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

Clinical and Molecular Spectrum of Wilson Disease in the Arab World: A Systematic Review

Wilson disease is a rare monogenic disease characterized by copper overload in various organs, mainly the liver, the brain and the eyes. It has a prevalence ranging between 1/30,000 and 1/50,000, and it is caused by pathogenic variants in the ATP7B gene, which encodes a copper-transporting ATPase essential for regulating liver copper levels by directing copper to the secretory pathway and exporting excess copper into bile. It is a fatal disease if left untreated; however early diagnosis and effective treatment enable patient's outcome improvement. Unfortunately, in the Arab world there is no collective data on Wilson disease. This systematic review presents an explicit overview on the clinical and molecular spectrum of Wilson disease in the Arab world. A literature search was conducted on five databases from their inception until April 2024, using a combination of words related to the genetics of Wilson disease in the Arab world. The search resulted in 48 relevant studies carried out in 13 Arab countries, in which 802 Wilson disease patients were reported, with a high rate of consanguinity, and a slight male predominance. Hepatic presentations were the most frequent features in patients, and a total of 92 variants were identified with a detection rate of 61.2%. Genotype-phenotype correlations were not established for the majority of variants. This review revealed a clinical and molecular heterogeneity of Wilson disease in the Arab world. Efforts from health authorities, clinicians and geneticists are recommended to improve diagnosis, reduce disease incidence and give more insights into the present-day understanding of Wilson disease in the Arab world.

Case report: Co-occurrence of Wilson's and Alexander's diseases revealed by genetic analysis

Wilson's disease (WD) and Alexander's disease (AxD) are two prevalent genetic illnesses in clinical practice. However, cases of concurrent WD and AxD have not been reported. A mutation in the ATP7B gene causes improper copper metabolism, whereas AxD is caused by a mutation in the GFAP gene, which causes glial fibrillary acidic protein to accumulate in astrocytes. We present the first instance of concurrent WD and AxD in order to increase the diagnosis accuracy of this type of disease and provide a more precise treatment plan for the patient. A 10-year-old girl who appeared with diminished speech, limb weakness, trouble walking, and mental behavioral problems within the last 2 months. The patient's copper biochemistry results and clinical manifestations supported the diagnosis of WD, however her uncommon bilateral frontal lobe cerebral white matter with considerable high signal in MRI differed from the normal neuroimaging presentations of WD. To clarify the patient's diagnosis, we did whole-exome sequencing testing. To further clarify the patient's diagnosis, we performed whole exome sequencing tests on the patient and her father and detected a single heterozygous mutation in the GFAP gene and a double heterozygous mutation in the ATP7B gene, with the two variant loci located on the same allele. Combined with the Leipzig score and characteristic MRI changes, the patient was diagnosed with co-morbid WD and AxD. The overlapping presentation of the two diseases on MRI suggests the importance of clinicians recognizing the features of both diseases. A comprehensive diagnostic strategy including genetic testing, neuroimaging, and detailed clinical evaluation is required.

Investigating common mutations in ATP7B gene and the prevalence of Wilson's disease in the Thai population using population-based genome-wide datasets

Wilson's disease (WD) is a rare metabolic disorder caused by variations in the ATP7B gene. It usually manifests hepatic, neurologic, and psychiatric symptoms due to excessive copper accumulation. The prevalence of WD and its common variants differ across populations. This study aimed to examine these aspects of WD within the Thai population, where information has been limited. We reviewed ClinVar and the Wilson Disease Mutation Database, organizing variants classified as pathogenic or likely pathogenic in one or both databases as "relaxed" and "strict" lists. Allele frequencies were estimated from genotyping array data (Asian Screening Array: ASA; Illumina Corp, CA) of 6291 Thai subjects, which also underwent genotype imputation. The prevalence of WD in the Thai population was estimated assuming Hardy-Weinberg Equilibrium. The strict list yielded a prevalence of 1/24,128 (carrier frequency=1/78), while the relaxed list yielded a prevalence of 1/9971 (carrier frequency=1/50). The most common WD variants in Thai subjects were c.2333 G > T, c.3443 T > C, and c.813 C > A from the strict list, and c.3316 G > A and c.2605 G > A from the relaxed list. The ASA chip covered approximately 59 and 24% of WD variants from the strict and relaxed lists, respectively. Based on the estimated prevalence, a carrier screening program for WD is not currently required in Thailand. However, as genotyping services become more affordable and accessible, such a program would facilitate early identification, treatment, and prevention of WD.

A novel mutation in the ATP7B gene causing hepatolenticular degeneration in a Chinese family: A case report

INTRODUCTION

Hepatolenticular degeneration (Wilson disease) is an autosomal recessive monogenic disorder caused by mutations in the ATPase copper transporting beta (ATP7B) gene located on human chromosome 13. This gene encodes a copper-transporting P-type ATPase (ATP7B). Recent studies have revealed that the ATP7B gene is predominantly affected by a few hotspot mutations, with the His1069Gln mutation in exon 14 accounting for 50 to 80% of cases. In China, the Arg778Leu mutation in exon 8 is the most prevalent. However, the discovery of novel mutant genes persists.

CASE PRESENTATION

A 56-year-old Chinese female was referred to our hospital with a liver injury and cirrhosis. Her parents, 2 younger brothers, and children exhibited no signs of liver function impairment. Whole-exome sequencing was conducted on the proband's genomic DNA, and Sanger sequencing was performed on 6 family members for first-generation verification.

CONCLUSIONS

We identified a novel c.3715G > T (p.Val1239Phe) variant mutation in the ATP7B gene in the patient. The ATP7B c.3715G > T (p.Val1239Phe) variant is predicted to impact the copper transport P-type ATPase. When combined with another mutant gene to form a compound heterozygous mutation, it can lead to hepatolenticular degeneration. This discovery broadens the range of pathogenic genes in the ATP7B gene.

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.

Laboratory and clinical evaluation of a microarray for the detection of ATP7B mutations in Wilson disease in China

BACKGROUND AND OBJECTIVE

Wilson disease (WD) is an autosomal recessive copper metabolic disorder caused by mutations in ATP7B. Sanger sequencing is currently used for ATP7B variant identification. However, the ATP7B gene contains 21 exons, which makes sequencing of the entire gene both complex and time-consuming. Therefore, a simpler assay is urgently needed.

