Relative exchangeable copper: a promising tool for family screening in Wilson disease

Challenges and dilemmas in pediatric hepatic Wilson's disease

Wilson disease is an autosomal recessive disorder affecting the ATP7B gene located on chromosome 13q. This leads to copper deposition in various organs, most importantly in the liver and brain. The genetic mutations are vast, well reported in the West but poorly documented in developing countries. Hence the diagnosis is made with a constellation of clinico-laboratory parameters which have significant overlap with other liver diseases and often pose a significant dilemma for clinicians. Diagnostic scoring systems are not fool-proof. The availability and affordability of chelators in developing countries impact the drug compliance of patients. While D-penicillamine is a potent drug, its side effects lead to drug discontinuation. Trientine is cost-prohibitive in developing countries. There is no single test to assess the adequacy of chelation. Exchangeable urinary copper is an essential upcoming diagnostic and prognostic tool. In the presence of cirrhosis, hypersplenism clouds the assessment of myelosuppression of drugs. Similarly, it may be difficult to distinguish disease tubulopathy from drug-induced glomerulonephritis. Neurological worsening due to chelators may appear similar to disease progression. Presentation as fulminant hepatic failure requires rapid workup. There is a limited window of opportunity to salvage these patients with the help of plasmapheresis and other liver-assisted devices. This review addresses the challenges and clinical dilemmas faced at beside in developing countries.

Recent advances in the diagnosis and management of Wilson's disease

In this editorial, the reader will be updated on novel epidemiological, diagnostic, and therapeutical proposals in the field of Wilson disease.

Benefits of using exchangeable copper and the ratio of exchangeable copper in a real-world cohort of patients with Wilson disease

Wilson disease (WD) is a complex disease in which diagnosis and long-term metabolic copper control remains challenging. The absence of accurate biomarkers requires the combination of different parameters to ensure copper homeostasis. Exchangeable copper and its ratio (REC) have been suggested to be useful biomarkers in this setting. We aimed at introducing these measurements and evaluate their performance and accuracy in our real-world cohort of WD patients. Exchangeable copper and REC were measured in 48 WD patients and 56 control individuals by inductively coupled plasma-mass-spectrometry. Demographic and clinical characteristics were collected. REC was shown to be significantly higher among WD patients compared to controls and useful for WD identification by using the previously established cutoffs: 71.4% of WD patients with a recent diagnosis had REC ≥18.5% and 95.1% of long-term treated WD had REC ≥14%; only four patients of the cohort presented discordant levels. Moreover, REC values were below 15% in all the control individuals. Exchangeable copper was significantly higher in WD patients compared to controls and tended to be reduced among WD patients who were compliant to medication. This real-life study confirmed that exchangeable copper and REC are useful serum biomarkers that can be used as complementary tests to ensure WD diagnosis (REC) and copper homeostasis whithin time (exchangeable copper). The desirable target levels for this last objective still needs to be validated in prospective cohorts.

Diagnosis and Outcomes of Late-Onset Wilson's Disease: A National Registry-Based Study

BACKGROUND

Wilson's disease (WD) is usually diagnosed in children and young adults; limited data exist on late-onset forms.

OBJECTIVE

The aim was to characterize the clinical and paraclinical presentations, therapeutic management, and outcomes in patients with late-onset WD.

METHODS

Patients diagnosed with WD after age 40 years were identified from the French Wilson's Disease Registry (FWDR). Clinical, laboratory, and imaging findings and treatment were reported at diagnosis and last follow-up.

RESULTS

Forty-five patients were identified (median age: 49, range: 40-64) and placed in three groups according to their clinical presentation: neurological (n = 20, median diagnostic delay: 20 months), hepatic (n = 13, diagnostic delay: 12 months), and family screening (n = 12), all confirmed genetically. Six neurological patients had an atypical presentation (1 torticollis, 2 writer's cramps, 2 functional movement disorders, and 1 isolated dysarthria), without T2/fluid-attenuated inversion recovery brain magnetic resonance imaging (MRI) hyperintensities; 5 of 6 had no Kayser-Fleischer ring (KFR); 5 of 6 had liver involvement. In the neurological group, 84% of patients improved clinically, and 1 developed copper deficiency. In the hepatic group, 77% had cirrhosis; 6 patients required liver transplantation. In the screened group, 43% had mild liver involvement; 3 were not treated and remained stable; 24-h urinary copper excretion was normal in 33% of patients at diagnosis.

