Neonatal Screening in Europe Revisited: An ISNS Perspective on the Current State and Developments Since 2010

Combinatorial batching of DNA for ultralow-cost detection of pathogenic variants

BACKGROUND

Next-generation sequencing (NGS) based population screening holds great promise for disease prevention and earlier diagnosis, but the costs associated with screening millions of humans remain prohibitive. New methods for population genetic testing that lower the costs of NGS without compromising diagnostic power are needed.

METHODS

We developed double batched sequencing where DNA samples are batch-sequenced twice - directly pinpointing individuals with rare variants. We sequenced batches of at-birth blood spot DNA using a commercial 113-gene panel in an explorative (n = 100) and a validation (n = 100) cohort of children who went on to develop pediatric cancers. All results were benchmarked against individual whole genome sequencing data.

RESULTS

We demonstrated fully replicable detection of cancer-causing germline variants, with positive and negative predictive values of 100% (95% CI, 0.91-1.00 and 95% CI, 0.98-1.00, respectively). Pathogenic and clinically actionable variants were detected in RB1, TP53, BRCA2, APC, and 19 other genes. Analyses of larger batches indicated that our approach is highly scalable, yielding more than 95% cost reduction or less than 3 cents per gene screened for rare disease-causing mutations. We also show that double batched sequencing could cost-effectively prevent childhood cancer deaths through broad genomic testing.

CONCLUSIONS

Our ultracheap genetic diagnostic method, which uses existing sequencing hardware and standard newborn blood spots, should readily open up opportunities for population-wide risk stratification using genetic screening across many fields of clinical genetics and genomics.

Moroccan Experience of Targeted Screening for Inborn Errors of Metabolism by Tandem Mass Spectrometry

BACKGROUND

Expanded newborn screening using tandem mass spectrometry (MS/MS) for inborn errors of metabolism (IEM), such as organic acidemias (OAs), fatty acid oxidation disorders (FAODs), and amino acid disorders (AAs), is increasingly popular but has not yet been introduced in Africa. With this study, we aim to establish the disease spectrum and frequency of inborn errors of OAs, FAODs, and AAs in Morocco.

METHODS

Selective screening was performed among infants and children suspected to be affected with IEM between 2016 and 2021. Amino acids and acylcarnitines spotted on filter paper were analyzed using MS/MS.

RESULTS

Out of 1178 patients with a clinical suspicion, 137 (11.62%) were diagnosed with IEM, of which 121 (88.3%) patients suffered from amino acids disorders, 11 (8%) were affected by FAOD, and 5 (3.7%) by an OA.

CONCLUSIONS

This study shows that various types of IEM are also present in Morocco. Furthermore, MS/MS is an indispensable tool for early diagnosis and management of this group of disorders.

Addition of galactose-1-phosphate measurement enhances newborn screening for classical galactosemia

Galactosemia is an inborn disorder of carbohydrate metabolism of which early detection can prevent severe illness. Although the assay for galactose-1-phosphate uridyltransferase (GALT) enzyme activity has been available since the 1960s, many issues prevented it from becoming universal. In order to develop the Israeli newborn screening pilot algorithm for galactosemia, flow injection analysis tandem mass spectrometry measurement of galactose-1-phosphate in archived dried blood spots from newborns with classical galactosemia, galactosemia variants, epimerase deficiency, and normal controls, was conducted. Out of 431 330 newborns screened during the pilot study (30 months), two with classical galactosemia and four with epimerase deficiency were identified and confirmed. Five false positives and no false negatives were recorded. Following this pilot study, the Israeli final and routine newborn screening algorithm, as recommended by the Advisory Committee to the National Newborn Screening Program, now consists of galactose-1-phosphate measurement integrated into the routine tandem mass spectrometry panel as the first-tier screening test, and GALT enzyme activity as the second-tier performed to identify only newborns suspected to be at risk for classical galactosemia. The GALT enzyme activity cut-off used in the final algorithm was lowered in order to avoid false positives.

Machine Learning Methods Improve Specificity in Newborn Screening for Isovaleric Aciduria

Isovaleric aciduria (IVA) is a rare disorder of leucine metabolism and part of newborn screening (NBS) programs worldwide. However, NBS for IVA is hampered by, first, the increased birth prevalence due to the identification of individuals with an attenuated disease variant (so-called "mild" IVA) and, second, an increasing number of false positive screening results due to the use of pivmecillinam contained in the medication. Recently, machine learning (ML) methods have been analyzed, analogous to new biomarkers or second-tier methods, in the context of NBS. In this study, we investigated the application of machine learning classification methods to improve IVA classification using an NBS data set containing 2,106,090 newborns screened in Heidelberg, Germany. Therefore, we propose to combine two methods, linear discriminant analysis, and ridge logistic regression as an additional step, a digital-tier, to traditional NBS. Our results show that this reduces the false positive rate by 69.9% from 103 to 31 while maintaining 100% sensitivity in cross-validation. The ML methods were able to classify mild and classic IVA from normal newborns solely based on the NBS data and revealed that besides isovalerylcarnitine (C5), the metabolite concentration of tryptophan (Trp) is important for improved classification. Overall, applying ML methods to improve the specificity of IVA could have a major impact on newborns, as it could reduce the newborns' and families' burden of false positives or over-treatment.

An update on the diagnosis and treatment of adrenoleukodystrophy

PURPOSE OF REVIEW

The present review summarizes recent advances in the diagnosis and management of patients with X-linked adrenoleukodystrophy (ALD).

RECENT FINDINGS

Although ALD screening has been on the list of Recommended Uniform Screening Panel since 2016, only 30 states in the United States are currently testing their newborns for this disease. Hematopoietic stem cell transplant (HSCT) remains the only successful treatment option available for early cerebral ALD but does not reverse neurological changes or affect the course of adrenal insufficiency. There remains a significant knowledge gap in our understanding and treatment of this disease. Novel therapies such as gene therapy and gene editing have shown promising results in animal models and are exciting potential treatment options for the future.Recently, the American Academy of Neurologists released their consensus guidelines on the diagnosis, surveillance, and management of ALD.

SUMMARY

Early diagnosis and HSCT are key to improving the morbidity and mortality associated with ALD. The implementation of universal newborn screening for ALD and rigorous investigations of novel diagnostic and therapeutic agents is the need of the hour.

Newborn Screening of Primary Carnitine Deficiency: An Overview of Worldwide Practices and Pitfalls to Define an Algorithm before Expansion of Newborn Screening in France

Primary Carnitine Deficiency (PCD) is a fatty acid oxidation disorder that will be included in the expansion of the French newborn screening (NBS) program at the beginning of 2023. This disease is of high complexity to screen, due to its pathophysiology and wide clinical spectrum. To date, few countries screen newborns for PCD and struggle with high false positive rates. Some have even removed PCD from their screening programs. To understand the risks and pitfalls of implementing PCD to the newborn screening program, we reviewed and analyzed the literature to identify hurdles and benefits from the experiences of countries already screening this inborn error of metabolism. In this study, we therefore, present the main pitfalls encountered and a worldwide overview of current practices in PCD newborn screening. In addition, we address the optimized screening algorithm that has been determined in France for the implementation of this new condition.

How guideline development has informed clinical research for organic acidurias (et vice versa)

Organic acidurias, such as glutaric aciduria type 1 (GA1), methylmalonic (MMA), and propionic aciduria (PA) are a prominent group of inherited metabolic diseases involving accumulation of eponymous metabolites causing endogenous intoxication. For all three conditions, guidelines for diagnosis and management have been developed and revised over the last years, resulting in three revisions for GA1 and one revision for MMA/PA. The process of clinical guideline development in rare metabolic disorders is challenged by the scarcity and limited quality of evidence available. The body of literature is often fragmentary and where information is present, it is usually derived from small sample sizes. Therefore, the development of guidelines for GA1 and MMA/PA was initially confronted with a poor evidence foundation that hindered formulation of concrete recommendations in certain contexts, triggering specific research projects and initiation of longitudinal, prospective observational studies using patient registries. Reversely, these observational studies contributed to evaluate the value of newborn screening, phenotypic diversities, and treatment effects, thus significantly improving the quality of evidence and directly influencing formulation and evidence levels of guideline recommendations. Here, we present insights into interactions between guideline development and (pre)clinical research for GA1 and MMA/PA, and demonstrate how guidelines gradually improved from revision to revision. We describe how clinical studies help to unravel the relative impact of therapeutic interventions on outcome and conclude that despite new and better quality of research data over the last decades, significant shortcomings of evidence regarding prognosis and treatment remain. It appears that development of clinical guidelines can directly help to guide research, and vice versa.

