Correlation of ATP7B genotype with phenotype in Chinese patients with Wilson disease

Wilson disease (novel ATP7B variants) with concomitant FLNC-related cardiomyopathy

We report a case of Wilson disease (WD) with dilated cardiomyopathy in which whole-genome sequencing (WGS) revealed the rare co-occurrence of two novel compound heterozygous ATP7B pathogenic variants (NM_001005918.3:c.2250del/p.N751Tfs*9 and c.3496C>T/p.L1166F) and a known FLNC pathogenic variant. Our results highlight the usefulness of WGS, even in the diagnosis of well-characterized genetic diseases such as WD.

Severe early-onset Wilson disease caused by a common pathogenic variant in the Bukharan Jewish population in Israel

BACKGROUND

Wilson disease is caused by pathogenic variants in the ATP7B gene which encodes a copper-transporting ATPase.

AIMS

Describe a common founder pathogenic variant among Bukharan Jews and to assess its prevalence, clinical features, and outcome.

METHODS

The cohort consisted of patients of Bukharan Jewish descent diagnosed with Wilson disease at a tertiary pediatric medical center in 2013-2018. Clinical and genetic data were collected and analyzed.

RESULTS

Six patients from 4 unrelated families who were homozygous for the c.3784G > T p.(Val1262Phe) pathogenic variant in ATP7B were identified. Five presented with elevated aminotransferase levels, and one, with acute liver failure. Mean age at diagnosis was 8.7 years (5-12.5). Serum ceruloplasmin level was extremely low in all patients (1.9-7 mg/dL; mean 3.2(. The variant was identified in a heterozygous state in 5/153 Bukharan Jews; 2/33 from our local exome database and 3/120 healthy unrelated Bukharan Jews in another cohort, for an estimated carrier frequency of ∼1:30.

CONCLUSIONS

We report a common founder pathogenic variant in the ATP7B gene among Bukharan Jews associated with severe early-onset Wilson disease. Given the clinical severity, high frequency of the variant, and being a treatable disease, its inclusion in pre-symptomatic screening in the Bukharan Jewish community should be considered. Furthermore, WD should be part of future genetic newborn screening programs in Israel and worldwide, to enable early treatment and prevention of future life-threatening complications.

A Systematic Review and Meta-Analysis of the R778L Mutation in ATP7B With Wilson Disease in China

BACKGROUND

Wilson disease (WD) is a hereditary disorder of copper metabolism, caused by mutations in the ATP7B gene. There are more than 1000 pathogenic variants identified in ATP7B. R778L is the most common ATP7B mutation in China.

METHODS

To estimate whether R778L is associated with the onset age of WD and other clinical variables. Genotyping results of ATP7B gene were collected in our 22 patients with WD. We then conducted a systematic review and meta-analysis in databases, using the keywords Wilson disease and R778L mutation.

RESULTS

After the screening, a total of 23 studies were included, including 3007 patients with WD. Patients with R778L mutation presented at an earlier age (standardized mean difference [SMD] = -0.18 [95% confidence interval, -0.28 to 0.08], P = 0.0004) and had lower ceruloplasmin concentration (SMD = -0.21 [95% confidence interval, -0.40 to -0.02], P = 0.03) than the patients without the R778L mutation. However, sex (odds ratio [OR] = 1.07 [95% confidence interval, 0.89 to 1.29], P = 0.32) and first presentation were not associated with R778L mutation in WD (hepatic: OR = 1.37 [95% confidence interval, 0.87 to 2.16, P = 0.17; neurological: OR = 0.79 [95% confidence interval, 0.48 to 1.30, P = 0.35; mix: OR = 1.04 [95% confidence interval, 0.42 to 2.53, P = 0.87; asymptomatic/others: OR = 1.98 [95% confidence interval, 0.49 to 7.96, P = 0.34).

CONCLUSIONS

Our results indicated that the R778L mutation is associated with an earlier presentation and lower ceruloplasmin concentration in China.

