Inborn errors of metabolism

Dissecting the role of vitamin B12 metabolism in craniofacial development through analysis of clinical phenotypes and model organism discoveries

Vitamin B12, otherwise known as cobalamin, is an essential water-soluble vitamin that is obtained from animal derived dietary sources. Mutations in the genes that encode proteins responsible for cobalamin uptake, transport, or processing cause inborn errors of cobalamin metabolism, a group of disorders characterized by accumulation of homocysteine and methylmalonic acid, neurodevelopmental defects, ocular dysfunction, anemia, and failure to thrive. Mild to moderate craniofacial phenotypes have been observed but these phenotypes are not completely penetrant and have not been consistently recognized in the literature. However, in the most recent decade, animal models of cblX and cblC, two cobalamin disorder complementation groups, have documented craniofacial phenotypes. These data indicate a function for cobalamin in facial development. In this review, we performed a literature review of all cobalamin complementation groups to identify which groups, and which human variants, are associated with dysmorphic features, microcephaly, or marfanoid phenotypes. We identified dysmorphic facial features in cblC, cblX, cblG, cblF, and cblJ, which are caused by mutations in MMACHC, HCFC1, MTR, LMBRD1, and ABCD4, respectively. Other complementation groups were associated primarily with microcephaly. Animal models (zebrafish and mouse) of cblC and cblX support these clinical phenotypes and have demonstrated neural crest cell deficits that include reduced expression of prdm1a, sox10, and sox9, key molecular markers of neural crest development. Characterization of a zebrafish mmachc germline mutant also suggests atypical chondrocyte development. Collectively, these data demonstrate an essential role for cobalamin in facial development and warrant future mechanistic inquiries that dissect the cellular and molecular mechanisms underlying human facial phenotypes in cobalamin disorders.

Spectrum analysis of inborn errors of metabolism for expanded newborn screening in Xinjiang, China

To determine the disease spectrum and genetic characteristics of inborn errors of metabolism (IEM) in Xinjiang province in the northwest of China, 41,690 newborn babies were screening by tandem mass spectrometry from November 2018 to December 2021. Of these, 57 newborn babies were referred for genetic analysis by next-generation sequencing, which was validated by Sanger sequencing. A total of 36 newborn babies and one relative were diagnosed with IEM, and the overall positive predictive value was 29.03%. The overall incidence of IEM in Xinjiang was 1:1,158 (36/41,690). The incidence of amino acidemias, organic acidemias, and fatty acid oxidation disorder were 1:1,668 (25/41,690), 1:4,632 (9/41,690), and 1:20,845 (2/41,690), respectively. Phenylketonuria and methylmalonic acidemia were the two most common inborn errors of metabolism (IEM), accounting for 83% (30/36) of all confirmed cases. Some hotspot mutations were observed for several IEMs, including PAH gene c.158G > A (p.Arg53His) and c.688G > A (p.Val230Ile) for hyperphenylalaninemia. Four mutation types of the MMACHC gene (e.g., c.609G > A (p.Trp203Ter), c.567dupT (p.Ile190fs)) and six mutation types of the MMUT gene (e.g., c.729_730insT (p.Asp244fs)) were found for methylmalonic acidemia. We also found 11 mutations in six genes: PCCB, IVD, GCDH, MCCC1, SLC22A5, and ACADS in this region. This study combined tandem mass spectrometry and next-generation sequencing technology for the screening and diagnosis of IEM. The study provides effective clinical guidance, and the data provide a basis for expanding newborn screening, genetic screening, and IEM gene consultation in Xinjiang, China.

A novel frameshift variant in LAMP2 gene mimicking choroideremia carrier retinopathy

BACKGROUND

Danon disease is a rare, multisystemic X-linked dominant disorder caused by variants in the LAMP2 gene. It can be associated with retinal degeneration, but this is not well characterized. Here we describe a late presentation of a mild retinal phenotype, initially diagnosed as choroideremia carrier, associated with a novel variant in the LAMP2 gene.

METHODS

Retrospective analysis of the case included medical history, ophthalmic examination, multimodal retinal imaging, and microperimetry. Genetic testing was conducted to establish the molecular diagnosis.

RESULTS

A 54-year-old female presented with worsening night vision, without any family history. BCVA was 6/6 bilaterally and fundus examination showed light peripheral pigmentary changes bilaterally. FAF demonstrated a widespread speckled pattern and OCT revealed hyper-reflective spots in the outer nuclear layer. Differentials included non-genetic and genetic causes, suspected of being a manifesting choroideremia carrier. However, initial genetic testing by targeted analysis of retinal disorders did not detect a pathogenic variant. Further systems review revealed that the patient had previously been diagnosed with dilated cardiomyopathy, mini-stroke and partial deafness. Subsequent whole mitochondrial genome sequencing analysis did not detect any pathogenic variants too. Finally, whole exome sequencing with targeted analysis of a panel of hypertrophic cardiomyopathy genes identified a novel pathogenic heterozygous variant (c.925del, p.(Ser309fs)) in the LAMP2 gene, confirming the diagnosis of X-linked Danon disease.

CONCLUSION

Recording previous medical history and extraocular symptoms is crucial. The similarity in choroideremia carrier and Danon disease retinal phenotypes suggests a possible common pathway in these two genes where pathogenic variants lead to retinal pigment epithelium degeneration.

The Efficacy and Outcomes of Renal Replacement Therapy in Pediatric Metabolic Disorders

Background/Objectives: This study aims to evaluate the efficacy and outcomes of renal replacement therapy (RRT) in pediatric patients with metabolic diseases, specifically focusing on the impact of hemodialysis (HD) and peritoneal dialysis (PD) on clinical parameters, toxin reduction, and long-term survival. Methods: This retrospective study included 10 pediatric patients (eight females and two males) treated at a pediatric nephrology department between 2020 and 2023. Patients diagnosed with metabolic disorders, including maple syrup urine disease (MSUD), methylmalonic acidemia (MMA), and glycogen storage disease (GSD), underwent RRT. Clinical data, demographic information, and biochemical parameters were collected and analyzed. Results: Among the patients, 50% were diagnosed with MSUD, 30% with MMA, and 20% with GSD. RRT, including HD and PD, was administered to manage acute metabolic crises. HD was particularly effective in rapidly reducing toxic metabolite levels. Patients treated with HD showed significant reductions in leucine and ammonium levels, with median reductions of 94.5% and 86%, respectively. Overall, 60% of the patients demonstrated long-term survival, highlighting the critical role of RRT in managing metabolic crises. In conclusion, RRT, including HD and PD, is crucial in managing pediatric metabolic disorders by effectively reducing toxic metabolite levels and improving clinical outcomes. Conclusions: The results of this study are consistent with previous research, highlighting the critical role of RRT in the acute management of metabolic crises and supporting its adoption as a standard treatment method.

Best Practices for Development and Validation of Enzymatic Activity Assays to Support Drug Development for Inborn Errors of Metabolism and Biomarker Assessment

Aberrant or dysfunctional cellular enzymes are responsible for a wide range of diseases including cancer, neurodegenerative conditions, and metabolic disorders. Deficiencies in enzyme level or biofunction may lead to intracellular accumulation of substrate to toxic levels and interfere with overall cellular function, ultimately leading to cell damage, disease, and death. Marketed therapeutic interventions for inherited monogenic enzyme deficiency disorders include enzyme replacement therapy and small molecule chaperones. Novel approaches of in vivo gene therapy and ex vivo cell therapy are under clinical evaluation and provide promising opportunities to expand the number of available disease-modifying treatments. To support the development of these different therapeutics, assays to quantify the functional activity of protein enzymes have gained importance in the diagnosis of disease, assessment of pharmacokinetics and pharmacodynamic response, and evaluation of drug efficacy. In this review, we discuss the technical aspects of enzyme activity assays in the bioanalytical context, including assay design and format as well as the unique challenges and considerations associated with assay development, validation, and life cycle management.

