Zebrafish in the sea of mineral (iron, zinc, and copper) metabolism

Iron, copper, zinc, and eight other minerals are classified as essential trace elements because they present in minute in vivo quantities and are essential for life. Because either excess or insufficient levels of trace elements can be detrimental to life (causing human diseases such as iron-deficiency anemia, hemochromatosis, Menkes syndrome and Wilson's disease), the endogenous levels of trace minerals must be tightly regulated. Many studies have demonstrated the existence of systems that maintain trace element homeostasis, and these systems are highly conserved in multiple species ranging from yeast to mice. As a model for studying trace mineral metabolism, the zebrafish is indispensable to researchers. Several large-scale mutagenesis screens have been performed in zebrafish, and these screens led to the identification of a series of metal transporters and the generation of several mutagenesis lines, providing an in-depth functional analysis at the system level. Moreover, because of their developmental advantages, zebrafish have also been used in mineral metabolism-related chemical screens and toxicology studies. Here, we systematically review the major findings of trace element homeostasis studies using the zebrafish model, with a focus on iron, zinc, copper, selenium, manganese, and iodine. We also provide a homology analysis of trace mineral transporters in fish, mice and humans. Finally, we discuss the evidence that zebrafish is an ideal experimental tool for uncovering novel mechanisms of trace mineral metabolism and for improving approaches to treat mineral imbalance-related diseases

Molecular genetics of intellectual disability

The goal of this chapter is to review the current knowledge of the genetic causes of intellectual disability, focusing on alterations at the chromosomal and single gene level, with particular mention to the new technological developments, including array technologies and next-generation sequencing, which allowed an enormous increase in yield from genetic studies. The cellular and physiological pathways that seem to be most affected in intellectual disability will also be addressed. Finally, a brief analysis of the contribution of the genetically modified animal models for the study of the pathogenesis of intellectual disability and for the development and testing of novel therapeutic approaches, with unexpectedly good results, previously thought to be impossible to achieve. The chapter will close with some considerations on the relevance and future perspectives of genetic testing in patients with intellectual disability

Future directions for the management of pain in osteoarthritis.

Osteoarthritis (OA) is the predominant form of arthritis worldwide, resulting in a high degree of functional impairment and reduced quality of life owing to chronic pain. To date, there are no treatments that are known to modify disease progression of OA in the long term. Current treatments are largely based on the modulation of pain, including NSAIDs, opiates and, more recently, centrally acting pharmacotherapies to avert pain. This review will focus on the rationale for new avenues in pain modulation, including inhibition with anti-NGF antibodies and centrally acting analgesics. The authors also consider the potential for structure modification in cartilage/bone using growth factors and stem cell therapies. The possible mismatch between structural change and pain perception will also be discussed, introducing recent techniques that may assist in improved patient phenotyping of pain subsets in OA. Such developments could help further stratify subgroups and treatments for people with OA in future

Pathophysiology of the Belgrade rat

The Belgrade rat is an animal model of divalent metal transporter 1 (DMT1) deficiency. This strain originates from an X-irradiation experiment first reported in 1966. Since then, the Belgrade rat’s pathophysiology has helped to reveal the importance of iron balance and the role of DMT1. This review discusses our current understanding of iron transport homeostasis and summarizes molecular details of DMT1 function. We describe how studies of the Belgrade rat have revealed key roles for DMT1 in iron distribution to red blood cells as well as duodenal iron absorption. The Belgrade rat’s pathology has extended our knowledge of hepatic iron handling, pulmonary and olfactory iron transport as well as brain iron uptake and renal iron handling. For example, relationships between iron and manganese metabolism have been discerned since both are essential metals transported by DMT1. Pathophysiologic features of the Belgrade rat provide us with a unique and interesting animal model to understand iron homeostasis

EPR Methods for Biological Cu(II): L-Band CW and NARS

Abstract: Copper has many roles in biology that involve the change of coordination sphere and/or oxidation state of the copper ion. Consequently, the study of copper in heterogeneous environments is an important area in biophysics. EPR is a primary technique for the investigation of paramagnetic copper, which is usually the isolated Cu(II) ion, but sometimes as Cu(II) in different oxidation states of multitransition ion clusters. The gross geometry of the coordination environment of Cu(II) can often be determined from a simple inspection of the EPR spectrum, recorded in the traditional X-band frequency range (9–10 GHz). Identification and quantitation of the coordinating ligand atoms, however, is not so straightforward. In particular, analysis of the superhyperfine structure on the EPR spectrum, to determine the number of coordinated nitrogen atoms, is fraught with difficulty at X-band, despite the observation that the overwhelming number of EPR studies of Cu(II) in the literature have been carried out at X-band. Greater reliability has been demonstrated at S-band (3–4 GHz), using the low-field parallel (gz) features. However, analysis relies on clear identification of the outermost superhyperfine line, which has the lowest intensity of all the spectral features. Computer simulations have subsequently indicated that the much more intense perpendicular region of the spectrum can be reliably interpreted at L-band (2 GHz). The present work describes the development of L-band EPR of Cu(II) into a routine method that is applicable to biological samples

