Isolation and characterization of a human liver cDNA as a candidate gene for Wilson disease

Changes in Hepatic Function After Splenectomy for Hepatolenticular Degeneration, Cirrhosis, and Hypersplenism

BACKGROUND

Patients with hepatic reticulum degeneration (HLD) may eventually develop complications of cirrhosis with splenomegaly and hypersplenism, requiring splenectomy to alleviate hypersplenism and complete lifelong copper therapy. The purpose of this study is to investigate the effect of splenectomy on liver function in patients with hypersplenism.

METHODS

A retrospective systematic analysis was conducted on the liver function indicators of 220 HLD patients who underwent splenectomy from January 2015 to January 2018 before surgery and on days 1, 3, 5, 7, and 14 after surgery. Among them, 30 patients were followed up for 6 months.

RESULTS

The Child score increased on the 1st day after surgery and gradually decreased after the 1st day. The level of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin (TB) increased 5 days after surgery (P < .01) and decreased on the 14th day after surgery (P < .01); the level of albumin (ALB) decreased on the 1st, 3rd, and 5th day after surgery (P < .01) and increased on the 14th day (P < .01). The follow-up results of the patient for 6 months showed that the levels of ALT and AST decreased, while the levels of ALB increased 6 months after surgery.

CONCLUSION

Splenectomy is proved to be beneficial for the improvement of liver function in HLD patients combined with hypersplenism, which realize a lifelong anti-copper treatment.

Hepatitis B virus infection in patients with Wilson disease: A large retrospective study

BACKGROUND

Wilson disease (WD) is the most common genetic metabolic liver disease. Some studies have shown that comorbidities may have important effects on WD. Data on hepatitis B virus (HBV) infection in patients with WD are limited.

AIM

To investigate the prevalence and clinical impact of HBV infection in patients with WD.

METHODS

The clinical data of patients with WD were analyzed retrospectively, and the data of patients with concurrent WD and HBV infection were compared with those of patients with isolated WD.

RESULTS

Among a total of 915 WD patients recruited, the total prevalence of current and previous HBV infection was 2.1% [95% confidence interval (CI): 1.2%-3.0%] and 9.2% (95%CI: 7.3%-11.1%), respectively. The main finding of this study was the identification of 19 patients with concurrent WD and chronic hepatitis B (CHB) infection. The diagnosis of WD was missed in all but two patients with CHB infection. The mean delay in the diagnosis of WD in patients with concurrent WD and CHB infection was 32.5 mo, which was significantly longer than that in patients with isolated WD (10.5 mo). The rates of severe liver disease and mortality in patients with concurrent WD and CHB infection were significantly higher than those in patients with isolated WD (63.1% vs 19.3%, P = 0.000 and 36.8% vs 4.1%, P < 0.001, respectively). Binary logistic regression analysis revealed a significantly higher risk of severe liver disease at the diagnosis of WD in patients with current HBV infection [odds ratio (OR) = 7.748; 95%CI: 2.890-20.774; P = 0.000)] or previous HBV infection (OR = 5.525; 95%CI: 3.159-8.739; P = 0.000) than in patients with isolated WD.

CONCLUSION

The total prevalence of current HBV infection in patients with WD was 2.1%. The diagnosis of WD in CHB patients is usually missed. HBV infection is an independent risk factor for severe liver disease in WD patients. The diagnosis of WD should be ruled out in some patients with CHB infection.

A Century of Progress on Wilson Disease and the Enduring Challenges of Genetics, Diagnosis, and Treatment

Wilson disease (WD) is a rare, inherited metabolic disorder manifested with varying clinical presentations including hepatic, neurological, psychiatric, and ophthalmological features, often in combination. Causative mutations in the ATP7B gene result in copper accumulation in hepatocytes and/or neurons, but clinical diagnosis remains challenging. Diagnosis is complicated by mild, non-specific presentations, mutations exerting no clear effect on protein function, and inconclusive laboratory tests, particularly regarding serum ceruloplasmin levels. As early diagnosis and effective treatment are crucial to prevent progressive damage, we report here on the establishment of a global collaboration of researchers, clinicians, and patient advocacy groups to identify and address the outstanding challenges posed by WD.

Clinical and genetic characterization of a large cohort of patients with Wilson’s disease in China

Background

Wilson’s disease (WD) is an autosomal recessive disorder of copper metabolism caused by ATP7B (encoding a copper-transporting P-type ATPase) variants that shows various characteristics according to race and geographical region. This study was aimed to provide a comprehensive analysis of ATP7B variants in China and to investigate a plausible role of common variants in WD manifestations.

Methods

A total of 1366 patients (1302 index patients and 64 siblings) clinically diagnosed with WD (Leipzig score ≥ 4) were recruited. They underwent ATP7B gene sequencing and information of age and symptoms at onset was collected. The genotype–phenotype correlation was assessed in the index patients who were examined with two pathogenic variants and onset with hepatic (n = 276) or neurologic (n = 665) symptoms.

Results

We identified 294 potentially pathogenic ATP7B variants (112 truncating, 174 missense, 8 in-frame) in the 1302 index patients, including 116 novel variants. The most frequent variant was c.2333G>T (R778L, allele frequency: 28.96%), followed by c.2975C>T (P992L, 13.82%), c.2621C>T (A874V, 5.99%), c.2755C>G (R919G, 2.46%), and c.3646G>A (V1216M, 1.92%). In 1167 patients, both pathogentic variants were identified, of which 532 different variant combinations were found. By binary logistic regression analysis, the factor associated with neurological presentation was high age-at-onset, but not sex, protein-truncating variant (PTV), or the common missense variants (R778L, P992L, and A874V). In the neurological group, low age-at-onset was a factor associated with dystonia, gait abnormality, and salivation; high age-at-onset was a factor associated with tremor; and the sex, low age-at-onset and A874V were independent factors associated with dysarthria. In addition, PTV, R778L, and P992L were predominant in early-onset patients, whereas A874V was predominant in late-onset patients, and patients with R778L/A874V genotype displayed a higher age-at-onset than patients with R778L/R778L or R778L/P992L genotype.

Conclusions

Our work expanded the ATP7B variant spectrum and highlighted the differences among patients with WD in age-at-onset and ATP7B variants, which may provide some valuable insights into the diagnosis, counseling, and treatment of patients with WD.