CONCLUSIONS

In the FWDR, late-onset forms of WD affect 8% of patients, mostly with neurological presentations. Thirty percent of the neurological forms were atypical (isolated long-lasting symptoms, inconspicuous brain MRI, no KFR). With personalized treatment, prognosis was good. This study emphasized that WD should be suspected at any age and even in cases of atypical presentation. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Long-Term Urinary Copper Excretion and Exchangeable Copper in Children With Wilson Disease Under Chelation Therapy

OBJECTIVES

Determining 24-hour urinary copper excretion (UCE) levels is useful for diagnosing Wilson's disease (WD) and for treatment monitoring. Exchangeable copper (ExC) is a novel potential marker, but its long-term changes have never been described in patients under chelation therapy. Our aim was to describe the long-term changes in ExC levels compared to UCE levels in symptomatic WD pediatric patients under chelation therapy.

METHODS

A retrospective, descriptive, and analytical study including all patients under 18 years of age, diagnosed between 2006 and 2020, and treated with chelation therapy was conducted at the National Reference Center for WD in Lyon. Ceruloplasmin levels, serum copper, 24 h-UCE, ExC, and liver enzymes at diagnosis and during follow-up were analyzed.

RESULTS

Our study included 36 patients, predominantly with hepatic form of WD (n = 31). The median [interquartile range (IQR)] age at diagnosis was 10.5 (8.4-13.1) years, and the median (IQR) follow-up duration was 6.3 (3.3-8.8) years. At diagnosis, the median (IQR) ExC value was 1.01 (0.60-1.52) µmol/L. There was a significant decrease during the first year of chelation treatment ( P = 0.0008), then a stabilization. The median (IQR) ExC values was 0.38 (0.22-0.63) µmol/L at 12-18 months and 0.43 (0.31-0.54) µmol/L at 5 years of chelation treatment ( P = 0.4057). Similarly, there was a significant decrease in 24-hour UCE ( P < 0.001) during the first year of chelation treatment, then a stabilization.

CONCLUSIONS

Our study showed a significant decrease in ExC and 24-hour UCE levels during the first year of follow-up; The dynamics of both biomarkers were similar along the follow-up, demonstrating their usefulness in clinical practice for monitoring WD.

Biochemical diagnosis of Wilson's disease: an update

Wilson's disease (WD) is an inherited disorder of copper metabolism caused by mutations in the ATP7B gene. This condition is characterized by the accumulation of copper in the liver and other organs and tissues causing hepatic and neuropsychiatric manifestations. This paper reviews the diagnostic performance and limitations of the biochemical tests commonly used to detect this underdiagnosed disease. It also provides some recommendations and suggests a set of standardized laboratory comments. At present, a rapid, simple, reliable biochemical test that confirms diagnosis of WD is not available. However, diagnosis can be established based on serum ceruloplasmin and urinary copper excretion. Total serum copper should be employed with caution, since it has a low negative predictive value. The use of estimated non-ceruloplasmin-bound copper is not recommended. Nevertheless, measured relative exchangeable copper has very high sensitivity and specificity and emerges as a potential gold standard for the biochemical diagnosis of WD. The development of novel assays for WD detection makes this disorder a potential candidate to be included in newborn screening programs.

Wilson disease in children and young adults - State of the art

Wilson disease (WD) is an autosomal recessive disorder caused by mutations of the ATP7B gene, with a reported prevalence of 1:30,000-50,000. ATP7B encodes an enzyme called transmembrane copper-transporting ATPase, which is essential for copper incorporation into ceruloplasmin and for copper excretion into the bile. A lack or dysfunction of this enzyme results in a progressive accumulation of copper in several organs, especially in the liver, the nervous system, corneas, kidneys, and heart. Children with WD can present with asymptomatic liver disease, cirrhosis, or acute liver failure, with or without neurological and psychiatric symptoms. Approximately 20%-30% of WD patients present with ALF, while most of the other patients have chronic progressive hepatitis or cirrhosis if untreated. Although genetic testing has become a more important diagnostic tool for WD, the diagnosis remains based on both clinical features and laboratory investigations. The aims of treatment are to reduce copper levels and prevent its accumulation in the liver and other organs, especially in the central nervous system. Liver transplantation in WD is a life-saving option for patients presenting with liver failure and encephalopathy. For WD patients treated with chelating agents, adherence to the therapy is essential for long-term success. In this review, we also address specific issues in young adults as compared to children.

