Newborn screening and changing face of inborn errors of metabolism in the United States

A Systematic Literature Review on the Global Status of Newborn Screening for Mucopolysaccharidosis II

A systematic literature review was conducted to determine the global status of newborn screening (NBS) for mucopolysaccharidosis (MPS) II (Hunter syndrome; OMIM 309900). Electronic databases were searched in July 2023 for articles referencing NBS for lysosomal storage diseases: 53 featured MPS II. Until recently, only Taiwan and two US states (Illinois and Missouri) formally screened newborns for MPS II, although pilot programs have been conducted elsewhere (Japan, New York, and Washington). In 2022, MPS II was added to the US Recommended Uniform Screening Panel, with increased uptake of NBS anticipated across the USA. While the overall MPS II birth prevalence, determined from NBS initiatives, was higher than in previous reports, it was lower in the USA (approximately 1 in 73,000 according to recent studies in Illinois and Missouri) than in Asia (approximately 1 in 15,000 in Japan). NBS programs typically rely on tandem mass spectrometry quantification of iduronate-2-sulfatase activity for first-tier testing. Diagnosis is often confirmed via molecular genetic testing and/or biochemical testing but may be complicated by factors such as pseudodeficiency alleles and variants of unknown significance. Evidence relating to MPS II NBS is lacking outside Taiwan and the USA. Although broad benefits of NBS are recognized, few studies specifically explored the perspectives of families of children with MPS II.

Feasibility of clinical newborn metabolic screening in a high-volume maternity center in Nepal

BACKGROUND

Strategic action plans around newborn health evaluation are needed, to address the high neonatal mortality rate in Nepal. Surveillance systems, like Newborn Metabolic Screening (NBS), could reveal unrecognized drivers of neonatal death. NBS is not routinely performed in Nepal. Our objective was to determine the feasibility of establishing NBS, and its acceptability among healthcare providers and parents, in Nepal.

METHODS

This prospective cohort study was conducted between November 2021 and May 2022 in term/late preterm infants born at Paropakar Maternity Hospital, Kathmandu, screening for 6 disorders that can be confirmed and managed locally. Staff were trained on dried-blood spot collection and transport protocols, performance metrics were established, and assays were performed at an accredited laboratory in Bangalore, India. Surveys were developed to determine acceptability among health-care providers and parents.

RESULTS

Of 835 parents approached for the study, 825 (98.8%) consented. Parental surveys showed that 92% considered "no cost" option most important in choosing to participate in the study. Samples were transported to laboratories in Kathmandu and Bangalore in 36 ± 24 h, and 4.75 ± 1 days, which exceeded expected metrics of 24 and 48 h, respectively. Results were communicated to parents by 9.5 ± 2 days, which was within the expected metric window of 14 days. Abnormalities were reported in 13 infants and included 5 hemoglobinopathy traits (4 Hb E and 1 Hb D), 3 congenital hypothyroidism, 2 glucose-6-phosphate dehydrogenase deficiency, 1 congenital adrenal hyperplasia, 1 elevated acylcarnitine, and 1 biotinidase deficiency. Healthcare providers surveyed (n = 116) showed that 67% reported a moderate understanding of NBS; all indicated that screening would be beneficial. Most cited early diagnosis and treatment, as well as, providing risk to future pregnancies as significant benefits. 90% thought screening should be routinely performed.

CONCLUSIONS

We demonstrate that it is feasible to introduce NBS in Nepal. Transport metrics were longer than expected due to COVID pandemic travel restrictions; however, it was possible to deliver results to families within 2 weeks of birth. Parents overwhelmingly considered "no cost" option as the most important in choosing to screen. A government-sponsored program will be a key factor in establishing NBS in Nepal.

Up-to-date quality survey and evaluation of neonatal screening programs in China

AIMS

To thoroughly evaluate the quality of the entire process of neonatal screening (NBS) in China.

METHODS

We collected survey questionnaires from 54.4% (135/248) of NBS institutions in China and conducted on-site visits to 20 of these facilities to validate the data. The quality performance of the institutions was evaluated, and differences across various factors were analysed.

RESULTS

Merely 62.5% of the provinces had acceptable performance in neonatal screening. Institutions with limited staff were more prone to organizational management shortcomings. Institutions in provinces with a per capita GDP below 10,000 USD exhibited lower quality control levels than those with a per capita GDP between 10,000 and 15,000 USD. Obstetrics departments have a lower awareness of quality control compared to other blood collection facilities.