Advances and Challenges of the Decade: The Ever-Changing Clinical and Genetic Landscape of Immunodeficiency

In the past 10 years, we have witnessed major advances in clinical immunology. Newborn screening for severe combined immunodeficiency has become universal in the United States and screening programs are being extended to severe combined immunodeficiency and other inborn errors of immunity globally. Early genetic testing is becoming the norm for many of our patients and allows for informed selection of targeted therapies including biologics repurposed from other specialties. During the COVID-19 pandemic, our understanding of essential immune responses expanded and the discovery of immune gene defects continued. Immunoglobulin products, the backbone of protection for antibody deficiency syndromes, came into use to minimize side effects. New polyclonal and monoclonal antibody products emerged with increasing options to manage respiratory viral agents such as SARS-CoV-2 and respiratory syncytial virus. Against these advances, we still face major challenges. Atypical is becoming typical as phenotypes of distinct genetic disease overlap whereas the clinical spectrum of the same genetic defect widens. Therefore, clinical judgment needs to be paired with repeated deep immune phenotyping and upfront genetic testing, as technologies rapidly evolve, and clinical disease often progresses with age. Managing patients with organ damage resulting from immune dysregulation poses a special major clinical challenge and management often lacks standardization, from autoimmune cytopenias, granulomatous interstitial lung disease, enteropathy, and liver disease to endocrine, rheumatologic, and neurologic complications. Clinical, translational, and basic science networks will continue to advance the field; however, cross-talk and education with practicing allergists/immunologists are essential to keep up with the ever-changing clinical and genetic landscape of inborn errors of immunity.

Sex-specific newborn screening for X-linked adrenoleukodystrophy

Males with X-linked adrenoleukodystrophy (ALD) are at high risk for developing adrenal insufficiency and/or progressive leukodystrophy (cerebral ALD) at an early age. Pathogenic variants in ABCD1 result in elevated levels of very long-chain fatty acids (VLCFA), including C26:0-lysophosphatidylcholine (C26:0-LPC). Newborn screening for ALD enables prospective monitoring and timely therapeutic intervention, thereby preventing irreversible damage and saving lives. The Dutch Health Council recommended to screen only male newborns for ALD without identifying untreatable conditions associated with elevated C26:0-LPC, like Zellweger spectrum disorders and single peroxisomal enzyme defects. Here, we present the results of the SCAN (Screening for ALD in the Netherlands) study which is the first sex-specific newborn screening program worldwide. Males with ALD are identified based on elevated C26:0-LPC levels, the presence of one X-chromosome and a variant in ABCD1, in heel prick dried bloodspots. Screening of 71 208 newborns resulted in the identification of four boys with ALD who, following referral to the pediatric neurologist and confirmation of the diagnosis, enrolled in a long-term follow-up program. The results of this pilot show the feasibility of employing a boys-only screening algorithm that identifies males with ALD without identifying untreatable conditions. This approach will be of interest to countries that are considering ALD newborn screening but are reluctant to identify girls with ALD because for girls there is no direct health benefit. We also analyzed whether gestational age, sex, birth weight and age at heel prick blood sampling affect C26:0-LPC concentrations and demonstrate that these covariates have a minimal effect.

Assessment of carnitine excretion and its ratio to plasma free carnitine as a biomarker for primary carnitine deficiency in newborns

In the Netherlands, newborns are referred by the newborn screening (NBS) Program when a low free carnitine (C0) concentration (<5 μmol/l) is detected in their NBS dried blood spot. This leads to ~85% false positive referrals who all need an invasive, expensive and lengthy evaluation. We investigated whether a ratio of urine C0 / plasma C0 (RatioU:P) can improve the follow-up protocol for primary carnitine deficiency (PCD). A retrospective study was performed in all Dutch metabolic centres, using samples from newborns and mothers referred by NBS due to low C0 concentration. Samples were included when C0 excretion and plasma C0 concentration were sampled on the same day. RatioU:P was calculated as (urine C0 [μmol/mmol creatinine])/(plasma C0 [μmol/l]). Data were available for 59 patients with genetically confirmed PCD and 68 individuals without PCD. The RatioU:P in PCD patients was significantly higher (p value < 0.001) than in those without PCD, median [IQR], respectively: 3.4 [1.2-9.5], 0.4 [0.3-0.8], area under the curve (AUC) 0.837. Classified for age (up to 1 month) and without carnitine suppletion (PCD; N = 12, Non-PCD; N = 40), medians were 6.20 [4.4-8.8] and 0.37 [0.24-0.56], respectively. The AUC for RatioU:P was 0.996 with a cut-off required for 100% sensitivity at 1.7 (yielding one false positive case). RatioU:P accurately discriminates between positive and false positive newborn referrals for PCD by NBS. RatioU:P is less effective as a discriminative tool for PCD in adults and for individuals that receive carnitine suppletion.

Intervención de enfermería en tamiz metabólico neonatal: Revisión integrativa

Introducción: El tamiz metabólico neonatal es el conjunto de procedimientos y pruebas que se realizan para separar entre recién nacidos aparentemente sanos, aquellos con sospecha de errores innatos del metabolismo. Por tanto, permite detectar la enfermedad antes que se manifieste e iniciar tratamiento oportuno para evitar complicaciones, discapacidad y muerte. Actualmente, es un programa neonatal prioritario para la salud infantil. En la etapa operativa, la estandarización de criterios es determinante para resultados confiables. Objetivo: Realizar revisión bibliográfica integrativa de la intervención de enfermería en tamiz metabólico neonatal. Metodología: Investigación integrativa en las bases de datos Web of Science, Scielo, Scopus, Pubmed, Sciencedirect, Dialnet, OVID y EBSCO, utilizando los descriptores tamizaje neonatal, atención de enfermería, errores innatos del metabolismo, neonatología y analgesia; con los operadores booleanos and, or y not. De 116 documentos obtenidos, 36 cumplen criterios de elegibilidad y representan el material de estudio. Resultados: La recolección de muestra de sangre para tamiz se realiza entre el tercer y quinto día de vida, esencialmente mediante punción capilar del talón. Las medidas analgésicas no farmacológicas son lactancia materna, método canguro y contención. La muestra debe protegerse de contaminación, y su estabilidad depende de la temperatura de conservación hasta su análisis. Conclusiones: La literatura científica revisada, faculta al profesional de enfermería para proporcionar atención integral y segura al recién nacido que participa en el programa.

Genotype-phenotype association in congenital adrenal hyperplasia due to 21-hydroxylase deficiency in children

OBJECTIVE

The purpose of this study was to investigate the clinical manifestation of various forms of congenital adrenal hyperplasia (CAH) in children of the Republic of Kazakhstan, depending on their genotype.

DESIGN

The study analysed 50 patients diagnosed with CAH from 7 regions of Kazakhstan with different ethnic origins: 35 Kazakhs (70.0%), 8 Russians (16.0%), 2 Turks (4.0%), 2 Ukrainians (4.0%), 2 Uzbeks (4%), 1 Uighur (2%). All the children studied were from 0 to 18 years old, and their average age was 5.7 years ±3.9. In addition, all children were divided into groups depending on the form of the disease according to the phenotypic manifestation of the disease: salt-wasting (SW) and simple virile (SV) forms. Most of the patients suffered from SW - 32 (64.0%), and a smaller group had SV - 18 (36.0%), also one boy with SW was diagnosed with TART syndrome.

