Metabolic Evaluation of Epilepsy: A Diagnostic Algorithm With Focus on Treatable Conditions

Although inborn errors of metabolism do not represent the most common cause of seizures, their early identification is of utmost importance, since many will require therapeutic measures beyond that of common anti-epileptic drugs, either in order to control seizures, or to decrease the risk of neurodegeneration. We translate the currently-known literature on metabolic etiologies of epilepsy (268 inborn errors of metabolism belonging to 21 categories, with 74 treatable errors), into a 2-tiered diagnostic algorithm, with the first-tier comprising accessible, affordable, and less invasive screening tests in urine and blood, with the potential to identify the majority of treatable conditions, while the second-tier tests are ordered based on individual clinical signs and symptoms. This resource aims to support the pediatrician, neurologist, biochemical, and clinical geneticists in early identification of treatable inborn errors of metabolism in a child with seizures, allowing for timely initiation of targeted therapy with the potential to improve outcomes

Designing eHealth interventions for children with complex care needs requires continuous stakeholder collaboration and co-creation

Objective: Hospital-to-home (H2H) transitions challenge families of children with medical complexity (CMC) and healthcare professionals (HCP). This study aimed to gain deeper insights into the H2H transition process and to work towards eHealth interventions for its improvement, by applying an iterative methodology involving both CMC families and HCP as end-users. Methods: For 20-weeks, the Dutch Transitional Care Unit consortium collaborated with the Amsterdam University of Applied Sciences, HCP, and CMC families. The agile SCREAM approach was used, merging Design Thinking methods into five iterative sprints to stimulate creativity, ideation, and design. Continuous communication allowed rapid adaptation to new information and the refinement of solutions for subsequent sprints. Results: This iterative process revealed three domains of care – care coordination, social wellbeing, and emotional support – that were important to all stakeholders. These domains informed the development of our final prototype, ‘Our Care Team’, an application tailored to meet the H2H transition needs for CMC families and HCP. Conclusion: Complex processes like the H2H transition for CMC families require adaptive interventions that empower all stakeholders in their respective roles, to promote transitional care that is anticipatory, rather than reactive. Innovation: A collaborative methodology is needed, that optimizes existing resources and knowledge, fosters innovation through collaboration while using creative digital design principles. This way, we might be able to design eHealth solutions with end-users, not just for them

Hospital-to-home transitions for children with medical complexity: part 1, a systematic review of reported outcomes

Outcome selection to evaluate interventions to support a successful transition from hospital to home of children with medical complexity (CMC) may be difficult due to the variety in available outcomes. To support researchers in outcome selection, this systematic review aimed to summarize and categorize outcomes currently reported in publications evaluating the effectiveness of hospital-to-home transitional care interventions for CMC. We searched the following databases: Medline, Embase, Cochrane library, CINAHL, PsychInfo, and Web of Science for studies published between 1 January 2010 and 15 March 2023. Two reviewers independently screened the articles and extracted the data with a focus on the outcomes. Our research group extensively discussed the outcome list to identify those with similar definitions, wording or meaning. Consensus meetings were organized to discuss disagreements, and to summarize and categorize the data. We identified 50 studies that reported in total 172 outcomes. Consensus was reached on 25 unique outcomes that were assigned to six outcome domains: mortality and survival, physical health, life impact (the impact on functioning, quality of life, delivery of care and personal circumstances), resource use, adverse events, and others. Most frequently studied outcomes reflected life impact and resource use. Apart from the heterogeneity in outcomes, we also found heterogeneity in designs, data sources, and measurement tools used to evaluate the outcomes. Conclusion: This systematic review provides a categorized overview of outcomes that may be used to evaluate interventions to improve hospital-to-home transition for CMC. The results can be used in the development of a core outcome set transitional care for CMC

Extending diagnostic practices in gyrate atrophy:Enzymatic characterization and the development of an in vitro pyridoxine responsiveness assay

