MEDNIK syndrome: a novel defect of copper metabolism treatable by zinc acetate therapy

Brain and the whole-body bone imaging appearances in Menkes disease: a case report and literature review

BACKGROUND

Menkes disease (MD) is a rare, inherited, multisystemic copper metabolism disorder. Classical Menkes disease is characterized by low serum copper and ceruloplasmin concentrations, leading to multiple abnormalities in the whole-body, especially in connective tissue and central nervous system. However, serum copper and ceruloplasmin levels are not reliable diagnostic biomarkers due to the low concentrations in healthy newborns either. The featured imaging manifestations play an important role in diagnosing Menkes disease. To our knowledge, there are few reports on the systemic imaging manifestations of Menkes disease.

CASE PRESENTATION

A 4-month-old male patient presented with recurrent seizures. He had cognitive, intellectual, growth, gross motor, precision movement, and language developmental lags. The patient's hemoglobin and serum ceruloplasmin level were low. On MRI, increased intracranial vascular tortuosity, cerebral and cerebellar atrophy, white matter changes, and basal ganglia abnormalities were observed. Plain radiograph revealed wormian bones, rib flaring, metaphyseal spurring, and periosteal reactions in the long bones of the limbs. A pathogenic variant in ATP7A gene was identified in the patient, so he was confirmed the diagnosis of Menkes disease. His symptoms did not improve despite symptomatic and supportive treatment during his hospitalization. Unfortunately, the infant died 3 months after leaving hospital.

CONCLUSION

A comprehensive and intuitive understanding of the disease's imaging manifestations can help clinicians to identify the disease and avoid delays in care.

A novel network-based method identifies a cuproplasia-related pan-cancer gene signature to predict patient outcome

Copper is a vital micronutrient involved in many biological processes and is an essential component of tumour cell growth and migration. Copper influences tumour growth through a process called cuproplasia, defined as abnormal copper-dependent cell-growth and proliferation. Copper-chelation therapy targeting this process has demonstrated efficacy in several clinical trials against cancer. While the molecular pathways associated with cuproplasia are partially known, genetic heterogeneity across different cancer types has limited the understanding of how cuproplasia impacts patient survival. Utilising RNA-sequencing data from The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) datasets, we generated gene regulatory networks to identify the critical cuproplasia-related genes across 23 different cancer types. From this, we identified a novel 8-gene cuproplasia-related gene signature associated with pan-cancer survival, and a 6-gene prognostic risk score model in low grade glioma. These findings highlight the use of gene regulatory networks to identify cuproplasia-related gene signatures that could be used to generate risk score models. This can potentially identify patients who could benefit from copper-chelation therapy and identifies novel targeted therapeutic strategies.

Regulation of the apico-basolateral trafficking polarity of the homologous copper-ATPases ATP7A and ATP7B

The homologous P-type copper-ATPases (Cu-ATPases) ATP7A and ATP7B are the key regulators of copper homeostasis in mammalian cells. In polarized epithelia, upon copper treatment, ATP7A and ATP7B traffic from the trans-Golgi network (TGN) to basolateral and apical membranes, respectively. We characterized the sorting pathways of Cu-ATPases between TGN and the plasma membrane and identified the machinery involved. ATP7A and ATP7B reside on distinct domains of TGN in limiting copper conditions, and in high copper, ATP7A traffics to basolateral membrane, whereas ATP7B traverses common recycling, apical sorting and apical recycling endosomes en route to apical membrane. Mass spectrometry identified regulatory partners of ATP7A and ATP7B that include the adaptor protein-1 complex. Upon knocking out pan-AP-1, sorting of both Cu-ATPases is disrupted. ATP7A loses its trafficking polarity and localizes on both apical and basolateral surfaces in high copper. By contrast, ATP7B loses TGN retention but retained its trafficking polarity to the apical domain, which became copper independent. Using isoform-specific knockouts, we found that the AP-1A complex provides directionality and TGN retention for both Cu-ATPases, whereas the AP-1B complex governs copper-independent trafficking of ATP7B solely. Trafficking phenotypes of Wilson disease-causing ATP7B mutants that disrupts putative ATP7B-AP1 interaction further substantiates the role of AP-1 in apical sorting of ATP7B.

Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets

Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.

Downregulation of AP1S1 causes the lysosomal degradation of EGFR in non-small cell lung cancer

Matrix stiffness has been shown to play a critical role in cancer progression by influencing various cellular processes, including epidermal growth factor (EGF) signaling. However, the underlying molecular mechanisms are not fully understood. Here, we investigated the role of adaptor-related protein complex 1 subunit sigma 1 (AP1S1), a component of adaptor protein complex-1, in the regulation of EGF receptor (EGFR) intracellular trafficking during cancer cell progression. We found that AP1S1 expression was upregulated under stiff matrix conditions, resulting in the regulation of EGFR trafficking in non-small cell lung adenocarcinoma cells. Knockout of AP1S1 caused the lysosomal degradation of EGFR, leading to suppressed EGF-induced anaplastic lymphoma receptor tyrosine kinase phosphorylation. In addition, the downregulation of AP1S1 increased the sensitivity of H1975 cancer cells, which are resistant to tyrosine kinase inhibitors, to erlotinib. Collectively, our results suggest that AP1S1 could regulate EGFR recycling under stiff matrix conditions, and AP1S1 inhibition could be a novel strategy for treating cancer cells resistant to EGFR-targeted anticancer drugs.

Do PACS1 variants impeding adaptor protein binding predispose to syndromic intellectual disability?

To date, PACS1-neurodevelopmental disorder (PACS1-NDD) has been associated with recurrent variation of Arg203 and is considered diagnostic of PACS1-NDD, an autosomal dominant syndromic intellectual disability disorder. Although incompletely defined, the proposed disease mechanism for this variant is altered PACS1 affinity for its client proteins. Given this proposed mechanism, we hypothesized that PACS1 variants that interfere with binding of adaptor proteins might also give rise to syndromic intellectual disability. Herein, we report a proposita and her mother with phenotypic features overlapping PACS1-NDD and a novel PACS1 variant (NM_018026.3:c.[755C > T];[=], p.(Ser252Phe)) that impedes binding of the adaptor protein GGA3 (Golgi-associated, gamma-adaptin ear-containing, ARF-binding protein 3). We hypothesize that attenuating PACS1 binding of GGA3 also gives rise to a disorder with features overlapping those of PACS1-NDD. This observation better delineates the mechanism by which PACS1 variation predisposes to syndromic intellectual disability.