METHODS

We performed a laboratory and clinical evaluation of an oligonucleotide microarray for the detection of 24 ATP7B recurrent mutations (except p.P992L) in Chinese patients with WD.

RESULTS

The accuracy of the microarray was evaluated by screening for ATP7B mutations in 126 patients including 106 suspected WD samples and 20 patients with other liver diseases as negative control. Results were confirmed by Sanger sequencing. We established a reliable microarray system for the rapid detection of the 24 ATP7B mutations, with a sensitivity of 30 ng/test genomic DNA and specificity of 100% for all loci; the coefficient of variation in repeatability tests was <10%. Clinical evaluation showed an overall concordance between the microarray detection and sequencing of 100%, and 81.13% (86/106) of suspected WD cases showed ATP7B mutations by microarray detection. Microarray and Sanger sequencing identified p.R778L (50.94%), p.A874V (17.92%), p.P992L (11.32%), p.V1106I (11.32%), and p.I1148T (6.60%) as the most common mutations in WD patients.

CONCLUSIONS

Our microarray system is customizable and easily used for high-throughput detection of certain recurrent ATP7B mutations, providing a simpler method suitable for WD genetic diagnosis in China.

Analysis of Wilson disease mutations in copper binding domain of ATP7B gene

Wilson’s disease (WD) is an autosomal recessive disorder, resulting from variations in ATP7B gene. Clinical heterogeneity, including neuropsychiatric and hepatic manifestations over a large range of age groups make diagnosis difficult. Most of WD patients suffer severe disabilities and even die. So, overall goal of proposed study is the genetic and clinical characterization of Wilson’s disease cases from Pakistani population. Clinical data was collected, and patients were investigated for variations in selected ATP7B exons using PCR based Sanger sequencing. Pathogenic effect predictions for detected variants were carried out using PROVEAN, MutationTaster2, and HSF software’s. Clinical heterogeneity was observed in patients including reduced serum ceruloplasmin, signs of chronic liver damage and raised 24 h urinary copper excretion. Mean age of onset was 11.3 years. Kayser-Fleischer rings were present in 75% of cases. About 82.5% patients belonged to inbred families. Patients having neurological disorder were above 12 years of age. Total ten variants in analyzed region of ATP7B gene, including a reported variation (p. L227Yfs*35) were found in patients. The study also identified 4 putative novel synonymous variants (c.251A>C, c.15T>A, c.6T>C, c.238C>T) and 5 reported polymorphisms (c.83C>A, c.39_40insCGGCG, p.V456L, c.39_40insCGCCG and c.1544-53A>C). Reliable understanding of clinical presentations and genotype-phenotype correlation provide insight to function and structure of ATP7B and may assist in disease prognosis and family counseling. The study revealed clinical presentation of Pakistani WD cases and identification of sequence variants in screened region of ATP7B.

Genetic studies discover novel coding and non-coding mutations in patients with Wilson's disease in China

OBJECTIVES

Wilson disease (WD) is a rare autosomal recessive genetic disorder associated with various mutations in the ATP7B gene and leads to significant disability or death if untreated. Early diagnosis and proper therapy usually predict a good prognosis, especially in pre-symptomatic WD. Genetic testing provides an accurate and effective diagnostic method for the early diagnosis of WD.

METHODS

We recruited 18 clinically diagnosed WD patients from 16 unrelated families and two independent individuals. The next-generation sequencing of the ATP7B gene was performed. The 293T cell lines were divided into wild-type (WT) ATP7B and mutated ATP7B groups. Cell proliferation was determined by Cell Counting Kit-8 (CCK-8) assay and apoptosis was detected by Annexin V/propidium iodide (PI) assays.

RESULTS

Pedigree analysis showed that compound heterozygous variants (17/18, 94.44%) were present in the majority of WD patients. A total of 33 ATP7B gene variants were identified, including three variants with uncertain significance (VUS) [two splice mutations (c.51+2T>G, c.1543+40G>A) and one frameshift mutation (c.3532_3535del)]. The CCK-8 and apoptosis assays demonstrated that the VUS of ATP7B could significantly affect the transportation of copper.

CONCLUSIONS

The study revealed genetic defects of 16 Chinese families and two independent individuals with WD, which enriched the mutation spectrum of the ATP7B gene worldwide and provided valuable information for studying the mutation types of ATP7B in the Chinese populations. Genetic testing in WD patients is necessary to shorten the time to initiate therapy, reduce damage to the liver and improve the prognosis.

Ending diagnostic odyssey using clinical whole-exome sequencing (CWES)

Objectives

Most rare diseases are genetic diseases. Due to the diversity of rare diseases and the high likelihood of patients with rare diseases to be undiagnosed or misdiagnosed, it is not unusual that these patients undergo a long diagnostic odyssey before they receive a definitive diagnosis. This situation presents a clear need to set up a dedicated clinical service to end the diagnostic odyssey of patients with rare diseases.

Methods

Therefore, in 2014, we started an Undiagnosed Diseases Program in Hong Kong with the aim of ending the diagnostic odyssey of patients and families with rare diseases by clinical whole-exome sequencing (CWES), who have not received a definitive diagnosis after extensive investigation.

Results

In this program, we have shown that genetic diseases diagnosed by CWES were different from that using traditional approaches indicating that CWES is an essential tool to diagnose rare diseases and ending diagnostic odysseys. In addition, we identified several novel genes responsible for monogenic diseases. These include the TOP2B gene for autism spectrum disorder, the DTYMK gene for severe cerebral atrophy, the KIF13A gene for a new mosaic ectodermal syndrome associated with hypomelanosis of Ito, and the CDC25B gene for a new syndrome of cardiomyopathy and endocrinopathy.

Conclusions

With the incorporation of CWES in an Undiagnosed Diseases Program, we have ended diagnostic odysseys of patients with rare diseases in Hong Kong in the past 7 years. In this program, we have shown that CWES is an essential tool to end diagnostic odysseys. With the declining cost of next-generation sequencers and reagents, CWES set-ups are now affordable for clinical laboratories. Indeed, owing to the increasing availability of CWES and treatment modalities for rare diseases, precedence can be given to both common and rare medical conditions.