Cellular therapies in liver and pancreatic diseases

Over the past two decades, developments in regenerative medicine in gastroenterology have been greatly enhanced by the application of stem cells, which can self-replicate and differentiate into any somatic cell. The discovery of induced pluripotent stem cells has opened remarkable perspectives on tissue regeneration, including their use as a bridge to transplantation or as supportive therapy in patients with organ failure. The improvements in DNA manipulation and gene editing strategies have also allowed to clarify the physiopathology and to correct the phenotype of several monogenic diseases, both in vivo and in vitro. Further progress has been made with the development of three-dimensional cultures, known as organoids, which have demonstrated morphological and functional complexity comparable to that of a miniature organ. Hence, owing to its protean applications and potential benefits, cell and organoid transplantation has become a hot topic for the management of gastrointestinal diseases. In this review, we describe current knowledge on cell therapies in hepatology and pancreatology, providing insight into their future applications in regenerative medicine.

Design, Optimization and Validation of the ARMS PCR Protocol for the Rapid Diagnosis of Wilson's Disease Using a Panel of 14 Common Mutations for the European Population

BACKGROUND

Wilson's disease (WD) is an autosomal recessive inherited disorder of copper metabolism resulting from various mutations in the ATP7B gene. Despite good knowledge and successful treatment options, WD is a severe disease that leads to disability, destructively affecting the quality of life of patients. Currently, none of the available laboratory tests can be considered universal and specific for the diagnosis of WD. Therefore, the introduction of genetic diagnostic methods that allow for the identification of the root cause at any stage over the course of the disease gave hope for an earlier solution of diagnostic issues in patients with WD.

METHODS

A method for the genetic diagnosis of WD based on ARMS PCR, DreamTaq Green PCR Master Mix and modified primers has been developed. This method is able to detect 14 mutant alleles: p.His1069Gln, p.Glu1064Lys, p.Met769HisfsTer26, p.Gly710Ser, p.Ser744Pro, p.Ala1135GlnfsTer13, p.Arg778Leu, p.Arg1041Trp, p.Arg616Gln, p.Arg778Gly, p.Trp779*, p.Val834Asp, p.Gly943Ser and p.3222_3243+21del43.

RESULTS

The primers for all mutations were highly specific with an absence of wild-type amplification. All the results were validated by direct DNA Sanger sequencing.

CONCLUSIONS

This fast and economical method provides coverage for the identified common mutations, thereby making ARMS PCR analysis using DreamTaq Green PCR Master Mix and modified primers feasible and attractive for large-scale routine use.

Early Diagnosis of Wilson’s Disease in Children in Southern China by Using Common Parameters

Objective: The aim of the study was to develop the early diagnostic criteria for Wilson’s disease (WD) in young children in southern China by using alanine aminotransferase (ALT) elevation as the first manifestation.

Methods: A cross-sectional retrospective analysis of the clinical data and genetic test results of children with WD in southern China in the past 4 years and the follow-up of their short-term prognosis were performed in this study.

Results: A total of 30 children (5.08 ± 2.06 years old) with elevated ALT as the first manifestation of WD in southern China were enrolled in this study, including 14 females and 16 males. Specifically, in all of the 30 cases (100%), the serum ceruloplasmin (CP) level was decreased, whereas the 24-h urinary copper level was increased. The genetic mutation test of the ATP7B gene was used to confirm the diagnosis. In particular, the two mutation sites, including p.R778L and p.I1148T, had the highest mutation frequencies, approximately 23.0 and 10.7%, respectively. Through follow-up, most of the children had good recovery.

Conclusion: Early diagnosis and treatment of WD would substantially increase the survival rate and have a better prognosis. In addition, in 5-year-old children from southern China, early diagnosis could be performed quickly by referring to the following three parameters: elevated ALT, decreased ceruloplasmin level, and increased 24-h urinary copper level. It lays a foundation for further studies with a larger sample size.

Mutation analysis of the ATP7B gene and genotype-phenotype correlation in Chinese patients with Wilson disease

AIM

To discover the novel ATP7B mutations in 103 southern Chinese patients with Wilson disease (WD), and to determine the spectrum and frequency of mutations in the ATP7B gene and genotype-phenotype correlation in a large-scale sample of Chinese WD patients.

METHODS

One hundred three WD patients from 101 unrelated families in southern China were enrolled in this study. Genomic DNA was extracted from the peripheral blood. Direct sequencing of all 21 exons within ATP7B was performed. Subsequently, an extensive study of the overall spectrum and frequency of ATP7B mutations and genotype-phenotype correlation was performed in all Chinese patients eligible from the literature, combined with the current southern group.