Non-invasive diagnosis and follow-up of rare genetic liver diseases

Rare genetic liver diseases can result in multi-systemic damage, which may compromise the patient's prognosis. Wilson's disease and alpha-1 antitrypsin deficiency must be investigated in any patient with unexplained liver disease. Cystic fibrosis screening of new-borns is now implemented in most high-prevalence countries. The diagnosis of these diseases can be strongly suggested with specific non-invasive tests. Molecular analysis gene for these diseases is long and tedious but is recommended to confirm the diagnosis and help for the family screening. Liver biopsy is not systematic and is discussed when it helps diagnosis. Currently, for these three diseases, non-invasive fibrosis markers could identify patients with risk of cirrhosis and complications. Rare genetic liver diseases can result in multi-systemic damage, which may compromise the patient's prognosis. Wilson's disease, must be investigated in any patient with unexplained liver disease and/or unexplained neurological or neuropsychiatric disorders. The diagnosis is based on a combination of clinical, biological features, including copper balance. The exchangeable copper/total copper ratio is a new sensible and specific biological marker, useful for the diagnosis of the disease. Timely diagnosis and treatment will prevent serious complications from the disease. Neurological evaluation and familial screening are essential in patients with Wilson's disease.

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.

Total and Exchangeable Copper Assay Using Inductively Coupled Plasma Mass Spectrometry and Establishment of a Pediatric Reference Interval

CONTEXT.—

Recently, an exchangeable copper (CuEXC) assay has been suggested as a robust and feasible diagnostic tool for Wilson disease (WD). Although WD is a disorder that requires lifelong treatment and monitoring, few data are currently available regarding the status of copper levels in children.

OBJECTIVE.—

To evaluate the performance of copper assays and establish a reference interval for total copper and CuEXC in the pediatric population.

DESIGN.—

Serum samples from children aged 1-5 (n = 122), 6-12 (n = 125), and 13-18 years (n = 120) were analyzed. Total copper and CuEXC concentrations were directly measured using inductively coupled plasma mass spectrometry, and relative CuEXC levels were calculated. Total copper reference intervals, CuEXC levels, and relative CuEXC levels were determined based on the 2.5th and 97.5th percentiles of the data with 90% confidence intervals.

RESULTS.—

There were significant differences in the median concentrations of total copper and relative CuEXC among the age groups. Reference intervals determined for total copper were 82 to 167, 75 to 139, and 64 to 133 μg/dL for children aged 1 to 5, 6 to 12, and 13 to 18 years, respectively. The reference intervals for CuEXC were 4.29 to 9.79, 4.02 to 9.09, and 3.55 to 8.25 μg/dL for children aged 1 to 5, 6 to 12, and 13 to 18 years, respectively. Among 11 patients with suspected WD, relative CuEXC values were elevated in all 3 diagnosed with WD.

CONCLUSIONS.—

The pediatric reference intervals derived in this study are expected to be useful for the diagnosis, differential diagnosis, treatment, and monitoring of pediatric patients with WD.

Wilson's disease: Revisiting an old friend

Wilson's disease (WD) is a rare condition caused by copper accumulation primarily in the liver and secondly in other organs, such as the central nervous system. It is a hereditary autosomal recessive disease caused by a deficiency in the ATP7B transporter. This protein facilitates the incorporation of copper into ceruloplasmin. More than 800 mutations associated with WD have been described. The onset of the disease frequently includes manifestations related to the liver (as chronic liver disease or acute liver failure) and neurological symptoms, although it can sometimes be asymptomatic. Despite it being more frequent in young people, WD has been described in all life stages. Due to its fatal prognosis, WD should be suspected in all patients with unexplained biochemical liver abnormalities or neurological or psychiatric symptoms. The diagnosis is established with a combination of clinical signs and tests, including the measurement of ceruloplasmin, urinary copper excretion, copper quantification in liver biopsy, or genetic assessment. The pharmacological therapies include chelating drugs, such as D-penicillamine or trientine, and zinc salts, which are able to change the natural history of the disease, increasing the survival of these patients. In some cases of end-stage liver disease or acute liver failure, liver transplantation must be an option to increase survival. In this narrative review, we offer an overview of WD, focusing on the importance of clinical suspicion, the correct diagnosis, and treatment.

Long-Term Urinary Copper Excretion on Chelation Therapy in Children with Wilson Disease

OBJECTIVES

In Wilson disease (WD), 24-hour urinary copper excretion (UCE) is recommended to be used for diagnosis. It may be a useful tool to assess the efficacy of treatment during follow-up; however, there are limited data regarding the cutoff value of 24-hour UCE during follow-up in children. Therefore, we aim to evaluate the clinical use of 24-hour UCE during follow-up in children with WD.

PATIENTS AND METHODS

Medical records of children diagnosed with WD at Kings' College Hospital from 2005 to 2018 were retrospectively reviewed. The UCE, serum copper, and ceruloplasmin levels, tested during follow-up, were statistically analyzed.

