Mass screening for Wilson's disease: results and recommendations

Technical Study of Automated High-Throughput High-Sensitive Ceruloplasmin Assay on Dried Blood Spots-Reinstate the Potential Use for Newborn Screening of Wilson Disease

In this study, we modified a fully automatic immunoassay on ceruloplasmin concentration on dried blood spots (DBS) to increase its analytical sensitivity in order to accurately differentiate newborns from true Wilson disease (WD) patients. Modifications to the assay parameters of the Roche/Hitachi Cobas c systems immunoturbidimetric assay are adjusted to lower the limit of quantitation to 0.60 mg/L from 30 mg/L. This enables sensitive measurement of ceruloplasmin in eluent after DBS extraction. In addition, reference intervals and receiver operating characteristic curve analysis for diagnostic cut-off were established using DBS of neonates and WD adult patients. After DBS whole blood calibration, the 95th percentile of the reference interval for newborns was 86-229 mg/L. The cut-off value of 54 mg/L was found to be the most optimal point for differentiating true adult WD from newborn controls. This test shows a high area under curve of 1.000 with 100% sensitivity and specificity in differentiating normal newborns from WD adult samples. However, the results should be further validated with true newborn WD patient samples together with the consideration of other factors that can also lead to low ceruloplasmin levels. This test shows application potential in newborn screening for WD, which can save lives through early identification and timely treatment.

Estimating the clinical prevalence of Wilson's disease in the UK

Background & Aims

The clinical prevalence of Wilson’s disease (WD) in the UK remains unknown. The estimated genetic prevalence in the UK, 142/million, is higher than the clinical prevalence (15/million) reported in other European studies. The aim of this study was to estimate the clinical prevalence of WD utilising readily available laboratory and clinical data.

Method

Patients with WD who attended Nottingham University Hospital NHS Trust (NUH) between 2011 and 2018 were identified using multiple sources of case ascertainment: serum ceruloplasmin, 24-hour urinary copper, ‘Wilson’ in liver biopsy report, hospital prescription for penicillamine/trientine/zinc and admission coded with ICD-10 Code E83.0 (disorder of copper metabolism). Potential cases were identified using the Leipzig score, diagnosis was confirmed in hospital records and the point prevalence was calculated using the Office for National Statistics mid-2017 population estimates.

Results

A total of 1,794 patients were identified from ≥1 source; 19 patients had WD, of whom 11 were from within the study catchment area and alive at the time of point prevalence estimation. Twenty-nine patients had a Leipzig score ≥2 without a diagnosis of WD, but none had WD on screening (n = 16). The overall prevalence of WD was 15.5/million; males 16.9/million and females 14.1/million.

Conclusion

This is the first UK population-based study to assess the clinical prevalence of WD. The reported clinical prevalence is lower than the UK genetic prevalence, but comparable to the clinical prevalence reported in Europe. The case ascertainment approach used in this study may be cost-effective, and similar practises could be adopted nationally.

Lay summary

Our study estimates the clinical prevalence of Wilson’s disease, a rare genetic disorder of copper metabolism, in the UK. The estimated clinical prevalence is this study is markedly lower than the estimated UK genetic prevalence.

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The clinical prevalence of Wilson’s disease in the UK is estimated to be 15.5/million (1/64,516).

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The clinical prevalence is significantly lower than the previously reported genetic prevalence.

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Routine clinical and laboratory data can be used to not only find existing cases, but also evaluate potential cases.

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Case ascertainment is potentially a cost-effective approach for Wilson’s disease and other rare diseases.

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

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

The Prevalence of Wilson's Disease: An Update

BACKGROUND AND AIMS

In 1984, Scheinberg and Sternlieb estimated the prevalence of Wilson's disease to be 1:30,000 based on the limited available data. This suggested a large number of overlooked cases with potentially fatal consequences. The "Scheinberg-Sternlieb Estimate" is still widely used, although more recent clinical and genetic studies of higher quality are now available. In the present study, we included these data to update the prevalence estimate.