Clinical and Biochemical Footprints of Inherited Metabolic Diseases. XV. Epilepsies

We provide a comprehensive overview of inherited metabolic disorders (IMDs) in which epilepsy is a prominent manifestation. Our unique database search has identified 256 IMDs associated with various types of epilepsies, which we classified according to the classic pathophysiology-based classification of IMDs, and according to selected seizure-related factors (neonatal seizures, infantile spasms, myoclonic seizures, and characteristic EEG patterns) and treatability for the underlying metabolic defect. Our findings indicate that inherited metabolic epilepsies are more likely to present in the neonatal period, with infantile spasms or myoclonic seizures. Additionally, the ∼20% of treatable inherited metabolic epilepsies found by our search were mainly associated with the IMD groups of "cofactor and mineral metabolism" and "Intermediary nutrient metabolism." The information provided by this study, including a comprehensive list of IMDs with epilepsy stratified according to age of onset, and seizure type and characteristics, along with an overview of the key clinical features and proposed diagnostic and therapeutic approaches, may benefit any epileptologist and healthcare provider caring for individuals with metabolic conditions

Kandidatengenstudien bei Fokaler Idiopathischer Torsionsdystonie (F-ITD)

Bei der fokalen idiopathischen Torsionsdystonie (F-ITD) handelt es sich um die häufigste Form der Dystonien, wobei die Ätiologie dieser Erkrankung bisher nicht geklärt ist. Es fanden sich in klinisch-genetischen Studien Anhaltspunkte dafür, dass genetische Faktoren in der Pathogenese eine Rolle spielen. Eine Identifikation spezieller Gene ist aber bisher nicht gelungen. Basierend auf dem bisherigen Wissen über die Pathogenese der F-ITD, wurden im Rahmen dieser Arbeit Kandidatengene analysiert um einen möglichen Zusammenhang zwischen ihnen und der F-ITD zu untersuchen. Studien berichteten über einen gestörten Kupfermetabolismus bei Patienten mit Dystonie, ohne aber dieses Phänomen ätiologisch klären zu können. In dieser Arbeit wurden mit dem Menkes-Gen, dem Wilson-Gen und dem ATOX1-Gen Gene des Kupfermetabolismus analysiert. Auch über gestörte autoimmune Mechanismen bei Patienten mit F-ITD ist mehrfach berichtet worden und genetische Studien zeigten eine Assoziation von Allelen des HLA-DRB Locus mit Dystonien. Es erfolgte eine HLA-DRB Typisierung, um zu untersuchen, ob spezielle Allele des HLA-DRB Locus eine Assoziation zur F-ITD zeigen. Berichtet wurde auch über phänotypische Ähnlichkeiten zwischen tardiven Dyskinesien (TD) und Dystonien, wobei im Gegensatz zur F-ITD bei der TD genetische Susceptibilitätsfaktoren bekannt sind. Unter der Hypothese, dass sich die phänotypischen Gemeinsamkeiten auch auf genetischer Ebene widerspiegeln, wurden die für die TD bekannten Susceptibilitätsfaktoren untersucht: Dieses sind Polymorphismen im µ-Opioid Rezeptor, der Manganesesuperoxiddismutase, im Dopamin-3-Rezeptorgen, im 5HT2A-Serotonin-Rezeptor und im Gen der CYP1A2. Grundlage weiterer Analysen waren die Daten verschiedener Studien, die einen Zusammenhang zwischen Dystonien und Störungen im Homocysteinmetabolismus zeigten. Analysiert wurden hier im Speziellen funktionelle Polymorphismen in der Cystathionin-ß-Synthase (CBS), in der Methylentetrahydrofolatreduktase (MTHFR) und in der Methioninsynthetase (MS), wobei es sich hier um Gene handelt, deren Enzyme Bestandteile des Homocysteinmetabolismus darstellen. Des Weiteren wurden zwei Polymorphismen im DYT1-Gen analysiert mit der Frage, ob sie gehäuft bei Patienten mit F-ITD zu finden sind. Grundlage für die Analyse eines Polymorphismus im Dopamin-D5-Rezeptor (DRD5) war zum einen, dass Studien über Assoziationen von Allelen dieses Polymorphismus mit F-ITD berichteten und zum anderen, dass es Anhaltspunkte für eine Beteiligung des dopaminergen Systems in der Pathogenese der Dystonien gibt. Die Analyse der Kupfertransportproteine ergab keine Anhaltspunkte für eine direkte Beteiligung der untersuchten Gene an der Pathogenese der F-ITD. Auch die Analyse des HLA-DRB Locus zeigte keine signifikanten Assoziationen bestimmter Allele mit der F-ITD. Die Susceptibilitätsfaktoren der tardiven Dyskinesien zeigten keine Assoziation zur F-ITD. Bei der Analyse der Polymorphismen in Genen des Homocysteinstoffwechsels zeigte sich, neben negativen Daten zur MTHFR und MS, in der initial untersuchten deutschen Population eine Assoziation des 31bp-VNTR und der 63bp-Insertion des CBS-Gens mit der F-ITD. Diese Daten konnten jedoch in der französischen Population nicht bestätigt werden. Die Verteilung der Polymorphismen im DYT1-Gen verfehlte im Vergleich von Patienten zu Kontrollen knapp statistisch signifikante Werte. Die Ergebnisse dieser Arbeit zur Analyse des Dopamin-D5-Rezeptors konnten die positiven Daten aus anderen Studien nicht bestätigen. Eine Beteiligung der hier untersuchten Kandidatengene an der Pathogenese der F-ITD wird durch die Daten dieser Arbeit nicht unterstützt. Zu den Ergebnissen der Analyse des CBS-Gens lässt sich festhalten, dass sie nicht das wichtige Kriterium der Replikabilität erfüllen, so dass weitere Studien in anderen Populationen notwendig sein werden. Auch die Bedeutung des Polymorphismus im DRD5-Gen kann nach den negativen Daten dieser Arbeit, die im Widerspruch zu positiven Ergebnissen anderer Studien stehen, nicht abschließend beurteilt werden. Weitere Studien mit großen Studienpopulationen werden notwendig sein, diesen Widerspruch zu klären und auch andere mögliche Kandidatengene bzw. Susceptibilitätsfaktoren zur F-ITD zu identifizieren. Dieses könnte dann die Grundlage für einen möglichen therapeutischen Ansatz sein, ganz ähnlich wie es bei der DYT1-Dystonie in vitro mit Erfolg bereits praktiziert wurde