RESULTS

In 103 patients with WD, we identified 48 different mutations (42 missense mutations, 4 nonsense mutations and 2 frameshifts). Of these, 3 mutations had not been previously reported: c.1510_1511insA, c.2233C>A (p.Leu745Met) and c.3824T>C (p.Leu1275Ser). The c.2333G>T (p.Arg778 Leu) at exon 8, was the most common mutation with an allelic frequency of 18.8%, followed by c.2975C>T (p.Pro992Leu) at exon 13, with an allelic frequency of 13.4%. In the comprehensive study, 233 distinct mutations were identified, including 154 missense mutations, 23 nonsense mutations and 56 frameshifts. Eighty-five variants were identified as novel mutations. The c.2333G>T (p.Arg778 Leu) and c.2975C>T (p.Pro992Leu) were the most common mutations, with allelic frequencies of 28.6% and 13.0%, respectively. Exons 8, 12, 13, 16 and 18 were recognised as hotspot exons. Phenotype-genotype correlation analysis suggested that c.2333G>T (p.Arg778 Leu) was significantly associated with lower levels of serum ceruloplasmin (P = 0.034). c.2975C>T (p.Pro992Leu) was correlated with earlier age of disease onset (P = 0.002). Additionally, we found that the c.3809A>G (p.Asn1270Ser) mutation significantly indicated younger onset age (P = 0.012), and the c.3884C>T (p.Ala1295Val) mutation at exon 18 was significantly associated with hepatic presentation (P = 0.048). Moreover, the patients with mixed presentation displayed the initial WD features at an older onset age than the groups with either liver disease or neurological presentation (P = 0.039, P = 0.015, respectively). No significant difference was observed in the presence of KF rings among the three groups with different clinical manifestations.

CONCLUSION

In this study, we identified three novel mutations in 103 WD patients from the southern part of China, which could enrich the previously established mutational spectrum of the ATP7B gene. Moreover, we tapped into a large-scale study of a Chinese WD cohort to characterise the overall phenotypic and genotypic spectra and assess the association between genotype and phenotype, which enhances the current knowledge about the population genetics of WD in China.

COMMD1, a multi-potent intracellular protein involved in copper homeostasis, protein trafficking, inflammation, and cancer

Copper is a trace element indispensable for life, but at the same time it is implicated in reactive oxygen species formation. Several inherited copper storage diseases are described of which Wilson disease (copper overload, mutations in ATP7B gene) and Menkes disease (copper deficiency, mutations in ATP7A gene) are the most prominent ones. After the discovery in 2002 of a novel gene product (i.e. COMMD1) involved in hepatic copper handling in Bedlington terriers, studies on the mechanism of action of COMMD1 revealed numerous non-copper related functions. Effects on hepatic copper handling are likely mediated via interactions with ATP7B. In addition, COMMD1 has many more interacting partners which guide their routing to either the plasma membrane or, often in an ubiquitination-dependent fashion, trigger their proteolysis via the S26 proteasome. By stimulating NF-κB ubiquitination, COMMD1 dampens an inflammatory reaction. Finally, targeting COMMD1 function can be a novel approach in the treatment of tumors.

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.

A novel gross deletion and breakpoint junction sequence analysis of ATP7B in a Chinese family with Wilson disease using next‑generation sequencing and Sanger sequencing

Wilson disease (WD) is a rare autosomal recessive genetic disorder that causes abnormal copper metabolism, resulting in pathological accumulation of copper in the liver, brain and other organs. Mutations in the ATPase copper transporter 7B (ATP7B) gene, which encodes a membrane P-type adenosine triphosphatase, have been identified as being responsible for WD. The present study analyzed clinical data and collected DNA samples from a pediatric patient with WD and her healthy parents. Mutation screening for ATP7B was performed using direct sequencing, multiplex ligation-dependent probe amplification(MLPA), next-generation sequencing (NGS) and Sanger sequencing of the breakpoint junction sequence. The patient (age, 2.7 years) presented with early-onset hepatic disease. The present study identified compound heterozygous mutations of ATP7B, including a heterozygous mutation (p.Arg1,041Trp) and a novel heterozygous gross deletion of a 57,771 bp fragment (chr13: 52490972-52548742) (GRCh37) from partial exon2- exon21 to external ATP7B sequence (15.833bp) in the patient. Analysis of the family members of the patient showed that the missense mutation and the gross deletion mutation were inherited from her mother and father, respectively. Microhomology and inverted repeat sequences, which may mediate the deletion mutation, were identified through sequence analysis on both sides of the breakpoints of this deletion. The present study provided additional information on the genotypic spectrum of the ATP7B gene, particularly with regard to early onset hepatic disease, as observed in the present patient with WD. The identification of the precise breakpoint junction sequence warrants further investigation of DNA break and recombination mechanisms. In detecting precise deletions, the NGS associated with Sanger sequencing of breakpoint junction sequence have been found to have more advantages than MLPA.