A new fluorescence probe for detection of Cu+2 in blood samples: Circuit logic gate

A Fluorescence probe was designed based on 8-hydroxyquinoline chitosan silica precursor (HQCS) for selective detection of Al³⁺, Cu²⁺. The HQCS has no observable fluorescence signal, but after the addition of Al³⁺, a huge fluorescence signal appeared, and the selective quenching was absorbed after the addition of Cu²⁺. The effect of other different cations, including Cu²⁺, Mg²⁺, Ca²⁺, Pb²⁺, Zn²⁺, Hg²⁺, Ag⁺, Fe^3+, and K⁺ was studied. The addition of Cu²⁺ to the probe (HQCSAL) decreased the fluorescence very repeatable, and the variation of the fluorescence vs. Cu²⁺ was monotonic and linear. Therefore, the prepared probe was used to determine Cu²⁺ ions in real samples. The mechanism of fluorescence variation by adding cations to the probe solution was studied using the Stern-Volmer equation. Under the optimum conditions, the linear range and detection limit were 3.5-31 μM and 1 μM, respectively. The probe accuracy on the copper determination in the blood and tap waters was comparable to the ICP-OES results. The circuit logic gate mimic was designed for the fluorescence behavior of the probe constituents.

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.

The copper chaperone CCS facilitates copper binding to MEK1/2 to promote kinase activation

Normal physiology relies on the precise coordination of intracellular signal transduction pathways that respond to nutrient availability to balance cell growth and cell death. The canonical MAPK pathway consists of the RAF-MEK-ERK signaling cascade and represents one of the most well-defined axes within eukaryotic cells to promote cell proliferation, which underscores its frequent mutational activation in the majority of human cancers. Our recent studies illuminated a function for the redox-active micronutrient copper (Cu) as an intracellular mediator of signaling by connecting Cu to the amplitude of MAPK signaling via a direct interaction between Cu and the kinases MEK1 and MEK2. Given the large quantities of molecules like glutathione and metallothionein that limit cellular toxicity from free Cu ions, evolutionarily conserved Cu chaperones facilitate the efficient delivery of Cu to cuproenzymes. Thus, a dedicated cellular delivery mechanism of Cu to MEK1/2 is likely to exist. Using surface plasmon resonance and proximity-dependent biotin ligase studies, we report here that the Cu chaperone CCS selectively bound to and facilitated Cu transfer to MEK1. Mutations in CCS that disrupt Cu(I) acquisition and exchange or a CCS small molecule inhibitor were employed and resulted in reduced Cu-stimulated MEK1 kinase activity. Our findings indicate that the Cu chaperone CCS provides fidelity within a complex biological system to achieve appropriate installation of Cu within the MEK1 kinase active site that in turn modulates kinase activity and support the development of novel MEK1/2 inhibitors that target the Cu structural interface or blunt dedicated Cu delivery mechanisms via CCS.

The molecular and cellular basis of copper dysregulation and its relationship with human pathologies

Copper (Cu) is an essential micronutrient required for the activity of redox-active enzymes involved in critical metabolic reactions, signaling pathways, and biological functions. Transporters and chaperones control Cu ion levels and bioavailability to ensure proper subcellular and systemic Cu distribution. Intensive research has focused on understanding how mammalian cells maintain Cu homeostasis, and how molecular signals coordinate Cu acquisition and storage within organs. In humans, mutations of genes that regulate Cu homeostasis or facilitate interactions with Cu ions lead to numerous pathologic conditions. Malfunctions of the Cu⁺ -transporting ATPases ATP7A and ATP7B cause Menkes disease and Wilson disease, respectively. Additionally, defects in the mitochondrial and cellular distributions and homeostasis of Cu lead to severe neurodegenerative conditions, mitochondrial myopathies, and metabolic diseases. Cu has a dual nature in carcinogenesis as a promotor of tumor growth and an inducer of redox stress in cancer cells. Cu also plays role in cancer treatment as a component of drugs and a regulator of drug sensitivity and uptake. In this review, we provide an overview of the current knowledge of Cu metabolism and transport and its relation to various human pathologies.

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.

Copper: An Intracellular Achilles' Heel Allowing the Targeting of Epigenetics, Kinase Pathways, and Cell Metabolism in Cancer Therapeutics

Copper is an essential transition metal frequently increased in cancer known to strongly influence essential cellular processes. Targeted therapy protocols utilizing both novel and repurposed drug agents initially demonstrate strong efficacy, before failing in advanced cancers as drug resistance develops and relapse occurs. Overcoming this limitation involves the development of strategies and protocols aimed at a wider targeting of the underlying molecular changes. Receptor Tyrosine Kinase signaling pathways, epigenetic mechanisms and cell metabolism are among the most common therapeutic targets, with molecular investigations increasingly demonstrating the strong influence each mechanism exerts on the others. Interestingly, all these mechanisms can be influenced by intracellular copper. We propose that copper chelating agents, already in clinical trial for multiple cancers, may simultaneously target these mechanisms across a wide variety of cancers, serving as an excellent candidate for targeted combination therapy. This review summarizes the known links between these mechanisms, copper, and copper chelation therapy.

Copper exposure association with prevalence of non-alcoholic fatty liver disease and insulin resistance among US adults (NHANES 2011-2014)

BACKGROUND

Excessive copper (Cu) has risky effect on insulin resistance (IR), oxidative stress and inflammation. Instead, some studies reported serum Cu to be protective for non-alcoholic fatty liver disease (NAFLD). The aim of this study was to reevaluate the evidence for a potential risky correlation of serum Cu to NAFLD in large-scale and non-institutionalized American subjects.

METHODS

A cross-sectional study of 3211 subjects was from the National Health and Nutrition Examination Survey (NHANES). Logistic regression and cubic spline-based curve-fitting analyses were used to estimate the independent risky effect of Cu to hepatic steatosis index (HSI), US fatty liver index (USFLI) and NAFLD and their dose-effect relationship. Moreover, this association was analyzed in stratification of HOMA-IR, Metabolic syndrome (MetS) and severity of NAFLD, besides age and gender.

RESULTS

The average level of serum Cu was 18.67 μmol/L and the prevalence of NAFLD was 54.53% and 32.60%, respectively defined by HSI and USFLI. Generally, the level of Cu was higher in females than males. Serum Cu was positively associated with higher HSI, USFLI index and risk of NAFLD. In fully adjusted models, compared with the lowest quartile, the risk of NAFLD increased 97% in the highest quartile of Cu. Interestingly, stratified analysis showed that the risky effect of Cu to NAFLD was more prominent in the middle-aged, females and subjects with improved status of IR (lower HOMA-IR and non-Mets) compared with their counterparts. Moreover, we further found that circulating copper was correlated to severity of NAFLD only in males.

