An appraisal of the Wilson & Jungner criteria in the context of genomic-based newborn screening for inborn errors of immunity

Expanded Newborn Screening for Inborn Errors of Immunity: The Experience of Tuscany

BACKGROUND

Inborn errors of immunity (IEIs) include 485 inherited disorders characterized by an increased susceptibility to life-threatening infectious diseases, autoimmunity, and malignant diseases with a high mortality rate in the first years of life. Severe combined immunodeficiency is the most severe of the IEIs, and its detection should be a primary goal in a newborn screening (NBS) program. The term "actionable" has recently been used for all IEIs with outcomes that can be demonstrably improved through early specialized intervention.

OBJECTIVE

To evaluate the results of the expanded NBS strategy for IEIs in Tuscany Region (Italy), based on T-cell receptor excision circle, kappa recombining excision circle, and tandem mass-based assays.

METHODS

This is a retrospective study collecting data from all infants born in Tuscany from October 10, 2018, to October 10, 2022. Tandem mass assay to identify adenosine deaminase and purine nucleoside phosphorylase deficiency, together with T-cell receptor excision circle and kappa recombining excision circle molecular analysis, was conducted on dried blood spot from the newborns' Guthrie Cards. A new dried blood spot and evaluation by an immunologist were carried out when the results of the first test were outside the diagnostic cutoffs.

RESULTS

A total of 94,319 newborns were evaluated. Referral rates for T-cell recombining excision circles (0.031%) and kappa recombining excision circles (0.074%) in this study are in line with the data available in literature. The results from the expanded NBS strategy revealed an incidence rate of 1 per 9431 affected newborns.

CONCLUSIONS

This work represents the first description of a sustainable and real-life-based expanded NBS program for IEIs with a high diagnostic incidence facilitating prompt management of identified patients.

Australian public perspectives on genomic newborn screening: which conditions should be included?

BACKGROUND

Implementing genomic sequencing into newborn screening programs allows for significant expansion in the number and scope of conditions detected. We sought to explore public preferences and perspectives on which conditions to include in genomic newborn screening (gNBS).

METHODS

We recruited English-speaking members of the Australian public over 18 years of age, using social media, and invited them to participate in online focus groups.

RESULTS

Seventy-five members of the public aged 23-72 participated in one of fifteen focus groups. Participants agreed that if prioritisation of conditions was necessary, childhood-onset conditions were more important to include than later-onset conditions. Despite the purpose of the focus groups being to elicit public preferences, participants wanted to defer to others, such as health professionals or those with a lived experience of each condition, to make decisions about which conditions to include. Many participants saw benefit in including conditions with no available treatment. Participants agreed that gNBS should be fully publicly funded.

CONCLUSION

How many and which conditions are included in a gNBS program will be a complex decision requiring detailed assessment of benefits and costs alongside public and professional engagement. Our study provides support for implementing gNBS for treatable childhood-onset conditions.

Early hematopoietic cell transplantation for familial hemophagocytic lymphohistiocytosis in a regional treatment network in Japan

Familial hemophagocytic lymphohistiocytosis (FHLH) is a fatal hyperinflammation syndrome arising from the genetic defect of perforin-mediated cytolysis. Curative hematopoietic cell transplantation (HCT) is needed before development of central nervous system (CNS) disease. We studied treatment outcomes of 13 patients (FHLH2 n = 11, FHLH3 n = 2) consecutively diagnosed from 2011 to 2022 by flow cytometric screening for non-myeloablative HCT in a regional treatment network in Kyushu, Japan. One patient with a novel PRF1 variant escaped screening, but all patients with FHLH2 reached diagnosis and 8 of them received HCT until 3 and 9 months of age, respectively. The earliest HCT was conducted 65 days after birth. Three pretransplant deaths occurred in newborns with liver failure at diagnosis. Ten posttransplant patients have remained disease-free, 7 of whom had no neurological involvement. Time from first etoposide infusion to HCT was shorter in patients without CNS disease or bleeding than in patients with those factors (median [range] days: 62 [50-81] vs. 122 [89-209], p = 0.016). Six of 9 unrelated patients had a PRF1 c.1090_1091delCT variant. These results suggest that the critical times to start etoposide and HCT are within 3 months after birth and during etoposide control, respectively. Newborn screening may increase the percentage of disease-free survivors without complications.

