Molybdenum cofactor deficiency

A zebrafish gephyrinb mutant distinguishes synaptic and enzymatic functions of Gephyrin

Gephyrin is thought to play a critical role in clustering glycine receptors at synapses within the central nervous system (CNS). The main in vivo evidence for this comes from Gephyrin (Gphn)-null mice, where glycine receptors are depleted from synaptic regions. However, these mice die at birth, possibly due to impaired molybdenum cofactor (MoCo) synthesis, an essential role Gephyrin assumes throughout an animal. This complicates the interpretation of synaptic phenotypes in Gphn-null mice and raises the question whether the synaptic and enzymatic functions of Gephyrin can be investigated separately. Here, we generated a gephyrinb zebrafish mutant, vo84, that almost entirely lacks Gephyrin staining in the spinal cord. gephyrinbvo84 mutants exhibit normal gross morphology at both larval and adult stages. In contrast to Gphn-null mice, gephyrinbvo84 mutants exhibit normal motor activity and MoCo-dependent enzyme activity. Instead, gephyrinbvo84 mutants display impaired rheotaxis and increased mortality in late development. To investigate what may mediate these defects in gephyrinbvo84 mutants, we examined the cell density of neurons and myelin in the spinal cord and found no obvious changes. Surprisingly, in gephyrinbvo84 mutants, glycine receptors are still present in the synaptic regions. However, their abundance is reduced, potentially contributing to the observed defects. These findings challenge the notion that Gephyrin is absolutely required to cluster glycine receptors at synapses and reveals a new role of Gephyrin in regulating glycine receptor abundance and rheotaxis. They also establish a powerful new model for studying the mechanisms underlying synaptic, rather than enzymatic, functions of Gephyrin.

Identifying potential dietary treatments for inherited metabolic disorders using Drosophila nutrigenomics

Inherited metabolic disorders are a group of genetic conditions that can cause severe neurological impairment and child mortality. Uniquely, these disorders respond to dietary treatment; however, this option remains largely unexplored because of low disorder prevalence and the lack of a suitable paradigm for testing diets. Here, we screened 35 Drosophila amino acid disorder models for disease-diet interactions and found 26 with diet-altered development and/or survival. Using a targeted multi-nutrient array, we examine the interaction in a model of isolated sulfite oxidase deficiency, an infant-lethal disorder. We show that dietary cysteine depletion normalizes their metabolic profile and rescues development, neurophysiology, behavior, and lifelong fly survival, thus providing a basis for further study into the pathogenic mechanisms involved in this disorder. Our work highlights the diet-sensitive nature of metabolic disorders and establishes Drosophila as a valuable tool for nutrigenomic studies for informing potential dietary therapies.

A case report of molybdenum cofactor deficiency type A: the first case diagnosed in Syria

Introduction

Molybdenum cofactor deficiency (MoCD) type A, a rare mitochondrial disorder with characteristic clinical presentation and imaging findings, is one of the forms of molybdenum cofactor deficiency. It presents with seizures, psychomotor delay, and breastfeeding difficulties. Seizures are especially prominent in patients with MoCD.

Case presentation

A 3-month-old girl presented with refractory generalized tonic-clonic seizures since the third day of life. Her parents were third-degree relatives. On physical examination, she demonstrated psychomotor delay, breastfeeding difficulties, seizures, doll-like facial features, and other neurological abnormalities. Her brain MRI scan revealed cortical and white matter atrophy of the cerebral hemispheres. Metabolic workup revealed elevated levels of liver enzymes, lactic acid, and ammonia. These results were inconclusive. She received anticonvulsants and vitamin therapy to manage her seizures. Based on a suspicion of mitochondrial disease, genetic analysis was performed, revealing a homozygous variant of uncertain significance in the MOCS1 gene associated with autosomal recessive molybdenum cofactor deficiency type A.

Conclusion

MoCD is a rare disease. Early diagnosis should be considered based on the patient's medical history and MRI findings, after excluding other possible diagnoses. The definitive diagnosis relies on genetic testing results.

Treatable inherited metabolic epilepsies

Inherited metabolic epilepsies (IMEs) represent inherited metabolic disorders predominately presenting with seizures. While most IMEs are currently managed with symptomatic and supportive therapies, some are amenable to disorder-specific targeted treatments. In most cases, these treatments are effective only if given in a narrow time window early in the lives of affected patients. Hence, prompt recognition of treatable inherited metabolic epilepsies at an early age and as soon as symptoms appear has paramount importance. Herein, we provide an overview of inherited metabolic epilepsies, which presently have established targeted treatments showing clinical efficacy in reducing seizure burden and improving neurodevelopmental outcomes. These therapeutic modalities range from specific diets, vitamins, and supplementation of organic compounds to synthetic pharmacological agents and novel genetic-based therapies that alter the biochemical pathways of these disorders at the cellular or molecular level, steering them to their normal function.

A milder form of molybdenum cofactor deficiency type A presenting as Leigh's syndrome-like phenotype highlighting the secondary mitochondrial dysfunction: a case report

Background

Molybdenum cofactor deficiency (MoCD) (OMIM# 252150) is an autosomal-recessive disorder caused by mutations in four genes involved in the molybdenum cofactor (MOCO) biosynthesis pathway.

Objectives

We report a milder phenotype in a patient with MOCS1 gene mutation who presented with a Leigh-like presentation.

Case report

We present the case of a 10-year-old boy who was symptomatic at the age of 5 months with sudden onset of dyskinesia, nystagmus, and extrapyramidal signs following a febrile illness. Initial biochemical, radiological, and histopathological findings a Leigh syndrome-like phenotype; however, whole-exome sequencing detected compound heterozygous mutations in MOCS1 gene, c.1133 G>C and c.217C>T, confirming an underlying MoCD. This was biochemically supported by low uric acid level of 80 (110-282 mmol/L) and low cystine level of 0 (3-49), and a urine S-sulfocysteine at 116 (0-15) mmol/mol creatinine. The patient was administered methionine- and cystine-free formulas. The patient has remained stable, with residual intellectual, speech, and motor sequelae.

Conclusion

This presentation expands the phenotypic variability of late-onset MoCD A and highlights the role of secondary mitochondrial dysfunction in its pathogenesis.

Synthetic Approaches to the New Drugs Approved During 2021

Each year, new drugs are introduced to the market, representing structures that have affinity for biological targets implicated in human diseases and conditions. These new chemical entities (NCEs), particularly small molecules and antibody-drug conjugates, provide insight into molecular recognition and serve as potential leads for the design of future medicines. This annual review is part of a continuing series highlighting the most likely process-scale synthetic approaches to 35 NCEs that were first approved anywhere in the world during 2021.