CONCLUSION

Excess serum Cu is significantly associated with risk of NAFLD, which is prominent in females, middle-aged and subjects with improved status of IR, and seems to be related to the severity of NAFLD, additionally. It is necessary to be cautious of the toxic effect of Cu and prospective cohort and mechanism studies are needed to verify the causal effect of Cu to NAFLD.

Cortical copper transporter expression in schizophrenia: interactions of risk gene dysbindin-1

Schizophrenia susceptibility factor dysbindin-1 is associated with cognitive processes. Downregulated dysbindin-1 expression is associated with lower expression of copper transporters ATP7A and CTR1, required for copper transport to the central nervous system. We measured dysbindin-1 isoforms-1A and -1BC, CTR1, and ATP7A via Western blots of the postmortem dorsolateral prefrontal cortex (DLPFC) of schizophrenia subjects (n = 28) and matched controls (n = 14). In addition, we subdivided the schizophrenia group by treatment status and comorbidity of alcohol use disorder (AUD) and assessed the relationships between proteins. Schizophrenia subjects exhibited similar protein levels to that of controls, with no effect of antipsychotic treatment. We observed a shift towards more dysbindin-1A expression in schizophrenia, as revealed by the ratio of dysbindin-1 isoforms. Dysbindin-1A expression was negatively correlated with ATP7A in schizophrenia, with no correlation present in controls. AUD subjects exhibited less dysbindin-1BC and CTR1 than those without AUD. Our results, taken together with previous data, suggest that alterations in dysbindin-1 and copper transporters are brain-region specific. For example, protein levels of ATP7A, dysbindin 1BC, and CTR1 are lower in the substantia nigra in schizophrenia subjects. AUD in the DLPFC was associated with lower protein levels of dysbindin-1 and CTR1. Changes in dysbindin-1 isoform ratio and relationships appear to be prevalent in the disease, potentially impacting symptomology.

Prevalent Pathogenic Variants of ATP7B in Chinese Patients with Wilson's Disease: Geographical Distribution and Founder Effect

Wilson’s disease (WD) is an autosomal recessive disorder caused by ATP7B pathogenic variants. This study aimed to show the geographical distribution and haplotype spectrum of three prevalent pathogenic variants (p.R778L, p.P992L, p.T935M) in mainland Chinese population and clarify whether the founder effect may account for their origins. We firstly summarized the frequency and geographical distribution of p.R778L, p.P992L and p.T935M in 715 WD patients. Then, to construct haplotypes associated with the three variants, Sanger sequencing and microsatellite typing at three dinucleotide-repeat markers (D13S314, D13S301, D13S316) flanking the ATP7B gene were performed in 102 WD families. An obvious regional-specific distribution feature was found in p.T935M. Linkage disequilibrium at the three markers was shown in all the three variants and we found the common haplotypes specific for p.R778L, p.P992L and p.T935M respectively, represented successively by 10-7-7, 10-9-5 and 12-4-8, which all exhibited great significance vs. the control chromosomes (p < 0.01). Meanwhile, haplotypes for the three variants differed from the studies in other regions to some extent. The common haplotypes we found indicate that three prevalent pathogenic variants emerge due to the founder effect. Furthermore, the study contributes to expand our knowledge of the genetic diversity of WD from a cross-regional perspective.

Activation of HIF-1 signaling ameliorates liver steatosis in zebrafish atp7b deficiency (Wilson's disease) models

Wilson's disease is an autosomal recessive disease characterized by excess copper accumulated in the liver and brain. It is caused by mutations in the copper transporter gene ATP7B. However, based on the poor understanding of the transcriptional program involved in the pathogenesis of Wilson's disease and the lack of more safe and efficient therapies, the identification of novel pathways and the establishment of complementary model systems of Wilson's disease are urgently needed. Herein, we generated two zebrafish atp7b-mutant lines using the CRISPR/Cas9 editing system, and the mutants developed hepatic and behavioral deficits similar to those observed in humans with Wilson's disease. Interestingly, we found that atp7b-deficient zebrafish embryos developed liver steatosis under low-dose Cu exposure, and behavioral deficits appeared under high-dose Cu exposure. Analyses of publicly available transcriptomic data from ATP7B-knockout HepG2 cells demonstrated that the HIF-1 signaling pathway is downregulated in ATP7B-knockout HepG2 cells compared with wildtype cells following Cu exposure. The HIF-1 signaling pathway was also downregulated in our atp7b-deficient zebrafish mutants following Cu exposure. Furthermore, we demonstrate that activation of the HIF-1 signaling pathway with the chemical compound FG-4592 or DMOG ameliorates liver steatosis and reduces accumulated Cu levels in zebrafish atp7b deficiency models. These findings introduce a novel prospect that modulation of the HIF-1 signaling pathway should be explored as a novel strategy to reduce copper toxicity in Wilson's disease patients.

Movement disorders in pregnancy

Movement disorders in women during pregnancy are uncommon. Therefore, high quality studies are limited, and guidelines are lacking for the treatment of movement disorders in pregnancy, thus posing a significant therapeutic challenge for the treating physicians. In this chapter, we discuss movement disorders that arise during pregnancy and the preexisting movement disorders during pregnancy. Common conditions encountered in pregnancy include but are not limited to restless legs syndrome, chorea gravidarum, Parkinson disease, essential tremor, and Huntington disease as well as more rare movement disorders (Wilson's disease, dystonia, etc.). This chapter summarizes the published literature on movement disorders and pharmacologic and surgical considerations for neurologists and physicians in other specialties caring for patients who are pregnant or considering pregnancy.

Role of endoplasmic reticulum stress and protein misfolding in disorders of the liver and pancreas

The endoplasmic reticulum (ER) is the site of synthesis and folding of membrane and secretory proteins. The fraction of protein passing through the ER represents a large proportion of the total protein in the cell. Protein folding, glycosylation, sorting and transport are essential tasks of the ER and a compromised ER folding network has been recognized to be a key component in the disease pathogenicity of common neurodegenerative, metabolic and malignant diseases. On the other hand, the ER protein folding machinery also holds significant potential for therapeutic interventions. Many causes can lead to ER stress. A disturbed calcium homeostasis, the generation of reactive oxygen species (ROS) and a persistent overload of misfolded proteins within the ER can drive the course of adisease. In this review the role of ER-stress in diseases of the liver and pancreas will be examined using pancreatitis and Wilson´s disease as examples. Potential therapeutic targets in ER-stress pathways will also be discussed.

