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

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.

Mutational analysis of exon 8 and exon 14 of ATP7B gene in Bangladeshi children with Wilson disease

BACKGROUND : Wilson disease (WD) is an autosomal recessive disorder caused by mutation in the Adenosine Triphosphate 7B (ATP7B) gene. The spectrum of ATP7B mutation varies in different populations. The objective of this study was to identify the mutation in exon 8 and exon 14 of ATP7B gene in Bangladeshi children clinically diagnosed as WD. We also aimed to explore the phenotypic presentation.

METHODS

It was a cross sectional observational study. The study was conducted at the Department of Paediatric Gastroenterology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh from January 2017 to June 2018. A total of 37 patients diagnosed with WD were enrolled for the study. Venous blood (about 3 mL) was drawn aseptically from each patient into tube containing ethyline diamine tetraacetic acid (EDTA) and preserved at -30°C for long-term preservation. The peripheral blood leukocytes of the patients and genomic DNAs were extracted. Exons 14 and 8 of ATP7B and their associated splice-site junctions were amplified by the polymerase chain reaction (PCR). The size and quantity of PCR products were verified by electrophoresis in 1.5% (w/v) agarose gel. 74 (37 × 2) PCR products were sent for Sanger Sequencing. The sequences were analyzed by Chromas version 2.6.6 software and the nucleotide blast was done by National Center for Biotechnology Information (NCBI) nucleoblast. Finally, the sequences were analyzed using AB Applied Bio systems and were matched with the reference sequences using MEGA software.

RESULTS

In this study, a single novel homozygous mutation pLeu.1071Val in the exon 14 was found in every (100%) studied child clinically diagnosed with WD. Heterozygous mutation p.Gly1061Glu in exon14 was also found in 6 patients (11%) with WD, which is one of the common mutations in this disease. In exon 8, p.Arg778Leu mutation was detected in one patient (2.7%), which is common in the Chinese and the South Asian populations and was heterozygous. Two novel heterozygous missense mutations p.K785R (2.7%) and p.S744F (2.7%) were also found in two other children in the exon 8.

CONCLUSION

We found three novel mutations in Bangladeshi children with WD, one of which may be tagged as founder mutation for Bangladeshi population. This finding indicates the necessity to study the mutation profiles of the whole ATP7B gene in our population for risk prediction. A further large-scale study will help in the development of a Mutational Data Base of Bangladeshi population with WD.

Assessment of the diagnostic value of serum ceruloplasmin for Wilson's disease in children

Background

Serum ceruloplasmin is one of the major diagnostic parameters for Wilson’s disease (WD). Age and gender difference of serum ceruloplasmin remain controversy. This study aims to assess diagnostic value of serum ceruloplasmin level for WD in children up to age of 15 years.

Methods

Serum ceruloplasmin levels were measured in 317 WD patients, 21 heterozygotes, 372 healthy control children and 154 non-WD patients with other liver diseases. Receiver operating characteristic (ROC) curve was used to determine the diagnostic accuracy of serum ceruloplasmin for WD in children.

Results

Among healthy controls, serum ceruloplasmin level was slightly low in the infants younger than 6 months, and then maintained from 26 to 33 mg/dl after age of 6 months. A total of 8.1% of healthy children had levels of serum ceruloplasmin < 20 mg/dL. Serum ceruloplasmin level was 5.7 ± 4.7 mg/dl in WD patients, and 25.6 ± 5.9 mg/dl in heterozygous carriers. Only 1.9% of WD patients had serum ceruloplasmin levels > 20 mg/dL. Serum ceruloplasmin levels had gender difference, being higher in healthy boys than healthy girls, and higher in asymptomatic WD boys than asymptomatic WD girls (p < 0.01, p < 0.05). Serum ceruloplasmin levels also presented genotypic difference. WD patients with R778L homozygotes exhibited lower levels of serum ceruloplasmin than the patients without R778L (p < 0.05). The ROC curve revealed that serum ceruloplasmin level, at a cutoff value of 16.8 mg/dL, had the highest AUC value (0.990) with a sensitivity of 95.9% and a specificity of 93.6%.

Conclusions

Serum ceruloplasmin is one of sensitive diagnostic biomarkers for WD in children. Gender and genotypic difference of serum ceruloplasmin level should be considered. The cutoff value of serum ceruloplasmin level < 16.8 mg/dL may provide the highest accuracy for diagnosis of WD in children.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02186-0.

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.

