) panels have expanded to include conditions for which treatment effects are less certain, creating debate about population-based screening criteria. We investigated Canadian public expectations and values regarding the types of conditions that should be included in NBS and whether parents should provide consent.

METHODS

Eight focus groups (FG; n = 60) included education, deliberative discussion and pre-/post-questionnaires. Data were analysed quantitatively and qualitatively.

RESULTS

Quantitatively, the majority supported NBS for serious disorders for which treatment is not available (95-98, 82%). A majority endorsed screening without explicit consent (77-88%) for treatable disorders, but 62% supported unpressured choice for screening for untreatable disorders. Qualitatively, participants valued treatment-related benefits for infants and informational benefits for families. Concern for anxiety, stigma and unwanted knowledge depended upon disease context and strength of countervailing benefits.

CONCLUSIONS

Anticipated benefits of expanded infant screening were prioritized over harms, with information provision perceived as a mechanism for mitigating harms and enabling choice. However, we urge caution around the potential for public enthusiasm to foster unlimited uptake of infant screening technologies.

Public views on participating in newborn screening using genome sequencing

Growing discussion on the use of whole-genome or exome sequencing (WG/ES) in newborn screening (NBS) has raised concerns regarding the generation of incidental information on millions of infants annually. It is unknown whether integrating WG/ES would alter public expectations regarding participation in universal NBS. We assessed public willingness to participate in NBS using WG/ES compared with current NBS. Our secondary objective was to assess the public's beliefs regarding a parental responsibility to participate in WG/ES-based NBS compared with current NBS. We examined self-reported attitudes regarding willingness to participate in NBS using a cross-sectional national survey of Canadian residents recruited through an internet panel, reflective of the Canadian population by age, gender and region. Our results showed that fewer respondents would be willing to participate in NBS using WG/ES compared with NBS using current technologies (80 vs 94%, P<0.001), or perceived a parental responsibility to participate in WG/ES-based NBS vs current NBS (30 vs 48%, P<0.001). Our findings suggest that integrating WG/ES into NBS might reduce participation, and challenge the moral authority that NBS programmes rely upon to ensure population benefits. These findings point to the need for caution in the untargeted use of WG/ES in public health contexts.

Inborn errors of metabolism and expanded newborn screening: review and update

Inborn errors of metabolism (IEM) are a phenotypically and genetically heterogeneous group of disorders caused by a defect in a metabolic pathway, leading to malfunctioning metabolism and/or the accumulation of toxic intermediate metabolites. To date, more than 1000 different IEM have been identified. While individually rare, the cumulative incidence has been shown to be upwards of 1 in 800. Clinical presentations are protean, complicating diagnostic pathways. IEM are present in all ethnic groups and across every age. Some IEM are amenable to treatment, with promising outcomes. However, high clinical suspicion alone is not sufficient to reduce morbidities and mortalities. In the last decade, due to the advent of tandem mass spectrometry, expanded newborn screening (NBS) has become a mandatory public health strategy in most developed and developing countries. The technology allows inexpensive simultaneous detection of more than 30 different metabolic disorders in one single blood spot specimen at a cost of about USD 10 per baby, with commendable analytical accuracy and precision. The sensitivity and specificity of this method can be up to 99% and 99.995%, respectively, for most amino acid disorders, organic acidemias, and fatty acid oxidation defects. Cost-effectiveness studies have confirmed that the savings achieved through the use of expanded NBS programs are significantly greater than the costs of implementation. The adverse effects of false positive results are negligible in view of the economic health benefits generated by expanded NBS and these could be minimized through increased education, better communication, and improved technologies. Local screening agencies should be given the autonomy to develop their screening programs in order to keep pace with international advancements. The development of biochemical genetics is closely linked with expanded NBS. With ongoing advancements in nanotechnology and molecular genomics, the field of biochemical genetics is still expanding rapidly. The potential of tandem mass spectrometry is extending to cover more disorders. Indeed, the use of genetic markers in T-cell receptor excision circles for severe combined immunodeficiency is one promising example. NBS represents the highest volume of genetic testing. It is more than a test and it warrants systematic healthcare service delivery across the pre-analytical, analytical, and post-analytical phases. There should be a comprehensive reporting system entailing genetic counselling as well as short-term and long-term follow-up. It is essential to integrate existing clinical IEM services with the expanded NBS program to enable close communication between the laboratory, clinicians, and allied health parties. In this review, we will discuss the history of IEM, its clinical presentations in children and adult patients, and its incidence among different ethnicities; the history and recent expansion of NBS, its cost-effectiveness, associated pros and cons, and the ethical issues that can arise; the analytical aspects of tandem mass spectrometry and post-analytical perspectives regarding result interpretation.