Wilson disease

Wilson disease (WD) is an inherited disorder of copper metabolism. The resultant defective handling of copper results in toxic effects on the hepatocytes and increased copper in the circulation. Copper accumulates in other organ sites especially the central nervous system. WD occurs worldwide, usually between 5 and 35 years; a wider age range is now recognized. Clinical presentations are diverse and include combinations of hepatic, neurological, ophthalmic and psychiatric manifestations. Biochemical abnormalities such as serum ceruloplasmin and 24-h urinary copper excretion are important for the diagnosis but are not always abnormal in WD. They can overlap with non-WD causes. Patients may present with hepatic or neurological disease or combinations thereof. Approx. 50% of WD patients present with liver disease. Liver presentation is variable: asymptomatic abnormal liver tests, chronic hepatitis picture, cirrhosis, and acute liver failure. Similarly, the histology has several different patterns: mild nonspecific changes, steatosis or steatohepatitis, chronic hepatitis, and acute hepatitis with submassive or massive necrosis. None of these are specific for WD. Aids to the histologic diagnosis include special stains for copper and copper associated protein, and copper concentration in liver tissue. The biopsy is performed in the context of the clinical algorithms for the diagnosis of WD put forth by the clinical hepatology organizations such as the European Association for the Study of Liver Disease and the American Association for the Study of Liver Disease. The discovery of the responsible gene ATP7B has made the molecular diagnosis feasible through genetic testing and sequencing of the gene.

Genetic analysis of ATP7B in 102 south Indian families with Wilson disease

Wilson disease (WD) is an autosomal recessive disorder, characterized by excessive deposition of copper in various parts of the body, mainly in the liver and brain. It is caused by mutations in ATP7B. We report here the genetic analysis of 102 WD families from a south Indian population. Thirty-six different ATP7B mutations, including 13 novel ones [p.Ala58fs*19, p.Lys74fs*9, p.Gln281*, p.Pro350fs*12, p.Ser481*, p.Leu735Arg, p.Val752Gly, p.Asn812fs*2, p.Val845Ala, p.His889Pro, p.Ile1184fs*1, p.Val1307Glu and p.Ala1339Pro], were identified in 76/102 families. Interestingly, the mutation analysis of affected individuals in two families identified two different homozygous mutations in each family, and thus each affected individual from these families harbored two mutations in each ATP7B allele. Of 36 mutations, 28 were missense, thus making them the most prevalent mutations identified in the present study. Nonsense, insertion and deletion represented 3/36, 2/36 and 3/36 mutations, respectively. The haplotype analysis suggested founder effects for all the 14 recurrent mutations. Our study thus expands the mutational landscape of ATP7B with a total number of 758 mutations. The mutations identified during the present study will facilitate carrier and pre-symptomatic detection, and prenatal genetic diagnosis in affected families.

[Diagnostics of Wilson's disease]

Wilson's disease is a rare genetic but treatable metabolic disorder which has a favorable prognosis when diagnosed early and treated adequately. Therefore, knowledge of this rare clinical condition and a reliable diagnosis are indispensable. The diagnostic work-up is initiated in cases of unexplained acute or chronic liver disease and/or an extrapyramidal motor disturbance occurring mostly between the 5th and 45th years of life. Manifestations with initial symptoms have occasionally been observed at an age younger than 1 year and later than 70 years. Immediate biochemical and genetic examinations for early diagnosis are essential. Further test methods, such as liver and transcranial sonography, cerebral magnetic resonance imaging (MRI) and ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET), ¹²³I-beta-CIT and ¹²³I-iodobenzamide (IBZM) single photon emission computed tomography (SPECT), electrophysiology as well as fine motor tests are unspecific but can be used to test for organ damage and for monitoring of progress. Immediate initiation of a therapy is required and justified on the basis of a confirmed diagnosis.

Impaired copper transport in schizophrenia results in a copper-deficient brain state: A new side to the dysbindin story

Objectives: Several schizophrenia brain regions exhibit decreased dysbindin. Dysbindin modulates copper transport crucial for myelination, monoamine metabolism and cellular homeostasis. Schizophrenia patients (SZP) exhibit increased plasma copper, while copper-decreasing agents produce schizophrenia-like behavioural and pathological abnormalities. Therefore, we sought to determine dysbindin and copper transporter protein expression and copper content in SZP.Methods: We studied the copper-rich substantia nigra (SN) using Western blot and inductively-coupled plasma mass spectrometry. We characterised specific protein domains of copper transporters ATP7A, CTR1, ATP7B and dysbindin isoforms 1 A and 1B/C in SZP (n = 15) and matched controls (n = 11), and SN copper content in SZP (n = 14) and matched controls (n = 11). As a preliminary investigation, we compared medicated (ON; n = 11) versus unmedicated SZP (OFF; n = 4).Results: SZP exhibited increased C terminus, but not N terminus, ATP7A. SZP expressed less transmembrane CTR1 and dysbindin 1B/C than controls. ON exhibited increased C terminus ATP7A protein versus controls. OFF exhibited less N terminus ATP7A protein than controls and ON, suggesting medication-induced rescue of the ATP7A N terminus. SZP exhibited less SN copper content than controls.Conclusions: These results provide the first evidence of disrupted copper transport in schizophrenia SN that appears to result in a copper-deficient state. Furthermore, copper homeostasis may be modulated by specific dysbindin isoforms and antipsychotic treatment.

The interactions between iron and copper in genetic iron overload syndromes and primary copper toxicoses in Japan

Iron and copper are trace elements essential for health, and iron metabolism is tightly regulated by cuproproteins. Clarification of the interactions between iron and copper may provide a better understanding of the pathophysiology and treatment strategy for hemochromatosis, Wilson disease, and related disorders. The hepcidin/ferroportin system was used to classify genetic iron overload syndromes in Japan, and ceruloplasmin and ATP7B were introduced for subtyping Wilson disease into the severe hepatic and classical forms. Interactions between iron and copper were reviewed in these genetic diseases. Iron overload syndromes were classified into pre-hepatic iron loading anemia and aceruloplasminemia, hepatic hemochromatosis, and post-hepatic ferroportin disease. The ATP7B-classical form with hypoceruloplasminemia has primary hepatopathy and late extra-hepatic complications, while the severe hepatic form is free from ATP7B mutation and hypoceruloplasminemia, and silently progresses to liver failure. A large amount of iron and trace copper co-exist in hepatocellular dense bodies of all iron overload syndromes. Cuproprotein induction to stabilize excess iron should be differentiated from copper retention in Wilson disease. The classical form of Wilson disease associated with suppressed hepacidin25 secretion may be double-loaded with copper and iron, and transformed to an iron disease after long-term copper chelation. Iron disease may not be complicated with the severe hepatic form with normal ferroxidase activity. Hepatocellular dense bodies of iron overload syndromes may be loaded with a large amount of iron and trace copper, while the classical Wilson disease may be double-loaded with copper and iron.