APPROACH AND RESULTS

A MEDLINE Ovid, Science Citation Index Expanded, and PubMed systematic search for all relevant studies on the prevalence of Wilson's disease was conducted. In total, 59 studies (50 clinical and 9 population-based genetic) were included in the final analysis. We identified 4 recent clinical studies based on nationwide databases of high quality, providing prevalence estimates from 1:29,000 to 1:40,000. Higher frequency populations do exist because of frequent first-cousin marriages and/or a higher mutation frequency. When calculating prevalence from the incidence related to number of births, estimates were 1:40,000-1:50,000. Clinical screening studies, including examination for Kayser-Fleischer rings or ceruloplasmin, did not improve these estimates because of insufficient sample size or selection biases. Population-based genetic studies in US and UK populations were not in disagreement with the clinically based estimates. At the same time, studies from France and Sardinia suggested that the genetic prevalence may be 3-4 times higher than the clinical disease prevalence. This raises the question whether the penetrance is indeed 100% as generally assumed.

CONCLUSIONS

The original prevalence estimate from 1984 of 1:30,000-1:50,000 still appears valid, at least for the United States, Europe, and Asia. In some population-based studies, the genetic prevalence was 3-4 times higher than clinically based estimates. The question of penetrance needs further evaluation.

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.

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.

The genetics of Wilson disease

Wilson disease (WD) is an autosomal-recessive disorder of hepatocellular copper deposition caused by pathogenic variants in the copper-transporting gene, ATP7B. Early detection and treatment are critical to prevent lifelong neuropsychiatric, hepatic, and systemic disabilities. Due to the marked heterogeneity in age of onset and clinical presentation, the diagnosis of Wilson disease remains challenging to physicians today. Direct sequencing of the ATP7B gene is the most sensitive and widely used confirmatory testing method, and concurrent biochemical testing improves diagnostic accuracy. More than 600 pathogenic variants in ATP7B have been identified, with single-nucleotide missense and nonsense mutations being the most common, followed by insertions/deletions, and, rarely, splice site mutations. The prevalence of Wilson disease varies by geographic region, with higher frequency of certain mutations occurring in specific ethnic groups. Wilson disease has poor genotype-phenotype correlation, although a few possible modifiers have been proposed. Improving molecular genetic studies continue to advance our understanding of the pathogenesis, diagnosis, and screening for Wilson disease.

Quantification of ATP7B Protein in Dried Blood Spots by Peptide Immuno-SRM as a Potential Screen for Wilson's Disease

Wilson's Disease (WD), a copper transport disorder caused by a genetic defect in the ATP7B gene, has been a long time strong candidate for newborn screening (NBS), since early interventions can give better results by preventing irreversible neurological disability or liver cirrhosis. Several previous pilot studies measuring ceruloplasmin (CP) in infants or children showed that this marker alone was insufficient to meet the universal screening for WD. WD results from mutations that cause absent or markedly diminished levels of ATP7B. Therefore, ATP7B could serve as a marker for the screening of WD, if the protein can be detected from dried blood spots (DBS). This study demonstrates that the immuno-SRM platform can quantify ATP7B in DBS in the picomolar range, and that the assay readily distinguishes affected cases from normal controls (p < 0.0001). The assay precision was <10% CV, and the protein was stable for a week in DBS at room temperature. These promising proof-of-concept data open up the possibility of screening WD in newborns and the potential for a multiplexed assay for screening a variety of congenital disorders using proteins as biomarkers in DBS.

Diagnostic Value of Ceruloplasmin in the Diagnosis of Pediatric Wilson's Disease

PURPOSE

Measurement of serum ceruloplasmin level is the first step in screening for Wilson's disease (WD). Despite the rarity of WD in the general population, ceruloplasmin levels are routinely measured through hepatitis screening in both adults and children. Herein, we evaluated the diagnostic value of ceruloplasmin for the diagnosis of WD among children with hepatitis.