RESULTS

Over the median duration of 7 years (range 1.4-14.4), 28 patients (age ranged 3.8-17.3 years) had UCE tests during follow-up. Of those, 21 patients had at least one 24-hour UCE test and 7 children had only spot UCE tests. In comparison with the level of 24-hour UCE collected at the first visit after penicillamine challenge test, the median excretion rate was significantly reduced over the follow-up period (P < 0.001), from 26.2 to 8.9 μmol/day following 1-2 years of therapy (P = 0.15), then reduced significantly to 2.2 μmol/day after 3-4 years (P = 0.009), and 5.6 μmol/day at >5 years of follow-up (P = 0.003).

CONCLUSIONS

Our study suggests that within 1 year of treatment, the level of nonceruloplasmin-bound copper concentration (NCC) drops to <0.8 μmol/L. In the absence of progressive liver disease or signs of copper deficiency, 24-hour UCE decreases to ≤8 μmol/day and <6 μmol/day after 1 and 5 years of treatment, respectively.

Challenges in the diagnosis of Wilson disease

The understanding and management of Wilson disease (WD) have dramatically improved since the first description of the disease by K. Wilson more than a century ago. However, the persistent long delay between the first symptoms and diagnosis emphasizes challenges in diagnosing earlier this copper overload disorder. As a treatable disease, WD should be detected early in the course of the disease by any health professionals at any care level, but the rare prevalence of the disease explains the lack of awareness of referring physicians. The most important challenge is to train physicians to recognize atypical or rare symptoms of WD that will lead to discuss the diagnosis more systematically. Atypia can come from the age of onset, the liver [non-alcoholic steatohepatitis (NASH) presentation], the central or peripheral nervous system (neuropathy, epilepsy, sleep disorders…) or may be due to lesions of other organs (renal manifestations, osteo-articular disorders or endocrine disturbances). Isolated biological anomalies, rare radiological findings or inadequate interpretation of copper test may also lead to misdiagnosis. The second challenge is to confirm the diagnosis faster and more effectively so as not to delay the initiation of treatment, and expand family screening as the genetic prevalence is higher than previously expected. Generalization of the exchangeable copper assay and the next generation sequencing (NGS) are two promising ways to overcome this ultimate challenge. By drawing attention to the earliest and rare symptoms and to new biomarkers and diagnostic tools, we hope that this article will increase diagnostic awareness and reduce delays so that patients can start their treatment earlier in the course of the illness and thus have a better disease prognosis.

New tools for Wilson's disease diagnosis: exchangeable copper fraction

Wilson's disease (WD) biochemical markers continue to evolve. Classical tests [serum copper, serum ceruloplasmin (Cp), urinary copper] have their own limits, and they are often insufficient to diagnose or exclude WD. So, calculated estimation of copper that is not bound to Cp has been proposed, but it is flawed. Therefore, we focused our research on a direct measurement of serum copper labile fraction. Exchangeable copper (CuEXC) offers a correct view of the free copper overload. It provides information on the spread and severity of WD. Relative exchangeable copper (REC) (percentage of exchangeable to total serum copper) that appreciates the toxic fraction of copper in blood is an excellent biomarker for WD diagnosis. These two tests are reliable and non-invasive. They give rapid answers for an appropriate diagnosis and make possible to start the treatment quickly without waiting for the result of the genetic tests. As early diagnosis and treatment are the keystones of successful management of patients with WD, different teams have already applied these tests in a routine framework to a large number of patients.

Wilson's Disease: Clinical Practice Guidelines of the Indian National Association for Study of the Liver, the Indian Society of Pediatric Gastroenterology, Hepatology and Nutrition, and the Movement Disorders Society of India

Clinical practice guidelines for Wilson's disease (WD) have been published by the American Association for the Study of Liver Diseases and European Association for the Study of the Liver in 2008 and 2012, respectively. Their focus was on the hepatic aspects of the disease. Recently, a position paper on pediatric WD was published by the European Society of Pediatric Gastroenterology Hepatology and Nutrition. A need was felt to harmonize guidelines for the hepatic, pediatric, and neurological aspects of the disease and contextualize them to the resource-constrained settings. Therefore, experts from national societies from India representing 3 disciplines, hepatology (Indian National Association for Study of the Liver), pediatric hepatology (Indian Society of Pediatric Gastroenterology, Hepatology and Nutrition), and neurology (Movement Disorders Society of India) got together to evolve fresh guidelines. A literature search on retrospective and prospective studies of WD using MEDLINE (PubMed) was performed. Members voted on each recommendation, using the nominal voting technique. The Grades of Recommendation, Assessment, Development and Evaluation system was used to determine the quality of evidence. Questions related to diagnostic tests, scoring system, and its modification to a version suitable for resource-constrained settings were posed. While ceruloplasmin and 24-h urine copper continue to be important, there is little role of serum copper and penicillamine challenge test in the diagnostic algorithm. A new scoring system - Modified Leipzig score has been suggested with extra points being added for family history and serum ceruloplasmin lower than 5 mg/dl. Liver dry copper estimation and penicillamine challenge test have been removed from the scoring system. Differences in pharmacological approach to neurological and hepatic disease and global monitoring scales have been included. Rising bilirubin and worsening encephalopathy are suggested as indicators predicting need for liver transplant but need to be validated. The clinical practice guidelines provide recommendations for a comprehensive management of WD which will be of value to all specialties.