Molecular analysis of 53 Chinese families with Wilson's disease: Six novel mutations identified

Background

Wilson's disease (WD) is a rare autosomal recessive inherited disorder that is induced by defects of the ATP7B gene and characterized by damage to the liver and nervous system caused by aberrant copper metabolism. The identification of pathogenic mutations on two homologous chromosomes has become the gold standard for the diagnosis of WD.

Methods

Sanger sequencing and multiplex ligation‐dependent probe amplification (MLPA) were combined to establish a genetic diagnosis for patients from 53 unrelated Chinese WD families.

Results

Biallelic mutations were detected by Sanger sequencing in 50 of the probands, while single heterozygous mutations were detected in the remaining three probands. A total of 45 diverse pathogenic mutations were detected, and 6 previously unreported mutations were involved. Five asymptomatic patients were screened from 85 family members of 38 probands participating in the study.

Conclusion

This study contributes to the enlargement of the mutational spectrum of the ATP7B gene among the population of China and highlights the significance of genetic testing for asymptomatic patients.

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

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

Management Perspective of Wilson's Disease: Early Diagnosis and Individualized Therapy

Wilson's disease (WD) is an inherited disease caused by mutations in ATP7B and is characterized by the pathological accumulation of copper in the liver and brain. Common clinical manifestations of WD include a wide range of liver disease and neurological symptoms. In some patients, psychiatric symptoms may be the only manifestation at the time of diagnosis. The clinical features of WD are highly variable and can mimic any disease of internal medicine. Therefore, for unexplained medical diseases, the possibility of WD should not be ignored. Early diagnosis and treatment can improve the prognosis of WD patients and reduce disability and early death. Gene sequencing is becoming a valuable method to diagnose WD, and if possible, all WD patients and their siblings should be genetically sequenced. Copper chelators including D-penicillamine, trientine, and dimercaptosuccinic acid can significantly improve the liver injury and symptoms of WD patients but may have a limited effect on neurological symptoms. Zinc salts may be more appropriate for the treatment of asymptomatic patients or for the maintenance treatment of symptomatic patients. High-quality clinical trials for the drug treatment of WD are still lacking, therefore, individualized treatment options for patients are recommended. Individualized treatment can be determined based on the clinical features of the WD patients, efficacy and adverse effects of the drugs, and the experience of the physician. Liver transplantation is the only effective method to save patients with acute liver failure or with severe liver disease who fail drug treatment.

Frequency and spectrum of actionable pathogenic secondary findings in Taiwanese exomes

Background

Exome sequencing has recently become more readily available, and more information about incidental findings has been disclosed. However, data from East Asia are scarce. We studied the application of exome sequencing to the identification of pathogenic/likely pathogenic variants in the ACMG 59 gene list and the frequency of these variants in the Taiwanese population.

Methods

This study screened 161 Taiwanese exomes for variants from the ACMG 59 gene list. The identified variants were reviewed based on information from different databases and the available literature and classified according to the ACMG standard guidelines.

Results

We identified seven pathogenic/likely pathogenic variants in eight individuals, with five participants with autosomal recessive variants in one allele and three participants with autosomal dominant variants. Approximately 1.86% (3/161) of the Taiwanese individuals had a reportable pathogenic/likely pathogenic variant as determined by whole‐exome sequencing (WES), which was comparable to the proportions published previously in other countries. We further investigated the high carrier rate of rare variants in the ATP7B gene, which might indicate a founder effect in our population.

Conclusion

This study was the first to provide Taiwanese population data of incidental findings and emphasized a high carrier rate of candidate pathogenic/likely pathogenic variants in the ATP7B gene.

Relationship between genetic mutations and clinical phenotypes in patients with Wilson disease

To study the relationship between genotype and clinical phenotype of major gene mutation sites in patients with Wilson disease (WD).Clinical and laboratory data were collected from 40 children with WD admitted to the hospital by high-pass sequencing. The basic clinical data of patients included the following: age, sex, first symptom, K-F ring, clinical classification, serum Ceruloplasmin (CP), 24 hours urine copper. High Frequency Mutations were identified in WD patients: Exon 8, Ar9778Leu, and study the relationship between high frequency mutation and clinical phenotype.The mutation frequency of 2333G>T(Arg778Leu) in Exon 8 was the highest (48%). The mutation frequency of Exon 13 at 2975C>T site was 29%. The age (t = 0.296, P = .768), sex (χ = 0.005, P = .944), first symptom (χ = 0.480, P = .449), K-F ring (χ = 0.321, P = .17), clinical classification (χ = 20.064, P > .969), serum CP levels (t = 0.007, P = .897) had no significant difference between Arg778Leu mutation group and non-Arg778Leu mutation group. Twenty-four-hour urinary copper levels (t = 12.134, P < .001,) in the Arg778Leu mutation group were higher than those in the Arg778Leu mutation group.Arg778Leu mutation is associated with 24 hours urinary copper. The study of the association between the type of gene mutation and the clinical phenotype has important implications for the occurrence regularity, pathogenesis, and disease progression in patients with WD.

Clinical features and mutational analysis in 114 young children with Wilson disease from South China

Wilson disease (WD) is a rare autosomal recessive disorder caused by mutations in the ATP7B gene. Clinical features and mutational analysis of Chinese children with WD at early age were rarely described. Herein, we retrospectively examined 114 children with WD at the mean of 5.9 years old age at diagnosis. Eight patients developed acute liver failure at mean age of 9.7 years old, 4 of whom died. Among the 114 patients, 86.0% were presymptomatic with isolated elevation of transaminases at diagnosis, 99.1% had decreased ceruloplasmin, and 68.4% had urinary copper excretion over 100 μg/24 hr. Bi-allele pathogenic ATP7B mutations were identified in all patients. Among the 60 mutations detected, 10 were novel, including 7 missense mutations (p.I566N, p.T704I, p.C980F, p.G1030 V, p.A1096Q, p.L1327P, and p.L1373F), 1 nonsense mutation (p.K866X), 1 small insertion (p.Y44LfsX2), and 1 small deletion (p.R1118PfsX10). The most frequent mutations were p.R778L, p.P992L, and p.I1148T, which affected 27.2, 25.4, and 20.2% of the 114 WD children, respectively. The patients carrying p.R778L presented a higher rate of acute liver failure than the patients without p.R778L (9.7% vs. 4.8%). These results will be helpful in establishing early diagnosis of WD at the gene level, offering beneficial information for genetic counseling and providing clues to genotype/phenotype correlation of ATP7B mutations.