METHODS

We retrospectively reviewed data on serum ceruloplasmin levels measured as a serologic marker for patients with hepatitis at Asan Medical Center (Seoul, Korea) between from January 2004 to November 2013. The diagnosis of WD was confirmed by the identification of pathogenic variants in the ATP7B gene. To determine the diagnostic accuracy of ceruloplasmin, receiver operation characteristic (ROC) curves were constructed and the area under curve (AUC) were calculated.

RESULTS

Measurements of serum ceruloplasmin were performed in 2,834 children who had hepatitis. Among these, 181 (6.4%) children were diagnosed with WD. The sensitivity, specificity, and accuracy of a ceruloplasmin level of <20 mg/dL in the discrimination of WD were 93.4%, 84.2%, and 84.8%, respectively. In this study, 418 (14.7%) false-positive cases and 12 (0.4%) false-negative cases were noted. Using a ROC curve, a ceruloplasmin level of ≤16.6 mg/dL showed the highest AUC value (0.956) with a sensitivity of 91.2%, a specificity of 94.9%, and an accuracy of 94.7%.

CONCLUSION

The measurement of serum ceruloplasmin was frequently used for the screening of WD in children, despite a low positive rate. The diagnostic value of ceruloplasmin may be strengthened by adopting a new lower cut-off level.

Population screening for Wilson's disease

Wilson's disease is an autosomal recessive disorder of copper transport caused by mutations in the gene encoding an ATPase, ATP7B. Early detection of Wilson's disease is critical because effective medical treatments such as chelating agents and zinc salts are available, which can prevent lifelong neurological disabilities and/or cirrhosis. It is unfortunate that most patients are brought to our attention after they have developed serious complications such as brain damage or cirrhosis, despite the availability of effective treatments. The diagnosis is usually made through copper measurement in the liver tissue, followed by confirmation with genetic testing of the ATP7B gene. Currently, there are no effective biomarkers or methods suitable for newborn screening for Wilson's disease. Ceruloplasmin has been tested for pediatric and newborn screening with limited outcome. Recently, liquid chromatography-multiple reaction monitoring-mass spectrometry (LC-MRM-MS) has emerged as a robust technology that may enable multiplex quantification of signature proteotypic peptides with low abundance. The application of this technology may help facilitate the research on Wilson's disease for protein expression, biomarker study, diagnosis, and, hopefully, screening.

Isolated persistent elevation of alanine transaminase for early diagnosis of pre-symptomatic Wilson's disease in Chinese children

BACKGROUND

Recent studies presented a contradictory approach for the investigation of pediatric patients with an isolated increase in alanine transaminase. While classical teaching advised for a thorough investigation, recent studies suggested the yield on further investigation was low and thus not necessary. Yet the approach to the same clinical problem may need to be different due to variable disease prevalence rates among different ethnic populations. For the population with a higher prevalence rate of genetic liver diseases like Wilson's disease, an abnormal liver function may be the first presenting feature for some patients.

METHODS

We reviewed 10 Chinese children with Wilson's disease who were diagnosed at a presymptomatic stage because of an isolated persistent elevation of alanine transaminase.

RESULTS

All 10 patients did not have overt symptoms of liver impairment or neurological deficit. They were picked up incidentally with an abnormal liver function test. All patients were started on treatment shortly after diagnosis, and they remained well and symptom-free on the latest follow-up.

CONCLUSIONS

This case series illustrated that an isolated persistent elevation of alanine transaminase is an important clue to the early diagnosis of pre-symptomatic Wilson's disease. It is particularly relevant in the Asian population where the disease is more prevalent.

Kayser-Fleischer ring in Wilson's disease: a cohort study

AIMS

To evaluate Wilson's disease (WD) features in Sardinian patients with Kayser-Fleischer (KF) ring and to evaluate correlations between modifications in KF and anti-copper therapy and systemic WD evolution.

