OBJECTIVE: Although recent discoveries regarding the biomarkers of newborn screening (NBS) programs by tandem mass spectrometry (MS/MS) highlight the critical need to establish reference intervals (RIs) specifically for preterm infants, no such RIs has been formally published yet. This study addressed the gap by offering a comprehensive set of reference intervals (RIs) for preterm neonates, and illustrating the dynamic changes of each biomarker with age.
METHODS: The NBS data of 199,693 preterm newborns (< 37 weeks of gestation) who met the inclusion and exclusion criteria from the NNSCP database were included in study analysis. The birth weight stratified dynamic trend of each biomarker were captured by their concentrations over age. Reference partitions were determined by the method of Harris and Boyd. RIs, corresponding to the 2.5th and 97.5th percentiles, as well as the 0.5th, 25th, 50th, 75th and 99.5th percentiles were calculated using a non-parametric rank approach.
RESULTS: Increasing birth weight is associated with an elevation in the levels of arginine, citrulline, glycine, leucine and isobarics, methionine, ornithine, phenylalanine, and valine, whereas the levels of alanine, proline and tyrosine decrease. Additionally, two short-chain acylcarnitines (butyrylcarnitine + isobutyrylcarnitine and isovalerylcarnitine + methylbutyrylcarnitine) and a median-chain acylcarnitine (octenoylcarnitine) decrease, while four long-chain acylcarnitines (tetradecanoylcarnitine, palmitoylcarnitine, palmitoleylcarnitine and oleoylcarnitine) increase with increasing birth weight. Age impacts the levels of all MS/MS NBS biomarkers, while sex only affects the level of malonylcarnitine + 3-hydroxybutyrylcarnitine (C3-DC + C4-OH) in very low birth weight preterm neonates.
CONCLUSIONS: The current study developed reference intervals (RIs) specific to birth weight, age, and/or sex for 35 MS/MS biomarkers, which can help in the timely evaluation of the health and disease of preterm neonates.

BACKGROUND: Compare the differences between normal newborns and high-risk children with inherited metabolic diseases. The disease profile includes amino acidemias, fatty acid oxidation disorders, and organic acidemias.
METHODS: Data was collected on newborns and children from high-risk populations in Shanghai from December 2010 to December 2020.
RESULTS: 232,561 newborns were screened for disorders of organic, amino acid, and fatty acid metabolism. The initial positive rate was 0.66 % (1,526/232,561) and the positive recall rate was 77.85 %. The positive predictive value is 4.71 %. Among them, 56 cases were diagnosed as metabolic abnormalities. The total incidence rate is 1:4153. Hyperphenylalaninemia and short-chain acyl-CoA dehydrogenase are the most common diseases in newborns. In addition, in 56 children, 39 (69.42 %) were diagnosed by genetic sequencing. Some hotspot mutations in 14 IEMs have been observed, including PAH gene c.728G > A, c.611A > G, and ACADS gene c. 1031A > G, c.164C > T. A total of 49,860 symptomatic patients were screened, of which 185 were diagnosed with IEM, with a detection rate of 0.37 %. The most commonly diagnosed diseases in high-risk infants aremethylmalonic acidemia and hyperphenylalaninemia.
CONCLUSIONS: There are more clinical cases of congenital metabolic errors diagnosed by tandem mass spectrometry than newborn screening. The spectrum of diseases, prevalence, and genetic characteristics of normal newborns and high-risk children are quite different.

Data on the prevalence of most inborn errors of metabolism are still unavailable in Kazakhstan. The study aims to perform selective screening for hereditary metabolic diseases among patients aged from 1 day to 18 years in western Kazakhstan using the LC-MS/MS method, with establishing the reference values for the content of amino acids, acylcarnitines, and succinylacetone in blood samples of healthy children. Tasks: 1. To assess the burden of metabolic disorders detected by LC-MS/MS in western Kazakhstan by examination of children at clinical risk in pediatric clinics throughout the region; https://www.frontiersin.org/register?returnUrl=https://loop.frontiersin.org 2. To set the reference values of metabolites in the child population; 3. To analyze the age distribution, prevalence, and age of onset for each identified IEM, further comparing the obtained findings with those from previously published reports in other populations.
METHODS: To set the reference values of 51 metabolites in the child population, 750 healthy children will be included. The selective screening will be performed among 1,500 patients aged 1 day to 18 years with suspected hereditary metabolic disorders.
RESULTS: The results of selective screening will be interpreted by comparison with the reference values established. Diagnosis will be based on clinical signs, blood levels of amino acids, acylcarnitines, succinylacetone, and urine levels of organic acids and tests for gene mutations. An assessment of 37 inborn errors of metabolism frequencies in high-risk children will be performed. The research will further develop the national as selective as expanded newborn screening programs. The study was registered in clinicaltrials. gov (https://www.
RESULTS: gov/study/NCT05910151) on 16 June 2023.