Sulfite Impairs Bioenergetics and Redox Status in Neonatal Rat Brain: Insights into the Early Neuropathophysiology of Isolated Sulfite Oxidase and Molybdenum Cofactor Deficiencies

Isolated sulfite oxidase (ISOD) and molybdenum cofactor (MoCD) deficiencies are genetic diseases biochemically characterized by the toxic accumulation of sulfite in the tissues of patients, including the brain. Neurological dysfunction and brain abnormalities are commonly observed soon after birth, and some patients also have neuropathological alterations in the prenatal period (in utero). Thus, we investigated the effects of sulfite on redox and mitochondrial homeostasis, as well as signaling proteins in the cerebral cortex of rat pups. One-day-old Wistar rats received an intracerebroventricular administration of sulfite (0.5 µmol/g) or vehicle and were euthanized 30 min after injection. Sulfite administration decreased glutathione levels and glutathione S-transferase activity, and increased heme oxygenase-1 content in vivo in the cerebral cortex. Sulfite also reduced the activities of succinate dehydrogenase, creatine kinase, and respiratory chain complexes II and II-III. Furthermore, sulfite increased the cortical content of ERK1/2 and p38. These findings suggest that redox imbalance and bioenergetic impairment induced by sulfite in the brain are pathomechanisms that may contribute to the neuropathology of newborns with ISOD and MoCD. Sulfite disturbs antioxidant defenses, bioenergetics, and signaling pathways in the cerebral cortex of neonatal rats. CII: complex II; CII-III: complex II-III; CK: creatine kinase; GST: glutathione S-transferase; HO-1: heme oxygenase-1; SDH: succinate dehydrogenase; SO32-: sulfite.

A New Pattern of Brain and Cord Gadolinium Enhancement in Molybdenum Cofactor Deficiency: A Case Report

Molybdenum cofactor deficiency (MoCD) is a rare and severe autosomal recessive in-born error of metabolism caused by the mutation in MOCS1, MOCS2, MOCS3 or GEPH genes, with an incidence ranging between 1 in 100,000 and 200,000 live births. The clinical presentation with seizures, lethargy and neurologic deficits reflects the neurotoxicity mediated via sulphite accumulation, and it occurs within the first hours or days after birth, often leading to severe neurodegeneration and the patient's death within days or months. The Imaging of Choice is a brain-specific MRI technique, which is usually performed without contrast and shows typical radiological findings in the early phase, such as diffuse cerebral oedema and infarction affecting the cortex and the basal ganglia and the white matter, as well as in the late phase, such as multicystic encephalomalacia. Our case report represents a novelty in the field, since the patient underwent a contrast-enhanced MRI to exclude a concomitant infectious disease. In the frame of the clinical presentation and laboratory data, we describe the MoCD Imaging findings for MRI morphological and advanced sequences, presenting a new contrast-enhanced MRI pattern characterized by the diffuse and linear leptomeningeal enhancement of brain, cord and spinal roots. The early identification of molybdenum cofactor deficiency is crucial because it may lead to the best multidisciplinary therapy for the patient, which is focused on the prompt and optimal management of the complications.

Myelin Disruption, Neuroinflammation, and Oxidative Stress Induced by Sulfite in the Striatum of Rats Are Mitigated by the pan-PPAR agonist Bezafibrate

Sulfite predominantly accumulates in the brain of patients with isolated sulfite oxidase (ISOD) and molybdenum cofactor (MoCD) deficiencies. Patients present with severe neurological symptoms and basal ganglia alterations, the pathophysiology of which is not fully established. Therapies are ineffective. To elucidate the pathomechanisms of ISOD and MoCD, we investigated the effects of intrastriatal administration of sulfite on myelin structure, neuroinflammation, and oxidative stress in rat striatum. Sulfite administration decreased Fluoromyelin^TM and myelin basic protein staining, suggesting myelin abnormalities. Sulfite also increased the staining of NG2, a protein marker of oligodendrocyte progenitor cells. In line with this, sulfite also reduced the viability of MO3.13 cells, which express oligodendroglial markers. Furthermore, sulfite altered the expression of interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1), indicating neuroinflammation and redox homeostasis disturbances. Iba1 staining, another marker of neuroinflammation, was also increased by sulfite. These data suggest that myelin changes and neuroinflammation induced by sulfite contribute to the pathophysiology of ISOD and MoCD. Notably, post-treatment with bezafibrate (BEZ), a pan-PPAR agonist, mitigated alterations in myelin markers and Iba1 staining, and IL-1β, IL-6, iNOS and HO-1 expression in the striatum. MO3.13 cell viability decrease was further prevented. Moreover, pre-treatment with BEZ also attenuated some effects. These findings show the modulation of PPAR as a potential opportunity for therapeutic intervention in these disorders.

Epilepsy in sulfite oxidase deficiency and related disorders: insights from neuroimaging and genetics

Sulfite oxidase deficiency (SOD) and related disorders, especially molybdenum cofactor deficiency (MoCD), are a group of rare and severe neurometabolic disorders caused by gene mutations that affect the sulfur-containing amino acid catabolic pathway. These disorders are characterized by distinctive neuroimaging features such as diffuse cerebral atrophy, multicystic encephalomalacia, and ventriculomegaly in early infancy. These features are essential for early diagnosis and treatment. Moreover, the genetics of these disorders are complex but have been increasingly elucidated in the era of molecular medicine. Therefore, we reviewed 28 articles (published from January 1967 until October 2021) on SOD and MoCD, focusing on their neuroimaging and genetic aspects. We highlighted the differences between SOD and MoCD and other conditions that may mimic them, such as common neonatal hypoxic-ischemic encephalopathy and uncommon neonatal metabolic disorder (Leigh syndrome). We also summarized the current knowledge on the genetic mechanisms and the manifestation of seizure disorders of SOD and MoCD. In conclusion, if clinical, neuroimaging, and neuropathological findings suggest a possible SOD or related disorder; extensive molecular diagnostics should be performed to confirm the diagnosis.

Peroxisome proliferator-activated receptor (PPAR) agonists as a potential therapy for inherited metabolic disorders

Inherited metabolic disorders (IMDs) are genetic disorders that cause a disruption of a specific metabolic pathway leading to biochemical, clinical and pathophysiological sequelae. While the metabolite abnormalities in body fluids and tissues can usually be defined by directed or broad-spectrum metabolomic analysis, the pathophysiology of these changes is often not obvious. Mounting evidence has revealed that secondary mitochondrial dysfunction, mainly oxidative phosphorylation impairment and elevated reactive oxygen species, plays a pivotal role in many disorders. Peroxisomal proliferator-activated receptors (PPARs) consist of a group of nuclear hormone receptors (PPARα, PPARβ/δ, and PPARγ) that regulate multiple cellular functions and processes, including response to oxidative stress, inflammation, lipid metabolism, and mitochondrial bioenergetics and biogenesis. In this context, the activation of PPARs has been shown to stimulate oxidative phosphorylation and reduce reactive species levels. Thus, pharmacological treatment with PPAR activators, such as fibrates, has gained much attention in the last 15 years. This review summarizes preclinical (animal models and patient-derived cells) and clinical data on the effect of PPARs in IMDs.