Emerging issues in public health genomics

This review highlights emerging areas of interest in public health genomics. First, we describe recent advances in newborn screening (NBS), with a focus on the practice and policy implications of current and future efforts to expand NBS programs (e.g., via next-generation sequencing). Next, we detail research findings from the rapidly progressing field of epigenetics and epigenomics, highlighting ways in which our emerging understanding in these areas could guide future intervention and research efforts in public health. We close by considering various ethical, legal, and social issues posed by recent developments in public health genomics; these include policies to regulate access to personal genomic information, the need to enhance genetic literacy in both health professionals and the public, and challenges in ensuring that the benefits (and burdens) of genomic discoveries and applications are equitably distributed. We also note needs for future genomic research that integrates across basic and social sciences.

Parents' interest in whole-genome sequencing of newborns

PURPOSE

The aim of this study was to assess parents' interest in whole-genome sequencing for newborns.

METHODS

We conducted a survey of a nationally representative sample of 1,539 parents about their interest in whole-genome sequencing of newborns. Participants were randomly presented with one of two scenarios that differed in the venue of testing: one offered whole-genome sequencing through a state newborn screening program, whereas the other offered whole-genome sequencing in a pediatrician's office.

RESULTS

Overall interest in having future newborns undergo whole-genome sequencing was generally high among parents. If whole-genome sequencing were offered through a state's newborn-screening program, 74% of parents were either definitely or somewhat interested in utilizing this technology. If offered in a pediatrician's office, 70% of parents were either definitely or somewhat interested. Parents in both groups most frequently identified test accuracy and the ability to prevent a child from developing a disease as "very important" in making a decision to have a newborn's whole genome sequenced.

CONCLUSION

These data may help health departments and children's health-care providers anticipate parents' level of interest in genomic screening for newborns. As whole-genome sequencing is integrated into clinical and public health services, these findings may inform the development of educational strategies and outreach messages for parents.

Clinical genomic database

Technological advances have greatly increased the availability of human genomic sequencing. However, the capacity to analyze genomic data in a clinically meaningful way lags behind the ability to generate such data. To help address this obstacle, we reviewed all conditions with genetic causes and constructed the Clinical Genomic Database (CGD) (http://research.nhgri.nih.gov/CGD/), a searchable, freely Web-accessible database of conditions based on the clinical utility of genetic diagnosis and the availability of specific medical interventions. The CGD currently includes a total of 2,616 genes organized clinically by affected organ systems and interventions (including preventive measures, disease surveillance, and medical or surgical interventions) that could be reasonably warranted by the identification of pathogenic mutations. To aid independent analysis and optimize new data incorporation, the CGD also includes all genetic conditions for which genetic knowledge may affect the selection of supportive care, informed medical decision-making, prognostic considerations, reproductive decisions, and allow avoidance of unnecessary testing, but for which specific interventions are not otherwise currently available. For each entry, the CGD includes the gene symbol, conditions, allelic conditions, clinical categorization (for both manifestations and interventions), mode of inheritance, affected age group, description of interventions/rationale, links to other complementary databases, including databases of variants and presumed pathogenic mutations, and links to PubMed references (>20,000). The CGD will be regularly maintained and updated to keep pace with scientific discovery. Further content-based expert opinions are actively solicited. Eventually, the CGD may assist the rapid curation of individual genomes as part of active medical care.

Diagnostic cancer genome sequencing and the contribution of germline variants

Whole-genome sequencing (WGS) is revolutionizing medical research and has the potential to serve as a powerful and cost-effective diagnostic tool in the management of cancer. We review the progress to date in the use of WGS to reveal how germline variants and mutations may be associated with cancer. We use colorectal cancer as an example of how the current level of knowledge can be translated into predictions of predisposition. We also address challenges in the clinical implementation of the variants in germline DNA identified through cancer genome sequencing. We call for the international development of standards to facilitate the clinical use of germline information arising from diagnostic cancer genome sequencing.