Complex ATP7B mutation patterns in Wilson disease and evaluation of a yeast model for functional analysis of variants

Wilson disease (WD) is a rare autosomal recessive genetic disorder that is associated with various mutations in the ATP7B gene. Although ATP7B variants are frequently identified, the exact mutation patterns remain unknown because of the absence of pedigree studies, and the functional consequences of individual ATP7B variants remain to be clarified. In this study, we recruited 65 clinically diagnosed WD patients from 60 unrelated families. Pedigree analysis showed that besides several ATP7B homozygous variants (8/65, 12.3%), compound heterozygous variants (43/65, 66.2%) were present in the majority of WD patients. There were 20% of the patients had one (12/65, 18.5%) or multiple (1/65, 1.5%) variants in only a single allele, characterized by a high ratio of splicing or frameshift variants. Nine ATP7B variants were cloned into the pAG426GPD yeast expression vector to evaluate their functional consequences, and the results suggested different degrees of functional disruption from mild or uncertain to severe, consistent with the corresponding phenotypes. Our study revealed the complex ATP7B mutation patterns in WD patients and the applicability of a yeast model system to the evaluation of the functional consequences of ATP7B variants, which is essential for WD cases that are difficult to interpret.

The global prevalence of Wilson disease from next-generation sequencing data

PURPOSE

Wilson disease (WD) is an autosomal recessive disorder of copper metabolism, caused by pathogenic variants in ATP7B. We aimed to (1) perform a meta-analysis of previous WD prevalence estimates, (2) estimate the prevalence of WD from population sequencing data, and (3) generate an ATP7B gene variant database.

METHODS

MEDLINE and EMBASE were systematically searched. Previous prevalence estimates were subjected to meta-analysis. All previously reported pathogenic ATP7B variants were compiled and annotated with gnomAD allele frequencies. Pooled global and ethnicity-specific genetic prevalences for WD were generated using the Hardy-Weinberg equation.

RESULTS

Meta-analysis of genetic studies of WD prevalence gave an estimate 12.7 per 100,000 (95% confidence interval [CI]: 6.3-23.0). We developed a referenced, searchable ATP7B database comprising 11,520 variants including 782 previously reported disease variants, which can be found at http://www.wilsondisease.tk/ ; 216/782 of these were present in gnomAD, remained after filtering by allele frequency, and met American College of Medical Genetics and Genomics criteria. Based on these, the genetic prevalence of WD was 13.9 per 100,000 (95% CI: 12.9-14.9), or 1 per 7194. Combining this with 60 predicted pathogenic variants gave a birth prevalence of 15.4 per 100,000 (95% CI: 14.4-16.5).

CONCLUSION

The genetic prevalence of Wilson disease may be greater than previous estimates.

Mutations of ATP7B gene in two Thai siblings with Wilson disease

Background: Wilson disease (WD) is an autosomal recessive disorder of copper metabolism caused by mutations in ATP7B gene. Objective: Report the clinical data and mutation analysis of two Thai siblings suspected of WD. Subject and methods: A 13-year-old boy who presented with cirrhosis, arthralgia, hypoalbuminemia, and coagulopathy, and his 11-year-old sister who was asymptomatic but had hepatomegaly with elevation of transaminases, were studied. Mutation analysis of ATP7B gene and mRNA analysis was performed in both patients and their parents. Results: Investigations were consistent with WD, and their liver diseases improved after standard treatment for WD. DNA analyses in these two patients revealed two novel mutations, which were a deletion of the first 2bp of exon 6 (c.1870_1871delGA), and a single base substitution from A to G at nucleotide 4075 (c.4075A>G) in the exon 20 (p.M1359V). PCR-restriction digestion with NcoI restriction enzyme was employed as the second method for confirmation of the c.4075A>G mutation and for rapid screening in 100 chromosomes from unrelated healthy controls, and this variant was not present in the controls. The c.1870_1871delGA deletion caused a frameshift effect, which results in a premature stop codon (p.E624fsX753), and the p.M1359V mutation is a substitution of methionine with valine, which may have effects upon its orientation and interaction with other adjacent amino acids. Conclusion: Two novel mutations of ATP7B gene were identified in two Thai siblings with WD.

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.

Epidemiology, diagnosis, and treatment of Wilson's disease

Wilson's disease (WD) is an autosomal recessive disease caused by a mutation of the ATP7B gene, resulting in abnormal copper metabolism. The major clinical features of WD include liver disease, neurological disorders, K-F rings, and osteoporosis. The prevalence of WD in China is higher than that in Western countries. Early diagnosis and lifelong treatment will lead to better outcomes. Drugs such as sodium dimercaptosuccinate (Na-DMPS), Zn, and Gandou Decoction can be used to treat WD. Some studies have shown that the combination of traditional Chinese medicine and Western medicine is the best approach to treating WD. In order to identify better treatments, this article describes the specific clinical symptoms of Wilson's disease, its diagnosis, and treatment options.

Development and evaluation of an unlabeled probe high-resolution melting assay for detection of ATP7B mutations in Wilson's disease

BACKGROUND

Wilson's disease (WD) is a rare autosomal recessive disorder characterized by the deposition of copper mainly in the liver or nerve system that leads to their dysfunction. Mutations in the gene encoding ATPase, Cu+ transporting, beta polypeptide (ATP7B) are causative for WD. The aim of this study was to develop a rapid and convenient assay for detection of the three most common causative ATP7B mutations, p.R778L, p.P992L, and p.V1106I.

METHODS

Plasmids containing DNA fragments harboring each of the three ATP7B mutations were constructed. High-resolution melting (HRM) analysis was conducted by asymmetric polymerase chain reaction (PCR) amplification with paired primer and unlabeled probe, performed in a 96-well plate formatted LightCycler 480 Real-Time PCR System. The assay was evaluated for accuracy and reproducibility by genotyping of 41 WD cases.

RESULTS

The unlabeled probe HRM assays performed on constructs with the p.R778L, p.P992L, and p.V1106I mutations in the ATP7B gene resulted in additional melting peaks. According to the unlabeled probe HRM molecular signature, we could differentiate homozygous mutations from wild-type with the ΔTm (difference between melting temperatures) >4°C, and the coefficient of variation in repeatability tests was <5%. In the validation assay using our method to examine clinical samples, a 100% accuracy rate was achieved.