Multiplex Ligation-dependent Probe Amplification Analysis Subsequent to Direct DNA Full Sequencing for Identifying ATP7B Mutations and Phenotype Correlations in Children with Wilson Disease

BACKGROUND

Mutations in ATP7B cause Wilson disease (WD). However, direct DNA full sequencing cannot detect all mutations in patients with WD. Multiplex ligation-dependent probe amplification (MLPA) analysis is reportedly useful in increasing the diagnostic yield in other genetic disorders with large deletions or insertions. The aim of this study was to evaluate whether the detection rate of ATP7B mutations can be increased by using MLPA.

METHODS

We enrolled 114 children with WD from 104 unrelated families based on biochemical tests and direct DNA full sequencing. The patients with one or zero mutant allele were investigated using MLPA. We analyzed phenotypic correlations.

RESULTS

Total allele frequency by full sequencing was 87.5%. Full sequencing revealed two mutant alleles in 80 of 104 unrelated children. One mutant allele was detected in 22 children, and no mutations were found in two children. Novel mutations including small deletions with frameshift mutations were identified by DNA sequencing. MLPA revealed no gross deletion or duplication in 24 children with one or zero mutant alleles. The number of detected mutations was not associated with hepatic manifestation, age of onset, Kayser-Fleischer ring, ceruloplasmin, and urinary Cu concentrations.

CONCLUSION

MLPA showed a limited role to increase the mutation detection rate in children who do not receive a definite genetic diagnosis of WD through DNA full sequencing. This finding suggests that large deletions or duplications might be extremely rare in WD. Further development is needed to improve the genetic diagnosis of WD.

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.

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.

A special case of recurrent gross hematuria: Answers

Wilson's disease (WD) is an autosomal recessive disorder, and has a variety of presentations. We reported a case of 9-year-old girl who presented with a history of recurrent gross hematuria, renal histological changes of IgA nephropathy, and finally had been confirmed to be Wilson's disease-associated IgA nephropathy.

Functional analysis and drug response to zinc and D-penicillamine in stable ATP7B mutant hepatic cell lines

AIM: To study the effect of anti-copper treatment for survival of hepatic cells expressing different ATP7B mutations in cell culture.

METHODS: The most common Wilson disease (WD) mutations p.H1069Q, p.R778L and p.C271*, found in the ATP7B gene encoding a liver copper transporter, were studied. The mutations represent major genotypes of the United States and Europe, China, and India, respectively. A human hepatoma cell line previously established to carry a knockout of ATP7B was used to stably express WD mutants. mRNA and protein expression of mutant ATP7B, survival of cells, apoptosis, and protein trafficking were determined.

RESULTS: Low temperature increased ATP7B protein expression in several mutants. Intracellular ATP7B localization was significantly impaired in the mutants. Mutants were classified as high, moderate, and no survival based on their viability on exposure to toxic copper. Survival of mutant p.H1069Q and to a lesser extent p.C271* improved by D-penicillamine (DPA) treatment, while mutant p.R778L showed a pronounced response to zinc (Zn) treatment. Overall, DPA treatment resulted in higher cell survival as compared to Zn treatment; however, only combined Zn + DPA treatment fully restored cell viability.

CONCLUSION: The data indicate that the basic impact of a genotype might be characterized by analysis of mutant hepatic cell lines.

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.

Wilson's disease with cognitive impairment and without extrapyramidal signs: improvement of neuropsychological performance and reduction of MRI abnormalities with trientine treatment

Extrapyramidal signs are neurological dysfunction commonly associated with Wilson's disease (WD). In addition, cognitive dysfunction has been reported in the early stages of WD. In this report, we describe a 49-year-old woman presenting with memory impairments and without Parkinsonian or extrapyramidal signs. She was diagnosed with WD based on the presence of Kayser-Fleischer rings around the irises of her eyes and two ATP7B gene mutations, R778L at exon 8 and A874V at exdyon 11. Serial magnetic resonance imaging analysis and neuropsychological tests showed improvements following treatment with trientine.