CONCLUSIONS

A nationwide, comprehensive quality control system for continuous enhancements in quality management, screening, diagnosis, and treatment is imperative to ensure prompt diagnosis and intervention.

3D Printing of Dietary Products for the Management of Inborn Errors of Intermediary Metabolism in Pediatric Populations

The incidence of Inborn Error of Intermediary Metabolism (IEiM) diseases may be low, yet collectively, they impact approximately 6-10% of the global population, primarily affecting children. Precise treatment doses and strict adherence to prescribed diet and pharmacological treatment regimens are imperative to avert metabolic disturbances in patients. However, the existing dietary and pharmacological products suffer from poor palatability, posing challenges to patient adherence. Furthermore, frequent dose adjustments contingent on age and drug blood levels further complicate treatment. Semi-solid extrusion (SSE) 3D printing technology is currently under assessment as a pioneering method for crafting customized chewable dosage forms, surmounting the primary limitations prevalent in present therapies. This method offers a spectrum of advantages, including the flexibility to tailor patient-specific doses, excipients, and organoleptic properties. These elements are pivotal in ensuring the treatment's efficacy, safety, and adherence. This comprehensive review presents the current landscape of available dietary products, diagnostic methods, therapeutic monitoring, and the latest advancements in SSE technology. It highlights the rationale underpinning their adoption while addressing regulatory aspects imperative for their seamless integration into clinical practice.

Role of Psychologists in Pediatric Metabolic Disorders

Metabolic disorders or inborn errors of metabolism (IEMs) can have a wide range of neurodevelopmental and behavioral presentations. These can vary with age and/or management or stressors from common childhood/intercurrent illnesses/procedures/interventions. Collaborative care models such as multidisciplinary metabolic clinics or colocated models with behavioral health clinics and metabolic clinics in the same location can be valuable resources in improving long-term outcomes in patients with IEM. Psychologists' expertise using behavioral interventions, screening, or adaptive/cognitive measures can help with diagnosis, treatment adherence, school performance, family support, community resources, transition to adolescence and young adulthood using health belief concepts to improve outcomes.

Newborn Screening in Pediatric Endocrine Disorders

Two endocrine disorders, congenital hypothyroidism (CH) and congenital adrenal hyperplasia (CAH), when untreated, can have devastating, irreversible and fatal outcomes. Permanent cognitive impairment, growth failure and dysmorphic appearance are seen in congenital hypothyroidism (CH) and early infant death in males with salt wasting CAH (as most females are discovered by presence of atypical genital appearance, while males appeared normal). Newborn screening (NBS) for CH was developed with broader engagement of centers, and was more rapidly adopted throughout the US and other large or developed countries, while NBS for CAH was pioneered by relatively few and was not fully adopted in the US until the initiation of Universal Expanded Newborn Screening Panel in 2005. Advances in genetic understanding of CH and CAH continue with NBS. Cost–benefit analysis, showing CH NBS as more successful than CAH NBS, may not fully recognize the cost of a life saved with CAH NBS. Early treatment of CH is much simpler with taking a pill a day unlike CAH requiring multiple medication doses, and possibly surgery apart from enteral and parenteral stress doses during adrenal crisis. CAH management outcomes with gender identity matters in persons with atypical genital appearance and androgen effects are still being studied.

Reduction in Newborn Screening False Positive Results Following a New Collection Protocol: a Quality Improvement Project

OBJECTIVE

Premature infants are known to have a higher rate of false positive newborn screening (NBS) results, with TPN as a contributing factor. The purpose of this quality improvement (QI) project is to reduce false positive NBS results via a TPN interruption protocol.

METHODS

A multidisciplinary team reviewed the literature and developed a new NBS collection protocol, which was implemented in 2 periods. In period 1, TPN was interrupted for 4 hours before NBS sample collection and initiation of carnitine supplements was avoided. In period 2, TPN was interrupted for 6 hours for infants birth weight (BW) < 1000 g, carnitine supplementation continued to be avoided. The rates of false positives NBS results were compared pre- and post-interventions in periods 1 and 2.

RESULTS

Four hundred twelve neonates were evaluated prior to implementation of this QI project (July 2013-June 2014) and 414 during period 1 intervention (July 2014-June 2016). False positive results decreased from 20.6% to 11.4% (p < 0.001) among all BW categories following the 4-hour TPN interruption. The rate of false positives was further reduced among infants < 1000 g (p = 0.035) in period 2 (n = 112), including a significant reduction in false positive results with elevated amino acid profiles (p = 0.005).