Seizure Characteristics and EEG Features in Intoxication Type and Energy Deficiency Neurometabolic Disorders in the Pediatric Intensive Care Unit: Single-Center Experience Over 10 Years

BACKGROUND

Acute metabolic crises in inborn errors of metabolism (such as urea cycle disorders, organic acidemia, maple syrup urine disease, and mitochondrial disorders) are neurological emergencies requiring management in the pediatric intensive care unit (PICU). There is a paucity of data pertaining to electroencephalograms (EEG) characteristics in this cohort. We hypothesized that the incidence of background abnormalities and seizures in this cohort would be high. Neuromonitoring data from our center's PICU over 10 years are presented in this article.

METHODS

Data were collected by retrospective chart review for patients with the aforementioned disorders who were admitted to the PICU at our institution because of metabolic/neurologic symptoms from 2008 to 2018. Descriptive statistics (χ2 test or Fisher's exact test) were used to study the association between EEG parameters and outcomes.

RESULTS

Our cohort included 40 unique patients (8 with urea cycle disorder, 7 with organic acidemia, 3 with maple syrup urine disease, and 22 with mitochondrial disease) with 153 admissions. Presenting symptoms included altered mentation (36%), seizures (41%), focal weakness (5%), and emesis (28%). Continuous EEG was ordered in 34% (n = 52) of admissions. Twenty-three admissions were complicated by seizures, including eight manifesting as status epilepticus (seven nonconvulsive and one convulsive). Asymmetry and focal slowing on EEG were associated with seizures. Moderate background slowing or worse was noted in 75% of EEGs. Among those patients monitored on EEG, 4 (8%) died, 3 (6%) experienced a worsening of their Pediatric Cerebral Performance Category (PCPC) score as compared to admission, and 44 (86%) had no change (or improvement) in their PCPC score during admission.

CONCLUSIONS

This study shows a high incidence of clinical and subclinical seizures during metabolic crisis in patients with inborn errors of metabolism. EEG background features were associated with risk of seizures as well as discharge outcomes. This is the largest study to date to investigate EEG features and risk of seizures in patients with neurometabolic disorders admitted to the PICU. These data may be used to inform neuromonitoring protocols to improve mortality and morbidity in inborn errors of metabolism.

Using preimplantation genetic testing for monogenic disease for preventing citrullinemia type 1 transmission

Aim

The aim of this study is to investigate if Preimplantation Genetic Testing (PGT) can effectively identify unreported variants according to American College of Medical Genetics and Genomics (ACMG)to prevent citrullinemia type 1 affection.

Design

This study involves a detailed case analysis of a family with history of citrullinemia type 1, focusing on the use of PGT for monogenic diseases (PGT-M). The genetic variants were identified using ACMG guidelines, and PGT was employed to prevent the inheritance of these variants. The study included haplotype analysis and Sanger sequencing to confirm the results.

Results

The study identified previously unreported variations in the ASS1 gene causing citrullinemia type 1. PGT successfully prevented the transmission of these variants, resulting in the birth of a healthy fetus. However, challenges such as allele dropout (ADO) and gene recombination were encountered during haplotype analysis, which could potentially defeat the diagnosis. The study demonstrated that combining haplotype analysis with Sanger sequencing can enhance the accuracy of PGT.

Conclusion

Preimplantation Genetic Testing (PGT) targeting likely pathogenic and pathogenic variants in the ASS1 gene, as rated by ACMG, allows the birth of healthy infants free from citrullinemia type 1. Additionally, the establishment of single haplotypes and Sanger sequencing can reduce the misdiagnosis rate caused by allele dropout (ADO) and genetic recombination.

CPT2 Deficiency Modeled in Zebrafish: Abnormal Neural Development, Electrical Activity, Behavior, and Schizophrenia-Related Gene Expression

Carnitine palmitoyltransferase 2 (CPT2) is an inner mitochondrial membrane protein of the carnitine shuttle and is involved in the beta-oxidation of long chain fatty acids. Beta-oxidation provides an alternative pathway of energy production during early development and starvation. CPT2 deficiency is a genetic disorder that we recently showed can be associated with schizophrenia. We hypothesize that CPT2 deficiency during early brain development causes transcriptional, structural, and functional abnormalities that may contribute to a CNS environment that is susceptible to the emergence of schizophrenia. To investigate the effect of CPT2 deficiency on early vertebrate development and brain function, CPT2 was knocked down in a zebrafish model system. CPT2 knockdown resulted in abnormal lipid utilization and deposition, reduction in body size, and abnormal brain development. Axonal projections, neurotransmitter synthesis, electrical hyperactivity, and swimming behavior were disrupted in CPT2 knockdown zebrafish. RT-qPCR analyses showed significant increases in the expression of schizophrenia-associated genes in CPT2 knockdown compared to control zebrafish. Taken together, these data demonstrate that zebrafish are a useful model for studying the importance of beta-oxidation for early vertebrate development and brain function. This study also presents novel findings linking CPT2 deficiency to the regulation of schizophrenia and neurodegenerative disease-associated genes.

Cardiac manifestations in inherited metabolic diseases

Inherited metabolic diseases (IMD) are caused by the functional defect of an enzyme, of genetic origin, that provokes a blockage in a specific metabolic pathway. Individually, IMD are considered rare diseases, with an incidence of less than 1/100,000 births. The symptoms are usually multisystemic, but frequently include cardiac manifestations. Of these, the most common are cardiomyopathies, especially hypertrophic cardiomyopathy. In addition, they can cause dilated or restrictive cardiomyopathy and non-compacted cardiomyopathy of the left ventricle. Characteristic signs also include rhythm alterations (atrio-ventricular conduction disturbances, Wolff-Parkinson-White syndrome or ventricular arrhythmias), valvular pathology and ischaemic coronary pathologies. The aim of this study is to present a narrative review of the IMD that may produce cardiac involvement. We describe both the specific cardiac manifestations of each disease and the systemic symptoms that guide diagnosis.

Neural and metabolic dysregulation in PMM2-deficient human in vitro neural models

Phosphomannomutase 2-congenital disorder of glycosylation (PMM2-CDG) is a rare inborn error of metabolism caused by deficiency of the PMM2 enzyme, which leads to impaired protein glycosylation. While the disorder presents with primarily neurological symptoms, there is limited knowledge about the specific brain-related changes caused by PMM2 deficiency. Here, we demonstrate aberrant neural activity in 2D neuronal networks from PMM2-CDG individuals. Utilizing multi-omics datasets from 3D human cortical organoids (hCOs) derived from PMM2-CDG individuals, we identify widespread decreases in protein glycosylation, highlighting impaired glycosylation as a key pathological feature of PMM2-CDG, as well as impaired mitochondrial structure and abnormal glucose metabolism in PMM2-deficient hCOs, indicating disturbances in energy metabolism. Correlation between PMM2 enzymatic activity in hCOs and symptom severity suggests that the level of PMM2 enzyme function directly influences neurological manifestations. These findings enhance our understanding of specific brain-related perturbations associated with PMM2-CDG, offering insights into the underlying mechanisms and potential directions for therapeutic interventions.

The significance of machine learning in neonatal screening for inherited metabolic diseases

Background

Neonatal screening for inherited metabolic diseases (IMDs) has been revolutionized by tandem mass spectrometry (MS/MS). This study aimed to enhance neonatal screening for IMDs using machine learning (ML) techniques.

Methods

The study involved the analysis of a comprehensive dataset comprising 309,102 neonatal screening records collected in the Ningbo region, China. An advanced ML system model, encompassing nine distinct algorithms, was employed for the purpose of predicting the presence of 31 different IMDs. The model was compared with traditional cutoff schemes to assess its diagnostic efficacy. Additionally, 180 suspected positive cases underwent further evaluation.