The Wilson and Jungner (W&J) and Andermann criteria are meant to help select diseases eligible for population-based screening. With the introduction of next-generation sequencing (NGS) methods for newborn screening (NBS), more inherited metabolic diseases (IMDs) can technically be included, and a revision of the criteria was attempted. This study aimed to formulate statements and investigate whether those statements could elaborate on the criterion of treatability for IMDs to decide on eligibility for NBS. An online Delphi study was started among a panel of Dutch IMD experts (EPs). EPs evaluated, amended, and approved statements on treatability that were subsequently applied to 10 IMDs. After two rounds of Delphi, consensus was reached on 10 statements. Application of these statements selected 5 out of 10 IMDs proposed for this study as eligible for NBS, including 3 IMDs in the current Dutch NBS. The statement: \'The expected benefit/burden ratio of early treatment is positive and results in a significant health outcome\' contributed most to decision-making. Our Delphi study resulted in 10 statements that can help to decide on eligibility for inclusion in NBS based on treatability, also showing that other criteria could be handled in a comparable way. Validation of the statements is required before these can be applied as guidance to authorities.

Analytical and therapeutic innovations led to a continuous but variable extension of newborn screening (NBS) programmes worldwide. Every extension requires a careful evaluation of feasibility, diagnostic (process) quality and possible health benefits to balance benefits and limitations. The aim of this study was to evaluate the suitability of 18 candidate diseases for inclusion in NBS programmes. Utilising tandem mass spectrometry as well as establishing specific diagnostic pathways with second-tier analyses, three German NBS centres designed and conducted an evaluation study for 18 candidate diseases, all of them inherited metabolic diseases. In total, 1 777 264 NBS samples were analysed. Overall, 441 positive NBS results were reported resulting in 68 confirmed diagnoses, 373 false-positive cases and an estimated cumulative prevalence of approximately 1 in 26 000 newborns. The positive predictive value ranged from 0.07 (carnitine transporter defect) to 0.67 (HMG-CoA lyase deficiency). Three individuals were missed and 14 individuals (21%) developed symptoms before the positive NBS results were reported. The majority of tested candidate diseases were found to be suitable for inclusion in NBS programmes, while multiple acyl-CoA dehydrogenase deficiency, isolated methylmalonic acidurias, propionic acidemia and malonyl-CoA decarboxylase deficiency showed some and carnitine transporter defect significant limitations. Evaluation studies are an important tool to assess the potential benefits and limitations of expanding NBS programmes to new diseases.

Substantial challenges in study design and methodology exist during clinical trial development to examine treatment response in patients with a rare disease, especially those with predominant central nervous system involvement and heterogeneity in clinical manifestations and natural history. Here we discuss crucial decisions which may significantly impact success of the study, including patient selection and recruitment, identification and selection of endpoints, determination of the study duration, consideration of control groups including natural history controls, and selection of appropriate statistical analyses. We review strategies for the successful development of a clinical trial to evaluate treatment of a rare disease with a focus on inborn errors of metabolism (IEMs) that present with movement disorders. The strategies presented using pantothenate kinase-associated neurodegeneration (PKAN) as the rare disease example can be applied to other rare diseases, particularly IEMs with movement disorders (e.g., other neurodegeneration with brain iron accumulation disorders, lysosomal storage disorders). The significant challenges associated with designing a clinical trial in rare disease can sometimes be successfully met through strategic engagement with experts in the rare disease, seeking regulatory and biostatistical guidance, and early involvement of patients and families. In addition to these strategies, we discuss the urgent need for a paradigm shift within the regulatory processes to help accelerate medical product development and bring new innovations and advances to patients with rare neurodegenerative diseases who need them earlier in disease progression and prior to clinical manifestations.