The elements of life: A biocentric tour of the periodic table

Living systems are built from a small subset of the atomic elements, including the bulk macronutrients (C,H,N,O,P,S) and ions (Mg,K,Na,Ca) together with a small but variable set of trace elements (micronutrients). Here, we provide a global survey of how chemical elements contribute to life. We define five classes of elements: those that are (i) essential for all life, (ii) essential for many organisms in all three domains of life, (iii) essential or beneficial for many organisms in at least one domain, (iv) beneficial to at least some species, and (v) of no known beneficial use. The ability of cells to sustain life when individual elements are absent or limiting relies on complex physiological and evolutionary mechanisms (elemental economy). This survey of elemental use across the tree of life is encapsulated in a web-based, interactive periodic table that summarizes the roles chemical elements in biology and highlights corresponding mechanisms of elemental economy.

Human ultrarare genetic disorders of sulfur metabolism demonstrate redundancies in H2S homeostasis

Regulation of H₂S homeostasis in humans is poorly understood. Therefore, we assessed the importance of individual enzymes in synthesis and catabolism of H₂S by studying patients with respective genetic defects. We analyzed sulfur compounds (including bioavailable sulfide) in 37 untreated or insufficiently treated patients with seven ultrarare enzyme deficiencies and compared them to 63 controls. Surprisingly, we observed that patients with severe deficiency in cystathionine β-synthase (CBS) or cystathionine γ-lyase (CSE) - the enzymes primarily responsible for H₂S synthesis - exhibited increased and normal levels of bioavailable sulfide, respectively. However, an approximately 21-fold increase of urinary homolanthionine in CBS deficiency strongly suggests that lacking CBS activity is compensated for by an increase in CSE-dependent H₂S synthesis from accumulating homocysteine, which suggests a control of H₂S homeostasis in vivo. In deficiency of sulfide:quinone oxidoreductase - the first enzyme in mitochondrial H₂S oxidation - we found normal H₂S concentrations in a symptomatic patient and his asymptomatic sibling, and elevated levels in an asymptomatic sibling, challenging the requirement for this enzyme in catabolizing H₂S under physiological conditions. Patients with ethylmalonic encephalopathy and sulfite oxidase/molybdenum cofactor deficiencies exhibited massive accumulation of thiosulfate and sulfite with formation of large amounts of S-sulfocysteine and S-sulfohomocysteine, increased renal losses of sulfur compounds and concomitant strong reduction in plasma total cysteine. Our results demonstrate the value of a comprehensive assessment of sulfur compounds in severe disorders of homocysteine/cysteine metabolism and provide evidence for redundancy and compensatory mechanisms in the maintenance of H₂S homeostasis.

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Cystathionine γ-lyase can compensate for decreased H₂S synthesis in cystathionine β-synthase deficiency.

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Sulfide:quinone oxidoreductase deficiency is compatible with normal H₂S plasma levels under non-stressed conditions.

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Persulfide dioxygenase deficiency (ethylmalonic encephalopathy) causes the largest accumulation of H₂S among disorders of sulfur metabolism.

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Excess sulfite forms S-sulfocysteine and S-sulfohomocysteine, and interferes with vitamin B₆ metabolism.

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S-sulfocysteine correlates directly with sulfite and is a stable biomarker of sulfite accumulation.

Case report: PLPHP deficiency, a rare but important cause of B6-responsive disorders: A report of three novel individuals and review of 51 cases

PLPHP (pyridoxal-phosphate homeostasis protein) deficiency is caused by biallelic pathogenic variants in PLPBP and is a rare cause of pyridoxine-responsive disorders. We describe three French-Canadian individuals with PLPHP deficiency, including one with unusual paroxysmal episodes lacking EEG correlation with a suspicious movement disorder, rarely reported in B6RDs. In addition, we review the clinical features and treatment responses of all 51 previously published individuals with PLPHP deficiency. Our case series underlines the importance of considering PLPBP mutations in individuals with partially B6-responsive seizures and highlights the presence of a founder effect in the French-Canadian population.

Ocular characteristics of a 6-year-Old boy with molybdenum cofactor deficiency type B

Purpose

To report a rare case of Molybdenum Cofactor Deficiency with novel ocular manifestations.

Observations

This is a case study of a 6-year-old boy who initially presented with conjunctival hyperemia and ocular pain of the left eye. Medical history revealed refractory convulsion, global developmental delay, microcephaly, feeding difficulties, aphasia, and spastic quadriplegia, as well as pathogenic MOCS2 mutations, indicating the diagnosis of molybdenum cofactor deficiency (MoCD). This case report highlights detailed ocular manifestations of late-onset MoCD-B, ectopia lentis of bilateral eyes, spherophakia, hyperemia, secondary glaucoma, cyclodialysis, and retinal detachment of the left eye, which will help further understanding of MoCD.

Conclusions and importance

MoCD as a rare genetic disease is tend to be easily neglected. The ophthalmic examination could provide important evidence for early diagnosis.

A year in pharmacology: new drugs approved by the US Food and Drug Administration in 2021

The second year of the COVID-19 pandemic had no adverse effect on the number of new drug approvals by the US Food and Drug Administration (FDA). Quite the contrary, with a total of 50 new drugs, 2021 belongs to the most successful FDA years. We assign these new drugs to one of three levels of innovation: (1) first drug against a condition ("first-in-indication"), (2) first drug using a novel molecular mechanism ("first-in-class"), and (3) "next-in-class", i.e., a drug using an already exploited molecular mechanism. We identify 21 first-in-class, 28 next-in-class, and only one first-in-indication drugs. By treatment area, the largest group is once again cancer drugs, many of which target specific genetic alterations. Every second drug approved in 2021 targets an orphan disease, half of them being cancers. Small molecules continue to dominate new drug approvals, followed by antibodies and non-antibody biopharmaceuticals. In 2021, the FDA continued to approve drugs without strong evidence of clinical effects, best exemplified by the aducanumab controversy.

Is There a Connection between the Metabolism of Copper, Sulfur, and Molybdenum in Alzheimer’s Disease? New Insights on Disease Etiology

Alzheimer’s disease (AD) and other forms of dementia was ranked 3rd in both the Americas and Europe in 2019 in a World Health Organization (WHO) publication listing the leading causes of death and disability worldwide. Copper (Cu) imbalance has been reported in AD and increasing evidence suggests metal imbalance, including molybdenum (Mo), as a potential link with AD occurrence.We conducted an extensive literature review of the last 60 years of research on AD and its relationship with Cu, sulfur (S), and Mo at out of range levels.Weanalyzed the interactions among metallic elements’ metabolisms;Cu and Mo are biological antagonists, Mo is a sulfite oxidase and xanthine oxidase co-factor, and their low activities impair S metabolism and reduce uric acid, respectively. We found significant evidence in the literature of a new potential mechanism linking Cu imbalance to Mo and S abnormalities in AD etiology: under certain circumstances, the accumulation of Cu not bound to ceruloplasmin might affect the transport of Mo outside the blood vessels, causing a mild Mo deficiency that might lowerthe activity of Mo and S enzymes essential for neuronal activity. The current review provides an updated discussion of the plausible mechanisms combining Cu, S, and Mo alterations in AD.