Evaluation of the accuracy of exchangeable copper and relative exchangeable copper (REC) in a mouse model of Wilson's disease

Wilson's disease (WD) is caused by mutations in the ATP7B gene responsible for a toxic copper overload mainly in the liver and the central nervous system. Phenotypic heterogeneity may challenge the diagnostic confirmation. Exchangeable copper (CuEXC) has recently been proposed as a new marker of WD, and its ratio to the total serum copper (Cus), Relative Exchangeable Copper (REC = CuEXC/Cus), as a diagnostic marker. This study aimed to investigate whether this could be confirmed in Atp7b^-/- mice, an engineered WD animal model. Atp7b^-/- (n = 137) and wild type (WT; n = 101) mice were investigated under the same conditions at 6-8, 20, 39, or 50 weeks of age. Twenty-four Atp7b^-/- mice received D-penicillamine treatment from 39 to 50 weeks of age. Serum and liver [histology and intrahepatic copper (IHCu)] data were evaluated. In the WT group, all serum and liver data were normal. Atp7b^-/- livers developed a chronic injury from isolated moderate inflammation (6-8 weeks: 16/33 = 48%) to inflammatory fibrosis with cirrhosis (50 weeks: 25/25 = 100% and 16/25 = 64% respectively). Cus and CuEXC increased until week 39, whereas IHCu and REC were stable with increasing age and much higher than in WT mice (mean ± SD: 669 ± 269 vs. 13 ± 3 μg/g dry liver and 39 ± 12 vs. 11 ± 3%, respectively). A threshold value of 20% for REC provided a diagnostic sensitivity and specificity of 100%, regardless of sex, age, or the use of D-penicillamine. Eleven weeks of 100 mg/kg D-penicillamine reduced liver fibrosis (p = 0.001), IHCu (p = 0.026) and CuEXC (p = 0.175). In conclusion, this study confirms REC as a WD diagnostic marker in a mouse model of chronic liver disease caused by copper overload. Further studies are needed to assess the usefulness of CuEXC to monitor the evolution of WD, particularly during treatment.

Wilson's disease: A 2017 update

Wilson's disease (WD) is characterised by a deleterious accumulation of copper in the liver and brain. It is one of those rare genetic disorders that benefits from effective and lifelong treatments that have dramatically transformed the prognosis of the disease. In Europe, its clinical prevalence is estimated at between 1.2 and 2/100,000 but the genetic prevalence is higher, at around 1/7000. Incomplete penetrance of the gene or the presence of modifier genes may account for the difference between the calculated genetic prevalence and the number of patients diagnosed with WD. The clinical spectrum of WD is broader as expected with mild clinical presentations and late onset of the disease after the age of 40 in 6% of patients. WD is usually suspected when ceruloplasmin and serum copper levels are low and 24h urinary copper excretion is elevated. Recently, a major diagnostic advance was achieved with implementation of the direct assay of "free copper", or exchangeable copper (CuEXC). The relative exchangeable copper (REC) that corresponds to the ratio between CuEXC and total serum copper enables a diagnosis of WD with high sensitivity and specificity when REC>18.5%. Moreover, CuEXC values at diagnosis are a marker of extrahepatic involvement and its severity. A value of >2.08μmol/L is suggestive of corneal and brain involvement (Se=86%, Sp=94%), and the disease will be more clinically and radiologically severe as values rise. The use of FibroScan^® is becoming more widespread to assess liver stiffness measurements in WD patients. 6.6kPa is considered to be a threshold value between mild and moderate fibrosis, whereas a value higher than 8.4 is indicative of severe fibrosis. More studies are now necessary to confirm the usefulness of Fibroscan^® in managing chronic therapy for WD patients. Treatment of this disease is based on an initial active and prolonged chelating phase (with D-Penicillamine or Trientine) followed by maintenance with Trientine or zinc salt. The two major problems that may be encountered are neurological worsening during the initial phase and non-compliance with treatment during maintenance therapy. Liver transplantation is the recommended therapeutic option in WD with acute liver failure or end-stage liver cirrhosis; its indication should be considered when neurological status deteriorates rapidly despite effective chelation. Regular clinical, biological and liver ultrasound follow-up is essential to evaluate efficacy, tolerance and treatment compliance, but also to detect the onset of hepatocellular carcinoma on a cirrhotic liver. There are hopes in the near future with the introduction of a new chelator and inhibitor of copper absorption, tetrathiomolybdate (TTM) and the development of gene therapy.