Identification and characterization of a novel 43-bp deletion mutation of the ATP7B gene in a Chinese patient with Wilson's disease: a case report

Background

Wilson’s disease (WD) is an autosomal recessive disorder characterized by copper accumulation. ATP7B gene mutations lead to ATP7B protein dysfunction, which in turn causes Wilson’s disease.

Case presentation

We describe a male case of Wilson’s disease diagnosed at 10 years after routine biochemical test that showed low serum ceruloplasmin levels and Kayser–Fleischer rings in both corneas. Analysis of the ATP7B gene revealed compound heterozygous mutations in the proband, including the reported c.3517G > A mutation and a novel c.532_574del mutation. The c.532_574del mutation covered a 43-bp region in exon 2, and resulted in a frameshift mutation (p.Leu178PhefsX10). By base sequence analysis, two microhomologies (TCTCA) were observed on both deletion breakpoints in the ATP7B gene. Meanwhile, the presence of some sequence motifs associated with DNA breakage near the deletion region promoted DNA strand break.

Conclusions

By comparison, a replication-based mechanism named fork stalling and template switching/ microhomology-mediated break-induced replication (FoSTeS/MMBIR) was used to explain the formation of this novel deletion mutation.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0567-z) contains supplementary material, which is available to authorized users.

Copper deposition in oligodendroglial cells in an autopsied case of hepatolenticular degeneration

We present a case of hepatolenticular degeneration, so-called Wilson's disease (WD), in a 31-year-old Japanese man with broader deposition of copper in the liver, kidney and brain. The liver showed severe cirrhotic changes with macronodular pseudolobule formation, but there was little difference in immunohistochemical expression patterns of the copper transporter ATP7B between the control and present case. In the brain, there were both WD-related lesions such as the scattering of Opalski cells and changes caused by hepatic encephalopathy including the appearance of Alzheimer type II glia. Of note, we identified copper deposits in the systemic organs, including hepatocytes, renal tubules, and in broad areas of the brain. Surprisingly, as a result of further pursuit, copper accumulation in the brain was rarely identified in neuronal cells, but in Olig2-positive glial cells with double immunohistochemical staining. Together, this rare autopsied case suggests a novel cellular candidate affected by abnormal copper metabolism and the necessity to perform the systemic examination of copper deposition in WD.

Alteration of Copper Fluxes in Brain Aging: A Longitudinal Study in Rodent Using 64CuCl2-PET/CT

Brain aging is associated with changes of various metabolic pathways. Copper is required for brain development and function, but little is known about changes in copper metabolism during brain aging. The objective of this study was to investigate alteration of copper fluxes in the aging mouse brain with positron emission tomography/computed tomography using ⁶⁴CuCl₂ as a radiotracer (⁶⁴CuCl₂-PET/CT). A longitudinal study was conducted in C57BL/6 mice (n = 5) to measure age-dependent brain and whole-body changes of ⁶⁴Cu radioactivity using PET/CT after oral administration of ⁶⁴CuCl₂ as a radiotracer. Cerebral ⁶⁴Cu uptake at 13 months of age (0.17 ± 0.05 %ID/g) was higher than the cerebral ⁶⁴Cu uptake at 5 months of age (0.11 ± 0.06 %ID/g, p < 0.001), followed by decrease to (0.14 ± 0.04 %ID/g, p = 0.02) at 26 months of age. In contrast, cerebral ¹⁸F-FDG uptake was highest at 5 months of age (7.8 ± 1.2 %ID/g) and decreased to similar values at 12 (5.2 ± 1.1 %ID/g, p < 0.001) and 22 (5.6 ± 1.1 %ID/g, p < 0.001) months of age. The findings demonstrated alteration of copper fluxes associated with brain aging and the time course of brain changes in copper fluxes differed from changes in brain glucose metabolism across time, suggesting independent underlying physiological processes. Hence, age-dependent changes of cerebral copper fluxes might represent a novel metabolic biomarker for assessment of human brain aging process with PET/CT using ⁶⁴CuCl₂ as a radiotracer.

Production of Wilson Disease Model Rabbits with Homology-Directed Precision Point Mutations in the ATP7B Gene Using the CRISPR/Cas9 System

CRISPR/Cas9 has recently been developed as an efficient genome engineering tool. The rabbit is a suitable animal model for studies of metabolic diseases. In this study, we generated ATP7B site-directed point mutation rabbits to simulate a major mutation type in Asians (p. Arg778Leu) with Wilson disease (WD) by using the CRISPR/Cas9 system combined with single-strand DNA oligonucleotides (ssODNs). The efficiency of the precision point mutation was 52.94% when zygotes were injected 14 hours after HCG treatment and was significantly higher than that of zygotes injected 19 hours after HCG treatment (14.29%). The rabbits carrying the allele with mutant ATP7B died at approximately three months of age. Additionally, the copper content in the livers of rabbits at the onset of WD increased nine-fold, a level similar to the five-fold increase observed in humans with WD. Thus, the efficiency of precision point mutations increases when RNAs are injected into zygotes at earlier stages, and the ATP7B mutant rabbits are a potential model for human WD disease with applications in pathological analysis, clinical treatment and gene therapy research.

Insights into the management of Wilson's disease

Wilson's disease is a rare, inherited autosomal recessive disease of copper metabolism, in which the causative gene, ATP7B, results in absent or reduced function of the ATP7B transporter important for biliary excretion of copper and incorporation of copper into caeruloplasmin. Affected patients accumulate excessive copper within the liver, brain and other tissues. A disease mainly of children, adolescents and young adults; clinical features vary from the asymptomatic state to chronic liver disease, acute liver failure, and neuropsychiatric manifestations. Diagnosis requires a high index of suspicion and is based on a combination of clinical signs, biochemical tests, hepatic copper content assay and mutation analysis of the ATP7B gene; to date, there are more than 500 mutations of ATP7B in patients with Wilson's disease. Early recognition and treatment can result in an excellent prognosis whereas untreated disease is almost always fatal. Drug therapies include chelating agents, such as penicillamine or trientine, and zinc salts. Liver transplantation is curative correcting the underlying pathophysiology and is traditionally indicated in acute liver failure or end-stage liver disease refractory to medical therapy. This review provides an overview of various aspects of Wilson's disease including molecular basis of the disease, clinical features, diagnostic and management strategies with their current limitations.