Results

The ML system exhibited a significantly reduced positive rate, from 1.17% to 0.33%, compared to cutoff schemes in the initial screening, minimizing unnecessary recalls and associated stress. In suspected positive cases, the ML system identified 142 true positives with high sensitivity (93.42%) and improved specificity (78.57%) compared to the cutoff scheme. While false negatives emerged, particularly in heterozygous carriers, our study revealed the potential of the ML system to detect asymptomatic cases.

Conclusion

This research provides valuable insights into the potential of ML in pediatric medicine for IMD diagnosis through neonatal screening, emphasizing the need for accurate carrier detection and further research in this domain.

Splice-Modulating Antisense Oligonucleotides as Therapeutics for Inherited Metabolic Diseases

The last decade (2013-2023) has seen unprecedented successes in the clinical translation of therapeutic antisense oligonucleotides (ASOs). Eight such molecules have been granted marketing approval by the United States Food and Drug Administration (US FDA) during the decade, after the first ASO drug, fomivirsen, was approved much earlier, in 1998. Splice-modulating ASOs have also been developed for the therapy of inborn errors of metabolism (IEMs), due to their ability to redirect aberrant splicing caused by mutations, thus recovering the expression of normal transcripts, and correcting the deficiency of functional proteins. The feasibility of treating IEM patients with splice-switching ASOs has been supported by FDA permission (2018) of the first "N-of-1" study of milasen, an investigational ASO drug for Batten disease. Although for IEM, owing to the rarity of individual disease and/or pathogenic mutation, only a low number of patients may be treated by ASOs that specifically suppress the aberrant splicing pattern of mutant precursor mRNA (pre-mRNA), splice-switching ASOs represent superior individualized molecular therapeutics for IEM. In this work, we first summarize the ASO technology with respect to its mechanisms of action, chemical modifications of nucleotides, and rational design of modified oligonucleotides; following that, we precisely provide a review of the current understanding of developing splice-modulating ASO-based therapeutics for IEM. In the concluding section, we suggest potential ways to improve and/or optimize the development of ASOs targeting IEM.

Frameshift Variant in AMPD2 in Cirneco dell'Etna Dogs with Retinopathy and Tremors

While the manifestations of many inherited retinal disorders are limited to loss of vision, others are part of a syndrome that affects multiple tissues, particularly the nervous system. Most syndromic retinal disorders are thought to be recessively inherited. Two dogs out of a litter of Cirneco dell' Etna dogs, both males, showed signs of retinal degeneration, along with tremors and signs described as either atypical seizures or paroxysmal dyskinesias, while the other two male littermates were normal. We named this oculo-neurological syndrome CONS (Cirneco oculo-neurological syndrome), and undertook homozygosity mapping and whole-genome sequencing to determine its potential genetic etiology. Notably, we detected a 1-bp deletion in chromosome 6 that was predicted to cause a frameshift and premature stop codon within the canine AMPD2 gene, which encodes adenosine monophosphate deaminase, an enzyme that converts adenosine 5'-monophosphate (AMP) to inosine 5'-monophosphate (IMP). Genotyping of the available Cirneco population suggested perfect segregation between cases and controls for the variant. Moreover, this variant was absent in canine genomic databases comprised of thousands of unaffected dogs. The AMPD2 genetic variant we identified in dogs presents with retinal manifestations, adding to the spectrum of neurological manifestations associated with AMPD2 variants in humans.

Towards personalized genome-scale modeling of inborn errors of metabolism for systems medicine applications

Inborn errors of metabolism (IEMs) are a group of more than 1000 inherited diseases that are individually rare but have a cumulative global prevalence of 50 per 100,000 births. Recently, it has been recognized that like common diseases, patients with rare diseases can greatly vary in the manifestation and severity of symptoms. Here, we review omics-driven approaches that enable an integrated, holistic view of metabolic phenotypes in IEM patients. We focus on applications of Constraint-based Reconstruction and Analysis (COBRA), a widely used mechanistic systems biology approach, to model the effects of inherited diseases. Moreover, we review evidence that the gut microbiome is also altered in rare diseases. Finally, we outline an approach using personalized metabolic models of IEM patients for the prediction of biomarkers and tailored therapeutic or dietary interventions. Such applications could pave the way towards personalized medicine not just for common, but also for rare diseases.

First-in-human single-dose study of nizubaglustat, a dual inhibitor of ceramide glucosyltransferase and non-lysosomal glucosylceramidase: Safety, tolerability, pharmacokinetics, and pharmacodynamics of single ascending and multiple doses in healthy adults

Nizubaglustat is a novel, orally available, brain penetrant, potent, and selective dual inhibitor of ceramide glucosyltranferase and non-lysosomal neutral glucosylceramidase (NLGase), which is currently under development for the treatment of subjects with neurological manifestations in primary and secondary gangliosidoses. The objectives of this first-in-human study were to evaluate the safety and tolerability, pharmacokinetics, and pharmacodynamics (PD) of single oral doses of nizubaglustat after single (1, 3, and 9 mg) and multiple oral doses (9 mg once per day (QD) over 14 days) in healthy adults. Nizubaglustat was rapidly absorbed and systemic exposure was dose-proportional. Steady-state was achieved after three days of QD multiple dosing with minimal accumulation. Renal clearance accounted for around 15% of nizubaglustat elimination. Following multiple dosing, plasma concentrations of glucosylceramide (GlcCer), lactosylceramide (LacCer), and monosialodihexosylganglioside (GM3) decreased to a nadir at Day 10. PD target engagement of GCS inhibition was shown by a median decrease from baseline of plasma concentrations of GlcCer, LacCer, and GM3 ganglioside by 70%, 50%, and 48%, respectively. NLGase inhibition was also manifested by increased concentrations of GlcCer in cerebrospinal fluid from Day 1 to Day 14. Nizubaglustat was safe and well-tolerated at all doses tested. Consistent with the high selectivity, and the absence of intestinal disaccharidases inhibition, no cases of diarrhea were reported. No decreased appetite or weight loss was noted. Only treatment-emergent adverse events with preferred terms belonging to the system organ class skin and subcutaneous disorders of mild intensity were reported as drug-related in the nizubaglustat arm, in line with the pharmacological mechanism targeting glucosylceramide metabolism. Taken together, these data support QD dosing of nizubaglustat and its ongoing development in patients with primary and secondary forms of gangliosidoses.

Early Energy Intake and Amino Acid Profile in Preterm Newborns: A Quasi-Experimental Study

(1) Background: An increased protein intake via parenteral nutrition (PN) in early life is associated with an improvement of the nitrogen balance in preterm newborns. However, the role of energy intake on amino acid (AA) utilization provided by PN remains to be defined. We investigated the effects of energy intake on blood AA levels and profiles. (2) Methods: Quasi-experimental study including preterm very low birth weight newborns who received an energy enhanced PN (Cohort A) or an energy standard PN (Cohort B), with a similar protein amount in the first week of life. Blood AA levels were measured between three and seven days of life (T0) and at fifteen days of life (T1) and compared between the two study cohorts. (3) Results: AA levels of 40 newborns from each group were analyzed. No difference was found for total essential and non-essential blood AA concentration at T0 between the two study cohorts. At T1, we found a significantly higher blood concentration of leucine, isoleucine and proline, and a significantly lower concentration of tyrosine in Cohort B. However, multivariate analysis did not confirm this result. (4) Conclusions: An enhanced PN protocol in terms of energy but not of protein did not influence AA levels and profiles. Considering the high risk of side effects, we suggest exercising caution when administering high energy intake via PN in the first week of life.

Recent Advances in Phenylketonuria: A Review

This article highlights the significance of inborn errors of metabolism and focuses specifically on phenylketonuria (PKU), a well-known inheritance disorder caused by the deficiency or absence of phenylalanine hydroxylase (PAH). This review discusses associated mutations in the PAH gene and their impact on phenylalanine metabolism. A total of 40 articles were analyzed between 2019 and 2023, covering diagnostic innovations, advancements in treatment and management strategies, and the long-term implications of PKU. This study emphasizes the importance of early diagnosis and highlights the ongoing need for advancements in screening methods and treatment approaches to optimize patient outcomes in PKU patients. This review provides valuable insights for healthcare professionals involved in the care of children with PKU and contributes to the enhancement of clinical practice in this field.