CONCLUSIONS

The newly developed assay to rapidly genotype the ATP7B mutations is convenient, accurate, and reproducible, and represents a favorable alternative to Sanger sequencing in the identification of specific ATP7B mutations.

Wilson's Disease in China

Wilson's disease (WD) is an autosomal recessive disorder of copper metabolism. Its incidence is higher in China than in western countries. ATP7B is the causative gene and encodes a P-type ATPase, which participates in the synthesis of holoceruloplasmin and copper excretion. Disease-causing variants of ATP7B disrupt the normal structure or function of the enzyme and cause copper deposition in multiple organs, leading to diverse clinical manifestations. Given the variety of presentations, misdiagnosis is not rare. Genetic diagnosis plays an important role and has gradually become a routine test in China. The first Chinese spectrum of disease-causing mutations of ATP7B has been established. As a remediable hereditary disorder, most WD patients have a good prognosis with an early diagnosis and chelation treatment. However, clinical trials are relatively few in China, and most treatments are based on the experience of experts and evidences from other countries. It is necessary to study and develop appropriate regimens specific for Chinese WD patients.

Spectrum of ATP7B mutations and genotype-phenotype correlation in large-scale Chinese patients with Wilson Disease

Wilson disease (WD), an inherited disorder associated with ATP7B gene, has a wide spectrum of genotypes and phenotypes. In this study, we developed a rapid multiplex PCR-MassArray method for detecting 110 mutant alleles of interest, and used it to examine genomic DNA from 1222 patients and 110 healthy controls. In patients not found to have any mutation in the 110 selected alleles, PCR-Sanger sequencing was used to examine the ATP7B gene. We identified 88 mutations, including 9 novel mutations. Our analyses revealed p.Arg778Leu, p.Arg919Gly and p.Thr935Met showed some correlations to phenotype. The p.Arg778Leu was related to younger onset age and lower levels of ceruloplasmin (Cp) and serum copper, while p.Arg919Gly and p.Thr935Met both indicated higher Cp levels. Besides, the p.Arg919Gly was related to neurological subtype, and p.Thr935Met showed significant difference in the percentage of combined neurological and visceral subtype. Moreover, for ATP7B mutations, the more severe impact on ATP7B protein was, the younger onset age and lower Cp level presented. The feasibility of presymptomatic DNA diagnosis and predicting clinical manifestation or severity of WD would be facilitated with identified mutations and genotype-phenotype correlation precisely revealed in the study.

Recent advance in the molecular genetics of Wilson disease and hereditary hemochromatosis

Metabolic liver diseases such as Wilson disease (WD) and hereditary hemochromatosis (HH) possess complicated pathogenesis and typical hereditary characteristics with the hallmarks of a deficiency in metal metabolism. Mutations in genes encoding ATPase, Cu + transporting, beta polypeptide (ATP7B) and hemochromatosis (HFE) or several non-HFE genes are considered to be causative for WD and HH, respectively. Although the identification of novel mutations in ATP7B for WD and HFE or the non-HFE genes for HH has increased, especially with the application of whole genome sequencing technology in recent years, the biological function of the identified mutations, as well as genotype-phenotype correlations remain to be explored. Further analysis of the causative gene mutation would be critical to clarify the mechanisms underlying specific disease phenotypes. In this review, we therefore summarize the recent advances in the molecular genetics of WD and HH including the updated mutation spectrums and the correlation between genotype and phenotype, with an emphasis on biological functional studies of the individual mutations identified in WD and HH. The weakness of the current functional studies and analysis for the clinical association of the individual mutation was also discussed. These works are essential for the understanding of the association between genotypes and phenotypes of these inherited metabolic liver diseases.

Wilson disease in the South chinese han population

PURPOSE

to prospectively investigate the incidence and prevalence of Wilson disease (Wd) in Chinese han population in anhui province, to analyze the genetic mutations in individuals with Wd, and to provide basic epidemiological data regarding Wd in this Chinese han population.

METHODS

between november 2008 and June 2010, individuals aged from 7 to 75 years were screened for the cornea K-f ring in both eyes using slit lamp examination and random sampling methods based on age stratification and cluster level 1. the participants were from anhui province’s hanshan County, Jinzhai County, and lixin County. the clinical manifestations of the brain, liver, kidney, skin, and other organs in each individual were also determined. individuals with positive K-f rings and clinical manifestations indicative of Wd underwent copper biochemistry evaluations, abdominal ultrasound testing, and ATP7B gene mutation screening to confirm or exclude the diagnosis of Wd.

RESULTS

of 153,370 individuals investigated in this study, nine were diagnosed with Wd. in these Wd individuals, three cases had neurological symptoms, one has hepatic symptoms, one was hepatic and neurological combined, and the other four cases were presymptomatic. of the eight individuals in whom genetic mutations were detected, seven individuals had mutations in the ATP7B gene. the other individual had no ATP7B gene mutations but her copper biochemical test results met the diagnostic criteria for Wd. the incidence and prevalence of Wd in this population were approximately 1.96/100,000 and 5.87/100,000 respectively.

CONCLUSION

the Chinese han population had a higher average prevalence of Wd than the populations of the united States or europe.

Currently Clinical Views on Genetics of Wilson's Disease

Objective:

The objective of this study was to review the research on clinical genetics of Wilson's disease (WD).

Data Sources:

We searched documents from PubMed and Wanfang databases both in English and Chinese up to 2014 using the keywords WD in combination with genetic, ATP7B gene, gene mutation, genotype, phenotype.

Study Selection:

Publications about the ATP7B gene and protein function associated with clinical features were selected.

Results:

Wilson's disease, also named hepatolenticular degeneration, is an autosomal recessive genetic disorder characterized by abnormal copper metabolism caused by mutations to the copper-transporting gene ATP7B. Decreased biliary copper excretion and reduced incorporation of copper into apoceruloplasmin caused by defunctionalization of ATP7B protein lead to accumulation of copper in many tissues and organs, including liver, brain, and cornea, finally resulting in liver disease and extrapyramidal symptoms. It is the most common genetic neurological disorder in the onset of adolescents, second to muscular dystrophy in China. Early diagnosis and medical therapy are of great significance for improving the prognosis of WD patients. However, diagnosis of this disease is usually difficult because of its complicated phenotypes. In the last 10 years, an increasing number of clinical studies have used molecular genetics techniques. Improved diagnosis and prediction of the progression of this disease at the molecular level will aid in the development of more individualized and effective interventions, which is a key to transition from molecular genetic research to the clinical study.