CONCLUSIONS

The implementation of a strict NBS collection protocol reduced false positive NBS results, which potentially can improve patient care by reducing unnecessary laboratory draws, pain, and parental anxiety. Interruption of TPN for 6 hours was significant in reducing NBS false positive results in neonates < 1000 g.

Neonatal Screening for Congenital Metabolic and Endocrine Disorders–Results From Germany for the Years 2006–2018

BACKGROUND

The purpose of neonatal screening is the early detection of congenital metabolic and endocrine disorders that, if untreated, could lead to fatal crises or other long-term adverse sequelae. In Germany, neonatal screening is legally regulated. Quality-assurance reports ("DGNS reports") are created and published annually by the German Society for Neonatal Screening (Deutsche Gesellschaft für Neugeborenen-Screening). Data from the DGNS reports for the years 2006-2018 serve as the basis of the present publication.

METHODS

For the years 2006-2018, prevalences were calculated and data on process quality were evaluated.

RESULTS

Among 9 218 538 births, 6917 neonates were identified who had one of the target diseases. The overall prevalence was 75 per 100 000 neonates; the disorders most commonly found were congenital hypothyroidism (30 per 100 000) followed by phenylketonuria (PKU) and medium-chain acyl-CoA dehydrogenase deficiency (MCAD) (10 per 100 000 each). Of the 272 205 follow-up screenings requested, 80% were received. The rate of positive screening findings (recall rate) declined over the observation period, from 0.90% in 2006 to 0.37% in 2018. For every five positive screening findings, one case of a target disorder was confirmed. 79% of the children for whom treatment was indicated began to receive treatment within two weeks.

CONCLUSION

The low recall rate and the early initiation of treatment in 79% of the affected children indicate that neonatal screening for metabolic and endocrine disorders in Germany is effective. The incorporation of tracking structures and the introduction of a registry could further improve the quality of the program.

Little to Give, Much to Gain-What Can You Do With a Dried Blood Spot?

PURPOSE OF REVIEW

Technological advances have allowed dried blood spots (DBS) to be utilized for various measurements, helpful in population-based studies. The following is a review of the literature highlighting the advantages and disadvantages of DBS and describing their use in multiple areas of research.

RECENT FINDINGS

DBS can track pollutant exposure to understand their impact on health. DBS can also be used for (epi-)genetic studies, to measure clinical biomarkers, and to monitor drug adherence. Advantages of DBS include being minimally invasive, requiring low blood volume, and being cost-effective to collect, transport, and store. Disadvantages of DBS include the hematocrit effect, which is related to the viscosity of the blood affecting its spread on to the filter paper, causing a major source of error when assessing concentrations, and the possibility of low DNA volume. Numerous uses for DBS make them an important source of biomaterial but they require additional validation for accuracy and reproducibility.

Ethical Issues Surrounding Newborn Screening

It would be difficult to overestimate the importance of persistent, thoughtful parents and their importance in the development of treatments for their children's rare disorders. Almost a century ago in Norway, observant parents led a brilliant young physician-scientist to his discovery of the underlying cause of their children's profound developmental delay-i.e., phenylketonuria, or PKU. Decades later, in a recovering war-ravaged Britain, an equally persistent mother pressed the scientists at Birmingham Children's Hospital to find a way to treat her seriously damaged daughter, Sheila, who suffered from PKU. Living on the financial edge, this mother insisted that Bickel and colleagues develop such a diet, and she volunteered Sheila to be the patient in the trial. The scientists concluded that the low phenylalanine diet helped but needed to be started very early-so, newborn screening was born to permit the implementation of this. Many steps brought us to where we are today, but these courageous parents made it all begin.

Identifying and overcoming barriers to harmonize newborn screening programs through consensus strategies

The benefits of newborn screening (NBS) programs have been widely demonstrated after more than 50 years since first established. NBS enables the detection of the disease before the child shows clinical symptoms, allowing clinicians to act early and facilitating appropriate interventions to prevent or improve adverse outcomes. Delay or lack of medical intervention in these infants may lead to developmental delay, severe disability, or premature death. NBS programs have grown exponentially both in the number of diseases screened and in complexity, creating controversy. New technological advances, as well as the emergence of new therapies that require early disease detection, have allowed for the inclusion of new diseases in NBS screening programs. However, different countries and even different regions have in turn adopted very diverse strategies and diagnostic algorithms when it comes to NBS. There are many factors responsible for these differences, such as the health care system, available funds, local politics, professional groups, and others that depend on the position taken by policymakers. These differences in NBS have led to discrepancies in detection opportunities between countries or regions, which has led to many varied attempts to harmonize NBS programs but not all have been equally satisfactory. Some countries have achieved good results, but always within their borders. Therefore, there are still many differences between NBS programs at the international level that must be overcome. These advances have also brought considerable uncertainty regarding ethical aspects and balance between benefits and harms. For this reason, and so that the situation of disparity in the global NBS programs can be minimized, health authorities must work to develop uniform criteria for decision-making and to take a further step toward harmonization. To do so, it is necessary to identify the crucial factors that lead to the adoption of different NBS programs worldwide, in order to analyze their influence and find ways to overcome them.