Metabolic Cardiomyopathies and Cardiac Defects in Inherited Disorders of Carbohydrate Metabolism: A Systematic Review

Heart failure (HF) is a progressive chronic disease that remains a primary cause of death worldwide, affecting over 64 million patients. HF can be caused by cardiomyopathies and congenital cardiac defects with monogenic etiology. The number of genes and monogenic disorders linked to development of cardiac defects is constantly growing and includes inherited metabolic disorders (IMDs). Several IMDs affecting various metabolic pathways have been reported presenting cardiomyopathies and cardiac defects. Considering the pivotal role of sugar metabolism in cardiac tissue, including energy production, nucleic acid synthesis and glycosylation, it is not surprising that an increasing number of IMDs linked to carbohydrate metabolism are described with cardiac manifestations. In this systematic review, we offer a comprehensive overview of IMDs linked to carbohydrate metabolism presenting that present with cardiomyopathies, arrhythmogenic disorders and/or structural cardiac defects. We identified 58 IMDs presenting with cardiac complications: 3 defects of sugar/sugar-linked transporters (GLUT3, GLUT10, THTR1); 2 disorders of the pentose phosphate pathway (G6PDH, TALDO); 9 diseases of glycogen metabolism (GAA, GBE1, GDE, GYG1, GYS1, LAMP2, RBCK1, PRKAG2, G6PT1); 29 congenital disorders of glycosylation (ALG3, ALG6, ALG9, ALG12, ATP6V1A, ATP6V1E1, B3GALTL, B3GAT3, COG1, COG7, DOLK, DPM3, FKRP, FKTN, GMPPB, MPDU1, NPL, PGM1, PIGA, PIGL, PIGN, PIGO, PIGT, PIGV, PMM2, POMT1, POMT2, SRD5A3, XYLT2); 15 carbohydrate-linked lysosomal storage diseases (CTSA, GBA1, GLA, GLB1, HEXB, IDUA, IDS, SGSH, NAGLU, HGSNAT, GNS, GALNS, ARSB, GUSB, ARSK). With this systematic review we aim to raise awareness about the cardiac presentations in carbohydrate-linked IMDs and draw attention to carbohydrate-linked pathogenic mechanisms that may underlie cardiac complications.

Drosophila as a diet discovery tool for treating amino acid disorders

Amino acid disorders (AADs) are a large group of rare inherited conditions that collectively impact one in 6500 live births, often resulting in rapid neurological decline and death during infancy. For several AADs, including phenylketonuria, dietary modification prevents physiological deterioration and ameliorates symptoms. Despite this remarkable potential for treatment success, dietary therapy for most AADs remains largely unexplored. Although animal models have provided novel insights into AAD mechanisms, few have been used for therapeutic diet discovery. Here, we find that of all the animal models, Drosophila is particularly well suited for nutrigenomic disease modelling, having amino acid pathways conserved with humans, exceptional genetic tractability, and the unique availability of a synthetic customisable diet.

The landscape of CRISPR/Cas9 for inborn errors of metabolism

Since its discovery as a genome editing tool, the clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9 (CRISPR/Cas9) system has opened new horizons in the diagnosis, research, and treatment of genetic diseases. CRISPR/Cas9 can rewrite the genome at any region with outstanding precision to modify it and further instructions for gene expression. Inborn Errors of Metabolism (IEM) are a group of more than 1500 diseases produced by mutations in genes encoding for proteins that participate in metabolic pathways. IEM involves small molecules, energetic deficits, or complex molecules diseases, which may be susceptible to be treated with this novel tool. In recent years, potential therapeutic approaches have been attempted, and new models have been developed using CRISPR/Cas9. In this review, we summarize the most relevant findings in the scientific literature about the implementation of CRISPR/Cas9 in IEM and discuss the future use of CRISPR/Cas9 to modify epigenetic markers, which seem to play a critical role in the context of IEM. The current delivery strategies of CRISPR/Cas9 are also discussed.

A narrative review of metabolomics in the era of "-omics": integration into clinical practice for inborn errors of metabolism

BACKGROUND AND OBJECTIVE

Traditional targeted metabolomic investigations identify a pre-defined list of analytes in samples and have been widely used for decades in the diagnosis and monitoring of inborn errors of metabolism (IEMs). Recent technological advances have resulted in the development and maturation of untargeted metabolomics: a holistic, unbiased, analytical approach to detecting metabolic disturbances in human disease. We aim to provide a summary of untargeted metabolomics [focusing on tandem mass spectrometry (MS-MS)] and its application in the field of IEMs.

METHODS

Data for this review was identified through a literature search using PubMed, Google Scholar, and personal repositories of articles collected by the authors. Findings are presented within several sections describing the metabolome, the current use of targeted metabolomics in the diagnostic pathway of patients with IEMs, the more recent integration of untargeted metabolomics into clinical care, and the limitations of this newly employed analytical technique.

KEY CONTENT AND FINDINGS

Untargeted metabolomic investigations are increasingly utilized in screening for rare disorders, improving understanding of cellular and subcellular physiology, discovering novel biomarkers, monitoring therapy, and functionally validating genomic variants. Although the untargeted metabolomic approach has some limitations, this "next generation metabolic screening" platform is becoming increasingly affordable and accessible.

CONCLUSIONS

When used in conjunction with genomics and the other promising "-omic" technologies, untargeted metabolomics has the potential to revolutionize the diagnostics of IEMs (and other rare disorders), improving both clinical and health economic outcomes.

Echoes of William Gowers's concept of abiotrophy

Among William Gowers's many contributions to neurology, the concept of abiotrophy ("an essential failure of vitality") has been relatively overlooked. In this article, we review the echoes of Gowers's concept in neurology, ophthalmology, and aging research. We also argue that abiotrophy is broader than both heredodegeneration and neurodegeneration. Unlike the common view that it simply means premature aging, abiotrophy currently can be understood as a progressive degenerative process of a mature specialized tissue, which is nonsynchronous with normal aging and may affect organs or systems early in life, resulting from the age-dependent effects of genetic mutations or variants, even if environmental factors may also causally contribute to the process. Although the term has largely fallen out of use, there are likely to be everlasting echoes of Gowers's concept, through which he is to be considered a source of the modern thinking about the etiology and nosology of neurological diseases.

A preliminary investigation of amino acid and acylcarnitine levels in neonates from the Tibet autonomous

Background: The purpose of the study was to investigate the levels of amino acids and acylcarnitines in newborns of the Tibet Autonomous Region for the first time and to provide an experimental basis for the diagnosis of genetic metabolic diseases. Methods: We detected concentrations of 43 kinds of amino acids, acylcarnitines and succinylacetone in the dried blood spots of 18482 newborns using liquid chromatography tandem mass spectrometry and diagnose the case by gene sequencing. We compared the indexes between Tibet and our lab, where most data come from an inland area and Han Chinese people. Then we compared amino acid and acylcarnitine levels of seven regions in Tibet and explored their impact factors. Results: We described the levels of amino acids and acylcarnitines in Tibet newborns using 95% confidence intervals. The distribution of amino acid and acylcarnitines were different in Tibet. Conclusion: This study has contributed to filling in the blanks of Tibet newborn screening, which should be considered in the newborn metabolic disease screening in this area.

Utilizing augmented artificial intelligence for aminoacidopathies using collaborative laboratory integrated reporting- A cross-sectional study

Introduction

Plasma amino acids profiling can aid in the screening and diagnosis of aminoacidopathies. The goal of the current study was to analyze and report the metabolic profiles of plasma amino acid (PAA) and additionally to compare PAA-reference intervals (RI) from Pakistan with more countries utilizing Clinical Laboratory Integrated Reports (CLIR).