Conclusions:

Clinical genetics studies are necessary to understand the mechanism underlying WD at the molecular level from the genotype to the phenotype. Clinical genetics research benefits newly emerging medical treatments including stem cell transplantation and gene therapy for WD patients.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Most frequent mutation c.3402delC (p.Ala1135GlnfsX13) among Wilson disease patients in Venezuela has a wide distribution and two old origins

Wilson disease is an infrequent autosomal recessive disorder caused by mutations in the ATP7B gene (13q14.3) producing pathologic phenotypes due to copper accumulation in critical tissues. The aim of the research was to probe Wilson disease genetic epidemiology in Venezuela, through the identification in diagnosed index cases, of ATP7B locus mutations, their geographic distribution, frequency, in-phase haplotypes and probable ethnic ancestry. During the last three decades 33 independent Wilson disease families from the country at large were ascertained and diagnosed through severely reduced ceruloplasmin activity, higher urinary copper excretion, and specific clinical signs. Molecular studies of the ATP7B gene were accomplished in 26 of the families. Disease prevalence was estimated as 1:94,000 families between 1985 and 2013, showing geographic aggregation in the state of Zulia with 1:27,000 families in it. DNA analysis in 26 families revealed 13 different mutations. The c.3402delC was the most frequent one (26.9%), presenting two independent in-phase haplotypes, both of likely European descent; which is followed by the not previously reported p.G691V (9.6%) and by the frequent European H1069Q (7.7%). Known mutations c.51 + 4A > T, c.1285 + 5G > T, M645R, T788I, V845SfsX28, T977M, L1088X, T1220M, R1319X and a novel P767L showed frequencies between 5.8 and 1.9%. Despite the ample mutation heterogeneity for Wilson disease in the country, the findings provide a diagnostic algorithm to ease mutation assessment in new patients; the predominant c.3402delC displayed wide geographic distribution and two genetic origins.

Mutational characterization of ATP7B gene in 103 Wilson's disease patients from Southern China: identification of three novel mutations

Wilson's disease (WD) is an autosomal recessive inheritance disorder of copper metabolism due to mutations in the ATP7B gene. The distribution of ATP7B gene mutations is diverse in different population. This study aimed to examine the genotypes of the ATP7B mutant alleles in WD patients from Southern China. Genomic DNA was extracted from 103 WD patients and 60 healthy patients. Mutations were screened and detected by DNA sequencing. A total of 51 different ATP7B mutations were identified in WD patients, including six homozygous, 51 compound heterozygous, and 39 single heterozygotes. Three mutations were found to be novel, including one missense mutation (c.2549C>T) and two frameshift mutations (c.3851_3876del and c.1057delC). The most frequent mutations are Arg778Leu (18.93%), Ile1148Thr (8.74%), and Pro992Leu (4.37%). Different from the published results of early studies, Ile1148Thr was found to be the second common mutation in our cohort. The highest mutation detection rate was on exon 8 (43.69%), followed by exon 16 (24.27%), and exon 12 (17.48%). The total mutation detection rate on exon 8, 12, and 16 was 85.44%. No ATP7B gene mutation was found in healthy patients. In conclusion, we identified three novel mutations and Ile1148Thr as another hotspot mutation in WD patients from Southern China. Most of the mutations can be detected by screening exon 8, 12, and 16. Our research has further enriched the mutation spectrum of the ATP7B gene in Chinese and may help to develop genetic screening strategies of WD.

New mutations and polymorphisms of the ATP7B gene in sporadic Wilson disease

Wilson's disease (WD) is a rare autosomal recessive genetic disorder of copper metabolism resulting in brain damage, liver failure, and neurological impairment and psychiatric disturbances, as a result of excessive copper accumulation in the brain, liver, kidneys and eyes. ATP7B, encoding a copper transporter P-ATPase was identified as the causative gene of WD. Mutations in the ATP7B gene lead to the defection of the transmembrane transporter so that it can not metabolize copper effectively. We reported the clinical and molecular features of three unrelated and non-consanguineous WD patients. We performed molecular genetic analysis of the ATP7B gene in all cases by DNA sequencing, and revealed 7 novel single nucleotide polymorphisms (SNPs) and 8 well known mutations. Among them, that novel SNP (c. -520 C>T) and two well known mutations (c. 2310 C>G/p. Leu700Leu, c. 2333 G>T/A/p. Arg778Leu/Gln) coexisted in all patients and they were heterozygous and homozygous in the youngest case, respectively, indicating that they may be correlated to the pathogenesis and potentially used as a genetic biomarker for early WD diagnosis.

Wilson's disease in Southern Brazil: genotype-phenotype correlation and description of two novel mutations in ATP7B gene

OBJECTIVE

Wilson's disease (WD) is an inborn error of metabolism caused by abnormalities of the copper-transporting protein encoding gene ATP7B. In this study, we examined ATP7B for mutations in a group of patients living in southern Brazil.

METHODS

36 WD subjects were studied and classified according to their clinical and epidemiological data. In 23 subjects the ATP7B gene was analyzed.

RESULTS

Fourteen distinct mutations were detected in at least one of the alleles. The c.3207C>A substitution at exon 14 was the most common mutation (allelic frequency=37.1%) followed by the c.3402delC at exon 15 (allelic frequency=11.4%). The mutations c.2018-2030del13 at exon 7 and c.4093InsT at exon 20 are being reported for the first time.

CONCLUSION

The c.3207C>A substitution at exon 14, was the most common mutation, with an allelic frequency of 37.1%. This mutation is the most common mutation described in Europe.

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.