Challenges in Clinicogenetic Correlations: One Gene - Many Phenotypes

Background

Progress in genetics – particularly the advent of next‐generation sequencing (NGS) – has enabled an unparalleled gene discovery and revealed unmatched complexity of genotype–phenotype correlations in movement disorders. Among other things, it has emerged that mutations in one and the same gene can cause multiple, often markedly different phenotypes. Consequently, movement disorder specialists have increasingly experienced challenges in clinicogenetic correlations.

Objectives

To deconstruct biological phenomena and mechanistic bases of phenotypic heterogeneity in monogenic movement disorders and neurodegenerative diseases. To discuss the evolving role of movement disorder specialists in reshaping disease phenotypes in the NGS era.

Methods

This scoping review details phenomena contributing to phenotypic heterogeneity and their underlying mechanisms.

Results

Three phenomena contribute to phenotypic heterogeneity, namely incomplete penetrance, variable expressivity and pleiotropy. Their underlying mechanisms, which are often shared across phenomena and non‐mutually exclusive, are not fully elucidated. They involve genetic factors (ie, different mutation types, dynamic mutations, somatic mosaicism, intragenic intra‐ and inter‐allelic interactions, modifiers and epistatic genes, mitochondrial heteroplasmy), epigenetic factors (ie, genomic imprinting, X‐chromosome inactivation, modulation of genetic and chromosomal defects), and environmental factors.

Conclusion

Movement disorders is unique in its reliance on clinical judgment to accurately define disease phenotypes. This has been reaffirmed by the NGS revolution, which provides ever‐growing sequencing data and fuels challenges in variant pathogenicity assertions for such clinically heterogeneous disorders. Deep phenotyping, with characterization and continual updating of “core” phenotypes, and comprehension of determinants of genotype–phenotype complex relationships are crucial for clinicogenetic correlations and have implications for the diagnosis, treatment and counseling.

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).

Late-onset acute liver failure due to Wilson's disease managed by plasmapheresis and hemodiafiltration successfully serving as a bridge for deceased donor liver transplantation: a case report and literature review

Late-onset acute liver failure due to Wilson's disease (WD-ALF) is rare. A 44-year-old female patient presenting acute hepatic decompensation with extreme coagulopathy was transferred to our hospital for evaluation for liver transplantation (LT). Alveolar hemorrhage and Coombs-negative acute hemolysis occurred during workup. Mechanical ventilation, plasmapheresis, and hemodiafiltration with zinc and chelation were started immediately before placing the patient on the waitlist for deceased donor LT (DDLT), with a tentative diagnosis of WD-ALF using the Leipzig score and quick diagnostic criteria suggested by the Acute Liver Failure Study Group Registry. The peak MELD score was 40, and the revised version of King's score for WD was 13. Serum free copper levels and the patient's overall general condition were stabilized with artificial support systems, although triphasic wave on electroencephalogram and liver atrophy were noted. She successfully underwent emergent DDLT approximately 2 weeks after suffering from acute hemolysis and survived. The genetic tests confirmed mutations at 2 loci in the ATP7B gene and, therefore, the diagnosis of WD. This is the first and oldest patient reported in Japan to present late-onset WD-ALF that was successfully treated with emergent DDLT.

Reference intervals of spot urine copper excretion in preschool children and potential application in pre-symptomatic screening of Wilson disease

The objectives were to determine the reference intervals of spot urine copper excretion indexes in pre-school children and to evaluate their utility in screening for Wilson disease (WD). With spot urine collected from a control sample of preschool children (aged 3-7 years, n=153), the reference intervals of spot urine copper excretion indexes and their biological variation were defined. In order to investigate their utility performance in screening for WD in this age group, multiple spot urine samples from six WD patients who were diagnosed at presymptomatic stage were also analysed and compared. Cut-off values useful for detection of WD were defined by receiver operator curve (ROC) analysis. Biological (inter-individual) variation of spot urine copper indexes expressed as coefficient of variation (CVg) were around 60% at this age group, which was moderate and similar to other clinically useful urine tests, such as urine albumin excretion ratio. Spot urine copper excretion strongly correlated with both urine creatinine and osmolality. Linear regression against both creatinine and osmolality showed that ∼94% of data points in healthy preschool children fell within the prediction interval, suggesting that both were useful normalisation factors. ROC showed that copper to osmolality ratio was the best index with an area under curve (AUC) greater than 0.98. Cut-off values of 0.5 μmol/L, 0.1 μmol/mmol and 0.00085 μmol/mOsmol (32 μg/L, 56 μg/g creatinine and 0.054 μg/mOsmol, respectively, in conventional units) for spot urine copper concentration, copper to creatinine ratio and copper to osmolality ratio, respectively, have potential application in the differentiation of WD patients. Based on the data, a new WD screening strategy targeting preschool children is proposed. Application of a bivariate screening strategy using spot urine copper concentration and urine osmolality may be useful in a population-wide screening program for WD among preschool children.