Gyrate atrophy of the choroid and retina (GACR) is caused by pathogenic biallelic variants in the gene encoding ornithine-δ-aminotransferase (OAT), and is characterized by progressive vision loss leading to blindness. OAT is a pyridoxal-5′-phosphate (PLP) dependent enzyme that is mainly involved in ornithine catabolism, and patients with a deficiency develop profound hyperornithinemia. Therapy is aimed at lowering ornithine levels through dietary arginine restriction and, in some cases, through enhancement of OAT activity via supraphysiological dosages of pyridoxine. In this study, we aimed to extend diagnostic practices in GACR by extensively characterizing the consequences of pathogenic variants on the enzymatic function of OAT, both at the level of the enzyme itself as well as the flux through the ornithine degradative pathway. In addition, we developed an in vitro pyridoxine responsiveness assay. We identified 14 different pathogenic variants, of which one variant was present in all patients of Dutch ancestry (p.(Gly353Asp)). In most patients the enzymatic activity of OAT as well as the rate of [14C]-ornithine flux was below the limit of quantification (LOQ). Apart from our positive control, only one patient cell line showed responsiveness to pyridoxine in vitro, which is in line with the reported in vivo pyridoxine responsiveness in this patient. None of the patients harboring the p.(Gly353Asp) substitution were responsive to pyridoxine in vivo or in vitro. In silico analysis and small-scale expression experiments showed that this variant causes a folding defect, leading to increased aggregation properties that could not be rescued by PLP. Using these results, we developed a diagnostic pipeline for new patients suspected of having GACR. Adding OAT enzymatic analyses and in vitro pyridoxine responsiveness to diagnostic practices will not only increase knowledge on the consequences of pathogenic variants in OAT, but will also enable expectation management for therapeutic modalities, thus eventually improving clinical care.</p

Hospital-to-home transitions for children with medical complexity: part 2-a core outcome set

Appropriate outcome measures as part of high-quality intervention trials are critical to advancing hospital-to-home transitions for Children with Medical Complexity (CMC). Our aim was to conduct a Delphi study and focus groups to identify a Core Outcome Set (COS) that healthcare professionals and parents consider essential outcomes for future intervention research. The development process consisted of two phases: (1) a three-round Delphi study in which different professionals rated outcomes, previously described in a systematic review, for inclusion in the COS and (2) focus groups with parents of CMC to validate the results of the Delphi study. Forty-five professionals participated in the Delphi study. The response rates were 55%, 57%, and 58% in the three rounds, respectively. In addition to the 24 outcomes from the literature, the participants suggested 12 additional outcomes. The Delphi rounds resulted in the following core outcomes: (1) disease management, (2) child's quality of life, and (3) impact on the life of families. Two focus groups with seven parents highlighted another core outcome: (4) self-efficacy of parents. Conclusion: An evidence-informed COS has been developed based on consensus among healthcare professionals and parents. These core outcomes could facilitate standard reporting in future CMC hospital to home transition research. This study facilitated the next step of COS development: selecting the appropriate measurement instruments for every outcome. What is Known: • Hospital-to-home transition for Children with Medical Complexity is a challenging process. • The use of core outcome sets could improve the quality and consistency of research reporting, ultimately leading to better outcomes for children and families. What is New: • The Core Outcome Set for transitional care for Children with Medical Complexity includes four outcomes: disease management, children's quality of life, impact on the life of families, and self-efficacy of parents

Effectiveness of L-serine supplementation in children with a GRIN2B loss-of-function mutation: Rationale and protocol for single patient (n-of-1) multiple cross-over trials

