Journal of Inherited Metabolic Disease最新文献

Many inborn errors of metabolism affect pathways involved in the synthesis of a metabolite that has an important biochemical or physiological function, and adverse effects of the disorder can be attributed to the lack of this metabolite. Thus, there is the opportunity for treatment by ‘product replacement’. One of the disorders in the pathways for the synthesis of bile acids from cholesterol, 3β-hydroxy-Δ5-C27-steroid dehydrogenase deficiency, causes cholestatic liver disease in infancy that can be treated very effectively with chenodeoxycholic acid (CDCA) and/or cholic acid (CA). There are several other enzyme deficiencies that can cause liver disease in infancy that improve with CDCA or CA or both (alongside a reduction of abnormal bile acids or alcohols); however, individuals with the same gene variant(s) may remain asymptomatic or have transient liver dysfunction that resolves spontaneously. In some disorders, the more usual presentation is with neurological disease later in childhood or in adolescence or adult life, for example, cerebrotendinous xanthomatosis (CTX), α-methylacyl-CoA racemase deficiency, and oxysterol 7α-hydroxylase deficiency. Treatment with CDCA has been dramatically effective in the neurological disease of CTX. In the disorders of peroxisome biogenesis, liver disease is a part of the clinical picture although neurological symptoms tend to be predominant. Treatment with CDCA and CA (or CA alone) leads to a reduction in the levels of C27 bile acids. Some trials suggest this treatment leads to significant improvement in clinical status and liver function tests; others do not. Defects in individual peroxisomal enzymes and transporters vary in their clinical presentations. Treatment of acyl-CoA oxidase 2 deficiency with ursodeoxycholic acid is discussed.

mRNA encapsulated in lipid nanoparticles (LNPs) provides a dual revolution in the field of gene therapy. mRNA brings fleeting efficacy and the possibility to adjust the therapy to clinical needs. LNP, as a non-viral vehicle with flexible organ-targeting, overcomes most immune complications of viral gene therapy. mRNA-LNP has rapidly progressed from preventive medicine and vaccine applications to therapeutic use, especially in inherited metabolic diseases (IMDs). Given their natural tropism for liver uptake, this platform has been utilised successfully in numerous preclinical programmes. Early phase clinical trials are recruiting to assess safety and efficacy in liver IMDs. Here, we provide the latest update on mRNA and LNP technologies, preclinical studies and clinical trials targeting IMDs, safety considerations with a spotlight on infusion-related reactions and safety modelling. We discuss the future directions of therapeutic mRNA-LNP in IMDs and the right clinical use of this adjustable therapy, still to be defined. The versatility of this technology is appealing, with multiple clinical applications as bridge, long-term cure, rescue, or adjuvant therapy. mRNA-LNP for gene editing/insertion is an alternative approach for one-off cure. Translating various successful preclinical programmes in patients remains an unsolved limitation. mRNA-LNP can be tuned according to the patient's needs and is the next step in personalised medicine and individualised gene therapy.

Cobalamin (vitamin B12) is an essential cofactor for two human enzymes, methionine synthase and methylmalonyl-CoA mutase. Inborn errors of cobalamin metabolism (IECMs) are inherited genetic defects resulting in improper transport, modification, or utilization of cobalamin and include inherited methylmalonic acidurias, a group of IECMs most frequently caused by a defect in the methylmalonyl-CoA mutase enzyme. Here, we performed genome-scale modeling of IECMs to gain insight into their metabolic perturbations. First, we simulated deficiencies in 11 IECM-related genes and demonstrated that they cluster based on impaired metabolic pathways. Next, we leveraged RNA sequencing data from fibroblasts of 202 individuals with methylmalonic aciduria and 19 unaffected controls to construct and interrogate personalized metabolic models. Finally, we analyzed fluxes differing between patients depending on reported symptom presentation. Our findings reveal that (i) metabolic pathways including fatty acid metabolism and heme biosynthesis have reduced flux in IECMs, (ii) in personalized simulations, succinate and fumarate production and heme biosynthesis are impaired, especially in methylmalonyl-CoA mutase deficiency, (iii) one-carbon metabolism reactions such as serine hydroxymethyltransferase and folylglutamate synthase have reduced flux in all individuals with methylmalonic aciduria, and (iv) specific metabolic pathways are up- or down-regulated according to symptoms, including failure to thrive and hematological abnormalities, and treatments, such as antibiotics and protein restriction. Overall, our study delineates metabolic pathways perturbed in IECMs. In future applications, our modeling framework could be applied to other rare genetic diseases or used to predict personalized therapeutic or dietary interventions.