Introduction: Inborn errors of metabolism (IEM) are scarce, and their diagnosis is often made after birth. This has led to the perception that most fetuses affected by these disorders do not become clinically apparent during pregnancy. Our aim was to determine the obstetrical characteristics of women with an offspring affected by IEM. Methods: This population-based retrospective cohort study included all women who delivered at the Soroka University Medical Center (SUMC) from 1988 to 2017 who met the inclusion criteria. Mothers who had an offspring with IEM were included in the study group, and those who had offsprings without IEM comprised the comparison group. Results: A total of 388,813 pregnancies were included in the study, and 184 of them were complicated by a fetus with IEM. The number of Bedouin women was higher in the IEM-affected infant group than in the comparison group (90.8% vs. 53.3%, p < 0.001); women who had a fetus with IEM had a higher rate of polyhydramnios (7.1% vs. 3.2%, p = 0.005), HELLP syndrome (3.3% vs. 1.1%, p = 0.014), and preterm birth (20.7% vs. 10.1%, p < 0.001); neonates with IEM had lower mean birth weight (p < 0.001), lower Apgar scores at 1\' and 5\' minutes (p < 0.001), and a higher rate of fetal growth restriction (FGR) (p < 0.001), postpartum death <28 days (p < 0.001), and neonatal death (p < 0.001) than those in the comparison group. Pregnancies with IEM fetuses were independently associated with preterm birth (OR 2.00; CI 1.4-3), polyhydramnios (OR 2.08; CI 1.17-3.71), and FGR (OR 2.24; CI 1.2-4.19). Each family of metabolic diseases is independently associated with specific pregnancy complications (i.e., mitochondrial diseases are associated with HELLP syndrome (OR 5.6; CI 1.8-17), and lysosomal storage disease are associated with nonimmune hydrops fetalis (OR 26.4; CI 3.39-206). Conclusion: This study reports for the first time, an independent association of IEM with specific complications of pregnancy. This observation has clinical implications, as the identification of specific pregnancy complications in a population at risk for IEM can assist in the prenatal diagnosis of an affected fetus.

To determine the long-term risk of mortality among children with inborn errors of metabolism.
We conducted a retrospective cohort study of 1750 children with inborn errors of metabolism (excluding mitochondrial disorders) and 1 036 668 children without errors of metabolism who were born in Quebec, Canada, between 2006 and 2019. Main outcome measures included all-cause and cause-specific mortality between birth and 14 years of age. We used adjusted survival regression models to estimate HRs and 95% CIs for the association between inborn errors of metabolism and mortality over time.
Mortality rates were greater for children with errors of metabolism than for unaffected children (69.1 vs 3.2 deaths per 10 000 person-years). During 7 702 179 person-years of follow-up, inborn errors of metabolism were associated with 21.2 times the risk of mortality compared with no error of metabolism (95% CI 17.23-26.11). Disorders of mineral metabolism were associated with greater mortality the first 28 days of life (HR 60.62, 95% CI 10.04-365.98), and disorders of sphingolipid metabolism were associated with greater mortality by 1 year (HR 284.73, 95% CI 139.20-582.44) and 14 years (HR 1066.00, 95% CI 298.91-3801.63). Errors of metabolism were disproportionately associated with death from hepatic/digestive (HR 208.21, 95% CI 90.28-480.22), respiratory (HR 116.57, 95% CI 71.06-191.23), and infectious causes (HR 119.83, 95% CI 40.56-354.04).
Children with errors of metabolism have a considerably elevated risk of mortality before 14 years, including death from hepatic/digestive, respiratory, and infectious causes. Targeting these causes of death may help improve long-term survival.

To determine the incidence and types of inborn errors of metabolism (IEMs) in high-risk children using mass spectrometry techniques.
Children considered high-risk for IEM were screened for metabolic diseases during a 3-y period. Dried blood spots and urine samples were analyzed by tandem mass spectrometry (LC-MS/MS) and gas chromatograph-mass spectrometry (GCMS). Samples with abnormal amino acids were confirmed by high-performance liquid chromatography (HPLC).
Eight hundred and twenty-two suspected cases were evaluated; of which, 87 possible cases of IEMs were identified. Homocystinuria (n = 51) was the most common IEM detected followed by biotinidase deficiency (n = 7), glutaric aciduria type 1 (n = 7), and carnitine uptake defect (n = 6). Overall, there were 45 (51.7%) cases of organic acidemia, 31 cases (35.6%) of amino acid defect, 9 (10.3%) cases of fatty-acid oxidation disorders, and 2 (2.3%) cases of probable mitochondrial disorder.
IEMs are common in India, with a hospital-based incidence of 1 in approximately 6642 among high-risk children. Screening of high-risk children by mass spectrometry techniques is a valuable strategy for early diagnosis of IEMs where universal newborn screening is not yet available.

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.