Newborn screening for severe combined immunodeficiency and inborn errors of immunity

PURPOSE OF REVIEW

Severe combined immune deficiency (SCID) is the most devastating genetic disease of the immune system with an unfavorable outcome unless diagnosed early in life. Newborn screening (NBS) programs play a crucial role in facilitating early diagnoses and timely interventions for affected infants.

RECENT FINDINGS

SCID marked the pioneering inborn error of immunity (IEI) to undergo NBS, a milestone achieved 15 years ago through the enumeration of T-cell receptor excision circles (TRECs) extracted from Guthrie cards. This breakthrough has revolutionized our approach to SCID, enabling not only presymptomatic identification and prompt treatments (including hematopoietic stem cell transplantation), but also enhancing our comprehension of the global epidemiology of SCID.

SUMMARY

NBS is continuing to evolve with the advent of novel diagnostic technologies and treatments. Following the successful implementation of SCID-NBS programs, a call for the early identification of additional IEIs is the next step, encompassing a broader spectrum of IEIs, facilitating early diagnoses, and preventing morbidity and mortality.

Genetic newborn screening and digital technologies: A project protocol based on a dual approach to shorten the rare diseases diagnostic path in Europe

Since 72% of rare diseases are genetic in origin and mostly paediatrics, genetic newborn screening represents a diagnostic "window of opportunity". Therefore, many gNBS initiatives started in different European countries. Screen4Care is a research project, which resulted of a joint effort between the European Union Commission and the European Federation of Pharmaceutical Industries and Associations. It focuses on genetic newborn screening and artificial intelligence-based tools which will be applied to a large European population of about 25.000 infants. The neonatal screening strategy will be based on targeted sequencing, while whole genome sequencing will be offered to all enrolled infants who may show early symptoms but have resulted negative at the targeted sequencing-based newborn screening. We will leverage artificial intelligence-based algorithms to identify patients using Electronic Health Records (EHR) and to build a repository "symptom checkers" for patients and healthcare providers. S4C will design an equitable, ethical, and sustainable framework for genetic newborn screening and new digital tools, corroborated by a large workout where legal, ethical, and social complexities will be addressed with the intent of making the framework highly and flexibly translatable into the diverse European health systems.

Critical diseases in neonates after discharge home from birth hospital: A retrospective study from a tertiary hospital in Japan

INTRODUCTION

To establish actionable neonatal screening during the first month of life, we investigated critical diseases in seemingly healthy newborns discharged from birth hospitals.

METHODS

This retrospective study enrolled previously healthy full-term infants who visited our hospital, a tertiary hospital in Japan, from home between 5 and 28 days after birth from 2009 to 2018. Infants with known perinatal or congenital diseases, positive newborn screening results, or accidental injuries were excluded. Data were collected from electronic medical records, including principal diagnosis, clinical details, and prognosis at 18 months of age.

RESULTS

Ninety-seven (58 %) of 168 eligible neonates were admitted to the hospital, and 71 (42 %) were not. The median admission rate in patients with disease onset at ≤14 days after birth (80 %) was significantly higher than that in patients with disease onset at ≥15 days (42 %). Among 45 patients who received intensive medical care, 5 died and 10 developed neurodevelopmental sequelae. Four of 5 patients died by 100 days. Among 25 diseases treated in intensive care unit, 17 (68 %) diseases had a prevalence of <1 per 2000 live births. The commonly used diagnostic methods were imaging (n = 58, 35 %) and physical examination (n = 34, 20 %).

