bims-meglyc 2023-07-02 papers

Nat Rev Genet. 2023 Jun 29.

Genomic newborn screening for rare diseases.

Rare diseases are a leading cause of infant mortality and lifelong disability. To improve outcomes, timely diagnosis and effective treatments are needed. Genomic sequencing has transformed the traditional diagnostic process, providing rapid, accurate and cost-effective genetic diagnoses to many. Incorporating genomic sequencing into newborn screening programmes at the population scale holds the promise of substantially expanding the early detection of treatable rare diseases, with stored genomic data potentially benefitting health over a lifetime and supporting further research. As several large-scale newborn genomic screening projects launch internationally, we review the challenges and opportunities presented, particularly the need to generate evidence of benefit and to address the ethical, legal and psychosocial issues that genomic newborn screening raises.

DOI: https://doi.org/10.1038/s41576-023-00621-w

Genes (Basel). 2023 05 31. pii: 1208. [Epub ahead of print]14(6):

Characteristics of Neuroimaging and Behavioural Phenotype in Polish Patients with PIGV-CDG-An Observational Study and Literature Review.

Michal Hutny, Patryk Lipinski, Aleksandra Jezela-Stanek.

Congenital disorders of glycosylation (CDGs) are a wide group of genetic diseases characterised by a severe clinical spectrum, consisting of developmental delays, dysmorphisms, and neurological deficits. Mutations in the PIGV gene lead to a disorder called hyperphosphatasia with impaired intellectual development syndrome 1 (HPMRS1), distinct from other CDGs in terms of hyperphosphatemia related to abnormal ALP activity and brachytelephalangy. This article discusses the phenotype of six Polish patients with HPMRS1 with a special focus on behavioural and imaging features, which were not addressed in 26 previously reported cases. The medical records of six patients aged 6 to 22 years were collected and analysed. In all cases, the same PIGV homozygotic mutation (c.1022C>A; p.Ala341Glu) was found, although the patients presented a diverse spectrum of neurological and developmental disorders, concerning in most cases the muscular tonus and general developmental delay. The most prevalent dysmorphic features included hypertelorism, high palate, and finger anomalies, whereas other characteristics present in all previously described cases, such as a short, broad nose and brachytelephalangy, were less frequently observed. Similarly to previous reports, the magnetic resonance (MR) and computed tomography (CT) head scans returned varied results, including physiological and pathological brain images in equal measure, the latter of which consisted of cortical atrophy, delayed myelination, hydrocephalus, and hypoplastic corpus callosum. Each patient exhibited symptoms characteristic of autism spectrum disorders, especially in terms of attention deficits, as well as controlling and expressing emotions. The most common type of sensory processing disorder was over-responsivity. Despite the low prevalence of HPMRS1, the patients reported in the literature presented a rather uniform phenotype, which does not correspond with the one found in each individual of the studied group. Behavioural disorders and sensory impairment require additional care and awareness considering the global developmental delay often observed in these patients.

Keywords: PIGV; behavioural disorders; developmental delay; neuroimaging

DOI: https://doi.org/10.3390/genes14061208

EMBO Mol Med. 2023 Jun 27. e17159

Targeting shared molecular etiologies to accelerate drug development for rare diseases.

Galliano Zanello, Macarena Garrido-Estepa, Ana Crespo, Daniel O'Connor, Rima Nabbout, Christina Waters, Anthony Hall, Maurizio Taglialatela, Chun-Hung Chan, David A Pearce, Marc Dooms, Philip John Brooks.

Rare diseases affect over 400 million people worldwide and less than 5% of rare diseases have an approved treatment. Fortunately, the number of underlying disease etiologies is far less than the number of diseases, because many rare diseases share a common molecular etiology. Moreover, many of these shared molecular etiologies are therapeutically actionable. Grouping rare disease patients for clinical trials based on the underlying molecular etiology, rather than the traditional, symptom-based definition of disease, has the potential to greatly increase the number of patients gaining access to clinical trials. Basket clinical trials based on a shared molecular drug target have become common in the field of oncology and have been accepted by regulatory agencies as a basis for drug approvals. Implementation of basket clinical trials in the field of rare diseases is seen by multiple stakeholders-patients, researchers, clinicians, industry, regulators, and funders-as a solution to accelerate the identification of new therapies and address patient's unmet needs.

Keywords: IRDiRC; basket clinical trials; rare diseases; shared molecular etiologies; therapeutic development

DOI: https://doi.org/10.15252/emmm.202217159

Endocr Metab Immune Disord Drug Targets. 2023 Jun 23.

Liver disorders caused by inborn errors of metabolism.

Omid Vakili, Alireza Mafi, Morteza Pourfarzam.

Inborn errors of metabolism (IEMs) are a vast array of inherited/congenital disorders, affecting a wide variety of metabolic pathways and/or biochemical processes inside the cells. Although IEMs are usually rare, they can be represented as serious health problems. During the neonatal period, these inherited defects can give rise to almost all key signs of liver malfunction, including jaundice, coagulopathy, hepato- and splenomegaly, ascites, etc. Since the liver is a vital organ with multiple synthetic, metabolic, and excretory functions, IEM-related hepatic dysfunction could seriously be considered life-threatening. In this context, the identification of those hepatic manifestations and their associated characteristics may promote the differential diagnosis of IEMs immediately after birth, making therapeutic strategies more successful in preventing the occurrence of subsequent events. Among all possible liver defects caused by IEMs, cholestatic jaundice, hepatosplenomegaly, and liver failure have been shown to be manifested more frequently. Therefore, the current study aims to review substantial IEMs that mostly result in the aforementioned hepatic disorders, relying on clinical principles, especially through the first years of life. In this article, a group of uncommon hepatic manifestations linked to IEMs is also discussed briefly.