Age-dependent changes of cerebral copper metabolism in Atp7b -/- knockout mouse model of Wilson's disease by [64Cu]CuCl2-PET/CT

Copper is a nutritional metal required for brain development and function. Wilson's disease (WD), or hepatolenticular degeneration, is an inherited human copper metabolism disorder caused by a mutation of the ATP7B gene. Many WD patients present with variable neurological and psychiatric symptoms, which may be related to neurodegeneration secondary to copper metabolism imbalance. The objective of this study was to explore the feasibility and use of copper-64 chloride ([⁶⁴C]CuCl₂) as a tracer for noninvasive assessment of age-dependent changes of cerebral copper metabolism in WD using an Atp7b ^-/- knockout mouse model of WD and positron emission tomography/computed tomography (PET/CT) imaging. Continuing from our recent study of biodistribution and radiation dosimetry of [⁶⁴C]CuCl₂ in Atp7b ^-/- knockout mice, PET quantitative analysis revealed low ⁶⁴Cu radioactivity in the brains of Atp7b ^-/- knockout mice at 7th weeks of age, compared with ⁶⁴Cu radioactivity in the brains of age- and gender-matched wild type C57BL/6 mice, at 24 h (h) post intravenous injection of [⁶⁴C]CuCl₂ as a tracer. Furthermore, age-dependent increase of ⁶⁴Cu radioactivity was detected in the brains of Atp7b ^-/- knockout mice from the 13th to 21th weeks of age, based on the data derived from a longitudinal [⁶⁴C]CuCl₂-PET/CT study of Atp7b ^-/- knockout mice with orally administered [⁶⁴Cu]CuCl₂ as a tracer. The findings of this study support clinical use of [⁶⁴Cu]CuCl₂-PET/CT imaging as a tool for noninvasive assessment of age-dependent changes of cerebral copper metabolism in WD patients presenting with variable neurological and psychiatric symptoms.

Treatment of Wilson's disease

Wilson's disease is an autosomal recessive disorder of copper metabolism, whose prevalence in the general population is 1/30000. Common manifestations are hepatic and neuropsychiatric, and in children, hepatic symptoms are most common. Copper chelating agents are effective in most cases, except for those who suffer from decompensated cirrhosis or fulminant liver disease. Liver transplantation, especially liver related living transplantation that has confirmed to be an effective method, has increasingly become a main method for treating children with late stage Wilson's disease.

Phenotypes and Chronic Organ Damage May Be Different among Siblings with Wilson's Disease

Background and Aims: Cloning of ATP7B provided evidence that Wilson's disease is a hepatic copper toxicosis with a variety of extrahepatic complications. Affected siblings with the same genetic background and exposure to similar environmental factors may be a good model for the study of genotype-phenotype correlation. Methods: Twenty-three affected siblings in 11 families were selected from a database. The first phenotypes were determined according to the international proposal. The final types of chronic organ damage were re-evaluated for life-long management. Results: Phenotypes were identical in 5 of the families and different in 6 of the families. The acute hepatic phenotype H1 was found in 3 younger siblings and 1 older sibling. All survived an acute episode of hemolysis with underlying chronic liver disease. One also presented complication with neurological disease. The neurological phenotype N1 with neuropsychiatric symptoms and hepatic disease was found in 2 aged siblings of 1 family, in an older sibling in 3 families and in the oldest sibling in 1 family. Phenotypes in siblings were mainly split by either H1 occurring in random order or age-dependent N1. Types of chronic organ damage were identical in 8 of the families and different in 3 of the families. The same combination of chronic liver disease was found in 6 families and chronic liver disease complicated with neurological disease in 2 families. Split organ damage in siblings was found when an older sibling was complicated by neurological disease. There was no reverse combination of a younger sibling being complicated by neurological disease in any of the families. Conclusion: Phenotype combinations of siblings were mainly modified by externally-induced hemolytic episodes, while chronic organ damage in siblings was split by age-dependent neurological complications.

Plasma exchange and chelator therapy rescues acute liver failure in Wilson disease without liver transplantation

AIM

Wilson disease (WD) in patients with a New Wilson Index (NWI) score ≥ 11 is fatal, and these patients are good candidates for liver transplantation (LT). However, plasma exchange and chelator therapy are indispensable and effective even for WD with a score ≥ 11. Moreover, continuous hemodiafiltration (CHDF) with these treatments is essential for acute liver failure (ALF) in WD with hepatic encephalopathy because CHDF can exclude toxic metabolites that may cause damage to the brain. Here, we describe four rescued patients presenting with ALF in WD and discuss the available treatment options.

METHODS

We have experienced 11 male and 8 female patients presenting with WD at the Department of Pediatrics, Kumamoto University Hospital between 1999 and 2014. A male and 4 female patients were diagnosed as WD with ALF using a combination of clinical findings and biochemical tests.

RESULTS

The NWI score was ≥ 11 in cases 1 to 3. Cases 1 and 2 with hepatic encephalopathy received plasma exchange, CHDF, coagulation factor replacement treatment (CFRT) and LT. Cases 3 and 4 without encephalopathy obtained stable status without LT by plasma exchange, blood infusion, and CFRT.

CONCLUSIONS

It is better to undergo LT for WD patients with a NWI score ≥ 11, however, there is a possibility of remission by plasma exchange and medical therapy even without LT. WD patients with a NWI score ≥ 11can be rescued by conservative therapy when the ALF of WD does not present with ALF and hepatic encephalopathy. Therefore, ALF with hepatic encephalopathy itself is an indication for LT in WD.