CONCLUSION

Critical diseases due to rare and heterogeneous causes in ostensibly healthy newborns occurred predominantly in the first two weeks of life. Optimal newborn screening and health check-up protocols may benefit from the wide spectrum of life-threatening diseases occurring in home after birth.

Are We Ready for Whole Population Genomic Sequencing of Asymptomatic Newborns?

The introduction of genomic sequencing technologies into routine newborn screening programs in some form is not only inevitable but also already occurring in some settings. The question is therefore not "if" but "when and how" genomic newborn screening (GNBS) should be implemented. In April 2022, the Centre for Ethics of Paediatric Genomics held a one-day symposium exploring ethical issues relating to the use of genomic sequencing in a range of clinical settings. This review article synthesises the panel discussion and presents both the potential benefits of wide-scale implementation of genomic newborn screening, as well as its practical and ethical issues, including obtaining appropriate consent, and health system implications. A more in-depth understanding of the barriers associated with implementing genomic newborn screening is critical to the success of GNBS programs, both from a practical perspective and also in order to maintain public trust in an important public health initiative.

Efficient screening strategies for severe combined immunodeficiencies in newborns

INTRODUCTION

Severe combined immunodeficiency (SCID) is one of the most severe forms of inborn errors of immunity (IEI), affecting both cellular and humoral immunity. Without curative treatment such as hematopoietic stem cell transplantation or gene therapy, affected infants die within the first year of life. Due to the severity of the disease, asymptomatic status early in life, and improved survival in the absence of pretransplant infections, SCID was considered a suitable candidate for newborn screening (NBS).

AREAS COVERED

Many countries have introduced SCID screening based on T-cell receptor excision circle (TREC) detection in their NBS programs. Screening an entire population is a radical departure from previous paradigms in the field of immunology. Efficient screening strategies are cost-efficient and balance high sensitivity while preventing high numbers of referrals. NBS for SCID is accompanied by (actionable) secondary findings, but many NBS programs have optimized their screening strategy by adjusting algorithms or including second-tier tests. Harmonization of screening terminology is of great importance for international shared learning.

EXPERT OPINION

The expansion of NBS is driven by the development of new test modalities and treatment options. In the near future, other techniques such as next-generation sequencing will pave the way for NBS of other IEI. Exciting times await for population-based screening programs.

Expanding the Australian Newborn Blood Spot Screening Program using genomic sequencing: do we want it and are we ready?

Since the introduction of genome sequencing in medicine, the factors involved in deciding how to integrate this technology into population screening programs such as Newborn Screening (NBS) have been widely debated. In Australia, participation in NBS is not mandatory, but over 99.9% of parents elect to uptake this screening. Gauging stakeholder attitudes towards potential changes to NBS is vital in maintaining this high participation rate. The current study aimed to determine the knowledge and attitudes of Australian parents and health professionals to the incorporation of genomic sequencing into NBS programs. Participants were surveyed online in 2016 using surveys adapted from previous studies. The majority of parents (90%) self-reported some knowledge of NBS, with 77% expressing an interest in NBS using the new technology. This was significantly lower than those who would utilise NBS using current technologies (99%). Although, many health professionals (62%) felt that new technologies should currently not be used as an adjunct to NBS, 79% foresaw the use of genomic sequencing in NBS by 2026. However, for genomic sequencing to be considered, practical and technical challenges as well as parent information needs were identified including the need for accurate interpretation of data; pre-and post-test counselling; and appropriate parental consent and opt-out process. Therefore, although some support for implementing genomic sequencing into Australian NBS does exist, there is a need for further investigation into the ethical, social, legal and practical implications of introducing this new technology as a replacement to current NBS methods.