MEASUREMENTS

50 Kazakh children with the classical form of CAH were analysed. Depending on the severity of the mutations, patients were divided into 4 groups: zero groups (the most severe mutations), A, B, and C.

RESULTS

According to the results of the study, the salt-wasting form of CAH turned out to be more common than the simple virile form. A high correlation was observed in groups with mutations of high and moderate severity - 0 and A, while group C showed a strong variability of the phenotype. Thus, the correspondence between genotype and phenotype decreased along with the decrease in the severity of the disease.

CONCLUSIONS

The relationship between the genotype and the phenotype of both forms of CAH exists indirectly, through the activity of the 21-hydroxylase enzyme. Mutations in the CYP21A2 gene affect the level of the synthesized enzyme, which, in turn, determines the degree of hormone production in the blood.

Clinical and Genetic Characterisation of Cystic Fibrosis Patients in Latvia: A Twenty-Five-Year Experience

Cystic fibrosis (CF) is the most common life-limiting genetic disorder in European descent populations. It is caused by pathogenic variants in the CFTR gene, and inheritance is autosomal recessive. This study provides an up-to-date, comprehensive estimation of the distribution of CFTR pathogenic variants in Latvia and their phenotypic characteristics. It also reports the first results of the CF newborn screening programme following its implementation in 2019. We analysed the clinical and molecular data of CF patients treated at the only tertiary hospital in Latvia providing specialised healthcare for the disorder. Between 1997 and 2022, 66 CF patients from 62 families were diagnosed based on symptoms or a molecular confirmation (six patients were diagnosed through the CF newborn screening programme). F508del was identified in 70.5% of all CF chromosomes. Known variants were identified in more than one family: dele2,3, R1006H, L1335P, W57R, R553X, 2143delT and 3849+10kb C>T (legacy names used). Furthermore, two novel variants were identified, namely, c.503C>A p.(Ser168Ter) and c.(743+1_744-1)_(1584+1_1585-1)del p.(?). The available follow-up results indicated that Latvian CF patients demonstrated similar tendencies to CF patients worldwide. The oldest age at diagnosis prior to the implementation of the CF newborn screening programme was 14 years. We provide here, for the first time, a comprehensive description of Latvian CF patients. An improvement in the healthcare of CF patients over time, including access to diagnosis, is evident. Two novel CF-causing variants are reported, and F508del is the most frequently occurring variant in the population, thus suggesting that F508del screening should be followed by the testing of the full CFTR gene.

Vitamin B12 (Cobalamin): Its Fate from Ingestion to Metabolism with Particular Emphasis on Diagnostic Approaches of Acquired Neonatal/Infantile Deficiency Detected by Newborn Screening

Acquired vitamin B12 (vB12) deficiency (vB12D) of newborns is relatively frequent as compared with the incidence of inherited diseases included in newborn screening (NBS) of different countries across the globe. Infants may present signs of vB12D before 6 months of age with anemia and/or neurologic symptoms when not diagnosed in asymptomatic state. The possibility of identifying vitamin deficient mothers after their pregnancy during the breastfeeding period could be an additional benefit of the newborn screening. Vitamin supplementation is widely available and easy to administer. However, in many laboratories, vB12D is not included in the national screening program. Optimized screening requires either second-tier testing or analysis of new urine and blood samples combined with multiple clinical and laboratory follow ups. Our scope was to review the physiologic fate of vB12 and the pathobiochemical consequences of vB12D in the human body. Particular emphasis was put on the latest approaches for diagnosis and treatment of vB12D in NBS.

Mitochondrial Fatty Acid β-Oxidation Disorders: From Disease to Lipidomic Studies-A Critical Review

Fatty acid oxidation disorders (FAODs) are inborn errors of metabolism (IEMs) caused by defects in the fatty acid (FA) mitochondrial β-oxidation. The most common FAODs are characterized by the accumulation of medium-chain FAs and long-chain (3-hydroxy) FAs (and their carnitine derivatives), respectively. These deregulations are associated with lipotoxicity which affects several organs and potentially leads to life-threatening complications and comorbidities. Changes in the lipidome have been associated with several diseases, including some IEMs. In FAODs, the alteration of acylcarnitines (CARs) and FA profiles have been reported in patients and animal models, but changes in polar and neutral lipid profile are still scarcely studied. In this review, we present the main findings on FA and CAR profile changes associated with FAOD pathogenesis, their correlation with oxidative damage, and the consequent disturbance of mitochondrial homeostasis. Moreover, alterations in polar and neutral lipid classes and lipid species identified so far and their possible role in FAODs are discussed. We highlight the need of mass-spectrometry-based lipidomic studies to understand (epi)lipidome remodelling in FAODs, thus allowing to elucidate the pathophysiology and the identification of possible biomarkers for disease prognosis and an evaluation of therapeutic efficacy.

Trends and outcomes of children, adolescents, and adults hospitalized with inherited metabolic disorders: A population-based cohort study

Inherited metabolic disorders (IMDs) comprise a heterogeneous class of genetic disorders characterized by impaired biochemical functions in metabolism. However, incidences and outcomes of patients hospitalized with IMDs are largely unknown. We conducted a population-based cohort study using nationwide in-hospital claims data in Switzerland from 2012 to 2020. We assessed incidence rates of hospitalizations and hospital-associated outcomes, stratified in five age groups (0-9, 10-19, 20-39, 40-59, and 60-90 years) and three types of IMDs (peptide, amine and amino acid metabolism disorders [AD], carbohydrate metabolism disorders [CD], fatty acid, and ketone body metabolism disorders [FD]). A total of 7293 hospitalizations with IMD were identified, of which 3638 had AD, 3153 CD, and 502 FD. Incidence rates for hospitalizations per 100 000 person-years were highest under the age of 10 years across all types of IMDs (8.69 for AD, 5.73 for CD, 3.71 for FD) and decreased thereafter. In patients with AD and CD, hospitalization rates increased again in adults aged 60-90 years (7.28 for AD, 7.25 for CD), while they remained low in patients with FD (0.31). Compared to inpatients without IMD, adult IMD patients had a higher burden of hospital-associated adverse outcomes including an increased risk of in-hospital mortality, intensive care unit admission, mechanical ventilation, and longer length of hospital or intensive care unit stay. Incremental risk of 30-day, 1-year, and 2-year hospital readmission was highest among children and adolescents with IMD.

Recommendations for diagnosing and managing individuals with glutaric aciduria type 1: Third revision

Glutaric aciduria type 1 is a rare inherited neurometabolic disorder of lysine metabolism caused by pathogenic gene variations in GCDH (cytogenic location: 19p13.13), resulting in deficiency of mitochondrial glutaryl-CoA dehydrogenase (GCDH) and, consequently, accumulation of glutaric acid, 3-hydroxyglutaric acid, glutaconic acid and glutarylcarnitine detectable by gas chromatography/mass spectrometry (organic acids) and tandem mass spectrometry (acylcarnitines). Depending on residual GCDH activity, biochemical high and low excreting phenotypes have been defined. Most untreated individuals present with acute onset of striatal damage before age 3 (to 6) years, precipitated by infectious diseases, fever or surgery, resulting in irreversible, mostly dystonic movement disorder with limited life expectancy. In some patients, striatal damage develops insidiously. In recent years, the clinical phenotype has been extended by the finding of extrastriatal abnormalities and cognitive dysfunction, preferably in the high excreter group, as well as chronic kidney failure. Newborn screening is the prerequisite for pre-symptomatic start of metabolic treatment with low lysine diet, carnitine supplementation and intensified emergency treatment during catabolic episodes, which, in combination, have substantially improved neurologic outcome. In contrast, start of treatment after onset of symptoms cannot reverse existing motor dysfunction caused by striatal damage. Dietary treatment can be relaxed after the vulnerable period for striatal damage, that is, age 6 years. However, impact of dietary relaxation on long-term outcomes is still unclear. This third revision of evidence-based recommendations aims to re-evaluate previous recommendations (Boy et al., J Inherit Metab Dis, 2017;40(1):75-101; Kolker et al., J Inherit Metab Dis 2011;34(3):677-694; Kolker et al., J Inherit Metab Dis, 2007;30(1):5-22) and to implement new research findings on the evolving phenotypic diversity as well as the impact of non-interventional variables and treatment quality on clinical outcomes.