Methods

This was a cross sectional prospective single center study. Twenty-two amino acids were analyzed in each sample received for one year at the clinical laboratory. Data was divided into reference and case data files after interpretation by a team of pathologists and technologists. All PAA samples were analyzed using ion-exchange high-performance chromatography. The CLIR application of Amino Acid in Plasma (AAQP) was used for statistical analysis for both data sets and post-analytical interpretive tools using a single condition tool was applied.

Result

The majority of 92% (n = 1913) of PAA profiles out of the total 2081 tests run were non-diagnostic; the PAA values were within the age-specific RI. The PAA median was in close comparison close to the 50th percentile of reference data available in CLIR software. Out of the total 2081 tests run, one hundred and sixty-eight had abnormal PAA levels; 27.38% were labeled as non-fasting samples, and the main aminoacidopathies identified were Phenylketonuria and Maple Syrup Urine Disorder.

Conclusion

An agreement of >95% was observed between the reporting done by the pathologists and technologists’ team and then after the application of CLIR. Augmented artificial intelligence using CLIR can improve the accuracy of reporting rare aminoacidopathies in a developing country like ours.

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Plasma amino acids helps in diagnosing and monitoring of various aminoacidopathies.

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Few aminoacidopathies present with a grossly abnormal investigation profile, with few diseases having subtle deviations.

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Their is 98% concordance of diagnosis concordance of diagnosis of aminoacidopathies between our lab and CLIR.

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CLIR tools can be utilized in a newborn screening program for screening and diagnosis in future.

Toxic Metabolites and Inborn Errors of Amino Acid Metabolism: What One Informs about the Other

In inborn errors of metabolism, such as amino acid breakdown disorders, loss of function mutations in metabolic enzymes within the catabolism pathway lead to an accumulation of the catabolic intermediate that is the substrate of the mutated enzyme. In patients of such disorders, dietarily restricting the amino acid(s) to prevent the formation of these catabolic intermediates has a therapeutic or even entirely preventative effect. This demonstrates that the pathology is due to a toxic accumulation of enzyme substrates rather than the loss of downstream products. Here, we provide an overview of amino acid metabolic disorders from the perspective of the ‘toxic metabolites’ themselves, including their mechanism of toxicity and whether they are involved in the pathology of other disease contexts as well. In the research literature, there is often evidence that such metabolites play a contributing role in multiple other nonhereditary (and more common) disease conditions, and these studies can provide important mechanistic insights into understanding the metabolite-induced pathology of the inborn disorder. Furthermore, therapeutic strategies developed for the inborn disorder may be applicable to these nonhereditary disease conditions, as they involve the same toxic metabolite. We provide an in-depth illustration of this cross-informing concept in two metabolic disorders, methylmalonic acidemia and hyperammonemia, where the pathological metabolites methylmalonic acid and ammonia are implicated in other disease contexts, such as aging, neurodegeneration, and cancer, and thus there are opportunities to apply mechanistic or therapeutic insights from one disease context towards the other. Additionally, we expand our scope to other metabolic disorders, such as homocystinuria and nonketotic hyperglycinemia, to propose how these concepts can be applied broadly across different inborn errors of metabolism and various nonhereditary disease conditions.

An integrated multiomic approach as an excellent tool for the diagnosis of metabolic diseases: our first 3720 patients

To present our experience using a multiomic approach, which integrates genetic and biochemical testing as a first-line diagnostic tool for patients with inherited metabolic disorders (IMDs). A cohort of 3720 patients from 62 countries was tested using a panel including 206 genes with single nucleotide and copy number variant (SNV/CNV) detection, followed by semi-automatic variant filtering and reflex biochemical testing (25 assays). In 1389 patients (37%), a genetic diagnosis was achieved. Within this cohort, the highest diagnostic yield was obtained for patients from Asia (57.5%, mainly from Pakistan). Overall, 701 pathogenic/likely pathogenic unique SNVs and 40 CNVs were identified. In 620 patients, the result of the biochemical tests guided variant classification and reporting. Top five diagnosed diseases were: Gaucher disease, Niemann-Pick disease type A/B, phenylketonuria, mucopolysaccharidosis type I, and Wilson disease. We show that integrated genetic and biochemical testing facilitated the decision on clinical relevance of the variants and led to a high diagnostic yield (37%), which is comparable to exome/genome sequencing. More importantly, up to 43% of these patients (n = 610) could benefit from medical treatments (e.g., enzyme replacement therapy). This multiomic approach constitutes a unique and highly effective tool for the genetic diagnosis of IMDs.

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.

Malformations of cerebral development and clues from the peripheral nervous system: A systematic literature review

Clinical manifestations of malformations of cortical development (MCD) are variable and can range from mild to severe intellectual disability, cerebral palsy and drug-resistant epilepsy. Besides common clinical features, non-specific or more subtle clinical symptoms may be present in association with different types of MCD. Especially in severely affected individuals, subtle but specific underlying clinical symptoms can be overlooked or overshadowed by the global clinical presentation. To facilitate the interpretation of genetic variants detailed clinical information is indispensable. Detailed (neurological) examination can be helpful in assisting with the diagnostic trajectory, both when referring for genetic work-up as well as when interpreting data from molecular genetic testing. This systematic literature review focusses on different clues derived from the neurological examination and potential further work-up triggered by these signs and symptoms in genetically defined MCDs. A concise overview of specific neurological findings and their associations with MCD subtype and genotype are presented, easily applicable in daily clinical practice. The following pathologies will be discussed: neuropathy, myopathy, muscular dystrophies and spastic paraplegia. In the discussion section, tips and pitfalls are illustrated to improve clinical outcome in the future.

Spectrum Analysis of Inherited Metabolic Disorders for Expanded Newborn Screening in a Central Chinese Population

Neonatal inherited metabolic disorders (IMDs) are closely associated with early neonatal death and abnormal growth and development. Increasing attention has been paid to IMDs because of their high incidence and diversity. However, there are no reports about the incidence of IMDs in Changsha, China. Therefore, we retrospectively analyzed the screening results of neonates to evaluate the characteristics of IMDs in the area. From January 2016 to December 2020, 300,849 neonates were enrolled for expanded newborn screening by tandem mass spectrometry in the Neonatal Disease Screening Center of the Changsha Hospital for Maternal & Child Health Care. Newborns with mild initial results were recalled for repeated tests; if the second test was still positive, the patient was referred for confirmatory tests. A total of 71 confirmed cases were identified in our study, with an incidence rate of 1:4,237. There were 28 cases of amino acid metabolic disorders, representing 39.44% of the IMDs diagnosed, with an incidence rate of 1:10,745. Twelve newborns were diagnosed with organic acid metabolic disorders, accounting for 16.66% of IMDs, with an incidence rate of 1:25,071. There were 31 cases of fatty acid oxidation disorders, representing 43.05% of IMDs, with an incidence rate of 1:9,705. Overall, 14 types of IMDs were found in Changsha. The most common disorders in the region were primary carnitine deficiency, hyperphenylalaninemia and short-chain acyl-CoA dehydrogenase deficiency. Their incidence rate is respectively 1:13,675, 1:16,714 and 1:42,978. The mutations in PAH, SLC22A5, and ACADS are the leading causes of IMDs in this area. This study demonstrates the importance of utilizing MS/MS in IMD screening for early diagnosis and treatment. This strategy may be used for prenatal genetic counseling to avoid irreversible growth and intellectual development disorders in children.