Animal Model Contributions to Congenital Metabolic Disease

Genetic model systems allow researchers to probe and decipher aspects of human disease, and animal models of disease are frequently specifically engineered and have been identified serendipitously as well. Animal models are useful for probing the etiology and pathophysiology of disease and are critical for effective discovery and development of novel therapeutics for rare diseases. Here we review the impact of animal model organism research in three examples of congenital metabolic disorders to highlight distinct advantages of model system research. First, we discuss phenylketonuria research where a wide variety of research fields and models came together to make impressive progress and where a nearly ideal mouse model has been central to therapeutic advancements. Second, we review advancements in Lesch-Nyhan syndrome research to illustrate the role of models that do not perfectly recapitulate human disease as well as the need for multiple models of the same disease to fully investigate human disease aspects. Finally, we highlight research on the GM2 gangliosidoses Tay-Sachs and Sandhoff disease to illustrate the important role of both engineered traditional laboratory animal models and serendipitously identified atypical models in congenital metabolic disorder research. We close with perspectives for the future for animal model research in congenital metabolic disorders.

Newborn Screening for Spinal Muscular Atrophy in China Using DNA Mass Spectrometry

Background: Spinal muscular atrophy (SMA) is the most common neurodegenerative disorder and the leading genetic cause of infant mortality. Early detection of SMA through newborn screening (NBS) is essential to selecting pre-symptomatic treatment and ensuring optimal outcome, as well as, prompting the urgent need for effective screening methods. This study aimed to determine the feasibility of applying an Agena iPLEX SMA assay in NBS for SMA in China.

Methods: We developed an Agena iPLEX SMA assay based on the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and evaluated the performance of this assay through assessment of 167 previously-genotyped samples. Then we conducted a pilot study to apply this assay for SMA NBS. The SMN1 and SMN2 copy number of screen-positive patients were determined by multiplex ligation-dependent probe amplification analysis.

Results: The sensitivity and specificity of the Agena iPLEX SMA assay were both 100%. Three patients with homozygous SMN1 deletion were successfully identified and conformed by multiplex ligation-dependent probe amplification analysis. Two patients had two SMN2 copies, which was correlated with severe SMA type I phenotype; both of them exhibited neurogenic lesion and with decreased muscle power. Another patient with four SMN2 copies, whose genotype correlated with milder SMA type III or IV phenotype, had normal growth and development without clinical symptoms.

Conclusions: The Agena iPLEX SMA assay is an effective and reliable approach for population-based SMA NBS. The first large-scale pilot study using this assay in the Mainland of China showed that large-scale implementation of population-based NBS for SMA is feasible.

Inborn Errors of Metabolism in the Era of Untargeted Metabolomics and Lipidomics

Inborn errors of metabolism (IEMs) are a group of inherited diseases with variable incidences. IEMs are caused by disrupting enzyme activities in specific metabolic pathways by genetic mutations, either directly or indirectly by cofactor deficiencies, causing altered levels of compounds associated with these pathways. While IEMs may present with multiple overlapping symptoms and metabolites, early and accurate diagnosis of IEMs is critical for the long-term health of affected subjects. The prevalence of IEMs differs between countries, likely because different IEM classifications and IEM screening methods are used. Currently, newborn screening programs exclusively use targeted metabolic assays that focus on limited panels of compounds for selected IEM diseases. Such targeted approaches face the problem of false negative and false positive diagnoses that could be overcome if metabolic screening adopted analyses of a broader range of analytes. Hence, we here review the prospects of using untargeted metabolomics for IEM screening. Untargeted metabolomics and lipidomics do not rely on predefined target lists and can detect as many metabolites as possible in a sample, allowing to screen for many metabolic pathways simultaneously. Examples are given for nontargeted analyses of IEMs, and prospects and limitations of different metabolomics methods are discussed. We conclude that dedicated studies are needed to compare accuracy and robustness of targeted and untargeted methods with respect to widening the scope of IEM diagnostics.