Inter-rater reliability assessment for the new-born screening quality assurance

Introduction

To ensure the quality of the new-born screening (NBS), our laboratory reviewed the analytical procedure to detect subjective steps that may represent a risk to the patient. Two subjective activities were identified in the extra-analytical phases: the classification of dried blood spots (DBS) according to their quality and the assignment of haemoglobin patterns. To keep these activities under control, inter-rater studies were implemented. This study aimed to evaluate the inter-rater reliability and the effectiveness of the measures taken to improve the agreement between observers, to assure NBS results’ quality.

Materials and methods

Dried blood spots specimens were used for the inter-rater studies. Ten studies were performed to assess DBS quality classification, and four to assess the assignment of haemoglobin patterns. Krippendorff’s alpha test was used to estimate inter-rater reliability. Causes were investigated when alpha values were below 0.80.

Results

For both activities, the reliability obtained in the first studies was inadequate. After investigation, we detected that the criterion to classify a DBS as scant was not consolidated, and also a lack of consensus on whether or not to report Bart’s haemoglobin depending on its percentage. Alpha estimates became higher once the training was reinforced and a consensus about the appropriate criteria to be applied was reached.

Conclusion

Inter-rater reliability assessment helped us to ensure the quality of subjective activities that could add variability to NBS results. Furthermore, the evolution of the alpha value over time allowed us to verify the effectiveness of the measures adopted.

Paediatric biobanking for health: The ethical, legal, and societal landscape

Biobanks play a central role in pediatric translational research, which deals primarily with genetic data from sample-based research. However, participation of children in biobanking has received only limited attention in the literature, even though research in general and in clinical trials in particular have a long history in involving minors. So, we resolved to explore specific challenging ethical, legal, and societal issues (ELSI) in the current pediatric biobanking landscape to propose a way forward for biobanking with children as partners in research. Methodologically, we first established the accessibility and utilization of pediatric biobanks, mainly in Europe. This was supported by a literature review related to children's participation, taking into account not only academic papers but also relevant guidelines and best-practices. Our findings are discussed under five themes: general vulnerability; ethical issues-balancing risks and benefits, right to an open future, return of results including secondary findings; legal issues-capacity and legal majority; societal issues-public awareness and empowerment; and responsible research with children. Ultimately, we observed an on-going shift from the parents'/guardians' consent being a sine-qua-non condition to the positive minor's agreement: confirming that the minor is the participant, not the parent(s)/guardian(s). This ethical rethinking is paving the way toward age-appropriate, dynamic and participatory models of involving minors in decision-making. However, we identified a requirement for dynamic tools to assess maturity, a lack of co-produced engagement tools and paucity of shared best practices. We highlight the need to provide empowerment and capability settings to support researchers and biobankers, and back this with practical examples. In conclusion, equipping children and adults with appropriate tools, and ensuring children's participation is at the forefront of responsible pediatric biobanking, is an ethical obligation, and a cornerstone for research integrity.

Newborn screening for severe combined immunodeficiency: The results of the first pilot TREC and KREC study in Ukraine with involving of 10,350 neonates

Severe combined immunodeficiency (SCID) is a group of inborn errors of immunity (IEI) characterized by severe T- and/or B-lymphopenia. At birth, there are usually no clinical signs of the disease, but in the first year of life, often in the first months the disease manifests with severe infections. Timely diagnosis and treatment play a crucial role in patient survival. In Ukraine, the expansion of hemostatic stem cell transplantation and the development of a registry of bone marrow donors in the last few years have created opportunities for early correction of IEI and improving the quality and life expectancy of children with SCID. For the first time in Ukraine, we initiated a pilot study on newborn screening for severe combined immunodeficiency and T-cell lymphopenia by determining T cell receptor excision circles (TRECs) and kappa-deleting recombination excision circles (KRECs). The analysis of TREC and KREC was performed by real-time polymerase chain reaction (RT-PCR) followed by analysis of melting curves in neonatal dry blood spots (DBS). The DBS samples were collected between May 2020 and January 2022. In total, 10,350 newborns were screened. Sixty-five blood DNA samples were used for control: 25 from patients with ataxia-telangiectasia, 37 - from patients with Nijmegen breakage syndrome, 1 – with X-linked agammaglobulinemia, 2 – with SCID (JAK3 deficiency and DCLRE1C deficiency). Retest from the first DBS was provided in 5.8% of patients. New sample test was needed in 73 (0.7%) of newborns. Referral to confirm or rule out the diagnosis was used in 3 cases, including one urgent abnormal value. CID (T^lowB+NK+) was confirmed in a patient with the urgent abnormal value. The results of a pilot study in Ukraine are compared to other studies (the referral rate 1: 3,450). Approbation of the method on DNA samples of children with ataxia-telangiectasia and Nijmegen syndrome showed a high sensitivity of TRECs (a total of 95.2% with cut-off 2000 copies per 10⁶ cells) for the detection of these diseases. Thus, the tested method has shown its effectiveness for the detection of T- and B-lymphopenia and can be used for implementation of newborn screening for SCID in Ukraine.

How longitudinal observational studies can guide screening strategy for rare diseases

Newborn screening (NBS) is an important secondary prevention program, aiming to shift the paradigm of medicine to the pre-clinical stage of a disease. Starting more than 50 years ago, technical advances, such as tandem mass spectrometry (MS/MS), paved the way to a continuous extension of NBS programs. However, formal evidence of the long-term clinical benefits in large cohorts and cost-effectiveness of extended NBS programs is still scarce. Although published studies confirmed important benefits of NBS programs, it also unraveled a significant number of limitations. These include an incompletely understood natural history and phenotypic diversity of some screened diseases, unreliable early and precise prediction of individual disease severity, uncertainty about case definition, risk stratification, and indication to treat, resulting in a diagnostic and treatment dilemma in individuals with ambiguous screening and confirmatory test results. Interoperable patient registries are multi-purpose tools that could help to close the current knowledge gaps and to inform further optimization of NBS strategy. Standing at the edge of introducing high throughput genetic technologies to NBS programs with the opportunity to massively extend NBS programs and with the risk of aggravating current limitations of NBS programs, it seems overdue to include mandatory long-term follow-up of NBS cohorts into the list of screening principles and to build an international collaborative framework that enables data collection and exchange in a protected environment, integrating the perspectives of patients, families, and the society.

Early Discovery of Children With Lysosomal Acid Lipase Deficiency With the Universal Familial Hypercholesterolemia Screening Program

Lysosomal acid lipase deficiency (LAL-D) is an autosomal recessive lysosomal storage disorder, caused by homozygous or compound heterozygous pathogenic variants in the LIPA gene. Clinically, LAL-D is under- and misdiagnosed, due to similar clinical and laboratory findings with other cholesterol or liver misfunctions. As a part of the Slovenian universal familial hypercholesterolemia (FH) screening, LAL-D is screened as a secondary condition among other rare dyslipidemias manifesting with hypercholesterolemia. Out of 669 children included, three were positive for a homozygous disease-causing splicing variant NM_000235.4: c.894G > A (NP_000226.2:p. Gln298Gln) in the LIPA gene (NG_008194.1). The mean age by the diagnosis of LAL-D was 9.8 ± 0.9 years. Moreover, all three LAL-D-positive children had an important elevation of transaminases and decreased activity of the lysosomal acid lipase enzyme. Abdominal MRI in all children detected an enlarged liver but a normal-sized spleen. In conclusion, universal FH screening algorithms with the confirmatory genetic analysis in the pediatric population enable also rare dyslipidemia detection at an early age. An important clinical criterion for differentiation between FH and the LAL-D-positive children has elevated transaminase levels (AST and ALT). In all three LAL-D positive children, an improvement in cholesterol and transaminase levels and steatosis of the liver has been seen after early treatment initiation.