Inborn Errors of Metabolism Screening in Neonates: Current Perspective with Diagnosis and Therapy

Inborn errors of metabolism (IEMs) are rare hereditary or acquired disorders resulting from an enzymatic deformity in biochemical and metabolic pathways influencing proteins, fats, carbohydrate metabolism, or hampered some organelle function. Even though individual IEMs are uncommon, together, they represent a diverse class of genetic diseases, with new issues and disease mechanisms being portrayed consistently. IEM includes the extraordinary multifaceted nature of the fundamental pathophysiology, biochemical diagnosis, molecular level investigation, and complex therapeutic choices. However, due to the molecular, biochemical, and clinical heterogeneity of IEM, screening alone will not detect and diagnose all illnesses included in newborn screening programs. Early diagnosis prevents the emergence of severe clinical symptoms in the majority of IEM cases, lowering morbidity and death. The appearance of IEM disease can vary from neonates to adult people, with the more serious conditions showing up in juvenile stages along with significant morbidity as well as mortality. Advances in understanding the physiological, biochemical, and molecular etiologies of numerous IEMs by means of modalities, for instance, the latest molecular-genetic technologies, genome engineering knowledge, entire exome sequencing, and metabolomics, have prompted remarkable advancement in detection and treatment in modern times. In this review, we analyze the biochemical basis of IEMs, clinical manifestations, the present status of screening, ongoing advances, and efficiency of diagnosis in treatment for IEMs, along with prospects for further exploration as well as innovation.

Complementary Feeding and Growth in Infants Born Preterm: A 12 Months Follow-Up Study

Evidences demonstrated that timing of weaning influences long-term growth in full term infants. However, studies on preterm infants are still lacking, and the international guidelines are focused only on healthy full-term newborn, without consensus for preterms. We aimed at evaluating, in a cohort study, the consequences of different timing of weaning on auxological outcomes up to 12 months of corrected age in a population of neonates born with gestational age < 32 weeks or birth weight < 1500 g. We divided the enrolled neonates in two cohorts according to the timing of weaning: (i) Early Weaning: introduction of complementary food before 6 months of corrected age; (ii) Late Weaning: complementary food introduced after 6 months of corrected age. Growth parameters (weight, length, body mass index, and ponderal index) were measured at 12 months of life. The two groups were statistically comparable for baseline clinical characteristics, and differences on growth parameters were not reported between the two study groups. These results were confirmed in linear and binary logistic regression multivariate models. Timing of weaning is not related to growth of preterm newborns in the first 12 months of corrected age. Studies are needed to reach consensus for the appropriate nutritional approach for preterm babies after discharge.

Early Enteral Feeding Improves Tolerance of Parenteral Nutrition in Preterm Newborns

(1) Background: The tolerance of preterm newborns for the high nutritional intakes given by parenteral nutrition (PN) is still debated because of the risk of metabolic complications. Despite enteral nutrition (EN) being the preferred route of nutrition, an exclusive enteral feeding is not always possible, as in preterm newborns, the gut is immature and less tolerant of EN. We aimed to study the impact of a minimal enteral feeding (MEF) on the possible early metabolic complications of PN in a cohort of preterms with gestational age at birth GA ≤ 29 + 6/7 weeks of postmenstrual age. (2) Methods: We divided the study sample in two cohorts: 1) Late-Feeding (cohort 1), newborns who received MEF starting from the 8th day of age, and (2) Early-Feeding (cohort 2), newborns who received MEF, consisting of the administration of at least 4–5 mL/kg/day by the enteral route, in the first 7 days of age. The primary outcome of the study was the rate of at least one metabolic complication, including hyperglycemia, hypertriglyceridemia, or metabolic acidosis. (3) Results: We enrolled 80 newborns (Late-Feeding cohort 51 vs. Early-Feeding cohort 29). The rate of all metabolic complications was statistically higher in the Late-Feeding cohort compared to the Early-Feeding cohort. Binary logistic regression analysis showed that late administration of MEF negatively influenced the rate of all metabolic complications. (4) Conclusions: Early minimal administration of EN is associated with less frequent PN-related metabolic side effects and a higher rate of survival in critically ill newborns.

Atopic Manifestations in Children Born Preterm: A Long-Term Observational Study

(1) Background: Preterm birth exposes the infant to the known risk factors for atopic diseases. We aimed to study the neonatal risk factors and to describe the clinical manifestations of atopy, including the march of symptoms, in a cohort of preschool children born preterm. (2) Methods: We enrolled neonates with gestational age < 32 weeks or birth weight < 1500 g. We classified patients in cases and controls according to the presence of at least one atopic manifestation. (3) Results: We observed 72 cases and 93 controls. Multivariate models showed that the administration of more than one cycle of antibiotics (B 0.902, p = 0.026) and gestational diabetes (B 1.207, p = 0.035) influence the risk of atopy in babies born preterm. In addition, risk of atopic dermatitis was influenced by gestational age < 29 weeks (B -1.710, p = 0.025) and gestational diabetes (B 1.275, p = 0.027). The risk of wheeze was associated with familiarity for asthma (B 1.392, p = 0.022) and the administration of more than one cycle of antibiotics (B 0.969, p = 0.025). We observed a significant reduction in the rate of atopic manifestation after 2 years of life (33.9% vs. 23.8%, p < 0.05). (4) Conclusions: Modifiable (gestational diabetes, antibiotics use) and unmodifiable (familiarity for asthma) conditions influence the risk of atopy in babies born preterm. Extreme prematurity reduces the risk of atopic dermatitis. Preterm babies showed a peculiar atopic march.

Ataluren-Promising Therapeutic Premature Termination Codon Readthrough Frontrunner

Around 12% of hereditary disease-causing mutations are in-frame nonsense mutations. The expression of genes containing nonsense mutations potentially leads to the production of truncated proteins with residual or virtually no function. However, the translation of transcripts containing premature stop codons resulting in full-length protein expression can be achieved using readthrough agents. Among them, only ataluren was approved in several countries to treat nonsense mutation Duchenne muscular dystrophy (DMD) patients. This review summarizes ataluren’s journey from its identification, via first in vitro activity experiments, to clinical trials in DMD, cystic fibrosis, and aniridia. Additionally, data on its pharmacokinetics and mechanism of action are presented. The range of diseases with underlying nonsense mutations is described for which ataluren therapy seems to be promising. What is more, experiments in which ataluren did not show its readthrough activity are also included, and reasons for their failures are discussed.

Orthopaedic Manifestations of Inborn Errors of Metabolism

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Inborn errors of metabolism are disorders of carbohydrate, amino acid, organic acid, or purine and pyrimidine metabolism; disorders of fatty acid oxidation; disorders of metal metabolism; and lysosomal storage defects that can cause metabolic derangements that have secondary musculoskeletal effects.

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Orthopaedic surgeons should be aware that patients with inborn errors of metabolism may be at high risk for spasticity, which may cause joint subluxations, scoliosis, and contractures, as well as poor bone quality, which is caused by malnutrition or disordered bone growth.

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Multidisciplinary care and follow-up are important to identify musculoskeletal problems in a timely manner in order to provide effective treatment.

Lethal hyperammonemia in a CAR-T cell recipient due to Ureaplasma pneumonia: a case report of a unique severe complication

We report the first incidence of Ureaplasma infection causing lethal hyperammonemia in a chimeric receptor antigen T cell (CAR-T) recipient. A 53-year-old woman, after receiving CAR-T therapy, suffered sepsis and encephalopathy. She was found to have hyperammonemia up to 643 µmol/L. Imaging revealed lung consolidations and bronchoalveolar lavage PCR was positive for U. parvum. Workup excluded liver failure and metabolic abnormalities. Antibiotics, lactulose, dextrose, arginine, levocarnitine, sodium phenylbutyrate and dialysis were used. Despite these, the patient suffered persistent elevations in ammonia, status epilepticus and cerebral oedema. Early recognition of this rare infection in susceptible populations is needed. CAR-T patients are at risk due to their immunocompromised state and may have amplified harm due to the impact of CAR-T therapy on astrocytes. An early aggressive multimodality approach is needed given the high mortality rates. These include antimicrobials, possibly with double coverage for Ureaplasma. Additionally, concurrent ammonia-suppressing and ammonia-eliminating treatments are necessary.