Neurogenetic and Metabolic Mimics of Common Neonatal Neurological Disorders

Neurogenetic and metabolic diseases often present in the neonatal period, masquerading as other disorders, most commonly as neonatal encephalopathy and seizures. Advancements in our understanding of inborn errors of metabolism are leading to an increasing number of therapeutic options. Many of these treatments can improve long-term neurodevelopment and seizure control. However, the treatments are frequently condition-specific. A high index of suspicion is required for prompt identification and treatment. When suspected, simultaneous metabolic and molecular testing are recommended along with concurrent treatment.

Enzyme Electrode Biosensors for N-Hydroxylated Prodrugs Incorporating the Mitochondrial Amidoxime Reducing Component

Human mitochondrial amidoxime reducing component 1 and 2 (mARC1 and mARC2) were immobilised on glassy carbon electrodes using the crosslinker glutaraldehyde. Voltammetry was performed in the presence of the artificial electron transfer mediator methyl viologen, whose redox potential lies negative of the enzymes' Mo^VI/V and Mo^V/IV redox potentials which were determined from optical spectroelectrochemical and EPR measurements. Apparent Michaelis constants obtained from catalytic limiting currents at various substrate concentrations were comparable to those previously reported in the literature from enzymatic assays. Kinetic parameters for benzamidoxime reduction were determined from cyclic voltammograms simulated using Digisim. pH dependence and stability of the enzyme electrode with time were also determined from limiting catalytic currents in saturating concentrations of benzamidoxime. The same electrode remained active after at least 9 days. Fabrication of this versatile and cost-effective biosensor is effective in screening new pharmaceutically important substrates and mARC inhibitors.

Molybdenum cofactor deficiency: A natural history

Molybdenum cofactor deficiency (MoCD) includes three ultrarare autosomal recessive inborn errors of metabolism (MoCD type A [MoCD-A], MoCD-B, and MoCD-C) that cause sulfite intoxication disorders. This natural history study analyzed retrospective data for 58 living or deceased patients (MoCD-A, n = 41; MoCD-B, n = 17). MoCD genotype, survival, neuroimaging, and medical history were assessed retrospectively. Prospective biomarker data were collected for 21 living MoCD patients. The primary endpoint was survival to 1 year of age in MoCD-A patients. Of the 58 MoCD patients, 49 (MoCD-A, n = 36; MoCD-B, n = 13) had first presenting symptoms by Day 28 (neonatal onset; median: 2 and 4 days, respectively). One-year survival rates were 77.4% (overall), 71.8% (neonatal onset MoCD-A), and 76.9% (neonatal onset MoCD-B); median ages at death were 2.4, 2.4, and 2.2 years, respectively. The most common presenting symptoms in the overall population were seizures (60.3%) and feeding difficulties (53.4%). Sequelae included profound developmental delay, truncal hypotonia, limb hypertonia that evolved to spastic quadriplegia or diplegia, dysmorphic features, and acquired microcephaly. In MoCD-A and MoCD-B, plasma and urinary xanthine and S-sulfocysteine concentrations were high; urate remained below the normal reference range. MOCS1 mutation homozygosity was common. Six novel mutations were identified. MoCD is a severe neurodegenerative disorder that often manifests during the neonatal period with intractable seizures and feeding difficulties, with rapidly progressive significant neurologic disabilities and high 1-year mortality rates. Delineation of MoCD natural history supports evaluations of emerging replacement therapy with cPMP for MoCD-A, which may modify disease course for affected individuals.

Genome-Wide Association Study Reveals Genomic Regions Associated With Molybdenum Accumulation in Wheat Grains

Molybdenum (Mo) is an essential micronutrient for almost all organisms. Wheat, a major staple crop worldwide, is one of the main dietary sources of Mo. However, the genetic basis for the variation of Mo content in wheat grains remains largely unknown. Here, a genome-wide association study (GWAS) was performed on the Mo concentration in the grains of 207 wheat accessions to dissect the genetic basis of Mo accumulation in wheat grains. As a result, 77 SNPs were found to be significantly associated with Mo concentration in wheat grains, among which 52 were detected in at least two sets of data and distributed on chromosome 2A, 7B, and 7D. Moreover, 48 out of the 52 common SNPs were distributed in the 726,761,412-728,132,521 bp genomic region of chromosome 2A. Three putative candidate genes, including molybdate transporter 1;2 (TraesCS2A02G496200), molybdate transporter 1;1 (TraesCS2A02G496700), and molybdopterin biosynthesis protein CNX1 (TraesCS2A02G497200), were identified in this region. These findings provide new insights into the genetic basis for Mo accumulation in wheat grains and important information for further functional characterization and breeding to improve wheat grain quality.

Chemical Information in the L3 X-ray Absorption Spectra of Molybdenum Compounds by High-Energy-Resolution Detection and Density Functional Theory

X-ray spectroscopy using high-energy-resolution fluorescence detection (HERFD) has critically increased the information content in X-ray spectra. We extend this technique to the tender X-ray range and present a study at the L₃-edge of molybdenum. We show how information on the oxidation state, phase composition, and local environment in molybdenum-based compounds can be obtained by analyzing the HERFD L₃ X-ray absorption near-edge structure (XANES). We demonstrate that the chemical shift of the L₃-edge HERFD spectra follows a parabolic dependence on the oxidation state and show that a qualitative analysis of high-resolution spectra can help to estimate parameters such as distortion of a ligand environment and radial order of atoms around the absorber. In certain cases, the spectra allow disentangling the contributions from bond lengths and angles to the distortion of the ligand polyhedron. Comparison of the high-resolution spectra with theoretical simulations shows that the single-electron approximation is able to reproduce the spectral shape. The results of this work may be useful in every branch of physics, inorganic and organometallic chemistry, catalysis, materials science, biochemistry, and mineralogy where observed changes in performance or chemical properties of Mo-based compounds, accompanied by small changes in spectral shape, are to be related to the details of electronic structure and local atomic environment.

Coexistence of molybdenum cofactor deficiency type A and hypertrophic pyloric stenosis, a new case

Molybdenum cofactor deficiency is a rare neurometabolic disease that is usually characterized by seizures, abnormal muscle tonus, developmental delay and poor nutrition, and is seen soon after birth. Pyloric stenosis causes serious vomiting in the first months of life. The presence of neurologic damage in molybdenum cofactor deficiency and possible abnormal innervations may cause pyloric stenosis; however, the pathogenesis is unclear. Pyloric stenosis with molybdenum cofactor deficiency has been described in two cases. Herein, we report the third case and suggest that hypertrophic pyloric stenosis should be kept in mind as a clinical manifestation of molybdenum cofactor deficiency.