Galactosemia: Biochemistry, Molecular Genetics, Newborn Screening, and Treatment

Galactosemia is an inborn disorder of carbohydrate metabolism characterized by the inability to metabolize galactose, a sugar contained in milk (the main source of nourishment for infants), and convert it into glucose, the sugar used by the body as the primary source of energy. Galactosemia is an autosomal recessive genetic disease that can be diagnosed at birth, even in the absence of symptoms, with newborn screening by assessing the level of galactose and the GALT enzyme activity, as GALT defect constitutes the most frequent cause of galactosemia. Currently, galactosemia cannot be cured, but only treated by means of a diet with a reduced content of galactose and lactose. Although the diet is able to reverse the neonatal clinical picture, it does not prevent the development of long-term complications. This review provides an overview of galactose metabolism, molecular genetics, newborn screening and therapy of galactosemia. Novel treatments for galactosemia currently being investigated in (pre)clinical studies and potentially able to prevent long-term complications are also presented.

Glutaric aciduria type 1: Diagnosis, clinical features and long-term outcome in a large cohort of 34 Irish patients

Glutaric aciduria type 1 (GA1) is a rare neurometabolic disorder that can lead to encephalopathic crises and severe dystonic movement disorders. Adherence to strict dietary restriction, in particular a diet low in lysine, carnitine supplementation and emergency treatment in pre-symptomatic patients diagnosed by high-risk screen (HRS) or newborn screen (NBS) leads to a favourable outcome. We present biochemical and clinical characteristics and long-term outcome data of 34 Irish patients with GA1 aged 1-40 years. Sixteen patients were diagnosed clinically, and 17 patients by HRS, prior to introduction of NBS for GA1 in the Republic of Ireland in 2018. One patient was diagnosed by NBS. Clinical diagnosis was at a median of 1 year (range 1 month to 8 years) and by HRS was at a median of 4 days (range 3 days to 11 years). 14/18 (77.8%) diagnosed by HRS or NBS had neither clinical manifestations nor radiological features of GA1, or had radiological features only, compared to 0/16 (0%) diagnosed clinically (p < 0.001). Patients diagnosed clinically who survived to school-age were more likely to have significant cerebral palsy and dystonia (7/11; 63.6% vs. 0/13; 0%, p < 0.001). They were less likely to be in mainstream school versus the HRS group (5/10; 50% vs. 12/13; 92.3%; p = 0.012). Clinical events occurring after 6 years of age were unusual, but included spastic diplegia, thalamic haemorrhage, Chiari malformation, pituitary hormone deficiency and epilepsy. The exact aetiology of these events is unclear.

Towards Achieving Equity and Innovation in Newborn Screening across Europe

Although individual rare disorders are uncommon, it is estimated that, together, 6000+ known rare diseases affect more than 30 million people in Europe, and present a substantial public health burden. Together with the psychosocial burden on affected families, rare disorders frequently, if untreated, result in a low quality of life, disability and even premature death. Newborn screening (NBS) has the potential to detect a number of rare conditions in asymptomatic children, providing the possibility of early treatment and a significantly improved long-term outcome. Despite these clear benefits, the availability and conduct of NBS programmes varies considerably across Europe and, with the increasing potential of genomic testing, it is likely that these differences may become even more pronounced. To help improve the equity of provision of NBS and ensure that all children can be offered high-quality screening regardless of race, nationality and socio-economic status, a technical meeting, endorsed by the Slovenian Presidency of the Council of the European Union, was held in October 2021. In this article, we present experiences from individual EU countries, stakeholder initiatives and the meeting's final conclusions, which can help countries attempting to establish new NBS programmes or expand existing provision.

Expanded newborn bloodspot screening: developed country examples and what can be done in Turkey

Bloodspot screening in newborns is an exemplary public health intervention as it is essential secondary prevention with proven efficacy and benefit for the early diagnosis and prompt treatment of rare diseases. In this mini review, newborn bloodspot screening (NBS) programs of 12 countries were examined in terms of the extent of diseases/disorders screened to form recommendations for Turkey's expanded newborn screening program. Essentially, Turkey and 11 selected countries' official policies/ national programs or strategies in terms of newborn screening and the number of diseases/conditions screened were examined. The current status of spinal muscular atrophy (SMA) screening was also checked through the SMA NBS Alliance. In addition, WHO and EURORDIS guidelines for newborn screening were also reviewed. On the Pubmed database, following the search strategy "((newborn screening[Title/Abstract]) OR (newborn screening program[Title/Abstract])) OR (newborn blood spot screening[Title/Abstract])" in the PubMed database from 1 January 2008 to 1 December 2021. Diseases that will be recommended to be included in the Turkish national newborn bloodspot screening program will be presented by evaluating the updated criteria of Wilson and Jungner by constructing international comparisons. The number of diseases/disorders screened by the inspected 12 countries is eminently variable and ranges from 5 in Turkey to 51 in New York, United States of America (USA). Acknowledging the programs of other countries, it is evident that Turkey must advance its program by evaluating the epidemiological data in Turkey, the health workforce, and infrastructure while relying on the updated screening criteria. The newborn bloodspot screening program should be expanded based on the cost estimates and implemented starting with pilot applications and the diseases/disorders that are deemed appropriate should be included in the national program.

Novel mutations in the HADHB gene causing a mild phenotype of mitochondrial trifunctional protein (MTP) deficiency

Mitochondrial trifunctional protein (MTP) deficiency is an ultrarare hereditary recessive disorder causing a broad spectrum of phenotypes with lethal infantile cardiomyopathy at the most severe end. Attenuated forms with polyneuropathy have been reported combined with myoglobinuria or rhabdomyolysis as key features. We here report three young adults (two siblings) in which three variants in the HADHB-gene were identified. All three cases had a similar mild phenotype with axonal neuropathy and frequent intermittent weakness episodes but without myoglobinuria. Special dietary precautions were recommended to minimize complications especially during infections and other catabolic states. MTP deficiency is therefore an important differential diagnosis in patients with milder fluctuating neuromuscular symptoms.

Take‐home message

Axonal neuropathy and recurrent muscular weakness without concomitant rhabdomyolysis may be due to MTP deficiency.

Opportunities and challenges in machine learning-based newborn screening-A systematic literature review

The development and continuous optimization of newborn screening (NBS) programs remains an important and challenging task due to the low prevalence of screened diseases and high sensitivity requirements for screening methods. Recently, different machine learning (ML) methods have been applied to support NBS. However, most studies only focus on single diseases or specific ML techniques making it difficult to draw conclusions on which methods are best to implement. Therefore, we performed a systematic literature review of peer-reviewed publications on ML-based NBS methods. Overall, 125 related papers, published in the past two decades, were collected for the study, and 17 met the inclusion criteria. We analyzed the opportunities and challenges of ML methods for NBS including data preprocessing, classification models and pattern recognition methods based on their underlying approaches, data requirements, interpretability on a modular level, and performance. In general, ML methods have the potential to reduce the false positive rate and identify so far unknown metabolic patterns within NBS data. Our analysis revealed, that, among the presented, logistic regression analysis and support vector machines seem to be valuable candidates for NBS. However, due to the variety of diseases and methods, a general recommendation for a single method in NBS is not possible. Instead, these methods should be further investigated and compared to other approaches in comprehensive studies as they show promising results in NBS applications.

Understanding Inborn Errors of Metabolism through Metabolomics

Inborn errors of metabolism (IEMs) are rare diseases caused by a defect in a single enzyme, co-factor, or transport protein. For most IEMs, no effective treatment is available and the exact disease mechanism is unknown. The application of metabolomics and, more specifically, tracer metabolomics in IEM research can help to elucidate these disease mechanisms and hence direct novel therapeutic interventions. In this review, we will describe the different approaches to metabolomics in IEM research. We will discuss the strengths and weaknesses of the different sample types that can be used (biofluids, tissues or cells from model organisms; modified cell lines; and patient fibroblasts) and when each of them is appropriate to use.