Neonatal Hyperglycemia Related to Parenteral Nutrition Affects Long-Term Neurodevelopment in Preterm Newborn: A Prospective Cohort Study

(1) Background: Recent evidence reported a reduced tolerance of macronutrient parenteral intakes in subjects in critically ill conditions. We designed a prospective cohort study to evaluate the effects of hyperglycemia (HG) related to parenteral nutrition (PN) on neurodevelopment (NDV) in survived preterm newborns. (2) Methods: Enrolled newborns with gestational age < 32 weeks or birth weight < 1500 g, were divided in two cohorts: (A) exposed to moderate or severe HG (glucose blood level > 180 mg/dL) in the first week of life; (B) not exposed to HG. We considered as the primary outcome the rate of preterm newborns survived without NDV delay at 24 months of life, evaluated with Bayley Scales of Infants Development III edition. (3) Results: We analyzed 108 (A 32 vs. B 76) at 24 months of life. Newborns in cohort A showed a higher rate of cognitive and motor delay (A 44% vs. B 22 %, p = 0.024; A 38% vs. B 8%, p < 0.001). When adjusting for background characteristics, HG remained a risk factor for motor delay. (4) Conclusions: High nutritional intakes through PN soon after birth increase the risk of HG. The consequences of this severe metabolic complication affect long-term NDV and survival in preterm newborns.

Use of nuclear magnetic resonance spectroscopy in diagnosis of inborn errors of metabolism

Nuclear Magnetic Resonance (NMR) spectroscopy has been applied in many fields of science and is increasingly being considered as a tool in the clinical setting. This review examines its application for diagnosis of inborn errors of metabolism (IEMs). IEMs, whether involving deficiency in the synthesis and degradation of metabolites, or in lipoprotein metabolism, affect nearly 3% of the global population. NMR is a preferred method for comprehensive evaluation of complex biofluids such as blood or urine, as it can provide a relatively unbiased overview of all compounds that are present and does not destroy or otherwise chemically alter the sample. While current newborn screening programs take advantage of other more sensitive methods, such as mass spectrometry, NMR has advantages especially for urine analysis with respect to ease of sample preparation and the reproducibility of results. NMR spectroscopy is particularly compatible with analysis of lipoproteins because it provides information about their size and density, not easily attained by other methods, that can help the clinician to better manage patients with dyslipidemia. We believe that NMR holds great potential for expanding clinical diagnosis in the future, in the field of IEMs and beyond.

Intravenous Lipid Emulsions Affect Respiratory Outcome in Preterm Newborn: A Case-Control Study

(1) Background: Hypertriglyceridemia (HiTG) is a metabolic complication of intravenous lipid emulsions (ILEs) infusion. We aimed to evaluate the influence of HiTG on the respiratory outcome of preterm babies; (2) Methods: We enrolled, in a case-control study, newborns with gestational age <32 weeks or birth weight <1500 g, over a 3-year period. They were divided into cases and controls; cases were defined by the detection of HiTG defined as serum triglycerides (TG) value >150 mg/dL; (3) Results: We enrolled 40 cases and 105 controls. Cases had an increased incidence of bronchopulmonary dysplasia (30.0% vs. 14.3%, p < 0.05) and longer duration of invasive mechanical ventilation (7 days, 95% CI 4-10 days vs. 4 days, 95% CI 1-7 days, p < 0.01) compared to controls. Multivariate analysis confirmed that HiTG independently influenced the duration of invasive mechanical ventilation, also in the subgroups with gestational age ≤28 + 6/7 weeks or birth weight ≤1000 g; (4) Conclusion: Newborns with HiTG related to ILEs had a longer duration of invasive mechanical ventilation. Temporary suspension or reduction in ILEs in the case of HiTG is associated with an improvement of respiratory outcome.

Inherited Neuromuscular Disorders: Which Role for Serum Biomarkers?

Inherited neuromuscular disorders (INMD) are a heterogeneous group of rare diseases that involve muscles, motor neurons, peripheral nerves or the neuromuscular junction. Several different lab abnormalities have been linked to INMD: sometimes they are typical of the disorder, but they usually appear to be less specific. Sometimes serum biomarkers can point out abnormalities in presymtomatic or otherwise asymptomatic patients (e.g., carriers). More often a biomarker of INMD is evaluated by multiple clinicians other than expert in NMD before the diagnosis, because of the multisystemic involvement in INMD. The authors performed a literature search on biomarkers in inherited neuromuscular disorders to provide a practical approach to the diagnosis and the correct management of INMD. A considerable number of biomarkers have been reported that support the diagnosis of INMD, but the role of an expert clinician is crucial. Hence, the complete knowledge of such abnormalities can accelerate the diagnostic workup supporting the referral to specialists in neuromuscular disorders.

Energy-enhanced parenteral nutrition and neurodevelopment of preterm newborns: A cohort study

OBJECTIVES

Preterm births are at higher risk for neurodevelopment (NDV) disabilities. To limit long-term consequences, guidelines recommend aggressive parenteral nutrition (PN) soon after birth. The aim of this study was to examine the effects of energy-enhanced PN in the first week of life on long-term NDV in preterm neonates.

METHODS

We compared two cohorts of newborns (group A: energy-enhanced PN and group B: energy-standard PN) with different energy intake in the first 7 d of life (DoL) given by PN with the same protein amount, to study the influences of an energy-enhanced PN on NDV at 24 mo of life evaluated with the Bayley Scale of Infant Development-III edition.

RESULTS

We analyzed 51 newborns (A: n = 24 versus B: n = 27). The two cohorts were similar in baseline characteristics (gestational age group A 29 wk, 95% confidence interval [CI], 28-30 wk versus group B 29 wk, 95% CI, 28-30 wk; birth weight A: 1214 g, 95% CI, 1062-1365 g versus B 1215 g, 95% CI, 1068-1363 g; boys A 62.5% versus B 55.6%). Infants in cohort B showed significantly (P < 0.05) better gross motor, total scaled, and total composite motor scores (A: 8 (1) versus B 9 (2); A 17 (4) versus B 19 (5); A 91 (12) versus B 97 (15); respectively). Cohort A showed a higher percentage of infants with delayed socioemotional competence (A 30.4% versus B 7.7%, P < 0.05). No differences were found in growth parameters at 24 mo of life. Linear regression analysis showed that socioemotional competence and motor score were negatively associated with energy intake of the first 7 DoL given by PN.

CONCLUSIONS

A more aggressive PN strategy results in lower motor score and socioemotional competence performance at 24 mo of life. More caution might be advocated for an energy-enhanced PN protocol, particularly in neonates with lower birth weight, for long-term NDV in preterm neonates.

Molecular and biochemical investigations of inborn errors of metabolism-altered redox homeostasis in branched-chain amino acid disorders, organic acidurias, and homocystinuria

India, resembling other developing nations, is confronting a hastening demographic switch to non-communicable diseases. Inborn errors of metabolism (IEM) constitute a varied heterogeneous group of disorders with variable clinical appearance, primarily in the pediatric populace. Congenital deformities and genetic disorders are significant for mortality throughout the world, and the Indian scenario is not very different. IEMs are a group of monogenic issues described by dysregulation of the metabolic networks that bring about development and homeostasis. Incipient evidence focuses on oxidative stress and mitochondrial dysfunction as significant contributors to the multiorgan modifications are detected in a few IEMs. The amassing of toxic metabolites in organic acidurias, respiratory chain, and fatty acid oxidation ailments inhibit mitochondrial enzymes and processes, bringing about elevated levels of reactive oxygen species (ROS). In different IEMs, as in homocystinuria, various sources of ROS have been suggested. In patients' samples along with cellular and experimental animal models, a few investigations have recognized substantial increments in ROS levels alongside diminishes in antioxidant defenses, relating with oxidative damage to proteins, lipids as well as DNA. Elevated ROS levels interrupt redox signaling pathways controlling biological processes such as cell development, differentiation, or apoptosis; however, few investigations explore these processes in IEMs. This review depicts the mitochondrial dysfunction, oxidative stress, redox signaling in branched-chain amino acid disorders, further organic acidurias, and homocystinuria, alongside the latest research investigating the proficiency of antioxidants in addition to mitochondria-targeted therapies as therapeutic components in these diseases.