Syndromic ichthyoses

Inherited ichthyoses are classified as Mendelian disorders of cornification (MEDOC), which are further defined on the basis of clinical and genetic features and can be divided into non-syndromic and syndromic forms. To date, mutations in more than 30 genes are known to result in various types of syndromic ichthyoses, which, in addition to mostly generalised scaling and hyperkeratosis of the skin, also show additional organ involvement. The syndromic ichthyoses are generally very rare and are classified based on the mode of inheritance, and can be further subdivided according to the predominant symptoms. In our review we provide a concise overview of the most prevalent syndromic forms of ichthyosis within each subgroup. We emphasize the importance of the clinical assessment of complex syndromes even in the era of genetic testing as a first-tier diagnostic and specifically the need to actively assess potential organ involvement in patients with ichthyosis, thereby enabling efficient diagnostic and therapeutic approaches and timely access to specialized centers for rare disorders of cornifications. As part of the Freiburg Center for Rare Diseases a Center for Cornification Disorders was recently established with collaboration of the Institute of Human Genetics and the Department of Dermatology. An early diagnosis of syndromes will be of direct benefit to the patient regarding interventional and therapeutic measures e. g. in syndromes with cardiac or metabolic involvement and allows informed reproductive options and access to prenatal and preimplantation genetic diagnosis in the family.

Mitochondrial copper in human genetic disorders

Copper is an essential micronutrient that serves as a cofactor for enzymes involved in diverse physiological processes, including mitochondrial energy generation. Copper enters cells through a dedicated copper transporter and is distributed to intracellular cuproenzymes by copper chaperones. Mitochondria are critical copper-utilizing organelles that harbor an essential cuproenzyme cytochrome c oxidase, which powers energy production. Mutations in copper transporters and chaperones that perturb mitochondrial copper homeostasis result in fatal genetic disorders. Recent studies have uncovered the therapeutic potential of elesclomol, a copper ionophore, for the treatment of copper deficiency disorders such as Menkes disease. Here we review the role of copper in mitochondrial energy metabolism in the context of human diseases and highlight the recent developments in copper therapeutics.

The genetics of monogenic intestinal epithelial disorders

Monogenic intestinal epithelial disorders, also known as congenital diarrheas and enteropathies (CoDEs), are a group of rare diseases that result from mutations in genes that primarily affect intestinal epithelial cell function. Patients with CoDE disorders generally present with infantile-onset diarrhea and poor growth, and often require intensive fluid and nutritional management. CoDE disorders can be classified into several categories that relate to broad areas of epithelial function, structure, and development. The advent of accessible and low-cost genetic sequencing has accelerated discovery in the field with over 45 different genes now associated with CoDE disorders. Despite this increasing knowledge in the causal genetics of disease, the underlying cellular pathophysiology remains incompletely understood for many disorders. Consequently, clinical management options for CoDE disorders are currently limited and there is an urgent need for new and disorder-specific therapies. In this review, we provide a general overview of CoDE disorders, including a historical perspective of the field and relationship to other monogenic disorders of the intestine. We describe the genetics, clinical presentation, and known pathophysiology for specific disorders. Lastly, we describe the major challenges relating to CoDE disorders, briefly outline key areas that need further study, and provide a perspective on the future genetic and therapeutic landscape.

Critical Points in the Methodology of Preparing Copper (II) Histidinate Injections and their Quality Assessment Applying Color Measurement

Copper (II) histidinate injection solution, applied in Menkes disease treatment, is characterized by low stability due to sensitivity to oxidation. The aim of this article was to determine the critical points of the injection preparation procedure, taking into account selection of appropriate packaging, determining the solution pH or application of an excess of L-histidine. In order to assess the stability of the Cu(His)2 complex, the spectrophotometric method (VIS: 400-800 nm), and the colorimetric method using a reflectance colorimeter were applied. The color changes observed using the CIELAB color system made it possible to determine: the differences in the observed color (ΔΕ) and the color chroma (C*) and hue (h°). It was found that the following parameters: λmax and ΔE enable fast and objective assessment of copper (II) histidinate injection solution quality. The advantage of the colorimetric method is the non-invasiveness of the analysis which is performed through the packaging material (transparent vial). The developed methodology of preparing Cu(His)2 injections in hospitals or community pharmacies guarantees their stability for at least 6 months, provided that the solution is stored at lower temperatures (2-8°C or 4°C).

Extrahepatic manifestations of progressive familial intrahepatic cholestasis syndromes: Presentation of a case series and literature review

BACKGROUND AND AIMS

Progressive familial intrahepatic cholestasis (PFIC) is a collective term for a heterogenous group of rare, inherited cholestasis syndromes. The number of genes underlying the clinical PFIC phenotype is still increasing. While progressive liver disease and its sequelae such as portal hypertension, pruritus and hepatocellular carcinoma determine transplant-free survival, extrahepatic manifestations may cause relevant morbidity.

METHODS

We performed a literature search for extrahepatic manifestations of PFIC associated with pathogenic gene variants in ATP8B1, ABCB11, ABCB4, TJP2, NR1H4 and MYO5B. To illustrate the extrahepatic symptoms described in the literature, PFIC cases from our centres were revisited.

RESULTS

Extrahepatic symptoms are common in PFIC subtypes, where the affected gene is expressed at high levels in other tissues. While most liver-associated complications resolve after successful orthotopic liver transplantation (OLT), some extrahepatic symptoms show no response or even worsen after OLT.

CONCLUSION

The spectrum of extrahepatic manifestations in PFIC highlights essential, non-redundant roles of the affected genes in other organs. Extrahepatic features contribute towards low health-related quality of life (HRQOL) and morbidity in PFIC. While OLT is often the only remaining, curative treatment, potential extrahepatic manifestations need to be carefully monitored and addressed.

Mechanisms regulating the sorting of soluble lysosomal proteins

Lysosomes are key regulators of many fundamental cellular processes such as metabolism, autophagy, immune response, cell signalling and plasma membrane repair. These highly dynamic organelles are composed of various membrane and soluble proteins, which are essential for their proper functioning. The soluble proteins include numerous proteases, glycosidases and other hydrolases, along with activators, required for catabolism. The correct sorting of soluble lysosomal proteins is crucial to ensure the proper functioning of lysosomes and is achieved through the coordinated effort of many sorting receptors, resident ER and Golgi proteins, and several cytosolic components. Mutations in a number of proteins involved in sorting soluble proteins to lysosomes result in human disease. These can range from rare diseases such as lysosome storage disorders, to more prevalent ones, such as Alzheimer’s disease, Parkinson’s disease and others, including rare neurodegenerative diseases that affect children. In this review, we discuss the mechanisms that regulate the sorting of soluble proteins to lysosomes and highlight the effects of mutations in this pathway that cause human disease. More precisely, we will review the route taken by soluble lysosomal proteins from their translation into the ER, their maturation along the Golgi apparatus, and sorting at the trans-Golgi network. We will also highlight the effects of mutations in this pathway that cause human disease.