PirePred: An Accurate Online Consensus Tool to Interpret Newborn Screening-Related Genetic Variants in Structural Context

PirePred is a genetic interpretation tool used for a variety of medical conditions investigated in newborn screening programs. The PirePred server retrieves, analyzes, and displays in real time genetic and structural data on 58 genes/proteins associated with medical conditions frequently investigated in the newborn. PirePred analyzes the predictions generated by 15 pathogenicity predictors and applies an optimized majority vote algorithm to classify any possible nonsynonymous single-nucleotide variant as pathogenic, benign, or of uncertain significance. PirePred predictions for variants of clear clinical significance are better than those of any of the individual predictors considered (based on accuracy, sensitivity, and negative predictive value) or are among the best ones (for positive predictive value and Matthews correlation coefficient). PirePred predictions also outperform the comparable in silico predictions offered as supporting evidence, according to American College of Medical Genetics and Genomics guidelines, by VarSome and Franklin. Also, PirePred has very high prediction coverage. To facilitate the molecular interpretation of the missense, nonsense, and frameshift variants in ClinVar, the changing amino acid residue is displayed in its structural context, which is analyzed to provide functional clues. PirePred is an accurate, robust, and easy-to-use tool for clinicians involved in neonatal screening programs and for researchers of related diseases. The server is freely accessible and provides a user-friendly gateway into the structural/functional consequences of genetic variants at the protein level.

Second-tier strategies in newborn screening - potential and limitations

Newborn screening (NBS) is a public health measure to identify children with treatable disorders within the first days of life allowing presymptomatic treatment. It is the most successful measure of secondary medical prevention and part of public health programs in many countries worldwide. Application of second-tier strategies in NBS allows for increased specificity and consecutively a higher positive predictive value. Second-tier strategies can include analysis of specific biomarkers for a target disorder or may be based on molecular genetic analyses. Improving the quality of NBS, for example by second-tier strategies, is of utmost importance to maintain the high acceptance of NBS by families - especially as an increasing number of target disorders is being consecutively included into NBS programs.

A New Approach to Objectively Evaluate Inherited Metabolic Diseases for Inclusion on Newborn Screening Programmes

Newborn screening (NBS) programmes are essential in the diagnosis of inherited metabolic diseases (IMDs) and for access to disease modifying treatment. Most European countries follow the World Health Organisation (WHO) criteria to determine which disorders are appropriate for screening at birth; however, these criteria are interpreted and implemented by individual countries differently, creating disparities. Advances in research and diagnostics, together with the promise of new treatments, offer new possibilities to accelerate the expansion of evidence-based screening programmes. A novel and robust algorithm was built to objectively assess and prioritise IMDs for inclusion in NBS programmes. The Wilson and Jungner classic screening principles were used as a foundation to develop individual and measurable criteria. The proposed algorithm is a point-based system structured upon three pillars: condition, screening, and treatment. The algorithm was tested by applying the six IMDs currently approved in the United Kingdom NBS programme. The algorithm generates a weight-based score that could be used as the first step in the complex process of evaluating disorders for inclusion on NBS programmes. By prioritising disorders to be further evaluated, individual countries are able to assess the economic, societal and political aspects of a potential screening programme.

Newborn Screening: Review of its Impact for Cystinosis

Newborn screening (NBS) programmes are considered to be one of the most successful secondary prevention measures in childhood to prevent or reduce morbidity and/or mortality via early disease identification and subsequent initiation of therapy. However, while many rare diseases can now be detected at an early stage using appropriate diagnostics, the introduction of a new target disease requires a detailed analysis of the entire screening process, including a robust scientific background, analytics, information technology, and logistics. In addition, ethics, financing, and the required medical measures need to be considered to allow the benefits of screening to be evaluated at a higher level than its potential harm. Infantile nephropathic cystinosis (INC) is a very rare lysosomal metabolic disorder. With the introduction of cysteamine therapy in the early 1980s and the possibility of renal replacement therapy in infancy, patients with cystinosis can now reach adulthood. Early diagnosis of cystinosis remains important as this enables initiation of cysteamine at the earliest opportunity to support renal and patient survival. Using molecular technologies, the feasibility of screening for cystinosis has been demonstrated in a pilot project. This review aims to provide insight into NBS and discuss its importance for nephropathic cystinosis using molecular technologies.

Application of a Novel Algorithm for Expanding Newborn Screening for Inherited Metabolic Disorders across Europe

Inherited metabolic disorders (IMDs) are mostly rare, have overlapping symptoms, and can be devastating and progressive. However, in many disorders, early intervention can improve long-term outcomes, and newborn screening (NBS) programmes can reduce caregiver stress in the journey to diagnosis and allow patients to receive early, and potentially pre-symptomatic, treatment. Across Europe there are vast discrepancies in the number of IMDs that are screened for and there is an imminent opportunity to accelerate the expansion of evidence-based screening programmes and reduce the disparities in screening programmes across Europe. A comprehensive list of IMDs was created for analysis. A novel NBS evaluation algorithm, described by Burlina et al. in 2021, was used to assess and prioritise IMDs for inclusion on expanded NBS programmes across Europe. Forty-eight IMDs, of which twenty-one were lysosomal storage disorders (LSDs), were identified and assessed with the novel NBS evaluation algorithm. Thirty-five disorders most strongly fulfil the Wilson and Jungner classic screening principles and should be considered for inclusion in NBS programmes across Europe. The recommended disorders should be evaluated at the national level to assess the economic, societal, and political aspects of potential screening programmes.

Global impact of COVID-19 on newborn screening programmes

Introduction

The global COVID-19 pandemic has presented extraordinary disruption to healthcare services and exposed them to numerous challenges. Newborn screening (NBS) programmes were also affected; however, scarce data exist on the impact of COVID-19 on NBS.

Methods

We conducted an international survey to assess the global impact of COVID-19 on NBS, with the main aim of gathering the experiences of the COVID-19 pandemic from a large and representative number of NBS centres worldwide.

Results

The results of our study showed that COVID-19 impacted the NBS programmes, at least partially, in 29 out of 38 responding countries. Majority of the screening centres experienced a broad spectrum of difficulties and most were affected more in the second wave of the pandemic. Delays and unreliability with the postal service as well as flight cancellations caused delays in samples arriving to screening centres and with the provision of laboratory equipment and reagents. The availability of laboratory staff was sometimes reduced due to infection, quarantine or reassignment within the healthcare facility. Sample collection at home, second-tier tests and follow-up were also affected. Social restrictions and interruptions in public transport added to these difficulties. Only a limited number of centres managed to retain a fully functioning NBS programme.

Conclusion

As the pandemic might continue or could recur in future years, it would be useful to develop guidelines to protect these valuable services.

Multidisciplinary Care of Patients with Inherited Metabolic Diseases and Epilepsy: Current Perspectives

More than 650 inherited metabolic diseases may present with epilepsy or seizures. These diseases are often multisystem, life-long and induce complex needs of patients and families. Multidisciplinary care involves all stages of disease management: diagnostics, specific or symptomatic, acute and chronic treatments, and integrated care that takes into account not only medical, but also manifold psychosocial, educational, vocational and other needs of patients and their caregivers. Care coordination is indispensable to ensure smooth transitions of care across life and disease stages, including management of emergencies, transition from pediatric to adult services and palliative care. Care pathways are highly diverse and have to find the right balance between highly specialized and locally provided services. While multidisciplinary teams consist of many professionals, a named supervising physician in a highly specialized healthcare setting and a care coordinator are highly important. As the greatest burden of care always falls onto the shoulders of patients and/or families, patient empowerment should be a part of every care pathway and include provision of required information, involvement into common decision-making, patient’s and family’s education, support for self-management, liaison with peer support groups and emotional/ psychological support. Due to the rarity and complexity of these diseases, sufficient expertise may not be available in a national healthcare system and cross-border services (virtual or physical) in the recently developed European Reference Networks should be ensured through the proper organization of referral systems in each EU and EEA country. Finally, digital technologies are particularly important in the provision of services for patients with rare diseases and can significantly increase the availability of highly specialized services and expertise.