PATIENTS AND METHODS

Sixty-seven WD patients (35 m/32 f; mean age 41 years) were retrospectively studied. At diagnosis and during follow up comprehensive ophthalmologic and neurologic examinations, brain RMN and ECD SPECT, detailed objective laboratory studies and hepatic histological examination were performed on all patients for analysis. All patients were given anti-copper therapy with d-Penicillamine in mono-therapy or in combination with Zinc Salts.

RESULTS

At diagnosis, KF was observed in 27% of patients with equal distribution in all age groups. Significant correlations between KF at diagnosis, neuro-psychiatric manifestations and pathologic features in brain RMN and in brain ECD SPECT were found at diagnosis. During follow up, a decrease in, or regression of KF was seen in 14% of patients. Anti-copper therapy leads to KF regression and prevents the appearance of KF. No significant correlations were observed between KF regression and clinical neurological or neuro-imaging improvement nor between KF modifications and clinical hepatic improvement.

CONCLUSIONS

Our study highlights the peculiar features of Sardinian WD patients: low representation of KF, its equal distribution in all age groups, significant correlation between KF at diagnosis and clinical neurological manifestations, pathologic brain RMN and brain ECD-SPECT are highlighted by our study. Anti-copper therapy induces KF regression and prevents its onset. Therefore, KF ring does appear to be a predictive factor in the neurological and hepatic evolution of WD.

Inherited copper transport disorders: biochemical mechanisms, diagnosis, and treatment

Copper is an essential trace element required by all living organisms. Excess amounts of copper, however, results in cellular damage. Disruptions to normal copper homeostasis are hallmarks of three genetic disorders: Menkes disease, occipital horn syndrome, and Wilson's disease. Menkes disease and occipital horn syndrome are characterized by copper deficiency. Typical features of Menkes disease result from low copper-dependent enzyme activity. Standard treatment involves parenteral administration of copper-histidine. If treatment is initiated before 2 months of age, neurodegeneration can be prevented, while delayed treatment is utterly ineffective. Thus, neonatal mass screening should be implemented. Meanwhile, connective tissue disorders cannot be improved by copper-histidine treatment. Combination therapy with copper-histidine injections and oral administration of disulfiram is being investigated. Occipital horn syndrome characterized by connective tissue abnormalities is the mildest form of Menkes disease. Treatment has not been conducted for this syndrome. Wilson's disease is characterized by copper toxicity that typically affects the hepatic and nervous systems severely. Various other symptoms are observed as well, yet its early diagnosis is sometimes difficult. Chelating agents and zinc are effective treatments, but are inefficient in most patients with fulminant hepatic failure. In addition, some patients with neurological Wilson's disease worsen or show poor response to chelating agents. Since early treatment is critical, a screening system for Wilson's disease should be implemented in infants. Patients with Wilson's disease may be at risk of developing hepatocellular carcinoma. Understanding the link between Wilson's disease and hepatocellular carcinoma will be beneficial for disease treatment and prevention.

Tryptic Peptide Analysis of Ceruloplasmin in Dried Blood Spots Using Liquid Chromatography–Tandem Mass Spectrometry: Application to Newborn Screening

Background: Newborn screening to identify infants with treatable congenital disorders is carried out worldwide. Recent tandem mass spectrometry (MS/MS) applications have markedly expanded the ability to screen for &gt;50 metabolic diseases with a single dried blood spot (DBS). The feature that makes metabolic disorders particularly amenable to screening is the presence of specific small-molecule metabolites. Many treatable disorders such as Wilson disease, however, are characterized by absent or diminished large proteins in plasma or within circulating blood cells, for which there are currently no cost-effective screening methods.

Methods: We developed an assay for quantifying ceruloplasmin (CP) in DBS for newborn screening of Wilson disease. CP-specific peptides from DBS samples digested by trypsin were quantified using isotopically labeled peptide internal standards and liquid chromatography–triple quadrupole mass spectrometry (LC-MS/MS).