The Overexpression and Clinical Significance of AP1S1 in Breast Cancer

Purpose

To explore the mechanism of AP1S1 in breast cancer.

Methods and Results

In different datasets, we found that AP1S1 is more highly expressed in breast tumors, which was furthermore verified in our local cohort.Immune infiltration analysis showed that AP1S1 was related to a variety of immune cells. The higher AP1S1 expression was negatively correlated with a variety of immune infiltrating cells, suggesting that AP1S1 may affect cellular immunity.Clinical analysis showed that patients with higher AP1S1 expression had higher estrogen receptor gene expression and were more prone to distant metastasis and lymph node metastasis.The overall survival rate, disease-specific survival rate, and progression-free interval time were worse in the group with higher AP1S1 expression. AP1S1 may be a potential oncogene of breast cancer, and overexpression is related to the poor prognosis of breast cancer.Therefore, a nomogram was constructed, along with correlated gene analysis and functional analysis to further explore the carcinogenic mechanism, practical clinical issues, and value of AP1S1.

Conclusion

AP1S1 is a potential oncogene of breast cancer.

Phenotypic spectrum of autosomal recessive Keratitis-Ichthyosis-Deafness Syndrome (KIDAR) due to mutations in AP1B1

Inborn errors in copper metabolism result in a diverse set of abnormalities such as Wilson disease and MEDNIK syndrome. Homozygous pathogenic variants in AP1B1 lead to KIDAR (Keratitis-Ichthyosis-Deafness Syndrome). The main phenotypic features of KIDAR are ichthyosis, keratitis, erythroderma, and progressive hearing loss accompanied by developmental delay and failure to thrive. Herein, we describe a six-and-a-half-year-old boy with KIDAR caused by a novel pathogenic variant in AP1B1 (NM_001127.4:c.1263C > A, p.Tyr421*). The proband presented with ichthyosis, erythroderma, palmoplantar keratoderma, hearing loss, and corneal scarring. He also had hypotonia, global developmental delay, and photophobia. Lastly, we review all of the previously reported cases and the clinical features associated with KIDAR.

Delineating toxicity mechanisms associated with MRI contrast enhancement through a multidimensional toxicogenomic profiling of gadolinium

Gadolinium is a metal used in contrast agents for magnetic resonance imaging. Although gadolinium is widely used in clinical settings, many concerns regarding its toxicity and bioaccumulation after gadolinium-based contrast agent administration have been raised and published over the last decade. To date, most toxicological studies have focused on identifying acute effects following gadolinium exposure, rather than investigating associated toxicity mechanisms. In this study, we employ functional toxicogenomics to assess mechanistic interactions of gadolinium with Saccharomyces cerevisiae. Furthermore, we determine which mechanisms are conserved in humans, and their implications for diseases related to the use of gadolinium-based contrast agents in medicine. A homozygous deletion pool of 4291 strains were screened to identify biological functions and pathways disturbed by the metal. Gene ontology and pathway enrichment analyses showed endocytosis and vesicle-mediated transport as the main yeast response to gadolinium, while certain metabolic processes, such as glycosylation, were the primary disrupted functions after the metal treatments. Cluster and protein-protein interaction network analyses identified proteins mediating vesicle-mediated transport through the Golgi apparatus and the vacuole, and vesicle cargo exocytosis as key components to reduce the metal toxicity. Moreover, the metal seemed to induce cytotoxicity by disrupting the function of enzymes (e.g. transferases and proteases) and chaperones involved in metabolic processes. Several of the genes and proteins associated with gadolinium toxicity are conserved in humans, suggesting that they may participate in pathologies linked to gadolinium-based contrast agent exposures. We thereby discuss the potential role of these conserved genes and gene products in gadolinium-induced nephrogenic systemic fibrosis, and propose potential prophylactic strategies to prevent its adverse health effects.

Induction of Bile Canaliculi-Forming Hepatocytes from Human Pluripotent Stem Cells

Cell polarity and formation of bile canaliculi can be achieved in hepatocytes which are generated from patient-derived induced pluripotent stem cells. This allows for the study of endogenous mutant proteins, patient-specific pathogenesis, and drug responses for diseases where hepatocyte polarity and bile canaliculi play a key role. Here, we describe a step-by-step protocol for the generation of bile canaliculi-forming hepatocytes from induced pluripotent stem cells and their evaluation.

Crossroads between membrane trafficking machinery and copper homeostasis in the nerve system

Imbalanced copper homeostasis and perturbation of membrane trafficking are two common symptoms that have been associated with the pathogenesis of neurodegenerative and neurodevelopmental diseases. Accumulating evidence from biophysical, cellular and in vivo studies suggest that membrane trafficking orchestrates both copper homeostasis and neural functions-however, a systematic review of how copper homeostasis and membrane trafficking interplays in neurons remains lacking. Here, we summarize current knowledge of the general trafficking itineraries for copper transporters and highlight several critical membrane trafficking regulators in maintaining copper homeostasis. We discuss how membrane trafficking regulators may alter copper transporter distribution in different membrane compartments to regulate intracellular copper homeostasis. Using Parkinson's disease and MEDNIK as examples, we further elaborate how misregulated trafficking regulators may interplay parallelly or synergistically with copper dyshomeostasis in devastating pathogenesis in neurodegenerative diseases. Finally, we explore multiple unsolved questions and highlight the existing challenges to understand how copper homeostasis is modulated through membrane trafficking.

Copper in tumors and the use of copper-based compounds in cancer treatment

Copper homeostasis is strictly regulated by protein transporters and chaperones, to allow its correct distribution and avoid uncontrolled redox reactions. Several studies address copper as involved in cancer development and spreading (epithelial to mesenchymal transition, angiogenesis). However, being endogenous and displaying a tremendous potential to generate free radicals, copper is a perfect candidate, once opportunely complexed, to be used as a drug in cancer therapy with low adverse effects. Copper ions can be modulated by the organic counterpart, after complexed to their metalcore, either in redox potential or geometry and consequently reactivity. During the last four decades, many copper complexes were studied regarding their reactivity toward cancer cells, and many of them could be a drug choice for phase II and III in cancer therapy. Also, there is promising evidence of using ⁶⁴Cu in nanoparticles as radiopharmaceuticals for both positron emission tomography (PET) imaging and treatment of hypoxic tumors. However, few compounds have gone beyond testing in animal models, and none of them got the status of a drug for cancer chemotherapy. The main challenge is their solubility in physiological buffers and their different and non-predictable mechanism of action. Moreover, it is difficult to rationalize a structure-based activity for drug design and delivery. In this review, we describe the role of copper in cancer, the effects of copper-complexes on tumor cell death mechanisms, and point to the new copper complexes applicable as drugs, suggesting that they may represent at least one component of a multi-action combination in cancer therapy.