Diagnosis of inborn errors of metabolism within the expanded newborn screening in the Madrid region

We present the results of our experience in the diagnosis of inborn errors of metabolism (IEM) since the Expanded Newborn Screening was implemented in our Region. Dried blood samples were collected 48 h after birth. Amino acids and acylcarnitines were quantitated by mass spectrometry (MS)/MS. Newborns with alterations were referred to the clinical centers for follow-up. Biochemical and molecular genetic studies for confirmation of a disease were performed. In the period 2011 to 2019, 592 822 children were screened: 902 of them were referred for abnormal results. An IEM was confirmed in 222 (1/2670): aminoacidopathies: 89 hyperphenylalaninemia (HPA) (51 benign HPA, 32 phenylketonuria, 4 DNAJC12 defect, and 2 primapterinuria), 6 hypermethioninemia, 3 tyrosinemia type 1 (TYR-1), 1 TYR-3, 4 maple syrup urine disease (MSUD), 2 branched-chain amino acid transferase 2 deficiency, 2 homocystinuria, 1 cystinuria, 2 ornithine transcarbamylase (OTC) deficiency, 2 citrullinemia type I (CTLN1); FAO defects: 43 medium-chain acyl-CoA dehydrogenase deficiency (MCADD), 13 very long-chain acyl-CoA dehydrogenase deficiency, 2 long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD), 1 multiple acyl-coA dehydrogenation deficiency, 11 systemic primary carnitine deficiency, 2 carnitine palmitoyltransferase type 2 (CPT-II) deficiency, 1 CPT-I deficiency; organic acidurias: 12 glutaric aciduria type 1 (GA-1), 4 methylmalonic acidemia (MMA), 7 MMA including combined cases with homocystinuria (MMAHC), 6 propionic acidemia (PA), 7 3-methylcrotonyl-CoA carboxylase, 1 3-hydroxy-3-methylglutaryl-CoA lyase deficiency lyase deficiency. Only 19 infants (8.5%) were symptomatic at newborn screening result (1 LCHADD, 5 PA, 1 CPT-II deficiency, 1 MMA, 3 MMAHC, 2 MSUD, 2 OTC deficiency, 1 CTLN1, 1 MCADD, 2 TYR-1). No false negative cases were identified. Genetic diagnosis was conclusive in all biochemically confirmed cases, except for two infants with HPA, identifying pathogenic variants in 32 different genes. The conditions with the highest incidence were HPA (1/6661) and MCAD deficiencies (1/13 787).

Towards Next-Generation Sequencing (NGS)-Based Newborn Screening: A Technical Study to Prepare for the Challenges Ahead

Newborn screening (NBS) aims to identify neonates with severe conditions for whom immediate treatment is required. Currently, a biochemistry-first approach is used to identify these disorders, which are predominantly inherited meta1bolic disorders (IMD). Next-generation sequencing (NGS) is expected to have some advantages over the current approach, for example the ability to detect IMDs that meet all screening criteria but lack an identifiable biochemical footprint. We have now designed a technical study to explore the use of NGS techniques as a first-tier approach in NBS. Here, we describe the aim and set-up of the NGS-first for the NBS (NGSf4NBS) project, which will proceed in three steps. In Step 1, we will identify IMDs eligible for NGS-first testing, based on treatability. In Step 2, we will investigate the feasibility, limitations and comparability of different technical NGS approaches and analysis workflows for NBS, eventually aiming to develop a rapid NGS-based workflow. Finally, in Step 3, we will prepare for the incorporation of this workflow into the existing Dutch NBS program and propose a protocol for referral of a child after a positive NGS test result. The results of this study will be the basis for an additional analytical route within NBS that will be further studied for its applicability within the NBS program, e.g., regarding the ethical, legal, financial and social implications.

Anthropometrics, Dietary Intake and Body Composition in Urea Cycle Disorders and Branched Chain Organic Acidemias: A Case Study of 18 Adults on Low-Protein Diets

Low-protein diets (LPDs) are the mainstream treatment for inborn errors of intermediary protein metabolism (IEIPM), but dietary management differs worldwide. Most studies have investigated pediatric populations and their goals such as growth and metabolic balance, showing a tendency toward increasing overweight and obesity. Only a few studies have examined nutritional status and dietary intake of adult IEIPM patients on LPDs. We assessed nutritional parameters (dietary intake using a 7-day food diary record, body composition by bioimpedance analysis, and biochemical serum values) in a group of 18 adult patients with urea cycle disorders (UCDs) and branched chain organic acidemia (BCOA). Mean total protein intake was 0.61 ± 0.2 g/kg/day (73.5% of WHO Safe Levels) and mean natural protein (PN) intake was 0.54 ± 0.2 g/kg/day; 33.3% of patients consumed amino acid (AA) supplements. A totally of 39% of individuals presented a body mass index (BMI) > 25 kg/m2 and patients on AA supplements had a mean BMI indicative of overweight. All patients reported low physical activity levels. Total energy intake was 24.2 ± 5 kcal/kg/day, representing 72.1% of mean total energy expenditure estimated by predictive formulas. The protein energy ratio (P:E) was, on average, 2.22 g/100 kcal/day. Plasmatic levels of albumin, amino acids, and lipid profiles exhibited normal ranges. Phase angle (PA) was, on average, 6.0° ± 0.9°. Fat mass percentage (FM%) was 22% ± 9% in men and 36% ± 4% in women. FM% was inversely and significantly related to total and natural protein intake. Data from IEIPM adults on LPDs confirmed the pediatric trend of increasing overweight and obesity despite a low energy intake. A low protein intake may contribute to an increased fat mass. Nutritional parameters and a healthy lifestyle should be routinely assessed in order to optimize nutritional status and possibly reduce risk of cardiovascular degenerative diseases in adult UCD and BCOA patients on LPDs.

The Birth Prevalence of Spinal Muscular Atrophy: A Population Specific Approach in Estonia

Background: Rare diseases are an important population health issue and many promising therapies have been developed in recent years. In light of novel genetic treatments expected to significantly improve spinal muscular atrophy (SMA) patients' quality of life and the urgent need for SMA newborn screening (NBS), new epidemiological data were needed to implement SMA NBS in Estonia. Objective: We aimed to describe the birth prevalence of SMA in the years 1996-2020 and to compare the results with previously published data. Methods: We retrospectively analyzed clinical and laboratory data of SMA patients referred to the Department of Clinical Genetics of Tartu University Hospital and its branch in Tallinn. Results: Fifty-seven patients were molecularly diagnosed with SMA. SMA birth prevalence was 1 per 8,286 (95% CI 1 per 6,130-11,494) in Estonia. Patients were classified as SMA type 0 (1.8%), SMA I (43.9%), SMA II (22.8%), SMA III (29.8%), and SMA IV (1.8%). Two patients were compound heterozygotes with an SMN1 deletion in trans with a novel single nucleotide variant NM_000344.3:c.410dup, p.(Asn137Lysfs*11). SMN2 copy number was assessed in 51 patients. Conclusion: In Estonia, the birth prevalence of SMA is similar to the median birth prevalence in Europe. This study gathered valuable information on the current epidemiology of SMA, which can guide the implementation of spinal muscular atrophy to the newborn screening program in Estonia.

Implementation of TREC/KREC detection protocol for newborn SCID screening in Bulgaria: a pilot study

Neonatal screening for inborn errors of immunity (IEI), based on quantification of T-cell-receptor- excision circles (TRECs) and kappa-deleting recombination-excision circles (KRECs) from dried blood spots (DBS), allows early diagnosis and improved outcomes for the affected children. Determination of TREC/KREC levels from prospectively collected newborns' Guthrie cards and from DBS samples of patients with confirmed IEI was done using a commercial kit. Retrospective assessment of flow cytometry evaluation of TREC/KREC correspondence with lymphocyte subpopulations and evaluation of the correlations between TREC and KREC with immune cells, based on the data from patients with suspected or confirmed immune disorders, were conducted. 2,228 Guthrie cards were tested, 1276 for TREC only and 952 for both TREC and KREC. Eight newborns (0.36%) were TREC positive and 10 (1.05%) had KREC below the cut-off. The re-testing rate was 1.88%. Retrospective analysis demonstrated that the TREC/KREC assay identifies 100% of severe combined immune deficiencies (SCID) cases when DBS were collected at birth. Correlation analysis showed moderate significant correlations between TREC and the absolute numbers of CD4 cells (r = 0.634, p < 0.01) and total T cells (r = 0.536, p < 0.01). The ability of KREC levels to predict abnormal absolute (AUC of 0.772) and relative (AUC 0.731) levels of B cells was demonstrated.