In Vivo Modeling of the Pathogenic Effect of Copper Transporter Mutations That Cause Menkes and Wilson Diseases, Motor Neuropathy, and Susceptibility to Alzheimer's Disease

Copper is an essential biometal, and several inherited diseases are directly associated with a disruption to normal copper homeostasis. The best characterized are the copper deficiency and toxicity disorders Menkes and Wilson diseases caused by mutations in the p-type Cu-ATPase genes ATP7A and ATP7B, respectively. Missense mutations in the C-terminal portion of ATP7A have also been shown to cause distal motor neuropathy, whereas polymorphisms in ATP7B are associated with increased risk of Alzheimer's disease. We have generated a single, in vivo model for studying multiple pathogenic mutations in ATP7 proteins using Drosophila melanogaster, which has a single orthologue of ATP7A and ATP7B. Four pathogenic ATP7A mutations and two ATP7B mutations were introduced into a genomic ATP7 rescue construct containing an in-frame C-terminal GFP tag. Analysis of the wild type ATP7-GFP transgene confirmed that ATP7 is expressed at the basolateral membrane of larval midgut copper cells and that the transgene can rescue a normally early lethal ATP7 deletion allele to adulthood. Analysis of the gATP7-GFP transgenes containing pathogenic mutations showed that the function of ATP7 was affected, to varying degrees, by all six of the mutations investigated in this study. Of particular interest, the ATP7B^K832R Alzheimer's disease susceptibility allele was found, for the first time, to be a loss of function allele. This in vivo system allows us to assess the severity of individual ATP7A/B mutations in an invariant genetic background and has the potential to be used to screen for therapeutic compounds able to restore function to faulty copper transport proteins.

History of Wilson disease: a personal account

This chapter focuses on the historic aspects of the development of much of our current knowledge of the diagnosis and treatment of Wilson disease. Included are descriptions of the clinical signs of neurologic and hepatic disease, the natural history of disease progression, studies of disease pathogenesis and a unique perspective on the development of diagnostic testing and pharmacological therapy.

[Ecchymosis as the presenting manifestation of Wilson disease: A case report]

INTRODUCTION

The presence of a psychiatric disorder during the course of an organic disease is a common cause of delayed diagnosis.

CASE REPORT

We report a 16-year-old girl who was admitted with thrombocytopenia and had a two-year history of neuropsychiatric disorder which was attributed to a difficult family situation. Neurological examination showed a frontal lobe disorder and extrapyramidal manifestations. The thrombocytopenia was attributed to liver cirrhosis. These neurological and hepatic injuries were consistent with a metabolic disease, most likely Wilson disease. This was supported by the presence of a corneal Kayser-Fleischer ring and a decreased ceruloplasmin concentration. An urgent liver transplantation was required due to worsening neurological symptoms.

CONCLUSION

Wilson disease is a rare genetic disease caused by copper toxicity. It is characterized by combined hepatic and neurologic damage to varying degrees and can develop at any age. Urgent treatment is required, but the diagnosis may be delayed by prevailing psychiatric symptoms.

Copper comes of age in Melbourne

When we were asked to produce articles for this volume, it seemed appropriate to us to co-author an article on the history and impact of copper research in Melbourne. It is appropriate because over many years, decades in fact, we worked closely together and with Professor David Danks to identify the molecular defect in Menkes disease. This work was always carried out with the intention of understanding the nature of the copper homeostatic mechanisms and a "copper pathway" in the cell, that David had the prescience to predict must exist despite scepticism from granting agencies! He indeed inspired us to pursue research careers in this field. This article outlines some of this history.

Copper induces hepatocyte injury due to the endoplasmic reticulum stress in cultured cells and patients with Wilson disease

Copper is an essential trace element, however, excess copper is harmful to human health. Excess copper-derived oxidants contribute to the progression of Wilson disease, and oxidative stress induces accumulation of abnormal proteins. It is known that the endoplasmic reticulum (ER) plays an important role in proper protein folding, and that accumulation of misfolded proteins disturbs ER homeostasis resulting in ER stress. However, copper-induced ER homeostasis disturbance has not been fully clarified. We treated human hepatoma cell line (Huh7) and immortalized-human hepatocyte cell line (OUMS29) with copper and chemical chaperones, including 4-phenylbutyrate and ursodeoxycholic acid. We examined copper-induced oxidative stress, ER stress and apoptosis by immunofluorescence microscopy and immunoblot analyses. Furthermore, we examined the effects of copper on carcinogenesis. Excess copper induced not only oxidative stress but also ER stress. Furthermore, excess copper induced DNA damage and reduced cell proliferation. Chemical chaperones reduced this copper-induced hepatotoxicity. Excess copper induced hepatotoxicity via ER stress. We also confirmed the abnormality of ultra-structure of the ER of hepatocytes in patients with Wilson disease. These findings show that ER stress plays a pivotal role in Wilson disease, and suggests that chemical chaperones may have beneficial effects in the treatment of Wilson disease.

Copper and conquer: copper complexes of di-2-pyridylketone thiosemicarbazones as novel anti-cancer therapeutics

Copper is an essential trace metal required by organisms to perform a number of important biological processes. Copper readily cycles between its reduced Cu(i) and oxidised Cu(ii) states, which makes it redox active in biological systems. This redox-cycling propensity is vital for copper to act as a catalytic co-factor in enzymes. While copper is essential for normal physiology, enhanced copper levels in tumours leads to cancer progression. In particular, the stimulatory effect of copper on angiogenesis has been established in the last several decades. Additionally, it has been demonstrated that copper affects tumour growth and promotes metastasis. Based on the effects of copper on cancer progression, chelators that bind copper have been developed as anti-cancer agents. In fact, a novel class of thiosemicarbazone compounds, namely the di-2-pyridylketone thiosemicarbazones that bind copper, have shown great promise in terms of their anti-cancer activity. These agents have a unique mechanism of action, in which they form redox-active complexes with copper in the lysosomes of cancer cells. Furthermore, these agents are able to overcome P-glycoprotein (P-gp) mediated multi-drug resistance (MDR) and act as potent anti-oncogenic agents through their ability to up-regulate the metastasis suppressor protein, N-myc downstream regulated gene-1 (NDRG1). This review provides an overview of the metabolism and regulation of copper in normal physiology, followed by a discussion of the dysregulation of copper homeostasis in cancer and the effects of copper on cancer progression. Finally, recent advances in our understanding of the mechanisms of action of anti-cancer agents targeting copper are discussed.