Metals and Metal-Nanoparticles in Human Pathologies: From Exposure to Therapy

An increasing number of pathologies correlates with both toxic and essential metal ions dyshomeostasis. Next to known genetic disorders (e.g., Wilson's Disease and β-Thalassemia) other pathological states such as neurodegeneration and diabetes are characterized by an imbalance of essential metal ions. Metal ions can enter the human body from the surrounding environment in the form of free metal ions or metal-nanoparticles, and successively translocate to different tissues, where they are accumulated and develop distinct pathologies. There are no characteristic symptoms of metal intoxication, and the exact diagnosis is still difficult. In this review, we present metal-related pathologies with the most common onsets, biomarkers of metal intoxication, and proper techniques of metal qualitative and quantitative analysis. We discuss the possible role of drugs with metal-chelating ability in metal dyshomeostasis, and present recent advances in therapies of metal-related diseases.

Immunoglobulin a nephropathy as the first clinical presentation of Wilson disease: a case report and literature review

Background

Wilson disease (WD) is a rare genetic disorder of copper metabolism. Differences in copper tissue accumulation lead to various clinical manifestations, including some atypical presentations. The complex clinical features of WD make diagnosis challenging, delaying the best chance for treatment.

Case presentation

We report a case of a 26-year-old man with nephritis-range proteinuria and elevated serum creatinine. The renal pathology indicated immunoglobulin A (IgA) nephropathy and tubular injury, which was inconsistent with glomerular lesions. Cirrhosis was also detected by imaging examination. Considering both kidney injury and liver damage, WD was suspected. Based on results showing abnormal copper metabolism, corneal Kayser–Fleischer rings, and genetic disorders in the ATP7B gene, the patient was finally diagnosed with WD. After treatment with oral penicillamine, zinc sulfate and losartan, the patient showed alleviation of both WD and nephropathy after 3 years of follow-up. He maintained a good quality of daily life.

Conclusion

This case highlights that unexplained neurological and liver symptoms in patients with IgA nephropathy can be clues for WD.

Axonal Charcot-Marie-Tooth Disease: from Common Pathogenic Mechanisms to Emerging Treatment Opportunities

Inherited peripheral neuropathies are a genetically and phenotypically diverse group of disorders that lead to degeneration of peripheral neurons with resulting sensory and motor dysfunction. Genetic neuropathies that primarily cause axonal degeneration, as opposed to demyelination, are most often classified as Charcot-Marie-Tooth disease type 2 (CMT2) and are the focus of this review. Gene identification efforts over the past three decades have dramatically expanded the genetic landscape of CMT and revealed several common pathological mechanisms among various forms of the disease. In some cases, identification of the precise genetic defect and/or the downstream pathological consequences of disease mutations have yielded promising therapeutic opportunities. In this review, we discuss evidence for pathogenic overlap among multiple forms of inherited neuropathy, highlighting genetic defects in axonal transport, mitochondrial dynamics, organelle-organelle contacts, and local axonal protein translation as recurrent pathological processes in inherited axonal neuropathies. We also discuss how these insights have informed emerging treatment strategies, including specific approaches for single forms of neuropathy, as well as more general approaches that have the potential to treat multiple types of neuropathy. Such therapeutic opportunities, made possible by improved understanding of molecular and cellular pathogenesis and advances in gene therapy technologies, herald a new and exciting phase in inherited peripheral neuropathy.

Copper Imbalance in Alzheimer's Disease and Its Link with the Amyloid Hypothesis: Towards a Combined Clinical, Chemical, and Genetic Etiology

The cause of Alzheimer's disease (AD) is incompletely defined. To date, no mono-causal treatment has so far reached its primary clinical endpoints, probably due to the complexity and diverse neuropathology contributing to the neurodegenerative process. In the present paper, we describe the plausible etiological role of copper (Cu) imbalance in the disease. Cu imbalance is strongly associated with neurodegeneration in dementia, but a complete biochemical etiology consistent with the clinical, chemical, and genetic data is required to support a causative association, rather than just correlation with disease. We hypothesize that a Cu imbalance in the aging human brain evolves as a gradual shift from bound metal ion pools, associated with both loss of energy production and antioxidant function, to pools of loosely bound metal ions, involved in gain-of-function oxidative stress, a shift that may be aggravated by chemical aging. We explain how this may cause mitochondrial deficits, energy depletion of high-energy demanding neurons, and aggravated protein misfolding/oligomerization to produce different clinical consequences shaped by the severity of risk factors, additional comorbidities, and combinations with other types of pathology. Cu imbalance should be viewed and integrated with concomitant genetic risk factors, aging, metabolic abnormalities, energetic deficits, neuroinflammation, and the relation to tau, prion proteins, α-synuclein, TAR DNA binding protein-43 (TDP-43) as well as systemic comorbidity. Specifically, the Amyloid Hypothesis is strongly intertwined with Cu imbalance because amyloid-β protein precursor (AβPP)/Aβ are probable Cu/Zn binding proteins with a potential role as natural Cu/Zn buffering proteins (loss of function), and via the plausible pathogenic role of Cu-Aβ.

Wilson's Disease: Facing the Challenge of Diagnosing a Rare Disease

Wilson disease (WD) is a rare disorder caused by mutations in ATP7B, which leads to the defective biliary excretion of copper. The subsequent gradual accumulation of copper in different organs produces an extremely variable clinical picture, which comprises hepatic, neurological psychiatric, ophthalmological, and other disturbances. WD has a specific treatment, so that early diagnosis is crucial to avoid disease progression and its devastating consequences. The clinical diagnosis is based on the Leipzig score, which considers clinical, histological, biochemical, and genetic data. However, even patients with an initial WD diagnosis based on a high Leipzig score may harbor other conditions that mimic the WD's phenotype (Wilson-like). Many patients are diagnosed using current available methods, but others remain in an uncertain area because of bordering ceruloplasmin levels, inconclusive genetic findings and unclear phenotypes. Currently, the available biomarkers for WD are ceruloplasmin and copper in the liver or in 24 h urine, but they are not solid enough. Therefore, the characterization of biomarkers that allow us to anticipate the evolution of the disease and the monitoring of new drugs is essential to improve its diagnosis and prognosis.

Genodermatoses with hearing impairment

Hearing loss is a prominent feature in multiple genodermatoses. Underappreciation of auditory deficits can misdirect proper diagnosis by the treating dermatologist. This review reviews the anatomic, developmental, and embryologic aspects that characterize the ear and summarizes genodermatoses that have aberrant auditory findings. The latter are classified into neural crest, metabolic, pigmentary, craniofacial, and a miscellaneous category of disorders lacking specific cutaneous findings. The algorithms provided in this review enable treating dermatologists to better recognize and manage genodermatoses with ear involvement.