Novel Compound Heterozygous Pathogenic Variants in SUOX Cause Isolated Sulfite Oxidase Deficiency in a Chinese Han Family

Aim

To explore the clinical imaging, laboratory and genetic characteristics of a newborn boy with isolated sulfite oxidase deficiency (ISOD) in a Chinese mainland cohort.

Methods

Homocysteine and uric acid in plasma and cysteine and total homocysteine in the blood spot were assessed in a Chinese newborn patient with progressive encephalopathy, tonic seizures, abnormal muscle tone, and feeding difficulties. Whole exome sequencing and Sanger sequencing facilitated an accurate diagnosis. The pathogenicity predictions and conservation analysis of the identified mutations were conducted by bioinformatics tools.

Results

Low total homocysteine was detected in the blood spot, while homocysteine and uric acid levels were normal in the plasma. S-sulfocysteine was abnormally elevated in urine. A follow-up examination revealed several progressive neuropathological findings. Also, intermittent convulsions and axial dystonia were observed. However, the coordination of sucking and swallowing was slightly improved. A novel paternal nonsense variant c.475G > T (p.Glu159^∗) and a novel maternal missense variant c.1201A > G (p.Lys401Glu) in SUOX were identified in this case by co-segregation verification.

Conclusion

This is the second report of early-onset ISOD case in a non-consanguineous Chinese mainland family. Combined with the clinical characteristics and biochemical indexes, we speculated that these two novel pathogenic variants of the SUOX gene underlie the cause of the disease in this patient. Next-generation sequencing (NGS) and Sanger sequencing provided reliable basis for clinical and prenatal diagnoses of this family, it also enriched the mutation spectrum of the SUOX gene.

Fosdenopterin: First Approval

Fosdenopterin (Nulibry^TM) is a synthetic cyclic pyranopterin monophosphate that is being developed by Origin Biosciences (a subsidiary of BridgeBio Pharma) for the treatment of molybdenum cofactor deficiency (MoCD) type A. Fosdenopterin was recently approved by the US FDA for use in reducing the risk of mortality in paediatric and adult patients with MoCD type A. This article summarizes the milestones in the development of fosdenopterin leading to this first approval.

Case Report: Compound Heterozygous Variants in MOCS3 Identified in a Chinese Infant With Molybdenum Cofactor Deficiency

Background: The molybdenum cofactor (Moco) deficiency in humans results in the inactivity of molybdenum-dependent enzymes and is caused by pathogenic variants in MOCS1 (Molybdenum cofactor synthesis 1), MOCS2 (Molybdenum cofactor synthesis 2), and GPHN (Gephyrin). These genes along with MOCS3 (Molybdenum cofactor synthesis 3) are involved in Moco biosynthesis and providing cofactors to Moco-dependent enzymes. Until now, there was no study to confirm that MOCS3 is a causative gene of Moco deficiency. Methods: Detailed clinical information was collected in the pedigree. The Whole-exome sequencing (WES) accompanied with Sanger sequencing validation were performed. Results: We described the clinical presentations of an infant, born to a non-consanguineous healthy family, diagnosed as having MOCS3 variants caused Moco deficiency and showing typical features of Moco deficiency including severe neurologic symptoms and cystic encephalomalacia in the brain MRI, resulting in neonatal death. Compound heterozygous variants in the MOCS3 gene were identified by WES. Positive sulfite and decreased levels of uric acid in plasma and urine were detected. Conclusion: To our knowledge, this is the first case of MOCS3 variants causing Moco deficiency. Our study may contribute to genetic diagnosis of Moco deficiency and future genetic counseling.

A neonate with molybdenum cofactor deficiency type B

Molybdenum cofactor deficiency (MoCD) is an autosomal recessive disease which leads to a combined deficiency of molybdenum cofactor dependent enzymes. There are four different genes in molybdenum cofactor biosynthesis, MOCS1, MOCS2, MOCS3, GEPH. The patients with MOCS2 homozygous mutation who onset in the neonatal period always have severe seizures, feeding difficulties, progressive neurological deterioration. The incidence of the disease is low, and certain types have never been reported in China. Here, we present a Chinese term infant with MOCS2 who presented seizure, intolerance to feed and hypotonia on the third day after birth. Treatment included intravenous nutrition, antibiotic, and anticonvulsant therapy. The seizure can't be controlled and her encephalopathy progressed. A homozygous mutation in exon 4 in MOSC2 gene was found and the mutation of the patient has not been reported before. In conclusion, the patients with MOCS2 who onset in neonatal period often shows uncontrolled seizure, feeding difficulties, hypotonia and early death. And the MRI of them shows severe encephalomalacia. There is no treatment for the disease by now, but early diagnosis and genetic detection can give the family genetic counseling.

Rare cause of xanthinuria: a pediatric case of molybdenum cofactor deficiency B

Molybdenum cofactor is essential for the activity of multiple enzymes including xanthine dehydrogenase. Molybdenum cofactor deficiencies are rare inborn errors of metabolism. Clinically, they present with intractable seizures, axial hypotonia, and hyperekplexia. They further develop cerebral atrophy, microcephaly, global developmental delay and ectopia lentis. We report a 5-year-old female with clinically, biochemically and genetically confirmed molybdenum cofactor deficiency type B due to compound heterozygous pathogenic variants in the molybdenum cofactor synthesis 2 gene found on whole exome sequencing. The xanthine stones were a key clue towards diagnosis. No mutation was detected in XDH gene. Implementation of a low-purine diet, urine alkalization and hydration lead to a near complete decrease in stone burden. The patient received pyridoxine supplementation with improvement in energy levels and attentiveness. Despite reports of high mortality at a young age, our patient was 9 years old at the time of this writing. Molybdenum cofactor deficiencies should be considered in neonates with early-onset seizures, hypotonia, and feeding difficulties. Screening with serum uric acid levels and empiric treatment may be considered while awaiting genetic results.

Lessons Learned from Inherited Metabolic Disorders of Sulfur-Containing Amino Acids Metabolism

The metabolism of sulfur-containing amino acids (SAAs) requires an orchestrated interplay among several dozen enzymes and transporters, and an adequate dietary intake of methionine (Met), cysteine (Cys), and B vitamins. Known human genetic disorders are due to defects in Met demethylation, homocysteine (Hcy) remethylation, or cobalamin and folate metabolism, in Hcy transsulfuration, and Cys and hydrogen sulfide (H2S) catabolism. These disorders may manifest between the newborn period and late adulthood by a combination of neuropsychiatric abnormalities, thromboembolism, megaloblastic anemia, hepatopathy, myopathy, and bone and connective tissue abnormalities. Biochemical features include metabolite deficiencies (e.g. Met, S-adenosylmethionine (AdoMet), intermediates in 1-carbon metabolism, Cys, or glutathione) and/or their accumulation (e.g. S-adenosylhomocysteine, Hcy, H2S, or sulfite). Treatment should be started as early as possible and may include a low-protein/low-Met diet with Cys-enriched amino acid supplements, pharmacological doses of B vitamins, betaine to stimulate Hcy remethylation, the provision of N-acetylcysteine or AdoMet, or experimental approaches such as liver transplantation or enzyme replacement therapy. In several disorders, patients are exposed to long-term markedly elevated Met concentrations. Although these conditions may inform on Met toxicity, interpretation is difficult due to the presence of additional metabolic changes. Two disorders seem to exhibit Met-associated toxicity in the brain. An increased risk of demyelination in patients with Met adenosyltransferase I/III (MATI/III) deficiency due to biallelic mutations in the MATIA gene has been attributed to very high blood Met concentrations (typically >800 μmol/L) and possibly also to decreased liver AdoMet synthesis. An excessively high Met concentration in some patients with cystathionine β-synthase deficiency has been associated with encephalopathy and brain edema, and direct toxicity of Met has been postulated. In summary, studies in patients with various disorders of SAA metabolism showed complex metabolic changes with distant cellular consequences, most of which are not attributable to direct Met toxicity.