Identification of a Novel Mutation in the ATP7A Gene in a Korean Patient with Menkes Disease

Menkes disease is an infantile-onset X-linked recessive neurodegenerative disorder caused by diverse mutations in a copper-transport gene, ATP7A. Affected patients are characterized by progressive hypotonia, seizures, failure to thrive and death in early childhood. Here, we report a case of Menkes disease presented by intractable seizures and infantile spasms. A 3-month-old male infant had visited our pediatric clinic for lethargy, floppy muscle tone, poor oral intake and partial seizures. His hair was kinky, brown colored and fragile. Partial seizures became more frequent, generalized and intractable to antiseizure medications. An EEG showed frequent posteriorly dominant generalized spikes that were consistent with a generalized seizure. From a genetic analysis, a c.2743C>T (p.Gln915X) mutation was detected and diagnosed as Menkes disease. The mutation is a novel one that has not been previously reported as a cause of Menkes disease

Inherited Copper Transport Disorders: Biochemical Mechanisms, Diagnosis, and Treatment

Copper is an essential trace element required by all living organisms. Excess amounts of copper, however, results in cellular damage. Disruptions to normal copper homeostasis are hallmarks of three genetic disorders: Menkes disease, occipital horn syndrome, and Wilson’s disease

Clinical and molecular characterization of Wilson's disease in China: identification of 14 novel mutations

<p>Abstract</p> <p>Background</p> <p>Wilson's disease (WND) is a rare autosomal recessive disorder. Here we have evaluated 62 WND cases (58 probands) from the Chinese Han population to expand our knowledge of <it>ATP7B </it>mutations and to more completely characterize WND in China.</p> <p>Methods</p> <p>The coding and promoter regions of the <it>ATP7B </it>gene were analyzed by direct sequencing in 62 Chinese patients (58 probands) with WND (male, n = 37; female, n = 25; age range, 2 ~ 61 years old).</p> <p>Results</p> <p>Neurologic manifestations were associated with older age at diagnosis (p < 0.0001) and longer diagnostic delay (p < 0.0001). Age at diagnosis was also correlated with urinary copper concentration (r = 0.58, p < 0.001). Forty different mutations, including 14 novel mutations, were identified in these patients. Common mutations included p.Arg778Leu (31.9%) and p.Pro992Leu (11.2%). Homozygous p.Arg778Leu and nonsense mutation/frameshift mutations were more often associated with primary hepatic manifestations (p = 0.0286 and p = 0.0383, respectively) and higher alanine transaminase levels at diagnosis (p = 0.0361 and p = 0.0047, respectively). Nonsense mutation/frameshift mutations were also associated with lower serum ceruloplasmin (p = 0.0065).</p> <p>Conclusions</p> <p>We identified 14 novel mutations and found that the spectrum of mutations of <it>ATP7B </it>in China is quite distinct from that of Western countries. The mutation type plays a role in predicting clinical manifestations. Genetic testing is a valuable tool to detect WND in young children, especially in patients younger than 8 years old. Four exons (8, 12, 13, and 16) and two mutations (p.Arg778Leu, p.Pro992Leu) should be considered high priority for cost-effective testing in China.</p