Copper-Induced Epigenetic Changes Shape the Clinical Phenotype in Wilson's Disease

Wilson's disease is a congenital disorder of copper metabolism whose pathogenesis remains, at least in part, unknown. Subjects carrying the same genotype may show completely different phenotypes, differing for the age at illness onset or for the hepatic, neurologic or psychiatric clinical presentation. The inability to find a unequivocal correlation between the type of mutation in the ATPase copper transporting beta (ATP7B) gene and the phenotypic manifestation, has encouraged many authors to look for epigenetic factors interacting with the genetic changes. Here, the evidences regarding the ability of copper overload to change the global DNA methylation status are discussed.

Adult diagnosis of congenital serine biosynthesis defect: A treatable cause of progressive neuropathy

A woman with ichthyosis, contractures, and progressive neuropathy represents the first case of phosphoserine aminotransferase deficiency diagnosed and treated in an adult. She has novel compound heterozygous mutations in the gene PSAT1. Treatment with high dose oral L-serine completely resolved the ichthyosis. Consideration of this diagnosis is important because early treatment with L-serine repletion can halt progression of neurodegeneration and potentially improve neurological disabilities. As exome sequencing becomes more widely implemented in the diagnostic evaluation of progressive neurodegenerative phenotypes, adult neurologists and geneticists will increasingly encounter later onset manifestations of inborn errors of metabolism classically considered in infancy and early childhood.

Genetic causes of fractures and subdural hematomas: fact versus fiction

Genetic disorders are in the differential diagnosis when young children present with unexplained fractures or intracranial hemorrhage. For medical and legal reasons, it is imperative to make the correct diagnosis and provide clear, evidence-based explanations of how alternative diagnoses were ruled out. A genetics consultation in cases of suspected child physical abuse should synthesize the history of present illness, medical history, family history, physical examination, and radiologic and laboratory findings in consultation with other specialists. The medical geneticist highlights how these disorders truly present. When the natural history of a genetic disorder is understood, it becomes clear that genetic disorders are not mysterious or difficult to diagnose. As highlighted in this case-based review, mainstream medical practice allows for differentiation among the intracranial and skeletal manifestations of osteogenesis imperfecta, Menkes disease, glutaric acidemia type 1 and child physical abuse. This review also highlights how a genetic disorder, Ehlers-Danlos syndrome, can be misused in a courtroom. Finally, this review summarizes when genetic testing is appropriate in cases of suspected child physical abuse.

Etiology and Management of Pediatric Intestinal Failure: Focus on the Non-Digestive Causes

Background: Intestinal failure (IF) is defined as reduction in functioning gut mass below the minimal amount necessary for adequate digestion and absorption. In most cases, IF results from intrinsic diseases of the gastrointestinal tract (digestive IF) (DIF); few cases arise from digestive vascular components, gut annexed (liver and pancreas) and extra-digestive organs or from systemic diseases (non-digestive IF) (NDIF). The present review revised etiology and treatments of DIF and NDIF, with special focus on the pathophysiological mechanisms, whereby NDIF develops. Methods: We performed a comprehensive search of published literature from January 2010 to the present by selecting the following search strings: “intestinal failure” OR “home parenteral nutrition” OR “short bowel syndrome” OR “chronic pseudo-obstruction” OR “chronic intestinal pseudo-obstruction” OR “autoimmune enteropathy” OR “long-term parenteral nutrition”. Results: We collected overall 1656 patients with well-documented etiology of IF: 1419 with DIF (86%) and 237 with NDIF (14%), 55% males and 45% females. Among DIF cases, 66% had SBS and among NDIF cases 90% had malabsorption/maldigestion. Conclusions: The improved availability of diagnostic and therapeutic tools has increased prevalence and life expectancy of rare and severe diseases responsible for IF. The present review greatly expands the spectrum of knowledge on the pathophysiological mechanisms through which the diseases not strictly affecting the intestine can cause IF. In view of the rarity of the majority of pediatric IF diseases, the development of IF Registries is strongly required; in fact, through information flow within the network, the Registries could improve IF knowledge and management.

Copper deficiency-associated myelopathy in cryptogenic hyperzincemia: a case report

Copper deficiency syndrome is an underestimated cause of posterior myelitis. We describe the case of a 41-year-old woman, who developed a subacute ataxic paraparesis associated with low back pain. Her 3T spine MRI showed a thin hyperintense FS-Echo T2 longitudinally extensive lesion involving the posterior columns of the cervical cord (from C2 to C6). An extensive diagnostic work-up excluded other causes of myelopathy and blood tests pointed out hypocupremia and mild hyperzincemia. Patients affected by this rare form of oligoelement deficiency typically develop progressive posterior column dysfunction with sensory ataxia and spasticity, sometimes associated with sensori-motor polyneuropathy. Clinical and radiological characteristics of posterior myelopathy due to copper deficiency are briefly reviewed. Physicians should be aware of this condition since a prompt introduction of copper supplementation can avoid progression of the neurological damage. (www.actabiomedica.it)

A Link between Intrahepatic Cholestasis and Genetic Variations in Intracellular Trafficking Regulators

Simple Summary

Cholestasis refers to a medical condition in which the liver is not capable of secreting bile. The consequent accumulation of toxic bile components in the liver leads to liver failure. Cholestasis can be caused by mutations in genes that code for proteins involved in bile secretion. Recently mutations in other genes have been discovered in patients with cholestasis of unknown origin. Interestingly, many of these newly discovered genes code for proteins that regulate the intracellular distribution of other proteins, including those involved in bile secretion. This group of genes thus suggests the deregulated intracellular distribution of bile-secreting proteins as an important but still poorly understood mechanism that underlies cholestasis. To expedite a better understanding of this mechanism, we have reviewed these genes and their mutations and we discuss these in the context of cholestasis.

Abstract

Intrahepatic cholestasis is characterized by the accumulation of compounds in the serum that are normally secreted by hepatocytes into the bile. Genes associated with familial intrahepatic cholestasis (FIC) include ATP8B1 (FIC1), ABCB11 (FIC2), ABCB4 (FIC3), TJP2 (FIC4), NR1H4 (FIC5) and MYO5B (FIC6). With advanced genome sequencing methodologies, additional mutated genes are rapidly identified in patients presenting with idiopathic FIC. Notably, several of these genes, VPS33B, VIPAS39, SCYL1, and AP1S1, together with MYO5B, are functionally associated with recycling endosomes and/or the Golgi apparatus. These are components of a complex process that controls the sorting and trafficking of proteins, including those involved in bile secretion. These gene variants therefore suggest that defects in intracellular trafficking take a prominent place in FIC. Here we review these FIC-associated trafficking genes and their variants, their contribution to biliary transporter and canalicular protein trafficking, and, when perturbed, to cholestatic liver disease. Published variants for each of these genes have been summarized in table format, providing a convenient reference for those who work in the intrahepatic cholestasis field.