Neonatal Presentations of Metabolic Disorders

Metabolic disorders in a neonate can present with involvement of any organ system and can be challenging to diagnose. A newborn can present with an acute metabolic crisis such as hyperammonemia or seizures needing immediate management, with a more chronic clinical picture such as cholestatic liver disease, or with structural abnormalities such as skeletal manifestations. Early detection of treatable metabolic conditions is important to improve outcomes. Newborn screening has facilitated early detection and initiation of therapy for many metabolic disorders. However, normal testing does not rule out a metabolic disorder and a high index of suspicion should remain when caring for any critically ill neonate without a diagnosis. Whole exome sequencing (WES) or whole genome sequencing (WGS) can be powerful tools in rapid diagnosis of a potentially treatable metabolic condition in a critically ill neonate. This review presents classic clinical presentations of neonatal metabolic disorders and also highlights some uncommon neonatal manifestations of metabolic disorders to improve the recognition and diagnosis of these conditions.

Integrated Analysis of Molybdenum Nutrition and Nitrate Metabolism in Strawberry

Molybdenum (Mo) is a component of the Mo cofactor (Moco) of nitrate reductase (NR) and is therefore essential for nitrate metabolism. However, little is known about Mo deficiency phenotypes or about how physiological and molecular mechanisms of Mo uptake and transport influence nitrate uptake and utilization in strawberry. Here, we used physiological and cytological techniques to identify Mo deficiency phenotypes in strawberry. Seedlings cultured with MoO₄ ^2- grew well and exhibited normal microstructure and ultrastructure of leaves and roots. By contrast, seedlings cultivated under Mo-deficient conditions showed yellow leaf blades and ultrastructural changes such as irregular chloroplasts and unclear membrane structures that were similar to the symptoms of nitrogen deficiency. We cloned and analyzed a putative molybdate transporter, FaMOT1, which may encode a molybdate transporter involved in the uptake and translocation of molybdate. Interestingly, the addition of the molybdate analog tungstate led to lower tissue Mo concentrations, reduced the translocation of Mo from roots to shoots, and increased the plants' sensitivity to Mo deficiency. Seedlings cultivated with MoO₄ ^2- altered expression of genes in Moco biosynthesis. As expected, NR activity was higher under sufficient MoO₄ ^2- levels. Furthermore, seedlings grown on Mo-deficient medium exhibited decreased ¹⁵NO₃ ^- translocation and lower ¹⁵NO₃ ^- use efficiency. These findings represent an important step towards understanding how molybdate transport, concentration, and deficiency symptoms influence nitrate uptake and utilization in strawberry.

8-Hydroxyquinoline-2-Carboxylic Acid as Possible Molybdophore: A Multi-Technique Approach to Define Its Chemical Speciation, Coordination and Sequestering Ability in Aqueous Solution

8-hydroxyquinoline-2-carboxylic acid (8-HQA) has been found in high concentrations (0.5–5.0 mmol·dm⁻³) in the gut of Noctuid larvae (and in a few other lepidopterans), in which it is proposed to act as a siderophore. Since it is known that many natural siderophores are also involved in the uptake and metabolism of other essential elements than iron, this study reports some results on the investigation of 8-HQA interactions with molybdate (MoO₄²⁻, i.e., the main molybdenum form in aqueous environments), in order to understand the possible role of this ligand as molybdophore. A multi-technique approach has been adopted, in order to derive a comprehensive set of information necessary to assess the chemical speciation of the 8-HQA/MoO₄²⁻ system, as well as the coordination behavior and the sequestering ability of 8-HQA towards molybdate. Chemical speciation studies have been performed in KCl_(aq) at I = 0.2 mol·dm⁻³ and T = 298.15 K by ISE-H⁺ (glass electrode) potentiometric and UV/Vis spectrophotometric titrations. CV (Cyclic Voltammetry), DP-ASV (Differential Pulse-Anodic Stripping Voltammetry), ESI-MS experiments and quantum mechanical calculations have been also performed to derive information about the nature and possible structure of species formed. These results are also compared with those reported for the 8-HQA/Fe³⁺ system in terms of chemical speciation and sequestering ability of 8-HQA.

Transcriptional profiling of multiple system atrophy cerebellar tissue highlights differences between the parkinsonian and cerebellar sub-types of the disease

Multiple system atrophy (MSA) is a rare adult-onset neurodegenerative disease of unknown cause, with no effective therapeutic options, and no cure. Limited work to date has attempted to characterize the transcriptional changes associated with the disease, which presents as either predominating parkinsonian (MSA-P) or cerebellar (MSC-C) symptoms. We report here the results of RNA expression profiling of cerebellar white matter (CWM) tissue from two independent cohorts of MSA patients (n = 66) and healthy controls (HC; n = 66). RNA samples from bulk brain tissue and from oligodendrocytes obtained by laser capture microdissection (LCM) were sequenced. Differentially expressed genes (DEGs) were obtained and were examined before and after stratifying by MSA clinical sub-type.We detected the highest number of DEGs in the MSA-C group (n = 747) while only one gene was noted in MSA-P, highlighting the larger dysregulation of the transcriptome in the MSA-C CWM. Results from both bulk tissue and LCM analysis showed a downregulation of oligodendrocyte genes and an enrichment for myelination processes with a key role noted for the QKI gene. Additionally, we observed a significant upregulation of neuron-specific gene expression in MSA-C and enrichment for synaptic processes. A third cluster of genes was associated with the upregulation of astrocyte and endothelial genes, two cell types with a key role in inflammation processes. Finally, network analysis in MSA-C showed enrichment for β-amyloid related functional classes, including the known Alzheimer's disease (AD) genes, APP and PSEN1.This is the largest RNA profiling study ever conducted on post-mortem brain tissue from MSA patients. We were able to define specific gene expression signatures for MSA-C highlighting the different stages of the complex neurodegenerative cascade of the disease that included alterations in several cell-specific transcriptional programs. Finally, several results suggest a common transcriptional dysregulation between MSA and AD-related genes despite the clinical and neuropathological distinctions between the two diseases.