Update on the Diagnosis and Management of Wilson Disease

PURPOSE OF REVIEW

Exciting developments relating to Wilson disease (WD) have taken place with respect to both basic biological and clinical research. This review critically examines some of these findings and considers their implications for current thinking about WD. It is not a comprehensive review of WD as a clinical disorder.

RECENT FINDINGS

The structure of the gene product of ATP7B, abnormal in WD, is being worked out in detail, along with a broader description of how the protein ATP7B (Wilson ATPase) functions in cells including enterocytes, not only in relation to copper disposition but also to lipid synthesis. Recent population studies raise the possibility that WD displays incomplete penetrance. Innovative screening techniques may increase ascertainment. New strategies for diagnosing and treating WD are being developed. Several disorders have been identified which might qualify as WD-mimics. WD can be difficult to diagnose and treat. Insights from its pathobiology are providing new options for managing WD.

High genetic carrier frequency of Wilson's disease in France: discrepancies with clinical prevalence

Background

Wilson’s disease (WD) is a rare autosomal recessive metabolic disease caused by ATP7B gene mutations tat cause excessively high copper levels, particularly in the liver and brain. The WD phenotype varies in terms of its clinical presentation and intensity. Diagnosing this metabolic disorder is important as a lifelong treatment, based on the use of copper chelating agents or zinc salts, is more effective if it’s started early. Worldwide prevalence of WD is variable, with an average of 1/30,000. In France, a recent study based on French health insurance data estimated the clinical prevalence of the disease to be around 3/200,000.

Methods

To estimate the genetic prevalence of WD in France, we analysed the ATP7B gene by Next Generation Sequencing from a large French cohort of indiscriminate subjects.

Results

We observed a high heterozygous carrier frequency of ATP7B in France. Among the 697 subjects studied, 18 variants classified as pathogenic or probably pathogenic were found at heterozygous level in 22 subjects (22 alleles/1394 alleles), yielding a prevalence of 0.032 or 1/31 subjects.

Conclusions

This considerable and unexplained discrepancy between the heterozygous carrier frequency and the clinical prevalence of WD may be explained by the clinical variability, the incomplete penetrance and the existence of modifiers genes. It suggests that the molecular analysis of ATP7B should be interpreted with caution, always alongside copper assays (ceruloplasmin, relative exchangeable copper, 24 h-urinary copper excretion) with particular respect to exome sequencing.

Epidemiology and introduction to the clinical presentation of Wilson disease

Our understanding of the epidemiology of Wilson disease has steadily grown since Sternlieb and Scheinberg's first prevalence estimate of 5 per million individuals in 1968. Increasingly sophisticated genetic techniques have led to revised genetic prevalence estimates of 142 per million. Various population isolates exist where the prevalence of Wilson disease is higher still, the highest being 885 per million from within the mountainous region of Rucar in Romania. In Sardinia, where the prevalence of Wilson disease has been calculated at 370 per million births, six mutations account for around 85% of Wilson disease chromosomes identified. Significant variation in the patterns of presentation may however exist, even between individuals carrying the same mutations. At either extremes of presentation are an 8-month-old infant with abnormal liver function tests and individuals diagnosed in their eighth decade of life. Three main patterns of presentation have been recognized - hepatic, neurologic, and psychiatric - prompting their presentation to a diverse range of specialists. Deviations in the family history from the anticipated autosomal-recessive mode of inheritance, with apparent "pseudodominance" and mechanisms of inheritance that include uniparental isodisomy (the inheritance of both chromosomal copies from a single parent), may all further cloud the diagnosis. It can therefore take the efforts of an astute clinician with a high clinical index of suspicion to clinch the diagnosis of this eminently treatable condition.

Characteristics and prevalence of Wilson's disease: A 2013 observational population-based study in France

BACKGROUND AND AIMS

Only a few epidemiological studies on the incidence and prevalence of Wilson's disease (WD) have been performed to date, and the results vary widely according to the reports. The aim of the study was to investigate the prevalence, ambulatory care and treatments of patients with WD in France.

METHODS

Among the 58 million general health scheme beneficiaries (86% of the French population), people managed for WD in 2013 were identified using hospitalisation diagnosis in 2011-2013 or specific long-term disease status with a 100% reimbursement for specific healthcare in 2013. Data were derived from the Sniiram (National Health Insurance Information System database). Prevalence by age and sex were calculated.