Patients with autosomal dominant spinocerebellar ataxia have more risk of falls, important balance impairment, and decreased ability to function

OBJECTIVES: To assess balance and ability to function in patients with spinocerebellar ataxia. METHODS: A total of 44 patients with different spinocerebellar ataxia types 1, 2, 3, and 6 were evaluated using the Tinetti balance and gait assessment and the functional independence measure. The scale for the assessment and rating of ataxia and the international cooperative ataxia rating scale were used to evaluate disease severity. RESULTS: Most patients showed significant risk of falls. The balance scores were significantly different in spinocerebellar ataxia types. A significant positive correlation between balance and disease severity was found. CONCLUSION: Patients with spinocerebellar ataxia have important balance impairment and risk of falls that influence the ability to function such as self-care, transfers, and locomotion. Furthermore, the more severe ataxia is, the more compromised are postural balance, risk of falls, and ability to function.

Novel ATPase Cu(2+) transporting beta polypeptide mutations in Chinese families with Wilson's disease

Wilson's disease (WD) is an autosomal recessive inherited disorder caused by mutations in the ATPase Cu(2+) transporting beta polypeptide gene (ATP7B). The detailed metabolism of copper-induced pathology in WD is still unknown. Gene mutations as well as the possible pathways involved in the ATP7B deficiency were documented. The ATP7B gene was analyzed for mutations in 18 Chinese Han families with WD by direct sequencing. Cell viability and apoptosis analysis of ATP7B small interfering RNA (siRNA)-treated human liver carcinoma (HepG2) cells were measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay and Hoechst 33342 staining. Finally, the expression of B-cell CLL/lymphoma 2 (BCL2), BCL2-associated X protein (BAX), sterol regulatory element binding protein 1 (SREBP1), and minichromosome maintenance protein 7 (MCM7) of ATP7B siRNA-treated cells were tested by real-time polymerase chain reaction (real-time PCR) and Western blot analysis. Twenty different mutations including four novel mutations (p.Val145Phe, p.Glu388X, p.Thr498Ser and p.Gly837X) in the ATP7B gene were identified in our families. Haplotype analysis revealed that founder effects for four mutations (p.Arg778Leu, p.Pro992Leu, p.Ile1148Thr and p.Ala1295Val) existed in these families. Transfection of HepG2 cells with ATP7B siRNA resulted in decreased mRNA expression by 86.3%, 93.1% and 90.8%, and decreased protein levels by 58.5%, 85.5% and 82.1% at 24, 48 and 72 hours, respectively (All P<0.01). In vitro study revealed that the apoptotic, cell cycle and lipid metabolism pathway may be involved in the mechanism of WD. Our results revealed that the genetic cause of 18 Chinese families with WD and ATP7B deficiency-induce apoptosis may result from imbalance in cell cycle and lipid metabolism pathway.

Identification of one novel and nine recurrent mutations of the ATP7B gene in 11 children with Wilson disease

BACKGROUND

Wilson disease (WND), also called hepatolenticular degeneration, is an autosomal recessive genetic disorder in which copper abnormally accumulates in several organs. WND arises from the defective ATP7B gene, which encodes a copper transporting P-type ATPase.

METHODS

The molecular defects in 11 unrelated Chinese WND patients aged from 3 to 12 years were investigated. The diagnosis of these patients was based on typical clinical symptoms and laboratory testing results. All 21 exons and exon-intron boundaries of the ATP7B gene were amplified by polymerase chain reaction from the genomic DNA of the patients and then analyzed by direct sequencing. One hundred healthy subjects served as controls to exclude gene polymorphism.

RESULTS

In one novel (c.3605 C>G) and nine recurrent mutations of ATP7B identified, there were eight missense mutations, one splice-site mutation, and one nonsense mutation. The novel c.3605 C>G mutation resulted in the substitution of alanine by glycine at amino acid position 1202 (p.Ala1202Gly). The most frequent ATP7B mutation was c.2333 G>T (p.Arg778Leu), followed by c.2975 C>T (p.Pro992Leu), which accounted for 63.6% of the WND mutated alleles.

CONCLUSIONS

The novel c.3605 C>G mutation in. ATP7B is one of the molecular mechanisms of WND.

A genetic study of Wilson's disease in the United Kingdom

Previous studies have failed to identify mutations in the Wilson's disease gene ATP7B in a significant number of clinically diagnosed cases. This has led to concerns about genetic heterogeneity for this condition but also suggested the presence of unusual mutational mechanisms. We now present our findings in 181 patients from the United Kingdom with clinically and biochemically confirmed Wilson's disease. A total of 116 different ATP7B mutations were detected, 32 of which are novel. The overall mutation detection frequency was 98%. The likelihood of mutations in genes other than ATP7B causing a Wilson's disease phenotype is therefore very low. We report the first cases with Wilson's disease due to segmental uniparental isodisomy as well as three patients with three ATP7B mutations and three families with Wilson's disease in two consecutive generations. We determined the genetic prevalence of Wilson's disease in the United Kingdom by sequencing the entire coding region and adjacent splice sites of ATP7B in 1000 control subjects. The frequency of all single nucleotide variants with in silico evidence of pathogenicity (Class 1 variant) was 0.056 or 0.040 if only those single nucleotide variants that had previously been reported as mutations in patients with Wilson's disease were included in the analysis (Class 2 variant). The frequency of heterozygote, putative or definite disease-associated ATP7B mutations was therefore considerably higher than the previously reported occurrence of 1:90 (or 0.011) for heterozygote ATP7B mutation carriers in the general population (P < 2.2 × 10(-16) for Class 1 variants or P < 5 × 10(-11) for Class 2 variants only). Subsequent exclusion of four Class 2 variants without additional in silico evidence of pathogenicity led to a further reduction of the mutation frequency to 0.024. Using this most conservative approach, the calculated frequency of individuals predicted to carry two mutant pathogenic ATP7B alleles is 1:7026 and thus still considerably higher than the typically reported prevalence of Wilson's disease of 1:30 000 (P = 0.00093). Our study provides strong evidence for monogenic inheritance of Wilson's disease. It also has major implications for ATP7B analysis in clinical practice, namely the need to consider unusual genetic mechanisms such as uniparental disomy or the possible presence of three ATP7B mutations. The marked discrepancy between the genetic prevalence and the number of clinically diagnosed cases of Wilson's disease may be due to both reduced penetrance of ATP7B mutations and failure to diagnose patients with this eminently treatable disorder.