Copper metabolism as a unique vulnerability in cancer

The last 25 years have witnessed tremendous progress in identifying and characterizing proteins that regulate the uptake, intracellular trafficking and export of copper. Although dietary copper is required in trace amounts, sufficient quantities of this metal are needed to sustain growth and development in humans and other mammals. However, copper is also a rate-limiting nutrient for the growth and proliferation of cancer cells. Oral copper chelators taken with food have been shown to confer anti-neoplastic and anti-metastatic benefits in animals and humans. Recent studies have begun to identify specific roles for copper in pathways of oncogenic signaling and resistance to anti-neoplastic drugs. Here, we review the general mechanisms of cellular copper homeostasis and discuss roles of copper in cancer progression, highlighting metabolic vulnerabilities that may be targetable in the development of anticancer therapies.

Wilson disease

PURPOSE OF REVIEW

The aim of this article is to review recent developments in the areas of the disease features and treatment of Wilson disease, and survey disorders that share its pathophysiology or clinical symptoms.

RECENT FINDINGS

Knowledge of the clinical spectrum of Wilson disease has expanded with recognition of patients who present in atypical age groups - patients with very early onset (<5 years) and those in whom symptoms present in mid-to-late adulthood. A disease phenotype with dominant psychiatric features and increased risk of cardiac problems and various sleep disorders have been identified.In addition to a better understanding of the phenotype of Wilson disease itself, features of some related disorders ('Wilson disease-mimics') have been described leading to a better understanding of copper homeostasis in humans. These disorders include diseases of copper disposition, such as mental retardation, enteropathy, deafness, neuropathy, ichthyosis, keratoderma syndrome, Niemann-Pick type C, and certain congenital disorders of glycosylation, as well as analogous disorders of iron and manganese metabolism.Outcomes for existing treatments, including in certain patient subpopulations of interest, are better known. Novel treatment strategies being studied include testing of bis-choline tetrathiomolybdate in phase 2 clinical trial as well as various preclinical explorations of new copper chelators and ways to restore ATP7B function or repair the causative gene.

SUMMARY

Recent studies have expanded the phenotype of Wilson disease, identified rare inherited metal-related disorders that resemble Wilson disease, and studied long-term outcomes of existing treatments. These developments can be expected to have an immediate as well as a long-term impact on the clinical management of the disease, and point to promising avenues for future research.

Are the new genetic tools for diagnosis of Wilson disease helpful in clinical practice?

The diagnosis of Wilson disease is not always easy. For many patients, a combination of tests reflecting disturbed copper metabolism may be needed. Testing for ATP7B variants has become part of the routine diagnostic approach. The methods of genetic testing include analysis of the 21 coding exons and intronic flanking sequences, in which exons with recurrent variants would be prioritised depending on the mutation frequency in the local population. If sequencing the entire ATP7B gene cannot identify 2 variants and the suspicion for Wilson disease is high, after reviewing the clinical data, WES (whole-exome sequencing) or WGS (whole-genome sequencing) could be applied. A workflow based on the type and number of ATP7B variants responsible for Wilson disease is proposed. Genetic testing is indicated for confirmation of diagnosis, family screening, and screening of newborns and infants and in unclear cases suspected of suffering from Wilson disease. However, genetic testing is not a routine screening test for Wilson disease. If no additional variants can be identified, it can be assumed that other hereditary disorders may mimic Wilson disease (congenital disorders of glycosylation, MEDNIK syndrome, idiopathic or primary copper toxicoses).

AP1S1 missense mutations cause a congenital enteropathy via an epithelial barrier defect

Congenital diarrheal disorders (CDD) comprise > 50 monogenic entities featuring chronic diarrhea of early-onset, including defects in nutrient and electrolyte absorption, enterocyte polarization, enteroendocrine cell differentiation, and epithelial integrity. Diarrhea is also a predominant symptom in many immunodeficiencies, congenital disorders of glycosylation, and in some defects of the vesicular sorting and transporting machinery. We set out to identify the etiology of an intractable diarrhea in 2 consanguineous families by whole-exome sequencing, and identified two novel AP1S1 mutations, c.269T>C (p.Leu90Pro) and c.346G>A (p.Glu116Lys). AP1S1 encodes the small subunit of the adaptor protein 1 complex (AP-1), which plays roles in clathrin coat-assembly and trafficking between trans-Golgi network, endosomes and the plasma membrane. An AP1S1 knock-out (KO) of a CaCo2 intestinal cell line was generated to characterize intestinal AP1S1 deficiency as well as identified mutations by stable expression in KO background. Morphology and prototype transporter protein distribution were comparable between parental and KO cells. We observed altered localization of tight-junction proteins ZO-1 and claudin 3, decreased transepithelial electrical resistance and an increased dextran permeability of the CaCo2-AP1S1-KO monolayer. In addition, lumen formation in 3D cultures of these cells was abnormal. Re-expression of wild-type AP1S1 in CaCo2-AP1S1-KO cells reverted these abnormalities, while expression of AP1S1 containing either missense mutation did not. Our data indicate that loss of AP1S1 function causes an intestinal epithelial barrier defect, and that AP1S1 mutations can cause a non-syndromic form of congenital diarrhea, whereas 2 reported truncating AP1S1 mutations caused MEDNIK syndrome, characterized by mental retardation, enteropathy, deafness, neuropathy, ichthyosis, and keratodermia.

Copper Does Not Induce Tenogenic Differentiation but Promotes Migration and Increases Lysyl Oxidase Activity in Adipose-Derived Mesenchymal Stromal Cells

Background

Copper belongs to the essential trace metals that play a key role in the course of cellular processes maintaining the whole body's homeostasis. As there is a growing interest in transplanting mesenchymal stromal cells (MSCs) into the site of injury to improve the regeneration of damaged tendons, the purpose of the study was to verify whether copper supplementation may have a positive effect on the properties of human adipose tissue-derived MSCs (hASCs) which potentially can contribute to improvement of tendon healing.