Novel mutations of the ATP7B gene in Han Chinese families with pre-symptomatic Wilson's disease

BACKGROUND

Wilson's disease (WD) is an autosomal recessive genetic disorder of copper metabolism, caused by mutations in the ATP7B gene, resulting in copper accumulation in the liver, brain, kidney, and cornea and leading to significant disability or death if untreated. Early diagnosis and proper therapy usually predict a good prognosis, especially in pre-symptomatic WD. Genetic testing is the most accurate and effective diagnostic method for early diagnosis.

METHODS

The clinical and biochemical features of three unrelated Han Chinese families with pre-symptomatic WD were reported. The molecular defects in these families were investigated by polymerase chain reaction and DNA sequencing. Hundred healthy children with the same ethnic background served as controls. Bioinformatic tools (polymorphism phenotyping-2, sorting intolerant from tolerant, protein analysis through evolutionary relationships, and predictor of human deleterious single nucleotide polymorphisms) were combined and used to predict the functional effects of mutations.

RESULTS

We identified 2 novel ATP7B mutations (p.Leu692Pro and p.Asn728Ser) and 3 known mutations (p.Met769fs, p.Arg778Leu and p.Val1216Met) in these Chinese WD families. These mutations were not observed in the 100 normal controls. The bioinformatic method showed that p.Leu692Pro and p.Asn728Ser mutations are pathogenic.

CONCLUSIONS

Our research enriches the mutation spectrum of the ATP7B gene worldwide and provides valuable information for studying the mutation types and mode of inheritance of ATP7B in the Chinese population. Liver function analysis and genetic testing in young children with WD are necessary to shorten the time to the initiation of therapy, reduce damage to the liver and brain, and improve prognosis.

Wilson's disease: a comprehensive review of the molecular mechanisms

Wilson’s disease (WD), also known as hepatolenticular degeneration, is an autosomal recessive inherited disorder resulting from abnormal copper metabolism. Reduced copper excretion causes an excessive deposition of the copper in many organs such as the liver, central nervous system (CNS), cornea, kidney, joints, and cardiac muscle where the physiological functions of the affected organs are impaired. The underlying molecular mechanisms for WD have been extensively studied. It is now believed that a defect in P-type adenosine triphosphatase (ATP7B), the gene encoding the copper transporting P-type ATPase, is responsible for hepatic copper accumulation. Deposited copper in the liver produces toxic effects via modulating several molecular pathways. WD can be a lethal disease if left untreated. A better understanding of the molecular mechanisms causing the aberrant copper deposition and organ damage is the key to developing effective management approaches.

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.

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.

Mutation analysis of ATP7B gene in Turkish Wilson disease patients: identification of five novel mutations

Wilson disease is an autosomal recessive disorder of copper metabolism caused by mutations in the ATP7B gene that encodes a P-type copper transporting ATPase. The aim of this study was to screen and detect mutations of the ATP7B gene in unrelated Turkish Wilson disease patients (n = 46) and control group (n = 52). Mutations were screened and detected by DNA sequencing. 30 out of 46 patients had mutations. 24 different Wilson disease related mutations were identified in those patients. The distribution of mutations in ATP7B gene was as follow: 17 missense, 3 nonsense, 1 silent, 3 frameshift (1 insertion, 2 deletion). None of them were not found in the control group. Five out of 24 mutations were found to be novel. Four of them were missense (c.2363C > T, c.3106G > A, c.3451C > T, c.3733C > A). The last one was deletion (c.3111delC). 10 single nucleotide polymorphisms (SNPs) given in the literature were found in both control and patients groups. Moreover one new polymorphism in exon 18 (c.3727G > A) not reported previously was discovered in both groups. It was striking that most of the mutations were found in exons 8, 12-14. This is the first study covering Turkish Wilson disease patients and control groups for mutation screening in all the coding regions of ATP7B gene by DNA sequencing method and adding five new mutations and one polymorphism into the HUGO Wilson disease mutation database.

Wilson's disease: update on integrated Chinese and Western medicine

Wilson's disease (WD), or hepatolenticular degeneration, is an autosomal recessive inheritance disorder of copper metabolism caused by ATP7B gene mutation. As WD is an inherited disease of the nervous system that is not curable; early diagnosis with early and life-long treatment leads to better prognoses. Currently, the recommended treatment for WD is integrated Chinese and Western medicine. A number of studies indicate that treatment of integrative medicine can not only enforce the de-copper effect but also improve liver function, intelligence, and other factors. This article reviewed in detail the advantages of WD treated with Chinese and Western medicine together.