Pyridox(am)ine 5′-phosphate oxidase (PNPO) deficiency is an ultrarare inherited neurometabolic disease, characterized by primarily neonatal-onset B6-responsive epileptic encephalopathies. Treatment often requires sustainable access to high-quality pyridoxal-5′-phosphate (PLP, i.e., active vitamin B6), although some patients (also) respond to pyridoxine (PN). While PN is authorized as a medicinal product, PLP is not, and this forces reliance on lesser-regulated food supplements, which risks dosing inaccuracies. This systematic review evaluates the effectiveness and safety of PLP in PNPO deficiency (PROSPERO, CRD42024542199). A systematic search was conducted in PubMed, Embase, and ClinicalTrials.gov, with risk of bias assessed and observational evidence summarized using a narrative synthesis approach. A total of 30 studies were included reporting on 49 patients treated with PLP. Clinical seizure responsiveness following PLP therapy was observed in the majority of patients (n = 38, 77.6%) and PLP treatment significantly improved survival (p < 0.001) compared with untreated siblings with a similar phenotype. The majority of PLP-responsive patients responded exclusively to PLP, with PN being attempted but ineffective in most of them (n = 30/33, 90.9%) Liver toxicity was the most frequently observed adverse event (n = 10, 20.4%) and although the underlying pathophysiological mechanism remains unclear, it may be associated with high-dose PLP. Therefore, regular liver disease screening is recommended during PLP therapy. This means that PLP remains the only effective therapy for achieving and maintaining seizure control in the majority of PNPO deficient patients, but the therapeutic window for optimal management is narrow. Thus, it is essential to ensure patient access to high-quality and appropriate forms of PLP.

Patients with metachromatic leukodystrophy (MLD) show variable motor and cognitive decline. The ARSA variants c.256C>T, p.(Arg86Trp), c.257G>A, p.(Arg86Gln) and c.542T>G, p.(Ile181Ser) are associated with predominantly cognitive decline. This multinational study analyzed MLD onset type, presenting signs/symptoms, cognitive function, gross motor function, central motor tract involvement, MRI severity score, peripheral neuropathy, and survival of 47 patients (three homozygous for c.256C>T and five, twelve and 27 compound heterozygous for c.256C>T, c.257G>A, or c.542T>G and another ARSA variant, respectively). Eleven underwent hematopoietic stem cell transplantation (HSCT). Onset was late-juvenile (46.8%) or adult (44.7%) with predominantly cognitive decline (n = 40/41 symptomatic patients). At diagnosis, untreated patients typically retained independent walking (100%), sparing of central motor tracts (87.5%), and absence of demyelinating neuropathy (95.5%), which persisted in follow-up for most (76.5%, 71.4%, and 64.7%, respectively). Early-juvenile onset and rapid motor decline occurred only in patients compound heterozygous for c.256C>T and a severe second variant (n = 4), showing central motor tract involvement at diagnosis. One untreated and one treated patient died of disease progression, and another from HSCT complications. All other treated patients retained independent walking, and four of five tested normal cognitive function. Median MRI severity score remained lower in treated (13) than untreated patients (25). The phenotype of c.256C>T carriers depends on the severity of the second ARSA variant. Patients harboring c.257G>A or c.542T>G show late-juvenile or adult onset with cognitive decline and preserved motor function, usually associated with sparing of central motor tracts. In these patients, cognitive function and MRI severity score should be preferred treatment outcomes.

Extensive studies have examined the clinical manifestations, pathogenic mechanisms, and genetic variations of phenylketonuria (PKU) across different populations, resulting in a substantial collection of molecular genetic data on the phenylalanine hydroxylase (PAH) gene and its variants. However, many genotypes are associated with a range of clinical phenotypes, as well as variable responsiveness to sapropterin, presenting ongoing challenges for effective treatment. To address this, we enhanced the PAH activity landscapes method by incorporating high-throughput techniques, including automated pipetting, integrated data processing via Gaussian modeling of 3D surfaces, and bioinformatics analyses with robust quality control. Using PAH activity landscapes, we visualized PAH enzymatic function across 99 common PAH genotypes under varying metabolic and therapeutic conditions. This deep functional phenotyping approach enabled us to identify distinct genotype subpopulations by using consensus clustering, correlate them with clinical phenotypes, and propose subpopulation-specific treatment protocols. Our findings suggest that clinical phenotypes can be predicted and treatment regimens can be adjusted based on residual PAH function profiles. To further support personalized treatment strategies, we revised our publicly accessible PAH genotype & activity landscapes database to share the latest insights into PAH function and patient phenotypes—namely residual enzyme activity and responsiveness to sapropterin as conveyed by two alleles. This resource underscores the translational significance of functional research in PKU and offers a practical tool to support personalized treatment in clinical settings.