Results

Cellular respiration of hASCs decreased with increasing cupric sulfate concentrations after 5 days of incubation. The treatment with CuSO₄ did not positively affect the expression of genes associated with tenogenesis (COL1α1, COL3α1, MKX, and SCX). However, the level of COL1α1 protein, whose transcript was decreased in comparison to a control, was elevated after a 5-day exposition to 25 μM CuSO₄. The content of the MKX and SCX protein in hASCs exposed to cupric sulfate was reduced compared to that of untreated control cells, and the level of the COL3α1 protein, whose transcript was decreased in comparison to a control, was elevated after a 5-day exposition to 25 μM CuSO₄. The content of the MKX and SCX protein in hASCs exposed to cupric sulfate was reduced compared to that of untreated control cells, and the level of the COL3.

Conclusion

Copper sulfate supplementation can have a beneficial effect on tendon regeneration not by inducing tenogenic differentiation, but by improving the recruitment of MSCs to the site of injury, where they can secrete growth factors, cytokines and chemokines, and prevent the effects of oxidative stress at the site of inflammation, as well as improve the stabilization of collagen fibers, thereby accelerating the process of tendon healing.

Genetic Disorders Associated with Metal Metabolism

Genetic disorders associated with metal metabolism form a large group of disorders and mostly result from defects in the proteins/enzymes involved in nutrient metabolism and energy production. These defects can affect different metabolic pathways and cause mild to severe disorders related to metal metabolism. Some disorders have moderate to severe clinical consequences. In severe cases, these elements accumulate in different tissues and organs, particularly the brain. As they are toxic and interfere with normal biological functions, the severity of the disorder increases. However, the human body requires a very small amount of these elements, and a deficiency of or increase in these elements can cause different genetic disorders to occur. Some of the metals discussed in the present review are copper, iron, manganese, zinc, and selenium. These elements may play a key role in the pathology and physiology of the nervous system.

Homozygous Loss-of-Function Mutations in AP1B1, Encoding Beta-1 Subunit of Adaptor-Related Protein Complex 1, Cause MEDNIK-like Syndrome

MEDNIK syndrome (mental retardation, enteropathy, deafness, peripheral neuropathy, ichthyosis, and keratoderma) is an autosomal-recessive disorder caused by bi-allelic mutations in AP1S1, encoding the small σ subunit of the AP-1 complex. Central to the pathogenesis of MEDNIK syndrome is abnormal AP-1-mediated trafficking of copper transporters; this abnormal trafficking results in a hybrid phenotype combining the copper-deficiency-related characteristics of Menkes disease and the copper-toxicity-related characteristics of Wilson disease. We describe three individuals from two unrelated families in whom a MEDNIK-like phenotype segregates with two homozygous null variants in AP1B1, encoding the large β subunit of the AP-1 complex. Similar to individuals with MEDNIK syndrome, the affected individuals we report display abnormal copper metabolism, evidenced by low plasma copper and ceruloplasmin, but lack evidence of copper toxicity in the liver. Functional characterization of fibroblasts derived from affected individuals closely resembles the abnormal ATP7A trafficking described in MEDNIK syndrome both at baseline and in response to copper treatment. Taken together, our results expand the list of inborn errors of copper metabolism.

Adaptor protein complexes and disease at a glance

Adaptor protein (AP) complexes are heterotetramers that select cargo for inclusion into transport vesicles. Five AP complexes (AP-1 to AP-5) have been described, each with a distinct localisation and function. Furthermore, patients with a range of disorders, particularly involving the nervous system, have now been identified with mutations in each of the AP complexes. In many cases this has been correlated with aberrantly localised membrane proteins. In this Cell Science at a Glance article and the accompanying poster, we summarize what is known about the five AP complexes and discuss how this helps to explain the clinical features of the different genetic disorders.

From and to the Golgi - defining the Wilson disease protein road map

Recent studies highlight the continued growth in the identification of a variety of cellular functions that involve the Golgi apparatus. Apart from well-known membrane sorting/trafficking and glycosylation machineries, the Golgi harbors molecular platforms operating in intracellular signaling, cytoskeleton organization, and protein quality control mechanisms. One of new emerging Golgi functions consists in the regulation of copper homeostasis by coordinating the relocation and activity of copper transporters. Of these, the Cu-transporting ATPase ATP7B (known as Wilson disease protein) plays a key role in the maintenance of the Cu balance in the body via the supply of essential Cu to the systemic circulation and via elimination of excess Cu into the bile. These activities require tightly regulated shuttling of ATP7B between the Golgi and different post-Golgi compartments. Despite significant progress over recent years, a number of issues regarding ATP7B trafficking remain to be clarified. This review summarizes current views on ATP7B trafficking pathways from and to the Golgi and underscores the challenges that should be addressed to define the ATP7B trafficking routes and mechanisms in health and disease.

Coatopathies: Genetic Disorders of Protein Coats

Protein coats are supramolecular complexes that assemble on the cytosolic face of membranes to promote cargo sorting and transport carrier formation in the endomembrane system of eukaryotic cells. Several types of protein coats have been described, including COPI, COPII, AP-1, AP-2, AP-3, AP-4, AP-5, and retromer, which operate at different stages of the endomembrane system. Defects in these coats impair specific transport pathways, compromising the function and viability of the cells. In humans, mutations in subunits of these coats cause various congenital diseases that are collectively referred to as coatopathies. In this article, we review the fundamental properties of protein coats and the diseases that result from mutation of their constituent subunits.

Pluripotent stem cell-derived bile canaliculi-forming hepatocytes to study genetic liver diseases involving hepatocyte polarity

BACKGROUND & AIMS

Hepatocyte polarity is essential for the development of bile canaliculi and for safely transporting bile and waste products from the liver. Functional studies of autologous mutated proteins in the context of the polarized hepatocyte have been challenging because of the lack of appropriate cell models. The aims of this study were to obtain a patient-specific hepatocyte model that recapitulated hepatocyte polarity and to employ this model to study endogenous mutant proteins in liver diseases that involve hepatocyte polarity.

METHODS

Urine cell-derived pluripotent stem cells, taken from a patient with a homozygous mutation in ATP7B and a patient with a heterozygous mutation, were differentiated towards hepatocyte-like cells (hiHeps). HiHeps were also derived from a patient with MEDNIK syndrome.

RESULTS

Polarized hiHeps that formed in vivo-like bile canaliculi could be generated from embryonic and patient urine cell-derived pluripotent stem cells. HiHeps recapitulated polarized protein trafficking processes, exemplified by the Cu²⁺-induced redistribution of the copper transporter protein ATP7B to the bile canalicular domain. We demonstrated that, in contrast to the current dogma, the most frequent yet enigmatic Wilson disease-causing ATP7B-H1069Q mutation per se did not preclude trafficking of ATP7B to the trans-Golgi Network. Instead, it prevented its Cu²⁺-induced polarized redistribution to the bile canalicular domain, which could not be reversed by pharmacological folding chaperones. Finally, we demonstrate that hiHeps from a patient with MEDNIK syndrome, suffering from liver copper overload of unclear etiology, showed no defect in the Cu²⁺-induced redistribution of ATP7B to the bile canaliculi.