Keywords: Cholestasis; Hepatosplenomegaly; Inborn errors of metabolism; Liver failure; Obstructive jaundice

DOI: https://doi.org/10.2174/1871530323666230623120935

Curr Protoc. 2023 Jun;3(6): e803

Measurement of GLUT4 Traffic to and from the Cell Surface in Muscle Cells.

Costin N Antonescu, Shuhei Ishikura, Philip J Bilan, Amira Klip.

Elevated blood glucose following a meal is cleared by insulin-stimulated glucose entry into muscle and fat cells. The hormone increases the amount of the glucose transporter GLUT4 at the plasma membrane in these tissues at the expense of preformed intracellular pools. In addition, muscle contraction also increases glucose uptake via a gain in GLUT4 at the plasma membrane. Regulation of GLUT4 levels at the cell surface could arise from alterations in the rate of its exocytosis, endocytosis, or both. Hence, methods that can independently measure these traffic parameters for GLUT4 are essential to understanding the mechanism of regulation of membrane traffic of the transporter. Here, we describe cell population-based assays to measure the steady-state levels of GLUT4 at the cell surface, as well as to separately measure the rates of GLUT4 endocytosis and endocytosis. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Measuring steady-state cell surface GLUT4myc Basic Protocol 2: Measuring steady-state cell surface GLUT4-HA Basic Protocol 3: Measuring GLUT4myc endocytosis Basic Protocol 4: Measuring GLUT4myc exocytosis.

Keywords: glucose; insulin; internalization; muscle contraction; regulated membrane traffic

DOI: https://doi.org/10.1002/cpz1.803

Sci Adv. 2023 Jun 30. 9(26): eade6308

N-acetylneuraminate pyruvate lyase controls sialylation of muscle glycoproteins essential for muscle regeneration and function.

Deleterious variants in N-acetylneuraminate pyruvate lyase (NPL) cause skeletal myopathy and cardiac edema in humans and zebrafish, but its physiological role remains unknown. We report generation of mouse models of the disease: NplR63C, carrying the human p.Arg63Cys variant, and Npldel116 with a 116-bp exonic deletion. In both strains, NPL deficiency causes drastic increase in free sialic acid levels, reduction of skeletal muscle force and endurance, slower healing and smaller size of newly formed myofibers after cardiotoxin-induced muscle injury, increased glycolysis, partially impaired mitochondrial function, and aberrant sialylation of dystroglycan and mitochondrial LRP130 protein. NPL-catalyzed degradation of sialic acid in the muscle increases after fasting and injury and in human patient and mouse models with genetic muscle dystrophy, demonstrating that NPL is essential for muscle function and regeneration and serves as a general marker of muscle damage. Oral administration of N-acetylmannosamine rescues skeletal myopathy, as well as mitochondrial and structural abnormalities in NplR63C mice, suggesting a potential treatment for human patients.

DOI: https://doi.org/10.1126/sciadv.ade6308

Arterioscler Thromb Vasc Biol. 2023 Jun 29.

MAGT1 Deficiency Dysregulates Platelet Cation Homeostasis and Accelerates Arterial Thrombosis and Ischemic Stroke in Mice.

BACKGROUND: MAGT1 (magnesium transporter 1) is a subunit of the oligosaccharide protein complex with thiol-disulfide oxidoreductase activity, supporting the process of N-glycosylation. MAGT1 deficiency was detected in human patients with X-linked immunodeficiency with magnesium defect syndrome and congenital disorders of glycosylation, resulting in decreased cation responses in lymphocytes, thereby inhibiting the immune response against viral infections. Curative hematopoietic stem cell transplantation of patients with X-linked immunodeficiency with magnesium defect causes fatal bleeding and thrombotic complications.
METHODS: We studied the role of MAGT1 deficiency in platelet function in relation to arterial thrombosis and hemostasis using several in vitro experimental settings and in vivo models of arterial thrombosis and transient middle cerebral artery occlusion model of ischemic stroke.
RESULTS: MAGT1-deficient mice (Magt1-/y) displayed accelerated occlusive arterial thrombus formation in vivo, a shortened bleeding time, and profound brain damage upon focal cerebral ischemia. These defects resulted in increased calcium influx and enhanced second wave mediator release, which further reinforced platelet reactivity and aggregation responses. Supplementation of MgCl2 or pharmacological blockade of TRPC6 (transient receptor potential cation channel, subfamily C, member 6) channels, but not inhibition of store-operated calcium entry, normalized the aggregation responses of Magt1-/y platelets to the control level. GP (glycoprotein) VI activation of Magt1-/y platelets resulted in hyperphosphorylation of Syk (spleen tyrosine kinase), LAT (linker for activation of T cells), and PLC (phospholipase C) γ2, whereas the inhibitory loop regulated by PKC (protein kinase C) was impaired. A hyperaggregation response to the GP VI agonist was confirmed in human platelets isolated from a MAGT1-deficient (X-linked immunodeficiency with magnesium defect) patient. Haploinsufficiency of TRPC6 in Magt1-/y mice could normalize GP VI signaling, platelet aggregation, and thrombus formation in vivo.
CONCLUSIONS: These results suggest that MAGT1 and TRPC6 are functionally linked. Therefore, deficiency or impaired functionality of MAGT1 could be a potential risk factor for arterial thrombosis and stroke.

Keywords: TRPC6 cation channel; animals; humans; ischemic stroke; mice

DOI: https://doi.org/10.1161/ATVBAHA.122.318115