Morbidity associated with patent ductus arteriosus in preterm newborns: a retrospective case-control study

INTRODUCTION

Association between persistency of a patent ductus arteriosus (PDA) and morbidity in preterm newborns is still controversial. We aimed to investigate the relation between PDA and morbidity in a large retrospective study.

METHODS

A case-control study including neonates consecutively admitted to the Neonatal Intensive Care Unit (NICU), with gestational age (GA) < 32 weeks or body birth weight (BW) < 1500 g, over a 5-year period. Newborns were divided into Cases and Controls, according with the presence or absence of a hemodynamically significant PDA (hs-PDA).

RESULTS

We enrolled 85 Cases and 193 Controls. Subjects with hs-PDA had significantly (p < 0.001) lower GA (26.7 w, 95%CI 27.1-28.0 vs. 30.1 w, 95%CI 29.7-30.4), BW (1024 g, 95% CI 952-1097 vs. 1310 g 95%CI 1263-1358) and an increased morbidity (60.0% vs. 18.7%). In a sub-group of extremely preterm newborns (GA ≤ 28 weeks and BW ≤ 1000 g), the rate of bronchopulmonary dysplasia (BPD) was significantly increased in Cases (31.7%) compared with Controls (5.9%, p = 0.033). Multivariate analysis showed that morbidity significantly depended on hs-PDA, GA and BW, and that, in extremely preterms, the hs-PDA represented an independent risk factor for BPD.

CONCLUSIONS

Occurrence of the main morbidities of prematurity depended by hs-PDA, in association with GA, BW, and use of prenatal steroids. In extremely premature babies, hs-PDA is a risk factor for BPD, one of the most important morbidity of prematurity, independently by other confounding variables.

Ethnic preference distribution of inborn errors of metabolism: A 4-year study in a multi-ethnic region of China

Chinese newborns have been screened for inborn errors of metabolism (IEM) for over 20 years. Although China features 56 different ethnic groups, there are no specific data describing the incidence of such genetic errors across difference ethnicities. To understand the ethnic preference distribution of the incidence and variants of IEM in the Ningxia Hui Autonomous Region of China, 189,354 newborns from 2016 to 2019 were screened by tandem mass spectrometry, including 87,482 from the Han ethnic population, 88,229 from the Hui population, 1,103 from other ethnicities, and 12,540 infants without ethnic registration. Suspected cases then underwent specific genetic profiling by targeted next generation sequencing. In total, 160 patients were diagnosed with 17 types of IEM, with a significant higher incidence in Hui infants (1/1,003) than in Han infants (1/1,232). Five diseases (eight patients) were specifically detected in Han infants, while three were exclusively diagnosed in six Hui infants. For shared diseases, the variants of keys genes also showed ethnic preference. Our findings enhance our understanding of the genetics underlying IEM, thus promoting the development of treatment plans for patients from different areas or ethnicities in China.

Syndromic Inherited Retinal Diseases: Genetic, Clinical and Diagnostic Aspects

Inherited retinal diseases (IRDs), which are among the most common genetic diseases in humans, define a clinically and genetically heterogeneous group of disorders. Over 80 forms of syndromic IRDs have been described. Approximately 200 genes are associated with these syndromes. The majority of syndromic IRDs are recessively inherited and rare. Many, although not all, syndromic IRDs can be classified into one of two major disease groups: inborn errors of metabolism and ciliopathies. Besides the retina, the systems and organs most commonly involved in syndromic IRDs are the central nervous system, ophthalmic extra-retinal tissues, ear, skeleton, kidney and the cardiovascular system. Due to the high degree of phenotypic variability and phenotypic overlap found in syndromic IRDs, correct diagnosis based on phenotypic features alone may be challenging and sometimes misleading. Therefore, genetic testing has become the benchmark for the diagnosis and management of patients with these conditions, as it complements the clinical findings and facilitates an accurate clinical diagnosis and treatment.

Metabolomics to Improve the Diagnostic Efficiency of Inborn Errors of Metabolism

Early diagnosis of inborn errors of metabolism (IEM)—a large group of congenital disorders—is critical, given that many respond well to targeted therapy. Newborn screening programs successfully capture a proportion of patients enabling early recognition and prompt initiation of therapy. For others, the heterogeneity in clinical presentation often confuses diagnosis with more common conditions. In the absence of family history and following clinical suspicion, the laboratory diagnosis typically begins with broad screening tests to circumscribe specialised metabolite and/or enzyme assays to identify the specific IEM. Confirmation of the biochemical diagnosis is usually achieved by identifying pathogenic genetic variants that will also enable cascade testing for family members. Unsurprisingly, this diagnostic trajectory is too often a protracted and lengthy process resulting in delays in diagnosis and, importantly, therapeutic intervention for these rare conditions is also postponed. Implementation of mass spectrometry technologies coupled with the expanding field of metabolomics is changing the landscape of diagnosing IEM as numerous metabolites, as well as enzymes, can now be measured collectively on a single mass spectrometry-based platform. As the biochemical consequences of impaired metabolism continue to be elucidated, the measurement of secondary metabolites common across groups of IEM will facilitate algorithms to further increase the efficiency of diagnosis.

Echocardiography-Guided Management of Preterms With Patent Ductus Arteriosus Influences the Outcome: A Cohort Study

Introduction: Echocardiography (ECHO) with color flow Doppler is considered as the gold standard to identify a hemodynamic patent ductus arteriosus (hs-PDA). However, the optimal diagnostic and therapeutic management for newborns with hs-PDA is still controversial. We aimed to investigate two clinical strategies: (1) targeted treatment based on ECHO criteria and (2) treatment based on ECHO criteria in addition to clinical signs and symptoms. Materials and Methods: This is a cohort study including all neonates consecutively admitted in the Neonatal Intensive Care Unit of University La Sapienza in Rome, with gestational age <32 weeks or body birth weight <1,500 g and with a diagnosis of hs-PDA as confirmed by ECHO evaluation performed within 72 h of life. We classified the babies in two cohorts: (A) pharmacological treatment immediately after ECHO screening and (B) pharmacological therapy for PDA was administered when the relevance of a hs-PDA was associated with clinical signs of hemodynamic instability. Results: We considered as primary outcome newborns who survived without any morbidities (A: 48.1% vs. B: 22.2%, p = 0.022). In particular, we found that the rate of intraventricular hemorrhage stage ≥2 was increased in cohort B (A: 3.7% vs. B 24.4%, p = 0.020). A multivariate analysis showed that assignment to cohort A independently influences the primary outcome. Conclusions: Adopting an hs-PDA management option based on ECHO-directed therapy regardless of symptoms may reduce the morbidity and improve the survival of very low birth weight infants.

Newborn screening and diagnosis of inborn errors of metabolism: A 5-year study in an eastern Chinese population

Inborn errors of metabolism (IEMs) can cause intellectual disability or even death in children. To evaluate the disease spectrum and genetic characteristics of IEMs in Jining City of Shandong Province in East China, we used tandem mass spectrometry (MS/MS) technology for IEMs screening combined with genetic analysis. Newborns were screened from July 14, 2014, to December 31, 2018. Amino acid and carnitine contents were detected by MS/MS. According to the results for normal newborns, the reference range of our laboratory was established with the percentile method. The suspected positive newborns were further diagnosed using next-generation sequencing. A total of 514,234 newborns were screened, and 265 were diagnosed with IEMs, with a detection rate of 1:1941. Of the 265 patients, 130 (49.06%) had organic acid disorders, 83 (31.32%) had amino acid disorders, 34 (12.83%) had fatty acid oxidation disorders, and 18 (6.79%) had urea circulatory disorders. PAHD and MMA were the two most common disorders. IEMs-associated genes were identified in 233 patients. Our data indicated that IEMs are never uncommon in Jining, and the disease spectrum and genetic background were clearly elucidated, contributing to the treatment and prenatal genetic counseling of these disorders in the region.