Results: The calibration curve was linear from 20 to 95 mg/dL (200–950 mg/L). Intraassay imprecision (mean CV) for CP concentrations of 25, 35, and 55 mg/dL (250, 350, and 550 mg/L) was 9.2%, 10.7%, and 10.2%, respectively. Interassay imprecision for 19 different batches was 8.9%, 5.8%, and 6.9%. A method comparison study on previously tested patient samples for CP gave comparable results with lower limit of quantification, around 0.7 mg/dL (7 mg/L).

Conclusions: Our study supports that newborn screening for Wilson disease is feasible using LC-MS/MS assay for CP quantification in DBS after tryptic digestion. This approach should be applicable to newborn screening for other treatable genetic conditions, such as primary immunodeficiencies, that have large proteins as biomarkers.

Diagnosis of Wilson's disease: a comprehensive review

Wilson's disease is an autosomal recessive disorder of copper metabolism. The culprit gene is ATP7B. The worldwide prevalence is about 1 in 30,000, which may vary by population. Higher prevalence rates were reported using more sensitive screening techniques and pilot population screening. Typical presentations include neuropsychiatric and hepatic dysfunction, whereas atypical presentations are protean. Diagnosis relies on a high clinical suspicion, typical neurological symptoms, presence of Kayser-Fleischer rings, and reduced serum ceruloplasmin concentration. The conventional value of < 0.20 g/l is not a universal diagnostic value. Age of the subjects and analytical variations should be considered when interpreting these levels. Patients with inconclusive findings require further investigations such as 24 h urinary free-copper excretion, penicillamine challenge test, liver copper measurement, and detection of gene mutations. Direct molecular diagnosis remains the most decisive tool. Other tests such as non-ceruloplasmin-bound copper are unreliable. Potential pitfalls and limitations of these diagnostic markers are critically reviewed in this paper. The mainstays of therapy are trientine, penicillamine, and/or zinc. Liver transplantation is lifesaving for those with advanced disease. Ceruloplasmin oxidase activity and serum free-copper concentration should be monitored in patients on long-term de-coppering therapy to prevent iatrogenic copper deficiency.

Early and presymptomatic detection of Wilson's disease at the mandatory 3-year-old medical health care examination in Hokkaido Prefecture with the use of a novel automated urinary ceruloplasmin assay

Wilson's disease (WND) is an autosomal recessive disorder of copper (Cu) accumulation leading to liver and/or brain damage. Oral chelating agents and diet are effective in treating WND. However, once irreversible damage has occurred, the effect of treatment is diminished and the patient's quality of life is compromised. For these reasons an effective method for screening has been needed for early detection of presymptomatic patients. We conducted an early and presymptomatic detection of WND using a novel automated assay of ceruloplasmin (Cp) concentration in urine and selected the mandatory medical health care examination for 3-year-old children in Hokkaido Prefecture (the largest administrative division in Japan) as a sampling point. We measured urinary Cp concentrations in 11,362 children using an immunological latex agglutination assay kit developed by us. Among these children we identified a positive case with markedly reduced urinary Cp concentration. Detailed medical examination provided no clinical manifestations to support the diagnosis of WND, although serum Cp and Cu levels were remarkably low in this case. Therefore, we analyzed the WND gene in order to confirm the diagnosis. Sequence analysis revealed that the case was compound heterozygous for the WND gene mutations 2871del.C and D1296N. According to the Ferenci scoring system for WND diagnosis, the case was established as a WND patient at the presymptomatic stage. Consequently, the patient has maintained a good quality of life under medical treatment with polaprezinc administration to date. Our investigation suggests that the screening system for WND using the automated urinary assay at the mandatory medical health care examination for 3-year-old children is a noninvasive and efficient method for the early and presymptomatic diagnosis of WND.