EEG Monitoring of the Epileptic Newborn

PURPOSE OF REVIEW

Although differentiating neonatal-onset epilepsies from acute symptomatic neonatal seizures has been increasingly recognized as crucial, existing guidelines, and recommendations on EEG monitoring are mainly based on acute symptomatic seizures, especially secondary to hypoxic-ischemic encephalopathy. We aimed to narratively review current knowledge on neonatal-onset epilepsies of genetic, metabolic, and structural non-acquired origin, with special emphasis on EEG features and monitoring.

RECENT FINDINGS

A wide range of rare conditions are increasingly described, reducing undiagnosed cases. Although distinguishing features are identifiable in some, how to best monitor and detect less described etiologies is still an issue. A comprehensive approach considering onset, seizure evolution, ictal semiology, clinical, laboratory, EEG, and neuroimaging data is key to diagnosis. Phenotypic variability prevents precise recommendations, but a solid, consistent method moving from existing published guidelines helps in correctly assessing these newborns in order to provide better care, especially in view of expanding precision therapies.

Metabolism by Aldehyde Oxidase: Drug Design and Complementary Approaches to Challenges in Drug Discovery

Aldehyde oxidase (AO) catalyzes oxidations of azaheterocycles and aldehydes, amide hydrolysis, and diverse reductions. AO substrates are rare among marketed drugs, and many candidates failed due to poor pharmacokinetics, interspecies differences, and adverse effects. As most issues arise from complex and poorly understood AO biology, an effective solution is to stop or decrease AO metabolism. This perspective focuses on rational drug design approaches to modulate AO-mediated metabolism in drug discovery. AO biological aspects are also covered, as they are complementary to chemical design and important when selecting the experimental system for risk assessment. The authors' recommendation is an early consideration of AO-mediated metabolism supported by computational and in vitro experimental methods but not an automatic avoidance of AO structural flags, many of which are versatile and valuable building blocks. Preferably, consideration of AO-mediated metabolism should be part of the multiparametric drug optimization process, with the goal to improve overall drug-like properties.

Inhibition of vertebrate aldehyde oxidase as a therapeutic treatment for cancer, obesity, aging and amyotrophic lateral sclerosis

The aldehyde oxidases (AOXs) are a small sub-family of cytosolic molybdo-flavoenzymes, which are structurally conserved proteins and broadly distributed from plants to animals. AOXs play multiple roles in both physiological and pathological processes and AOX inhibition is of increasing significance in the development of novel drugs and therapeutic strategies. This review provides an overview of the evolution and the action mechanism of AOX and the role of each domain. The review provides an update of the polymorphisms in the human AOX. This review also summarises the physiology of AOX in different organs and its role in drug metabolism. The inhibition of AOX is a promising therapeutic treatment for cancer, obesity, aging and amyotrophic lateral sclerosis.

The Clinical and Molecular Characteristics of Molybdenum Cofactor Deficiency Due to MOCS2 Mutations

BACKGROUND

We explored the clinical and molecular characteristics of molybdenum cofactor deficiency due to MOCS2 muations.

METHODS

We summarize the genetic and clinical findings of previously reported patients with a MOCS2 mutation. We also present a new patient with novel neuroradiological findings associated with molybdenum cofactor deficiency due to a novel homozygous variant in the 5' untranslated region of the MOCS2 gene.

RESULTS

The study population comprised 35 patients with a MOCS2 gene mutation. All reported children had delayed motor milestones. The major initial symptom was seizures in neonatal period. Facial dysmorphism was present in 61% of the patients. Only one patient had ectopia lentis. Agenesis of the corpus callosum and an associated interhemispheric cyst in our case are novel neuroradiological findings.

CONCLUSIONS

The occurrence of neonatal seizures and feeding difficulties can be the first clinical signs of molybdenum cofactor deficiency. Although there is no effective therapy for this condition, early diagnosis and genetic analysis of these lethal disorders facilitate adequate genetic counseling.

Molybdenum cofactor deficiency type B knock-in mouse models carrying patient-identical mutations and their rescue by singular AAV injections

Molybdenum cofactor deficiency is an autosomal, recessively inherited metabolic disorder, which, in the absence of an effective therapy, leads to early childhood death due to neurological deterioration. In type A of the disease, cyclic pyranopterin monophosphate (cPMP) is missing, the first intermediate in the biosynthesis of the cofactor, and a biochemical substitution therapy using cPMP has been developed. A comparable approach for type B of the disease with a defect in the second step of the synthesis, formation of molybdopterin, so far has been hampered by the extreme instability of the corresponding metabolites. To explore avenues for a successful and safe gene therapy, knock-in mouse models were created carrying the mutations c.88C>T (p.Q30X) and c.726_727delAA, which are also found in human patients. Recombinant adeno-associated viruses (rAAVs) were constructed and used for postnatal intrahepatic injections of MoCo-deficient mice in a proof-of-concept approach. Singular administration of an appropriate virus dose in 60 animals prevented the otherwise devastating phenotype to a variable extent. While untreated mice did not survive for more than 2 weeks, some of the treated mice grew up to adulthood in both sexes.

Inborn errors of metabolism

Inborn errors of metabolism, also known as inherited metabolic diseases, constitute an important group of conditions presenting with neurologic signs in newborns. They are individually rare but collectively common. Many are treatable through restoration of homeostasis of a disrupted metabolic pathway. Given their frequency and potential for treatment, the clinician should be aware of this group of conditions and learn to identify the typical manifestations of the different inborn errors of metabolism. In this review, we summarize the clinical, laboratory, electrophysiologic, and neuroimaging findings of the different inborn errors of metabolism that can present with florid neurologic signs and symptoms in the neonatal period.

Genetics of neonatal-onset epilepsies

Although the majority of seizures in neonates are related to acute brain injury, a substantial minority are the first symptom of a neonatal-onset epilepsy often linked to a pathogenic genetic variant. Historically, studies on neonatal seizures including treatment response and long-term consequences have lumped all etiologies together. However, etiology has been consistently shown to be the most important determinant of outcome. In the past few years, an increasing number of monogenic disorders have been described and might explain up to a third of neonatal-onset epilepsy syndromes previously included under the umbrella of Ohtahara syndrome and early myoclonic encephalopathy. In this chapter, we define the concept of genetic epilepsy and review the classification. Then, we review the most relevant monogenic neonatal-onset epilepsies, detail their underlying pathophysiologic mechanisms, and present their electroclinical phenotypes. We highlight that, in some cases, such as neonates with KCNQ2 or KCNT1 gene mutations, the early recognition of the electroclinical phenotype can lead to targeted diagnostic testing and precision medicine treatment, enabling the possibility of improved outcome.