Homozygosity for Non-H1069Q Missense Mutations in ATP7B Gene and Early Severe Liver Disease: Report of Two Families and a Meta-analysis

Most patients with Wilson's disease (WD) are compound heterozygote, which complicates establishing genotype-phenotype correlations. We identified five patients who presented with early and/or severe hepatic disease who are homozygous for W939C missense mutation on exon 12 of ATP7B. We therefore conducted a meta-analysis to determine the phenotype of patients homozygous for missense or nonsense mutations in all ATP7B exons.The meta-analysis showed that 69% and 31% of patients are homozygous for H1069Q and non-H1069Q mutations, respectively. Compared to patients with H1069Q, those with non-H1069Q mutations were significantly more likely to have a hepatic phenotype, severe liver disease, a mixed phenotype, and less likely to have a neurologic phenotype. Compared to patients with nonsense mutations, those with non-H1069Q ones were equally likely to present with a hepatic phenotype and to have severe liver disease. Mean age at symptom onset in the non-H1069Q versus the H1069Q group was 15.5 versus 20.5years (p<0.001).Our data suggest that mutation W939C and other non-H1069Q missense mutations are associated with early disease onset, a hepatic phenotype, and a high risk of hepatic failure in homozygous patients. Early identification of such patients by genetic screening is important for timely initiation of treatment and prevention of complications.

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.

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.

Homozygous mutations in the conserved ATP hinge region of the Wilson disease gene: association with liver disease

OBJECTIVE

To determine whether any correlation exists between the phenotype and genotype of 2 Lebanese families with members affected with Wilson disease (WD).

BACKGROUND

WD is an autosomal-recessive disorder of copper transport with significant phenotypic diversity. Most patients are compound heterozygous making it difficult to establish a clear link between phenotype and genotype.

STUDY

We investigated 14 members from 2 Lebanese families (H and Z) with 5 members affected with WD. Mutation analysis of the ATP7B gene, and clinical assessments were carried out for both families. We also performed a literature search retrieving reported phenotypes of all patients homozygous to mutations in any of the 21 exons of the ATP7B.

RESULTS

Patients of the H and Z-families were found homozygous for the respective Asn1270Ser and Pro1273Leu mutations in the adenosine triphosphate (ATP) hinge region of exon 18. Of the healthy members, 6 were heterozygous and 3 had normal sequences. Clinically, 4 patients had liver cirrhosis and 1 had asymptomatic transaminitis. One of the patients also had neurologic symptoms. Screening the literature for patients homozygous for mutations in the ATP hinge region identified 25 patients including ours. The overall prevalence of the hepatic phenotype among patients homozygous for mutation in exon 18 was 80% and was significantly higher than those in exons 7, 14, and 21.

CONCLUSIONS

We hereby report the association of liver disease with homozygous mutations in the conserved ATP hinge region of exon 18 of the ATP7B gene.

Atp7b-/- mice as a model for studies of Wilson's disease

Wilson's disease is a severe human disorder of copper homoeostasis. The disease is associated with various mutations in the ATP7B gene that encodes a copper-transporting ATPase, and a massive accumulation of copper in the liver and several other tissues. The most frequent disease manifestations include a wide spectrum of liver pathologies as well as neurological and psychiatric abnormalities. A combination of copper chelators and zinc therapy has been used to prevent disease progression; however, accurate and timely diagnosis of the disease remains challenging. Similarly, side effects of treatments are common. To understand better the biochemical and cellular basis of Wilson's disease, several animal models have been developed. This review focuses on genetically engineered Atp7b(-/-) mice and describes the properties of these knockout animals, insights into the disease progression generated using Atp7b(-/-) mice, as well as advantages and limitations of Atp7b(-/-) mice as an experimental model for Wilson's disease.

High frequency of the c.3207C>A (p.H1069Q) mutation in ATP7B gene of Lithuanian patients with hepatic presentation of Wilson's disease

AIM

To investigate the prevalence of the ATP7B gene mutation in patients with hepatic presentation of Wilson's disease (WD) in Lithuania.