Diagnostic accuracy of serum ceruloplasmin in Wilson disease: determination of sensitivity and specificity by ROC curve analysis among ATP7B-genotyped subjects

BACKGROUND

A serum ceruloplasmin concentration below 0.20 g/L is conventionally considered as one of the major diagnostic criteria for Wilson disease. This decision threshold has not been fully validated for its diagnostic characteristics, however. In this study, we evaluated various decision thresholds of serum ceruloplasmin concentration in the diagnosis of Wilson disease based on genotype-verified Wilson disease patients, carriers, and normal individuals.

METHODS

Serum ceruloplasmin concentration was measured by a nephelometric method in 57 Wilson disease patients and 71 family members (49 heterozygotes and 22 wild-type homozygotes), a validation group of 25 subjects clinically suspected of Wilson disease, and 690 normal individuals. We performed ROC analysis using Analyze-it software and confirmed the genotypes by direct DNA sequencing of ATP7B.

RESULTS

Serum ceruloplasmin concentrations <0.20, 0.14, and 0.10 g/L showed positive predictive values of 48.3%, 100%, and 100%, respectively, and negative predictive values of 98.7%, 97.1%, and 91.9%. In the validation group, a serum ceruloplasmin threshold of 0.14 g/L rendered 100% sensitivity and specificity. Forty of 690 healthy subjects had serum ceruloplasmin concentrations <0.20 g/L; however, these 40 individuals had normal genotypes by DNA sequencing, and none of the 40 had ceruloplasmin concentrations <0.14 g/L.

CONCLUSIONS

The diagnostic accuracy for Wilson disease using a serum ceruloplasmin concentration of 0.14 g/L as the local decision threshold was better than that using a threshold of 0.20 g/L. We suggest that laboratories providing ceruloplasmin assays determine decision thresholds based on local populations.

Mutational analysis of 65 Wilson disease patients in Hong Kong Chinese: identification of 17 novel mutations and its genetic heterogeneity

Wilson disease (WD), an autosomal recessive disorder of copper transport, is the most common inherited liver disorder in Hong Kong Chinese. This was the first local study to elucidate the molecular basis and establish an effective DNA-based diagnostic protocol. The ATP7B genes of 65 patients were amplified by polymerase chain reaction (PCR) and sequenced. Haplotype analysis was performed using D13S301, D13S314, and D13S316. The p.L770L/p.R778L status in 660 subjects was determined to estimate WD prevalence. Allele age of p.R778L was determined by the smallest homozygosity region between D13S301 and D13S270. We identified 42 different mutations with 17 being novel. p.R778L (17.3%) was the most prevalent. Exons 2, 8, 12, 13, and 16 harbored 70% mutations. Thirty-two haplotypes were associated with WD chromosomes. The estimated prevalence rate was 1 in 5,400. Three out of 660 normal subjects had p.L770L/p.R778L. In the remaining 657 individuals, neither p.L770L nor p.R778L was found. We characterized a Hong Kong Chinese-specific ATP7B mutation spectrum with great genetic diversity. Exons 2, 8, 12, 13, and 16 should be screened first. The perfect linkage disequilibrium suggested that p.R778L and its private polymorphism p.L770L originated from a single ancestor. This East-Asian-specific mutation p.R778L/p.L770L is aged at least 5,500 years.

Ion selectivity of a poly(3-pentylmethoxythiophene) LB-layer modified carbon-fiber microelectrode as a consequence of the second order filtering in voltcoulometry

Ion selective properties of poly(3-pentylmethoxythiophene) Langmuir-Blodgett film modified carbon-fiber microelectrode are described. The study of the electrode behavior indicates that important features occur if two electrochemical methods, one of them being kinetics sensitive, are used. While in case of the typical steady-state voltammetry the electrode remains sensitive to both the cations and anions, the kinetics-sensitive properties of voltcoulometry based on the second-order filtering scheme disable the observation of anions. As a model system a mixture of copper and dopamine ions is used.