Biochemical testing for inborn errors of metabolism: experience from a large tertiary neonatal centre

Inborn errors of metabolism are an individually rare but collectively significant cause of mortality and morbidity in the neonatal period. They are identified by either newborn screening programmes or clinician-initiated targeted biochemical screening. This study examines the relative contribution of these two methods to the identification of inborn errors of metabolism and describes the incidence of these conditions in a large, tertiary, neonatal unit. We also examined which factors could impact the reliability of metabolic testing in this cohort. This is a retrospective, single-site study examining infants in whom a targeted metabolic investigation was performed from January 2018 to December 2020 inclusive. Data was also provided by the national newborn screening laboratory regarding newborn screening diagnoses. Two hundred and four newborns received a clinician-initiated metabolic screen during the time period examined with 5 newborns being diagnosed with an inborn error of metabolism (IEM) (2.4%). Of the 25,240 infants born in the hospital during the period examined, a further 11 newborns had an inborn error of metabolism diagnosed on newborn screening. This produced an incidence in our unit over the time described of 6.34 per 10,000 births. This number reflects a minimum estimate, given that the conditions diagnosed refer to early-onset disorders and distinctive categories of IEM only. Efficiency of the clinician-initiated metabolic screening process was also examined. The only statistically significant variable in requiring repeat metabolic screening was early day of life (z-score = - 2.58, p = 0.0098). A total of 28.4% was missing one of three key metabolic investigation parameters of blood glucose, ammonia or lactate concentration with ammonia the most common investigation missing. While hypoglycemia was the most common clinical rationale for a clinician-initiated metabolic test, it was a poor predictor of inborn error of metabolism with no newborns of 25 screened were diagnosed with a metabolic disorder.

CONCLUSION

Clinician-targeted metabolic screening had a high diagnostic yield given the relatively low prevalence of inborn errors of metabolism in the general population. Thoughts should be given to the rationale behind each targeted metabolic test and what specific metabolic disease or category of inborn error of metabolism they are concerned along with commencing targeted testing.

WHAT IS KNOWN

• Inborn errors of metabolism are a rare but potentially treatable cause of newborn mortality and morbidity. • A previous study conducted in a tertiary unit in an area with limited newborn screening demonstrated a diagnostic yield of 5.4%.

WHAT IS NEW

• Clinician-initiated targeted metabolic screening has a good diagnostic performance even with a more expanded newborn screening programme. • Further optimisation could be achieved by examining the best timing and also the rationale of metabolic testing in the newborn period.

Rare Disease Registries Are Key to Evidence-Based Personalized Medicine: Highlighting the European Experience

Rare diseases, such as inherited metabolic diseases, have been identified as a health priority within the European Union more than 20 years ago and have become an integral part of EU health programs and European Reference Networks. Having the potential to pool data, to achieve sufficient sample size, to overcome the knowledge gap on rare diseases and to foster epidemiological and clinical research, patient registries are recognized as key instruments to evidence-based medicine for individuals with rare diseases. Patient registries can be used for multiple purposes, such as (1) describing the natural history and phenotypic diversity of rare diseases, (2) improving case definition and indication to treat, (3) identifying strategies for risk stratification and early prediction of disease severity (4), evaluating the impact of preventive, diagnostic, and therapeutic strategies on individual health, health economics, and the society, and (5) informing guideline development and policy makers. In contrast to clinical trials, patient registries aim to gather real-world evidence and to achieve generalizable results based on patient cohorts with a broad phenotypic spectrum. In order to develop a consistent and sustained framework for rare disease registries, uniform core principles have been formulated and have been formalized through the European Rare Disease Registration Infrastructure. Adherence to these core principles and compliance with the European general data protection regulations ensures that data collected and stored in patient registries can be exchanged and pooled in a protected environment. To illustrate the benefits and limitations of patient registries on rare disease research this review focuses on inherited metabolic diseases.

Sensitive and Robust LC-MS/MS Assay to Quantify 25-Hydroxyvitamin D in Leftover Protein Extract from Dried Blood Spots

Neonatal dried blood spots (DBS) provide a remarkable resource for biobanks. These microsamples can provide information related to the genetic correlates of disease and can be used to quantify a range of analytes, such as proteins and small molecules. However, after routine neonatal screening, the amount of DBS sample available is limited. To optimize the use of these samples, there is a need for sensitive assays which are integrated across different analytic platforms. For example, after DNA extraction, protein extracts are available for additional analyses. We describe a sensitive and robust LC-MS/MS method for 25-hydroxyvitamin D₂ and 25-hydroxyvitamin D₃ optimized for leftover protein extracts from DBS, which has excellent recovery, precision, and accuracy.

Passive Immunity to SARS-CoV-2 at Birth Induced by Vaccination in the First Trimester of Pregnancy

As is well known, the COVID-19 infection is affecting the whole world, causing a serious health, social and economic crisis. The viral infection can cause a mild or severe illness, depending on how effectively the virus is countered by the immune system. In this context, the position of pregnant women remains rather unknown. The case described here reports the immune response in a woman in good health and in her newborn son, having undergone complete vaccination during the first trimester of her pregnancy. We performed a serological assay, measuring IgG antibodies to SARS-CoV-2, by a fully automated solid phase DELFIA (time-resolved fluorescence) immunoassay in a few drops of blood, collected by a finger-prick and spotted on filter paper. The dried blood spot (DBS) sample we used is the same type of sample routinely used in a newborn screening program test. Such a simple and minimally invasive approach allowed us to monitor both the mother and the newborn soon after birth for their anti-SARS-CoV-2 IgG levels. The serological test on the DBS carried out on both mother and newborn revealed the presence of anti-SARS-CoV-2 IgG antibodies up to 7 months after vaccination in the mother, and already at 48 h of life in the newborn.

The Discovery of GALM Deficiency (Type IV Galactosemia) and Newborn Screening System for Galactosemia in Japan

The Leloir pathway, which consists of highly conserved enzymes, metabolizes galactose. Deficits in three enzymes in this pathway, namely galactose-1-phosphate uridylyltransferase (GALT), galactokinase (GALK1), and UDP-galactose-4'-epimerase (GALE), are associated with genetic galactosemia. We recently identified patients with galactosemia and biallelic variants in GALM, encoding galactose epimerase (GALM), an enzyme that is directly upstream of GALK1. GALM deficiency was subsequently designated as type IV galactosemia. Currently, all the published patients with biallelic GALM variants were found through newborn screening in Japan. Here, we review GALM deficiency and describe how we discovered this relatively mild but not rare disease through the newborn screening system in Japan.

Newborn screening of neuromuscular diseases

Neuromuscular diseases represent an heterogenous group of more than 400 diseases, with a very broad phenotypic spectrum. Given their rarity and complexity, neuromuscular diseases are often diagnosed with a very significant delay after which irreversible muscle damage may limit the efficacy of treatments when available. In this context, neonatal screening could constitute a solution for early detection and treatment. A systematic review of the literature in PubMed up to May 1, 2021, was conducted according to PRISMA guidelines, including classical neuromuscular diseases and diseases with a clear peripheral nervous system involvement (including central nervous system disease with severe neuropathy). We found seven diseases for which newborn screening data were reported: spinal muscular atrophy (9), Duchenne muscular dystrophy (9), Pompe disease (8), X-linked adrenoleukodystrophy (5), Krabbe disease (4), myotonic dystrophy type 1 (1), metachromatic leukodystrophy (1). The future of newborn screening for neuromuscular disorders pass through a global technological switch, from a biochemical to a genetic-based approach. The rapid development of therapy also requires the possibility to quickly adapt the list of treated conditions, to allow innovative therapies to achieve their best efficacy.