METHODS

Eleven unrelated Lithuanian families, including 13 WD patients were tested. Clinically WD diagnosis was established in accordance to the Leipzig scoring system. Genomic DNA was extracted from whole venous blood using a salt precipitation method. Firstly, the semi-nested polymerase chain reaction (PCR) technique was used to detect the c.3207C>A (p.H1069Q) mutation. Patients not homozygous for the c.3207C>A (p.H1069Q) mutation were further analyzed. The 21 exons of the WD gene were amplified in a thermal cycler (Biometra T3 Thermocycler, Gottingen, Germany). Direct sequencing of the amplified PCR products was performed by cycle sequencing using fluorescent dye terminators in an automatic sequencer (Applied Biosystems, Darmstadt, Germany).

RESULTS

Total of 13 WD patients (mean age 26.4 years; range 17-40; male/female 3/10) presented with hepatic disorders and 16 their first degree relatives (including 12 siblings) were studied. Some of WD patients, in addition to hepatic symptoms, have had extrahepatic disorders (hemolytic anemia 3; Fanconi syndrome 1; neurophsychiatric and behavioural disorder 2). Liver biopsy specimens were available in all of 13 WD patients (8 had cirrhosis; 1-chronic hepatitis; 3-acute liver failure, 1-liver steatosis). Twelve of 13 (92.3%) WD patients had the c.3207C>A (p.H1069Q) mutation, 6 of them in both chromosomes, 6 were presented as compound heterozygotes with additional c.3472-82delGGTTTAACCAT, c.3402delC, c.3121C>T (p.R1041W) or unknown mutations. For one patient with liver cirrhosis and psychiatric disorder (Leipzig score 6), no mutations were found. Out of 16 first degree WD relatives, 11 (68.7%) were heterozygous for the c.3207C>A (p.H1069Q) mutation. Two patients with fulminant WD died from acute liver failure and 11 are in full remission under penicillamine or zinc acetate treatment. Three women with WD successfully delivered healthy babies.

CONCLUSION

The c.3207C>A (p.H1069Q) missense mutation is the most characteristic mutation for Lithuanian patients with WD. Even 92.3% of WD patients with hepatic presentation of the disease are homozygous or compound heterozygotes for the p.H1069Q mutation.

Diagnosis of Wilson's disease: a comprehensive review

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

Rapid diagnosis of Wilson disease by a 28-mutation panel: real-time amplification refractory mutation system in diagnosing acute Wilsonian liver failure

BACKGROUND

Wilson disease is one of the commonest inherited and potentially fatal yet treatable liver disorders. About 5-27% patients present with acute liver failure and require prompt chelation therapy and life-saving liver transplantation. Diagnosis during acute liver failure is particularly difficult with short time allowance. Direct molecular diagnosis remains the most decisive tool but is often hindered by demanding techniques and numerous mutations. We developed a one-step, 3-h, reproducible, and accurate real-time amplification refractory mutation system which can simultaneously detect 28 ATP7B mutations.

METHODS

Primers were designed to complement the mutant sequence at the 3' end. The mutations were p.S105X, p.Q511X, p.R616Q, p.S693P, p.S693C, p.R778L, p.A874V, p.T888P, p.R919G, p.T935M, p.P992L, p.M1025R, p.D1047V, p.I1148T, p.R1156H, p.T1178A, p.V1216M, p.P1273Q, p.G1281C, p.R1320S, p.V1334D, p.V176SfsX28, p.G869EfsX4, IVS3+1G>T, IVS4-1G>C, IVS4-5T>G, IVS6+9A>G, and IVS9+5G>T. Reaction was performed using QuantiTect SYBR Green PCR Master Mix on an Applied Biosystems StepOne thermal cycler. Values of the threshold cycle were compared between normal and mutant alleles.

RESULTS

Primers of all mutations were highly specific with absence of wild-type amplification. All the results were validated by direct DNA sequencing.

CONCLUSIONS

This rapid and cost-efficient method allows wide mutation coverage, rendering the SYBR-green assay feasible and attractive for large-scale routine application.