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.

The dilemma to diagnose Wilson disease by genetic testing alone

BACKGROUND

Wilson disease (WD) is an autosomal recessive disorder of hepatic copper excretion. About sixty per cent of patients present with liver disease. WD is considered a fatal disease if undiagnosed and/or untreated but recent data indicate that disease penetrance may not be 100%.

MATERIALS AND METHODS

All patients underwent liver biopsy as part of the diagnostic workup. Genetic testing for ATP7B was performed by Sanger sequencing.

RESULTS

We report on a large family with multiple affected siblings. The first patient (male, 31 years) underwent orthotopic liver transplantation (OLT) because of fulminant WD. He was homozygous for p.G710A. One asymptomatic brother (37 years) had the same mutation. He is doing well on chelation therapy. Fifteen years later, a second-degree sibling (female, 16 years) presented with fulminant WD and underwent OLT. She was compound heterozygote (p.G710A/p.G710S). Further family screening revealed a third mutation (p.V536A) in a female (21 years) and male (16 years) compound-heterozygote sibling (p.G710A/p.V536A). In both, serum ceruloplasmin and 24-hour urinary copper excretion were normal. Liver biopsy showed normal histology and a quantitative hepatic copper content within the normal range or only slightly elevated (19 and 75 μg/g dry weight, respectively). No decoppering treatment was initiated so far.

CONCLUSION

Genetic testing alone is not always sufficient to diagnose WD in asymptomatic patients, and human mutation databases should be used with caution. Even patients carrying two disease-causing mutations do not necessarily have demonstrable alteration of copper metabolism. Asymptomatic siblings diagnosed by genetic screening require further testing before initiating treatment.

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.

Carrier frequency of Wilson's disease in the Korean population: a DNA-based approach

Wilson's disease (WD) is an autosomal recessive disorder caused by ATP7B gene mutation. The frequency of WD is about 1 in 30 000 worldwide. In the present study, we screened 14 835 dried blood spots (DBSs) from asymptomatic Korean neonates and retrospectively reviewed massively parallel sequencing of 1090 control individuals to estimate carrier frequency. TaqMan real-time PCR assays were conducted to detect six mutations that account for 58.3% of mutations in Korean WD patients: c.2333G>T (p.Arg778Leu), c.2621C>T (p.Ala874Val), c.3086C>T (p.Thr1029Ile), c.3247C>T (p.Leu1083Phe), c.3556G>A (p.Gly1186Ser) and c.3809A>G (p.Asn1270Ser). We also retrospectively reviewed data from 1090 individuals with various indications other than WD for whom whole-exome or panel sequencing data were available. Mutant allele frequency based on the six most common mutations was 0.0067 among the total of 14 835 DBSs screened. Given that these six mutations account for 58.3% of mutations in Korean WD patients, the corrected mutant allele frequency is 0.0115 (95% confidence interval (CI): 0.0103-0.0128). Corresponding incidence (q²) and carrier frequency (2pq) were estimated to be 1:7561 and 1:44, respectively. In retrospective data analysis of 1090 control individuals, allele frequency of pathogenic or likely pathogenic variants was 0.0096 (95% CI: 0.0063-0.0146). Corresponding carrier frequency was estimated to be 1:53. Estimated allele and carrier frequencies based on DNA screening were relatively higher than those reported previously based on clinical ascertainment.

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.

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.

Wilson disease in children

Wilson disease (WD) is an inherited disorder mainly of hepatocellular copper disposition, due to dysfunction of the Wilson ATPase, a P_1B-ATPase encoded by the gene ATP7B. In children, as in older age brackets, clinical disease is highly diverse. Although hepatic disease is the common presentation in children/adolescents, neurologic, psychiatric, and hematologic clinical presentations do occur. Very young children may have clinically evident liver disease due to WD. Early diagnosis, preferably when the child/adolescent is asymptomatic, is most likely to result in near-normal longevity with generally good health so long as the patient tolerates effective medication, is adherent to the lifelong treatment regimen, and has consistent access to the medication. Apart from a lively index of clinical suspicion on the part of physicians, biochemical tests including liver tests, serum ceruloplasmin, and basal 24-hour urinary copper excretion and genotype determination are key to diagnosis. Oral chelation treatment remains central to medical management, although zinc appears to be an attractive option for the presymptomatic child. Pediatric patients presenting with Wilsonian fulminant hepatic failure must be differentiated from those with decompensated cirrhosis, since the latter may respond to intensive medical interventions and not require liver transplantation. Recently identified WD-mimic disorders reveal important aspects of WD pathogenesis.

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.

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.

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.