Rationale: Loss-of-function (LoF) mutations in GRIN2B result in neurologic abnormalities due to N-methyl-D-aspartate receptor (NMDAR) dysfunction. Affected persons present with various symptoms, including intellectual developmental disability (IDD), hypotonia, communication deficits, motor impairment, complex behavior, seizures, sleep disorders and gastrointestinal disturbance. Recently, in vitro experiments showed that D-serine mitigates function to GluN2B (mutation)-containing NMDARs. 11 previous case reports are published on (experimental) L-serine treatment of patients between 1.5 and 12 years old with GRIN2B missense or null mutations, some of whom showed notable improvement in motor and cognitive performance, communication, behavior and abnormalities on electro encephalography (EEG). Our objective is to further evaluate the effectiveness of L-serine for GRIN2B-related neurodevelopmental disorder (GRIN2B-NDD), using an n-of-1 trial design, increasing the level of evidence. Methods/design: These n-of-1 trials, consisting of 2 cycles of 6 months, will be performed to evaluate the effect of L-serine compared to placebo in 4 patients with a GRIN2B LoF mutation. The aggregation of multiple n-of-1 trials will provide an estimate of the average treatment effects. The primary outcome is the Perceive-Recall-Plan-Perform of Task Analysis, assessing developmental skills. Secondary outcomes include Goal Attainment Scaling, seizure log books, EEGs, sleep log books, the irritability subscale of the Aberrant Behavior Checklist, the Bristol Stool Scale and the Pediatric Quality of Life Inventory. Conclusion: This study employs an innovative methodological approach to evaluate the effectiveness of L-serine for patients with a GRIN2B LoF mutation. The results will establish a foundation for implementing L-serine as a disease-modifying treatment in GRIN2B-NDD

Untreated PKU Patients without Intellectual Disability: What Do They Teach Us?

Phenylketonuria (PKU) management is aimed at preventing neurocognitive and psychosocial dysfunction by keeping plasma phenylalanine concentrations within the recommended target range. It can be questioned, however, whether universal plasma phenylalanine target levels would result in optimal neurocognitive outcomes for all patients, as similar plasma phenylalanine concentrations do not seem to have the same consequences to the brain for each PKU individual. To better understand the inter-individual differences in brain vulnerability to high plasma phenylalanine concentrations, we aimed to identify untreated and/or late-diagnosed PKU patients with near-normal outcome, despite high plasma phenylalanine concentrations, who are still alive. In total, we identified 16 such cases. While intellectual functioning in these patients was relatively unaffected, they often did present other neurological, psychological, and behavioral problems. Thereby, these "unusual" PKU patients show that the classical symptomatology of untreated or late-treated PKU may have to be rewritten. Moreover, these cases show that a lack of intellectual dysfunction despite high plasma phenylalanine concentrations does not necessarily imply that these high phenylalanine concentrations have not been toxic to the brain. Also, these cases may suggest that different mechanisms are involved in PKU pathophysiology, of which the relative importance seems to differ between patients and possibly also with increasing age. Further research should aim to better distinguish PKU patients with respect to their cerebral effects to high plasma phenylalanine concentrations

Maintenance of cellular vitamin B 6 levels and mitochondrial oxidative function depend on pyridoxal 5′-phosphate homeostasis protein

Recently, biallelic variants in PLPBP coding for pyridoxal 5'-phosphate homeostasis protein (PLPHP) were identified as a novel cause of early-onset vitamin B 6-dependent epilepsy. The molecular function and precise role of PLPHP in vitamin B 6 metabolism are not well understood. To address these questions, we used PLPHP-deficient patient skin fibroblasts and HEK293 cells and YBL036C (PLPHP ortholog)-deficient yeast. We showed that independent of extracellular B 6 vitamer type (pyridoxine, pyridoxamine, or pyridoxal), intracellular pyridoxal 5'-phosphate (PLP) was lower in PLPHP-deficient fibroblasts and HEK293 cells than controls. Culturing cells with pyridoxine or pyridoxamine led to the concentration-dependent accumulation of pyridoxine 5'-phosphate and pyridoxamine 5'-phosphate (PMP), respectively, suggesting insufficient pyridox(am)ine 5'-phosphate oxidase activity. Experiments utilizing 13C 4-pyridoxine confirmed lower pyridox(am)ine 5'-phosphate oxidase activity and revealed increased fractional turnovers of PLP and pyridoxal, indicating increased PLP hydrolysis to pyridoxal in PLPHP-deficient cells. This effect could be partly counteracted by inactivation of pyridoxal phosphatase. PLPHP deficiency had a distinct effect on mitochondrial PLP and PMP, suggesting impaired activity of mitochondrial transaminases. Moreover, in YBL036C-deficient yeast, PLP was depleted and PMP accumulated only with carbon sources requiring mitochondrial metabolism. Lactate and pyruvate accumulation along with the decrease of tricarboxylic acid cycle intermediates downstream of α-ketoglutarate suggested impaired mitochondrial oxidative metabolism in PLPHP-deficient HEK293 cells. We hypothesize that impaired activity of mitochondrial transaminases may contribute to this depletion. Taken together, our study provides new insights into the pathomechanisms of PLPBP deficiency and reinforces the link between PLPHP function, vitamin B 6 metabolism, and mitochondrial oxidative metabolism