From the Eukaryotic Molybdenum Cofactor Biosynthesis to the Moonlighting Enzyme mARC

All eukaryotic molybdenum (Mo) enzymes contain in their active site a Mo Cofactor (Moco), which is formed by a tricyclic pyranopterin with a dithiolene chelating the Mo atom. Here, the eukaryotic Moco biosynthetic pathway and the eukaryotic Moco enzymes are overviewed, including nitrate reductase (NR), sulfite oxidase, xanthine oxidoreductase, aldehyde oxidase, and the last one discovered, the moonlighting enzyme mitochondrial Amidoxime Reducing Component (mARC). The mARC enzymes catalyze the reduction of hydroxylated compounds, mostly N-hydroxylated (NHC), but as well of nitrite to nitric oxide, a second messenger. mARC shows a broad spectrum of NHC as substrates, some are prodrugs containing an amidoxime structure, some are mutagens, such as 6-hydroxylaminepurine and some others, which most probably will be discovered soon. Interestingly, all known mARC need the reducing power supplied by different partners. For the NHC reduction, mARC uses cytochrome b5 and cytochrome b5 reductase, however for the nitrite reduction, plant mARC uses NR. Despite the functional importance of mARC enzymatic reactions, the structural mechanism of its Moco-mediated catalysis is starting to be revealed. We propose and compare the mARC catalytic mechanism of nitrite versus NHC reduction. By using the recently resolved structure of a prokaryotic MOSC enzyme, from the mARC protein family, we have modeled an in silico three-dimensional structure of a eukaryotic homologue.

Amino acid disorders

Amino acids serve as key building blocks and as an energy source for cell repair, survival, regeneration and growth. Each amino acid has an amino group, a carboxylic acid, and a unique carbon structure. Human utilize 21 different amino acids; most of these can be synthesized endogenously, but 9 are "essential" in that they must be ingested in the diet. In addition to their role as building blocks of protein, amino acids are key energy source (ketogenic, glucogenic or both), are building blocks of Kreb's (aka TCA) cycle intermediates and other metabolites, and recycled as needed. A metabolic defect in the metabolism of tyrosine (homogentisic acid oxidase deficiency) historically defined Archibald Garrod as key architect in linking biochemistry, genetics and medicine and creation of the term 'Inborn Error of Metabolism' (IEM). The key concept of a single gene defect leading to a single enzyme dysfunction, leading to "intoxication" with a precursor in the metabolic pathway was vital to linking genetics and metabolic disorders and developing screening and treatment approaches as described in other chapters in this issue. Amino acid disorders also led to the evolution of the field of metabolic nutrition and offending amino acid restricted formula and foods. This review will discuss the more common disorders caused by inborn errors in amino acid metabolism.

HPLC Determination of Bioactive Sulfur Compounds, Amino Acids and Biogenic Amines in Biological Specimens

There is an increasing interest for analytical methods aimed to detect biological sulfur-containing amines, because of their involvement in human diseases and metabolic disorders. This work describes an improved HPLC method for the determination of sulfur containing amino acids and amines from different biological matrices. We optimized a pre-column derivatization procedure using dabsyl chloride, in which dabsylated products can be monitored spectrophotometrically at 460 nm. This method allows the simultaneous analysis of biogenic amines, amino acids and sulfo-amino compounds including carnosine, dopamine, epinephrine, glutathione, cysteine, taurine, lanthionine, and cystathionine in brain specimens, urines, plasma, and cell lysates. Moreover, the method is suitable for the study of physiological and non-physiological derivatives of taurine and glutathione such as hypotaurine, homotaurine, homocysteic acid and S-acetylglutathione. The present method displays good efficiency of derivatization, having the advantage to give rise to stable products compared to other derivatizing agents such as o-phthalaldehyde and dansyl chloride.With this method, we provide a tool to study sulfur cycle from a metabolic point of view in relation to the pattern of biological amino-compounds, allowing researchers to get a complete scenario of organic sulfur and amino metabolism in tissues and cells.

MPTAC Determines APP Fragmentation via Sensing Sulfur Amino Acid Catabolism

Metabolic disorder has been suggested to underlie Alzheimer's disease (AD). However, the decisive molecular linkages remain unclear. We discovered that human Molybdopterin Synthase Associating Complex, MPTAC, promotes sulfur amino acid catabolism to prevent oxidative damage from excess sulfur amino acids, which, in turn, advances fatty acid oxidation and acetyl coenzyme A (acetyl-CoA) synthesis. The association of MPTAC with Protein arginine (R) Methyltransferase 5 (PRMT5) complex and small nuclear ribonucleoprotein (SNRP) splicing factors enables SNRPs to sense metabolic states through their methylation. This promotes the splicing fidelity of amyloid precursor protein (APP) pre-mRNA and proper APP fragmentation, abnormalities of which have been observed in the platelets of AD patients. The functions of MPTAC are crucial to maintain expression of drebrin 1, which is required for synaptic plasticity, through prevention from oxidative damage. Thus, adjustment of sulfur amino acid catabolism by MPTAC prevents events that occur early in the onset of AD.

Neonatal epilepsies: Clinical management

Whereas the majority of seizures in neonates are related to acute brain injury, a substantial minority are the first symptom of a neonatal-onset epilepsy, often linked to a pathogenic genetic variant. This defect may disrupt cortical development (e.g., lissencephaly, focal cortical dysplasia), lead to metabolic changes (e.g., pyridoxine-dependent epilepsy, sulfite oxidase deficiency) or lead to cortical dysfunction without metabolic or macroscopic structural changes (e.g., channelopathies, STXBP1). Historically, studies on treatment response and long-term consequences of neonatal seizures have lumped all etiologies together. However, etiology has been consistently shown to be the most important determinant of outcome. Here, we address the elements differentiating neonatal-onset epilepsies from acute symptomatic seizures. We review some common neonatal-onset epilepsies and emphasize how pathognomonic electro-clinical phenotypes such as the ones associated with KCNQ2 or KCNT1 gene mutation, when recognized early, can lead to targeted diagnostic testing and precision medicine treatment, enabling the possibility of improved outcome.

Placental adaptations to micronutrient dysregulation in the programming of chronic disease

Poor nutrition during pregnancy is known to impair foetal development and increase the risk of chronic disease in offspring. Both macronutrients and micronutrients are required for a healthy pregnancy although significantly less is understood about the role of micronutrients in the programming of chronic disease. This is despite the fact that modern calorie rich diets are often also deficient in key micronutrients. The importance of micronutrients in gestational disorders is clearly understood but how they impact long term disease in humans requires further investigation. In contrast, animal studies have demonstrated how diets high or low in specific micronutrients influence offspring physiology. Many of these studies highlight the importance of the placenta in determining disease risk. This review will explore the effects of individual vitamins, minerals and trace elements on offspring disease outcomes and discuss several key placental adaptations that are affected by multiple micronutrients. These placental adaptations include micronutrient induced dysregulation of oxidative stress, altered methyl donor availability and its impact on epigenetic mechanisms as well as endocrine dysfunction. Critical gaps in our current knowledge and the relative importance of different micronutrients at different gestational ages will also be highlighted. Finally, this review will discuss the need for further studies to characterise the micronutrient status of Australian women of reproductive age and correlate micronutrient status to placental adaptations, pregnancy complications and offspring disease.