Element bioimaging of liver needle biopsy specimens from patients with Wilson's disease by laser ablation-inductively coupled plasma-mass spectrometry

A laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) method is developed and applied for the analysis of paraffin-embedded liver needle biopsy specimens of patients with Wilson's disease (WD), a rare autosomal recessive disorder of the copper metabolism causing various hepatic, neurological and psychiatric symptoms due to a copper accumulation in the liver and the central nervous system. The sample set includes two WD liver samples and one negative control sample. The imaging analysis was performed with a spatial resolution of 10 μm. Besides copper, iron was monitored because an elevated iron concentration in the liver is known for WD. In addition to this, both elements were quantified using an external calibration based on matrix-matched gelatine standards. The presented method offers low limits of detection of 1 and 5 μg/g for copper and iron, respectively. The high detection power and good spatial resolution allow the analysis of small needle biopsy specimen using this method. The two analyzed WD samples can be well differentiated from the control sample due to their inhomogeneous copper distribution and high copper concentrations of up to 1200 μg/g. Interestingly, the WD samples show an inverse correlation of regions with elevated copper concentrations and regions with high iron concentrations.

Spectrum and Classification of ATP7B Variants in a Large Cohort of Chinese Patients with Wilson's Disease Guides Genetic Diagnosis

BACKGROUND

Wilson's disease (WD) is an autosomal recessive disorder of copper metabolism caused by ATP7B pathogenic mutations. The symptoms of WD can be effectively prevented if the affected individuals are identified and intervened early. However, clinical utility of this molecular analysis is challenging due to hundreds of variants with various clinical effects in the gene. Here, we aim to describe the spectrum of ATP7B variants and assess their clinical effects in the Han Chinese population.

METHODS

The ATP7B gene was directly sequenced in 632 unrelated WD patients and 503 unrelated healthy individuals. The effects of identified variants were classified according to the American College of Medical Genetics and Genomics (ACMG) standards and guidelines. Different frequency of variants observed in both cases and controls were tested using Chi-square or Fisher's exact tests.

RESULTS

We detected 161 non-synonymous variants in these 632 WD patients, 58 of which were novel. Among these variants, 78, 64, 8, 4, and 7 were classified as 'pathogenic variants', 'likely pathogenic variants', 'variants with uncertain significance', 'likely benign variants', and 'benign variants', respectively. Ninety percent (569/632) of these WD patients can be genetically diagnosed with two or more 'pathogenic' or 'likely pathogenic' variants. The 14 most common disease-causing variants were found at least once in 94% (537/569) of genetically diagnosed patients.

CONCLUSIONS

These data expand the spectrum of ATP7B variants and facilitate effective screening for ATP7B variants for early diagnosis of WD and development of individualized treatment regimens.

Acute Hepatic Phenotype of Wilson Disease: Clinical Features of Acute Episodes and Chronic Lesions Remaining in Survivors

BACKGROUND AND AIMS

Wilson disease (WD) is an inherited disorder of copper metabolism, and an international group for the study of WD (IGSW) has proposed three phenotypes for its initial presentation: acute hepatic, chronic hepatic, and neurologic phenotypes. Characterization of the acute hepatic phenotype may improve our understanding of the disease.

METHODS

Clinical features of 10 WD patients with the acute hepatic phenotype and characteristics of chronic lesions remaining in survivors were assessed by the European Association for the Study of the Liver (EASL) guidelines.

RESULTS

All six patients younger than 30 years had survived an acute episode of hemolytic anemia with residual liver disease of cirrhosis or chronic hepatitis. The acute episode was self-limiting in two of the four patients over the age of 30 years and progressed to acute liver failure in the other two patients. One of the two survivors had residual liver disease of chronic hepatitis, while the other had chronic hepatitis and neurologic disease. Neurologic disease remained in a patient who successfully received a liver transplantation. During acute episodes, serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) changed rapidly along with anemia. Liver-specific ALT levels were age-dependently correlated with hemoglobin (Hb) concentrations. Enzyme reduction was milder for AST than ALT, which resulted in a high AST/ALT ratio in the anemic stage. The anemic stage in two patients transformed to acute liver failure.

CONCLUSIONS

All survivors of an acute episode of the acute hepatic phenotype had residual liver disease or both liver and neurologic diseases. The rapid changes in liver enzymes during the acute episode and the liver and neurologic diseases remaining in survivors may provide a better understanding of WD.

Geographic distribution of ATP7B mutations in Wilson disease

CONTEXT

Geographic distribution of ATP7B mutations in different populations.

OBJECTIVE

To summarise common mutations in the ATP7B gene and graphically illustrate their prevalence in different populations.

METHODS

A literature search was done using PubMed and the Wilson Disease Mutation Database (http://www.wilsondisease.med.ualberta.ca/database).

RESULTS

p.His1069Gln is the most prevalent mutation seen in Europe. In the Mediterranean countries, the array of prevalent mutations is different from the rest of Europe. In Far East Asian countries, the mutation p.Arg778Leu is the most common. In India, no single mutation seems to be dominant, owing to the vast ethnic diversity of the country. The p.Cys271* mutation is dominant in the east, west and south, but not reported in the north. In the Middle East, data from Saudi Arabia shows the p.Gln1399Arg mutation as the most prevalent. In the US, the p.His1069Gln is dominant, whereas in Brazil the mutation c.3402delC dominates.

CONCLUSION

Clinical features in WD patients can be misleading and often absent. Genetic testing is used to confirm the diagnosis. However, owing to the large gene size and vast diversity in the mutations, genetic testing can be time-consuming and tedious. This study reviews ATP7B mutations seen in different populations and can help develop time-saving methods and expediate the process of genetic analysis of WD.

Defective roles of ATP7B missense mutations in cellular copper tolerance and copper excretion

Wilson's disease (WD) is a hereditary disorder of copper metabolism resulting from mutations within ATP7B. Clinical investigations showed that ATP7B missense mutations cause a wide variety of symptoms in WD patients, which implies that those mutations might affect ATP7B function in a number of ways and each would have deleterious consequences on normal copper distribution and lead to WD. Nonetheless, it is still unknown about the influences of those mutations on ATP7B function of increasing copper excretion and enhancing cellular copper tolerance. Here we established the stable expression cell lines of wild-type (WT) ATP7B and its four missense mutants (R778L, R919G, T935M and P992L), tested cellular copper tolerance and copper excretion using those cell lines, and also observed cellular distribution of WT ATP7B proteins and those mutants in transiently transfected cells. We found that extrinsic expressing WT ATP7B reduced CuCl2-induced copper accumulation and enhanced cellular copper tolerance by accelerating copper excretion, which was selectively compromised by R778L and P992L mutations. Further investigation showed that R778L mutation disrupted the subcellular localization and trafficking of ATP7B proteins, whereas P992L mutation only affected the trafficking of ATP7B. This indicates that ATP7B missense mutants have distinct effects on cellular copper tolerance.