RESULTS

In 2013, 906 prevalent cases were identified, yielding a crude prevalence of 1.5 cases per 100,000; 1.65 per 100,000 in males and 1.44 per 100,000 in females. This prevalence is comparable to that reported in other population-based studies in European countries and to a study using a similar method. Almost 40% of patients were treated by D-penicillamine and 14.3% were treated by zinc acetate. Trientine, delivered on a compassionate basis, was not available in the reimbursement database. In 2013, 1.3% of patients underwent liver transplantation and 4% had already undergone liver transplantation in previous years. Fifteen per cent of patients received antidepressants, a higher rate than in general population.

CONCLUSIONS

This is the first French population-based epidemiological study of WD in a comprehensive population based on administrative data and constitutes an important step to understand the impact of WD and to study quality of care.

Wilson's Disease in Children: A Position Paper by the Hepatology Committee of the European Society for Paediatric Gastroenterology, Hepatology and Nutrition

BACKGROUND

Clinical presentations of Wilson's disease (WD) in childhood ranges from asymptomatic liver disease to cirrhosis or acute liver failure, whereas neurological and psychiatric symptoms are rare. The basic diagnostic approach includes serum ceruloplasmin and 24-hour urinary copper excretion. Final diagnosis of WD can be established using a diagnostic scoring system based on symptoms, biochemical tests assessing copper metabolism, and molecular analysis of mutations in the ATP7B gene. Pharmacological treatment is life-long and aims at removal of copper excess by chelating agents as D-penicillamine, trientine, or inhibition of intestinal copper absorption with zinc salts. Acute liver failure often requires liver transplantation. This publication aims to provide recommendations for diagnosis, treatment, and follow-up of WD in children.

METHODS

Questions addressing the diagnosis, treatment, and follow-up of WD in children were formulated by a core group of ESPGHAN members. A systematic literature search on WD using MEDLINE, EMBASE, Cochrane Database from 1990 to 2016 was performed focusing on prospective and retrospective studies in children. Quality of evidence was assessed according to the GRADE system. Expert opinion supported recommendations where the evidence was regarded as weak. The ESPGHAN core group and ESPGHAN Hepatology Committee members voted on each recommendation, using the nominal voting technique.

Relative exchangeable copper: A valuable tool for the diagnosis of Wilson disease

BACKGROUND & AIMS

Measuring of the relative exchangeable copper seems to be a promising tool for the diagnosis of Wilson disease. The aim of our study is to determine the performance of REC for the diagnosis of Wilson disease in a population of patients with chronic liver diseases.

METHODS

Measuring of exchangeable serum copper levels and relative exchangeable copper was performed in a group of Wilson disease patients at diagnosis or at clinical deterioration because of non-compliance (group 1, n=9), a group of stable WD patients (group 2, n=40), and two groups of patients (adult and paediatric) followed for non-Wilsonian liver diseases (group 3, n=103 and group 4, n=49 respectively).

RESULTS

Exchangeable serum copper (N: 0.6-1.1 μmol/L) was significantly higher in group 1 (mean 2.2±0.7 μmol/L) compared to the other three groups: group 2=0.9±0.4 μmol/L, group 3=1.2±0.4 μmol/L, group 4=1.1±0.3 μmol/L (P<0.05). Relative exchangeable copper was significantly higher in Wilson disease patients group 1 and 2 (mean 52.6% and 43.8%) compared to patients suffering from other liver diseases (mean 7.1% and 5.9%) (P<0.05).

CONCLUSIONS

Our study confirms that the determination of relative exchangeable copper is a highly valuable tool for the diagnosis of Wilson disease.

Dual signal amplification strategy for high-sensitivity detection of copper species in bio-samples with a tunable dynamic range

A facile method was constructed and applied to detection of copper species in bio-samples with a tunable dynamic range.

Diagnosis of Wilson disease

Clinical presentation of Wilson disease can vary widely; therefore diagnosis is not always straightforward. Wilson disease is not just a disease of children and young adults, but may present at any age. The key features of Wilson disease are liver disease and cirrhosis, neuropsychiatric disturbances, Kayser-Fleischer rings, and acute episodes of hemolysis, often in association with acute liver failure. Diagnosis is particularly difficult in children and in adults presenting with active liver disease. None of the available laboratory tests is perfect and may not be specific for Wilson disease. A detailed neurologic examination is required for all cases. Neuroimaging and electrophysiologic methods are helpful. To overcome the diagnostic challenge, several clinical signs (Kayser-Fleischer rings, neurologic symptoms) and laboratory features (copper in serum, urine, liver; serum ceruloplasmin; genetic testing) are scored 0 (absent) to 2 (present) and the Leipzig score is calculated. If the score is ≥4, the diagnosis of Wilson disease is very likely. For asymptomatic siblings of index patients, mutation analysis is the most reliable approach.