Genomic-Based Newborn Screening for Inborn Errors of Immunity: Practical and Ethical Considerations

Inborn errors of immunity (IEI) are a group of over 450 genetically distinct conditions associated with significant morbidity and mortality, for which early diagnosis and treatment improve outcomes. Newborn screening for severe combined immunodeficiency (SCID) is currently underway in several countries, utilising a DNA-based technique to quantify T cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC). This strategy will only identify those infants with an IEI associated with T and/or B cell lymphopenia. Other severe forms of IEI will not be detected. Up-front, first-tier genomic-based newborn screening has been proposed as a potential approach by which to concurrently screen infants for hundreds of monogenic diseases at birth. Given the clinical, phenotypic and genetic heterogeneity of IEI, a next-generation sequencing-based newborn screening approach would be suitable. There are, however, several ethical, legal and social issues which must be evaluated in detail prior to adopting a genomic-based newborn screening approach, and these are discussed herein in the context of IEI.

Newborn Tandem Mass Spectroscopy Screening for Adenosine Deaminase Deficiency-First Two Years' Experience

BACKGROUND

Newborn screening (NBS) via T-cell receptor excision circles (TREC) is now universal in the United States, Puerto Rico, and the Navajo Nation as a strategy to identify severe combined immunodeficiency (SCID) in newborns. Due to the characteristics of adenosine deaminase (ADA) deficiency, small but significant number of cases can be missed by this screening.

OBJECTIVE

To evaluate the results of the first year of statewide NBS for ADA via dried blood spot newborn screening.

METHODS

On October 7, 2019, the state of Michigan began screening newborn dried blood spots for ADA deficiency via the Neobase-2 tandem mass spectroscopy (TMS) kit. We report one known case of ADA deficiency in the 18 months prior to screening. We then reviewed the results of the first two years of TMS ADA screening in Michigan.

RESULTS

There was one ADA deficient patient known to our centers in the 18 months before initiation of TMS ADA screening, this patient died of complications of their disease. In the first two years of TMS ADA NBS, 206,321 infants were screened, and two patients had positive ADA screens. Both patients had ADA deficiency confirmed through biochemical and genetic testing. One patient identified also had a positive TREC screen and was confirmed to have ADA SCID.

CONCLUSION

In our first two years, TMS NBS for ADA deficiency identified two patients with ADA deficiency at negligible cost; including one patient who would not have been identified by TREC NBS. This report provides initial evidence of the value of specific NBS for ADA deficiency.

Polygenic risk score for embryo selection—not ready for prime time

Numerous chronic diseases have a substantial hereditary component. Recent advances in human genetics have allowed the extent of this to be quantified via genome-wide association studies, producing polygenic risk scores (PRS), which can then be applied to individuals to estimate their risk of developing a disease in question. This technology has recently been applied to embryo selection in the setting of IVF and preimplantation genetic testing, with limited data to support its utility. Furthermore, there are concerns that the inherent limitations of PRS makes it ill-suited for use as a screening test in this setting. There are also serious ethical and moral questions associated with this technology that are yet to be addressed. We conclude that further research and ethical reflection are required before embryo selection based on PRS is offered to patients outside of the research setting.

Leveraging Systems Immunology to Optimize Diagnosis and Treatment of Inborn Errors of Immunity

Inborn errors of immunity (IEI) are monogenic disorders that can cause diverse symptoms, including recurrent infections, autoimmunity and malignancy. While many factors have contributed, the increased availability of next-generation sequencing has been central in the remarkable increase in identification of novel monogenic IEI over the past years. Throughout this phase of disease discovery, it has also become evident that a given gene variant does not always yield a consistent phenotype, while variants in seemingly disparate genes can lead to similar clinical presentations. Thus, it is increasingly clear that the clinical phenotype of an IEI patient is not defined by genetics alone, but is also impacted by a myriad of factors. Accordingly, we need methods to amplify our current diagnostic algorithms to better understand mechanisms underlying the variability in our patients and to optimize treatment. In this review, we will explore how systems immunology can contribute to optimizing both diagnosis and treatment of IEI patients by focusing on identifying and quantifying key dysregulated pathways. To improve mechanistic understanding in IEI we must deeply evaluate our rare IEI patients using multimodal strategies, allowing both the quantification of altered immune cell subsets and their functional evaluation. By studying representative controls and patients, we can identify causative pathways underlying immune cell dysfunction and move towards functional diagnosis. Attaining this deeper understanding of IEI will require a stepwise strategy. First, we need to broadly apply these methods to IEI patients to identify patterns of dysfunction. Next, using multimodal data analysis, we can identify key dysregulated pathways. Then, we must develop a core group of simple, effective functional tests that target those pathways to increase efficiency of initial diagnostic investigations, provide evidence for therapeutic selection and contribute to the mechanistic evaluation of genetic results. This core group of simple, effective functional tests, targeting key pathways, can then be equitably provided to our rare patients. Systems biology is thus poised to reframe IEI diagnosis and therapy, fostering research today that will provide streamlined diagnosis and treatment choices for our rare and complex patients in the future, as well as providing a better understanding of basic immunology.