Timing of therapy and neurodevelopmental outcomes in 18 families with pyridoxine-dependent epilepsy

Background: Seventy-five percent of patients with pyridoxine-dependent epilepsy due to a-aminoadipic semialdehyde dehydrogenase deficiency (PDE-ALDH7A1) suffer intellectual developmental disability despite pyridoxine treatment. Adjunct lysine reduction therapies (LRT), aimed at lowering putative neurotoxic metabolites, are associated with improved cognitive outcomes. However, possibly due to timing of treatment, not all patients have normal intellectual function. Methods: This retrospective, multi-center cohort study evaluated the effect of timing of pyridoxine monotherapy and pyridoxine with adjunct LRT on neurodevelopmental outcome. Patients with confirmed PDE-ALDH7A1 with at least one sibling with PDE-ALDH7A1 and a difference in age at treatment initiation were eligible and identified via the international PDE registry, resulting in thirty-seven patients of 18 families. Treatment regimen was pyridoxine monotherapy in ten families and pyridoxine with adjunct LRT in the other eight. Primary endpoints were standardized and clinically assessed neurodevelopmental outcomes. Clinical neurodevelopmental status was subjectively assessed over seven domains: overall neurodevelopment, speech/language, cognition, fine and gross motor skills, activities of daily living and behavioral/psychiatric abnormalities. Results: The majority of early treated siblings on pyridoxine monotherapy performed better than their late treated siblings on the clinically assessed domain of fine motor skills. For siblings on pyridoxine and adjunct LRT, the majority of early treated siblings performed better on clinically assessed overall neurodevelopment, cognition, and behavior/psychiatry. Fourteen percent of the total cohort was assessed as normal on all domains. Conclusion: Early treatment with pyridoxine and adjunct LRT may be beneficial for neurodevelopmental outcome. When evaluating a more extensive neurodevelopmental assessment, the actual impairment rate may be higher than the 75% reported in literature. Take- home message: Early initiation of lysine reduction therapies adjunct to pyridoxine treatment in patients with PDE-ALDH7A1 may result in an improved neurodevelopmental outcome. (C) 2022 Published by Elsevier Inc

The malate-aspartate shuttle is important for de novo serine biosynthesis

The malate-aspartate shuttle (MAS) is a redox shuttle that transports reducing equivalents across the inner mitochondrial membrane while recycling cytosolic NADH to NAD +. We genetically disrupted each MAS component to generate a panel of MAS-deficient HEK293 cell lines in which we performed [U- 13C]-glucose tracing. MAS-deficient cells have reduced serine biosynthesis, which strongly correlates with the lactate M+3/pyruvate M+3 ratio (reflective of the cytosolic NAD +/NADH ratio), consistent with the NAD + dependency of phosphoglycerate dehydrogenase in the serine synthesis pathway. Among the MAS-deficient cells, those lacking malate dehydrogenase 1 (MDH1) show the most severe metabolic disruptions, whereas oxoglutarate-malate carrier (OGC)- and MDH2-deficient cells are less affected. Increasing the NAD +-regenerating capacity using pyruvate supplementation resolves most of the metabolic disturbances. Overall, we show that the MAS is important for de novo serine biosynthesis, implying that serine supplementation could be used as a therapeutic strategy for MAS defects and possibly other redox disorders