Mutational analysis of ATP7B in north Chinese patients with Wilson disease

Wilson disease (WD) is an autosomal recessive inherited disease caused by abnormalities of the copper-transporting protein encoding gene ATP7B. In this study, we examined ATP7B for mutations in 114 individuals of Chinese Han population living in north China who were diagnosed as WD. Totally, we identified 36 mutations and 11 single-nucleotide polymorphisms (SNPs), of which 14 mutations have never been reported previously and 5 were firstly described in Chinese. Among these, p.R778L (21.5%), p.A874V (7.5%) and p.P992L (6.1%) were the most frequent mutations. A genotype of p.L770L+p.R778L+p.P992L was the most frequent triple mutations and two pairs of mutations, p.L770L/p.R778L and p.A874V/p.I929V, were closely related. In addition, a database was established to summarize all ATP7B mutations, including those reported previously and those identified in this study. Popular algorithms were used to predict the functional effects of these mutations, and finally, by comparative genomics approaches, we predicted a group of mutation hot spots for ATP7B. Our study will broaden our knowledge about ATP7B mutations in WD patients in north China, and be helpful for clinical genetic testing.

Genetics of Wilson's disease: a clinical perspective

Hepatic Wilson's disease is often a difficult diagnosis to confirm. This review examines the current role of genetic tests for Wilson's disease and is aimed at clinicians caring for patients with this disease. We discuss how genetic testing is carried out for Wilson's disease, indications for these tests, and genetic counseling for the family. In contrast to the advances in diagnosis of Wilson's disease by testing for ATP7B mutations, genotype-phenotype correlations are not yet sufficiently established. The non-Wilsonian copper overload syndromes causing cirrhosis in children are another important area for study. The review also identifies further areas for research into the genetics of Wilson's disease in India.

Mutation analysis of 73 southern Chinese Wilson's disease patients: identification of 10 novel mutations and its clinical correlation

This study was designed to investigate the molecular basis and the correlation between genotype and phenotype in the southern Chinese patients with Wilson's disease (WD). Genotypes of the ATP7B gene in 73 WD patients were examined by denaturing high-performance liquid chromatography (DHPLC) and DNA sequencing. A total of 38 different disease-causing mutations were identified, including 10 novel mutations: missense mutations (p.Gln707Arg, p.Cys1079Phe, p.Gly1149Glu, p.Ser855Tyr, p.Ala874Pro and p.Ser921Arg), nonsense mutation (p.Arg1228Stop), splice-site mutations (2121+3A>T and 3244-2A>G) and frameshift mutation (1875_1876insAATT). We found that a pair of siblings carried the same genotype but different clinical type, and two patients were found to have three mutations. In addition, we compared the clinical data for p.Arg778Leu homozygotes and compound heterozygotes. Our research has enriched the mutation spectrum of the ATP7B gene in the Chinese population and can serve as the basis for genetic counseling and clinical/prenatal diagnosis to prevent WD in China.

Systems biology approach to Wilson's disease

Wilson's disease (WD) is a severe disorder of copper misbalance, which manifests with a wide spectrum of liver pathology and/or neurologic and psychiatric symptoms. WD is caused by mutations in a gene encoding a copper-transporting ATPase ATP7B and is accompanied by accumulation of copper in tissues, especially in the liver. Copper-chelation therapy is available for treatment of WD symptoms and is often successful, however, significant challenges remain with respect to timely diagnostics and treatment of the disease. The lack of genotype-phenotype correlation remains unexplained, the causes of fulminant liver failure are not known, and the treatment of neurologic symptoms is only partially successful, underscoring the need for better understanding of WD mechanisms and factors that influence disease manifestations. Recent gene and protein profiling studies in animal models of WD began to uncover cellular processes that are primarily affected by copper accumulation in the liver. The results of such studies, summarized in this review, revealed new molecular players and pathways (cell cycle and cholesterol metabolism, mRNA splicing and nuclear receptor signaling) linked to copper misbalance. A systems biology approach promises to generate a comprehensive view of WD onset and progression, thus helping with a more fine-tune treatment and monitoring of the disorder.

Clinical and molecular characterization of Wilson's disease in China: identification of 14 novel mutations

BACKGROUND

Wilson's disease (WND) is a rare autosomal recessive disorder. Here we have evaluated 62 WND cases (58 probands) from the Chinese Han population to expand our knowledge of ATP7B mutations and to more completely characterize WND in China.

METHODS

the coding and promoter regions of the ATP7B gene were analyzed by direct sequencing in 62 Chinese patients (58 probands) with WND (male, n = 37; female, n = 25; age range, 2 ~ 61 years old).

RESULTS

neurologic manifestations were associated with older age at diagnosis (p < 0.0001) and longer diagnostic delay (p < 0.0001). Age at diagnosis was also correlated with urinary copper concentration (r = 0.58, p < 0.001). Forty different mutations, including 14 novel mutations, were identified in these patients. Common mutations included p.Arg778Leu (31.9%) and p.Pro992Leu (11.2%). Homozygous p.Arg778Leu and nonsense mutation/frameshift mutations were more often associated with primary hepatic manifestations (p = 0.0286 and p = 0.0383, respectively) and higher alanine transaminase levels at diagnosis (p = 0.0361 and p = 0.0047, respectively). Nonsense mutation/frameshift mutations were also associated with lower serum ceruloplasmin (p = 0.0065).

CONCLUSIONS

we identified 14 novel mutations and found that the spectrum of mutations of ATP7B in China is quite distinct from that of Western countries. The mutation type plays a role in predicting clinical manifestations. Genetic testing is a valuable tool to detect WND in young children, especially in patients younger than 8 years old. Four exons (8, 12, 13, and 16) and two mutations (p.Arg778Leu, p.Pro992Leu) should be considered high priority for cost-effective testing in China.

Genetics of Wilsons disease

Wilson's disease is a rare autosomal recessive disorder of copper transport due to mutations in the ATP7B gene, responsible for transport of copper into bile from hepatocytes and its incorporation into apoceruloplasmin to form ceruloplasmin resulting in excessive accumulation of copper in the liver and extrahepatic tissues. Clinical features of WD result from toxic accumulation of copper in liver, brain and kidney. Early diagnosis is mandatory to initiate early treatment to prevent morbidity and mortality. More than 400 mutations have been reported, some of which are rather characteristic of geographical regions and ethnic population. Genetic testing is not useful as a routine procedure, but has its role in at risk individuals such as siblings and children of probands and in individuals with suggestive symptoms but where other tests are contradictory.