Exome/Genome-Wide Testing in Newborn Screening: A Proportionate Path Forward

Population-based newborn screening (NBS) is among the most effective public health programs ever launched, improving health outcomes for newborns who screen positive worldwide through early detection and clinical intervention for genetic disorders discovered in the earliest hours of life. Key to the success of newborn screening programs has been near universal accessibility and participation. Interest has been building to expand newborn screening programs to also include many rare genetic diseases that can now be identified by exome or genome sequencing (ES/GS). Significant declines in sequencing costs as well as improvements to sequencing technologies have enabled researchers to elucidate novel gene-disease associations that motivate possible expansion of newborn screening programs. In this paper we consider recommendations from professional genetic societies in Europe and North America in light of scientific advances in ES/GS and our current understanding of the limitations of ES/GS approaches in the NBS context. We invoke the principle of proportionality—that benefits clearly outweigh associated risks—and the human right to benefit from science to argue that rigorous evidence is still needed for ES/GS that demonstrates clinical utility, accurate genomic variant interpretation, cost effectiveness and universal accessibility of testing and necessary follow-up care and treatment. Confirmatory or second-tier testing using ES/GS may be appropriate as an adjunct to conventional newborn screening in some circumstances. Such cases could serve as important testbeds from which to gather data on relevant programmatic barriers and facilitators to wider ES/GS implementation.

Inborn Errors of Immunity in the Premature Infant: Challenges in Recognition and Diagnosis

Due to heightened awareness and advanced genetic tools, inborn errors of immunity (IEI) are increasingly recognized in children. However, diagnosing of IEI in premature infants is challenging and, subsequently, reports of IEI in premature infants remain rare. This review focuses on how common disorders of prematurity, such as sepsis, necrotizing enterocolitis, and bronchopulmonary dysplasia, can clinically overlap with presenting signs of IEI. We present four recent cases from a single neonatal intensive care unit that highlight diagnostic dilemmas facing neonatologists and clinical immunologists when considering IEI in preterm infants. Finally, we present a conceptual framework for when to consider IEI in premature infants and a guide to initial workup of premature infants suspected of having IEI.

Future Perspectives of Newborn Screening for Inborn Errors of Immunity

Newborn screening (NBS) programs continue to expand due to innovations in both test methods and treatment options. Since the introduction of the T-cell receptor excision circle (TREC) assay 15 years ago, many countries have adopted screening for severe combined immunodeficiency (SCID) in their NBS program. SCID became the first inborn error of immunity (IEI) in population-based screening and at the same time the TREC assay became the first high-throughput DNA-based test in NBS laboratories. In addition to SCID, there are many other IEI that could benefit from early diagnosis and intervention by preventing severe infections, immune dysregulation, and autoimmunity, if a suitable NBS test was available. Advances in technologies such as KREC analysis, epigenetic immune cell counting, protein profiling, and genomic techniques such as next-generation sequencing (NGS) and whole-genome sequencing (WGS) could allow early detection of various IEI shortly after birth. In the next years, the role of these technical advances as well as ethical, social, and legal implications, logistics and cost will have to be carefully examined before different IEI can be considered as suitable candidates for inclusion in NBS programs.