Exchangeable copper: a reflection of the neurological severity in Wilson's disease

BACKGROUND AND PURPOSE

The severity of Wilson's disease (WD) is linked to free copper accumulating in the liver and brain. Exchangeable copper (CuEXC) is a new technique to determine plasmatic copper and is useful in the diagnosis of WD. It is hypothesized that it may also enable a good evaluation of extra-hepatic involvement and its severity.

METHODS

Forty-eight newly diagnosed WD patients were prospectively evaluated using hepatic, neurological, ophthalmological and brain magnetic resonance imaging (MRI) scores. Three phenotypic presentations were distinguished: pre-symptomatic, hepatic and extra-hepatic. CuEXC was determined in addition to standard copper assays before decoppering therapy. Correlations between biological parameters and the different scores were determined and compared in the hepatic and extra-hepatic groups.

RESULTS

Extra-hepatic patients had significantly higher CuEXC values than those with the hepatic form (P < 0.0001). The overall ability of CuEXC to separate the two forms was satisfactory, with an area under the curve of 0.883 (95% confidence interval 0.771-0.996) and an optimal threshold for extra-hepatic diagnosis of 2.08 μmol/l (sensitivity 85.7%; specificity 94.1%). In extra-hepatic patients, CuEXC was the only biological marker to be positively correlated with the Unified Wilson Disease Rating Score (r = 0.45, P = 0.016), the Kayser-Fleischer ring score (r = 0.46, P = 0.014) and the brain MRI score (r = 0.38, P = 0.048), but it was not correlated with the hepatic score.

CONCLUSIONS

Exchangeable copper determination is useful when diagnosing WD as a value >2.08 μmol/l is indicative of the severity of the extra-hepatic involvement. In the case of purely hepatic presentation, atypical or mild neurological signs, it should encourage physicians to search for lesions in the brain and eyes.

[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.

Rapid and reliable diagnosis of Wilson disease using X-ray fluorescence

Wilson's disease (WD) is a rare autosomal recessive disease due to mutations of the gene encoding the copper-transporter ATP7B. The diagnosis is hampered by the variability of symptoms induced by copper accumulation, the inconstancy of the pathognomonic signs and the absence of a reliable diagnostic test. We investigated the diagnostic potential of X-ray fluorescence (XRF) that allows quantitative analysis of multiple elements. Studies were performed on animal models using Wistar rats (n = 10) and Long Evans Cinnamon (LEC) rats (n = 11), and on human samples including normal livers (n = 10), alcohol cirrhosis (n = 8), haemochromatosis (n = 10), cholestasis (n = 6) and WD (n = 22). XRF experiments were first performed using synchrotron radiation to address the elemental composition at the cellular level. High-resolution mapping of tissue sections allowed measurement of the intensity and the distribution of copper, iron and zinc while preserving the morphology. Investigations were further conducted using a laboratory X-ray source for irradiating whole pieces of tissue. The sensitivity of XRF was highlighted by the discrimination of LEC rats from wild type even under a regimen using copper deficient food. XRF on whole formalin-fixed paraffin embedded needle biopsies allowed profiling of the elements in a few minutes. The intensity of copper related to iron and zinc significantly discriminated WD from other genetic or chronic liver diseases with 97.6% specificity and 100% sensitivity. This study established a definite diagnosis of Wilson's disease based on XRF. This rapid and versatile method can be easily implemented in a clinical setting.

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.

Genetic and Clinical Analysis in a Cohort of Patients with Wilson's Disease in Southwestern China

BACKGROUND AND AIMS

Wilson's disease (WD), characterized by a disorder of copper metabolism, is an inherited autosomal recessive disease caused by mutations in the ATP7B gene.

METHODS

To explore genotype-phenotype correlations in Chinese WD patients and to evaluate the frequency of the ATP7B mutations, we described 77 clinically and biochemically confirmed WD patients and detected mutations in ten WD families from southwestern China. Clinical features were presented and all the exons of the ATP7B gene were screened.

RESULTS

The appearance of Kayser-Fleischer (K-F) rings was closely related to onset age, particularly before 10 years old. For those patients with predominantly neurological symptoms, MRI was the most sensitive and preferred examination. Eight mutations of the ATP7B gene were detected including seven reported mutations (c.2302dup, c.2304delC, c.2333 G>T, c.2621 C>T, c.2755 C>G, c.2975 C>T and c.1366 G>C) and four novel mutations (c.3446 G>A, c.3767insCA, c.3406 G>A and c.3700delG). c.2333 G>T was detected in 6/20 alleles (30%), accounting for the largest proportion, which could be regarded as a mutation hotspot in this region.

CONCLUSIONS

Our study extends the mutation spectrum of ATP7B and analyzes the relationship between mutations in the ATP7B gene and clinical findings of WD.