CONCLUSIONS

Functional cell polarity can be achieved in patient pluripotent stem cell-derived hiHeps, enabling, for the first time, the study of the endogenous mutant proteins, patient-specific pathogenesis and drug responses for diseases where hepatocyte polarity is a key factor.

LAY SUMMARY

This study demonstrates that cells that are isolated from urine can be reprogrammed in a dish towards hepatocytes that display architectural characteristics similar to those seen in the intact liver. The application of this methodology to cells from patients diagnosed with inherited copper metabolism-related liver diseases (that is, Wilson disease and MEDNIK syndrome) revealed unexpected and novel insights into patient mutation-specific disease mechanisms and drug responses.

Proposal for a simplified classification of IMD based on a pathophysiological approach: A practical guide for clinicians

In view of the rapidly expanding number of IMD discovered by next generation sequencing, we propose a simplified classification of IMD that mixes elements from a clinical diagnostic perspective and a pathophysiological approach based on three large categories. We highlight the increasing importance of complex molecule metabolism and its connection with cell biology processes. Small molecule disorders have biomarkers and are divided in two subcategories: accumulation and deficiency. Accumulation of small molecules leads to acute or progressive postnatal "intoxication", present after a symptom-free interval, aggravated by catabolism and food intake. These treatable disorders must not be missed! Deficiency of small molecules is due to impaired synthesis of compounds distal to a block or altered transport of essential molecules. This subgroup shares many clinical characteristics with complex molecule disorders. Complex molecules (like glycogen, sphingolipids, phospholipids, glycosaminoglycans, glycolipids) are poorly diffusible. Accumulation of complex molecules leads to postnatal progressive storage like in glycogen and lysosomal storage disorders. Many are treatable. Deficiency of complex molecules is related to the synthesis and recycling of these molecules, which take place in organelles. They may interfere with fœtal development. Most present as neurodevelopmental or neurodegenerative disorders unrelated to food intake. Peroxisomal disorders, CDG defects of intracellular trafficking and processing, recycling of synaptic vesicles, and tRNA synthetases also belong to this category. Only few have biomarkers and are treatable. Disorders involving primarily energy metabolism encompass defects of membrane carriers of energetic molecules as well as cytoplasmic and mitochondrial metabolic defects. This oversimplified classification is connected to the most recent available nosology of IMD.

An overview of inborn errors of metabolism affecting the brain: from neurodevelopment to neurodegenerative disorders

Inborn errors of metabolism (IEMs) are particularly frequent as diseases of the nervous system. In the pediatric neurologic presentations of IEMs neurodevelopment is constantly disturbed and in fact, as far as biochemistry is involved, any kind of monogenic disease can become an IEM. Clinical features are very diverse and may present as a neurodevelopmental disorder (antenatal or late-onset), as well as an intermittent, a fixed chronic, or a progressive and late-onset neurodegenerative disorder. This also occurs within the same disorder in which a continuum spectrum of severity is frequently observed. In general, the small molecule defects have screening metabolic markers and many are treatable. By contrast only a few complex molecules defects have metabolic markers and most of them are not treatable so far. Recent molecular techniques have considerably contributed in the description of many new diseases and unexpected phenotypes. This paper provides a comprehensive list of IEMs that affect neurodevelopment and may also present with neurodegeneration.

Classification and differential diagnosis of Wilson's disease

Wilson's disease is characterized by hepatic and extrapyramidal movement disorders (EPS) with variable manifestation primarily between age 5 and 45. This variability often makes an early diagnosis difficult. A classification defines different clinical variants of Wilson's disease, which enables classifying the current clinical findings and making an early tentative diagnosis. Until the unequivocal proof or an autosomal recessive disorder of the hepatic copper transporter ATP7B has been ruled out, differential diagnoses have to be examined. Laboratory-chemical parameters of copper metabolism can both be deviations from the norm not related to the disease as well as other copper metabolism disorders besides Wilson's disease. In addition to known diseases such as Menkes disease, occipital horn syndrome (OHS), Indian childhood cirrhosis (ICC) and ceruloplasmin deficiency, recently discovered disorders are taken into account. These include MEDNIK syndrome, Huppke-Brendel syndrome and CCS chaperone deficiency. Another main focus is on differential diagnoses of childhood icterus correlated with age and anaemia as well as disorders of the extrapyramidal motor system. The Kayser-Fleischer ring (KFR) is qualified as classical ophthalmologic manifestation. The recently described manganese storage disease presents another rare metabolic disorder with symptoms similar to Wilson's disease. As this overview shows, Wilson's disease fits into a broad spectrum of internal and neurological disease patterns with icterus, anaemia and EPS.

Trafficking mechanisms of P-type ATPase copper transporters

Copper is an essential micronutrient required for oxygen-dependent enzymes, yet excess of the metal is a toxicant. The tug-of-war between these copper activities is balanced by chaperones and membrane transporters, which control copper distribution and availability. The P-type ATPase transporters, ATP7A and ATP7B, regulate cytoplasmic copper by pumping copper out of cells or into the endomembrane system. Mutations in ATP7A and ATP7B cause diseases that share neuropsychiatric phenotypes, which are similar to phenotypes observed in mutations affecting cytoplasmic trafficking complexes required for ATP7A/B dynamics. Here, we discuss evidence indicating that phenotypes associated to genetic defects in trafficking complexes, such as retromer and the adaptor complex AP-1, result in part from copper dyshomeostasis due to mislocalized ATP7A and ATP7B.

Golgipathies in Neurodevelopment: A New View of Old Defects

The Golgi apparatus (GA) is involved in a whole spectrum of activities, from lipid biosynthesis and membrane secretion to the posttranslational processing and trafficking of most proteins, the control of mitosis, cell polarity, migration and morphogenesis, and diverse processes such as apoptosis, autophagy, and the stress response. In keeping with its versatility, mutations in GA proteins lead to a number of different disorders, including syndromes with multisystem involvement. Intriguingly, however, > 40% of the GA-related genes known to be associated with disease affect the central or peripheral nervous system, highlighting the critical importance of the GA for neural function. We have previously proposed the term "Golgipathies" in relation to a group of disorders in which mutations in GA proteins or their molecular partners lead to consequences for brain development, in particular postnatal-onset microcephaly (POM), white-matter defects, and intellectual disability (ID). Here, taking into account the broader role of the GA in the nervous system, we refine and enlarge this emerging concept to include other disorders whose symptoms may be indicative of altered neurodevelopmental processes, from neurogenesis to neuronal migration and the secretory function critical for the maturation of postmitotic neurons and myelination.