Pilot study of mass screening for Wilson's disease in Korea

Wilson's disease (WD) is an autosomal recessive disorder of copper metabolism with copper accumulation in the liver as well as in the central nervous system. Treatment of WD includes oral chelating agents and diet and it is effective. However, once irreversible damage has occurred, the effect of treatment is diminished and the patient's quality of life is compromised. It is estimated that at least half of the patients with WD remain undiagnosed and die of untreated disease. Early detection of patients presymptomatically has been hampered by the lack of effective methods for mass screening. Recently, a sandwich ELISA method for ceruloplasmin measurement in blood spots was developed. We have used this method to analyze blood specimens collected on filter paper from 3667 children aged 3 months-15 years. The mean value of ceruloplasmin was 30.5+/-9.5 mg/dL. Among these children, we identified one WD case, a 32-month-old boy with markedly reduced ceruloplasmin concentration (2.3 mg/dL). Measurement of CP level in dried blood spot sample is proposed as a reliable method for population screening of WD.

[Wilson's disease. Clinical presentation, treatment and evolution in 21 cases]

PURPOSE

Wilson's disease is characterized by neuropsychiatric symptoms with frequent extrapyramidal and intellectual presentations. They have an insidious evolution that leads to a late diagnosis and less therapeutic effectiveness in the advanced forms.

METHODS

We report 21 cases of Wilson's disease with neurological complications, emphasizing clinical semiology, diagnostic means and problems of the therapeutics in our country.

RESULTS

The average age at the beginning of the disease was 17.6 years, with a female prevalence (8/13). The signs at first were mostly all neurological (71.4%), then psychiatric (19%) or hepatic (19%). The most common neurological signs were dystonia of members (81%), dysarthria (76%), tremors (76%) or disorders of motoricity (71.4%). Sometimes there were sialorrhea or disorders of the handwriting. The Kayser-Fleischer ring was present in 19 patients. Eighteen patients had clinical and/or biological hepatic involvement. The diagnosis was confirmed by biochemical examinations, which found a low rate of copper in blood, a sinking rate of ceruloplasmin and a very high rate of urinary copper. The cerebral computer tomography shows a cortical and/or subcortical atrophy (37%), and/or a low density of the central grey cores (35%). The treatment was based on D-penicillamine and/or zinc sulfate, according to the availability of the drugs. The evolution was favourable among 18 patients (85%) and not good in 42.8% of the cases. Six of the first patients had poor evolution after many years of follow-up. Finally, only 12 patients (57%) had a very good outcome. The family investigation made among 17 patients revealed 13 family cases. The only predictive factor of a poor evolution was the therapeutic noncompliance (P = 0.006).

CONCLUSIONS

The neurological presentations are traditional during the Wilson's disease, but are often ignored. We must suspect the disease in children when faced with disorders of handwriting or school failures and in the adult, when faced with neurological symptoms in a patient having a hepatic disease. We must not hesitate to consider it even given purely psychiatric signs, and we had better know to seek the neurological ones.

Biological functions of ceruloplasmin and their deficiency caused by mutation in genes regulating copper and iron metabolism

Ceruloplasmin, a multicopper ferroxidase, is involved in iron and copper homeostasis and integrates these metabolic pathways. Impaired biosynthesis of ceruloplasmin caused by gene mutations disturbs iron metabolism with iron deposition in different organs, especially in the basal ganglia, and severe neuronal damage. Dysfunction of ATP7B, a copper-transporting ATPase leads to the development of Wilson's disease, i.e., multiple abnormalities in copper metabolism associated with reduced synthesis of holoceruloplasmin and biliary copper excretion controlled by both proteins. The lowest content of serum ceruloplasmin is observed in the most grave early neurological form of Wilson's disease (according to N. V. Konovalov's classification), which confirms the important role of ceruloplasmin in the striatal metabolism of catecholamines.