Sequence variation database for the Wilson disease copper transporter, ATP7B

Wilson disease (WND) is a disorder of copper transport resulting in copper accumulation in liver, kidney, and brain. This recessive disorder expresses variable clinical symptoms affecting liver, brain, and/or kidney. The age of onset of symptoms varies from 3 to almost 70 years, so the diagnosis for this treatable disorder is easily missed. The defective gene is a membrane P-type ATPase, with similar structure to the other metal transporting ATPases. Most patients with Wilson disease are compound heterozygotes. This report describes the database we have developed for reporting of mutations in ATP7B, the gene defective in WND. The database includes more than 518 variants (379 probable disease-causing and the remainder possible normal variants) from populations worldwide (Available at: www.medicalgenetics.med.ualberta.ca/wilson/index.php; Last accessed: 20 June 2007). The tables in this database are a valuable resource for the study of population variation and the function of the transporter, and will assist in the identification of disease and non-disease-causing sequence variants.

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

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

Identification of novelATP7Bgene mutations and their functional roles in Korean patients with Wilson disease

Wilson disease (WND), an autosomal recessive disorder of copper transport, is characterized by excessive accumulation of intracellular copper in liver and extrahepatic tissues because of impaired biliary copper excretion and disturbed incorporation of copper into ceruloplasmin. Hepatic cirrhosis and neuronal degeneration are the major symptoms of WND, and mutations in the ATP7B gene are associated with WND. We have identified 28 different mutations in the ATP7B gene, including six novel variations, in 120 unrelated Korean patients with WND. Molecular defects in ATP7B were present in only 75.0% of Korean WND patients, with the most common mutation, p.Arg778Leu, having an allele frequency of 39.2%. To evaluate the functional defects of ATP7B caused by novel mutations, we used a yeast complementation system, and we used confocal microscopy to localize each mutation after transient expression in mammalian cells. Six novel variations were cloned into a yeast expression vector and two into a mammalian expression vector for confocal analysis. We found that c.2785A>G (p.Ile929Val) and c.3316G>A (p.Val1106Ile) were rare polymorphisms, whereas the others were novel variations disturbing ATP7B function.

Wilson disease: Identification of two novel mutations and clinical correlation in Eastern Chinese patients

AIM: To study mutations in the P-type ATPase (ATP7B) gene responsible for Wilson disease (WD) in the Eastern Chinese population, and the possible correlation of specific mutations with clinical characteristics.

METHODS: Mutations of the ATP7B gene were sought by means of direct sequencing in 50 Eastern Chinese WD patients of Han ethnic origin.

RESULTS: Two novel mutations, Asp96Gly and Asp196Glu, were first identified. We also compared the characterization of mutations in ATP7B with the clinical findings, and a significant correlation with hepatic manifestations between patients carrying the Arg778Leu mutation and those without was found.

CONCLUSION: Gene sequencing analysis was shown to have a high detection rate and accuracy. It may become the first priority in screening of WD patients.

Analysis of the T1288R mutation of the Wilson disease ATP7B gene in four generations of a family: possible genotype-phenotype correlation with hepatic onset

Wilson disease, an autosomal recessive disorder due to mutations of the ATP7B gene, is characterized by copper accumulation and toxicity in the liver and subsequently in other organs, mainly the brain and cornea. A new missense mutation (T1288R) of the ATP7B gene has recently been discovered in a Wilson disease patient in our laboratory. The aim of the present study was to analyze clinical and genetic features of more generations of the family of the patient in which the new mutation T1288R was discovered. A total of 19 subjects were studied; in particular, four generations of the patient's family were analyzed. The ATP7B gene was analyzed by single-strand conformational polymorphism followed by direct sequencing. Two brothers presented a clinical diagnosis of Wilson disease with an hepatic phenotype and a genotype characterized by the homozygotic mutation T1288R. The heterozygotic mutation T1288R was found in seven subjects belonging to all four generations. The present study represents the first screening for a Wilson disease mutation through four generations of a nonconsanguineous family. All the patients with the homozygotic T1288R mutation in the present pedigree presented an hepatic phenotype without a neurological presentation. Consequently, a genotype-phenotype correlation could be hypothesized, although further studies are necessary to clarify this topic.

Molecular pathogenesis of Wilson and Menkes disease: correlation of mutations with molecular defects and disease phenotypes

The trace metal copper is essential for a variety of biological processes, but extremely toxic when present in excessive amounts. Therefore, concentrations of this metal in the body are kept under tight control. Central regulators of cellular copper metabolism are the copper-transporting P-type ATPases ATP7A and ATP7B. Mutations in ATP7A or ATP7B disrupt the homeostatic copper balance, resulting in copper deficiency (Menkes disease) or copper overload (Wilson disease), respectively. ATP7A and ATP7B exert their functions in copper transport through a variety of interdependent mechanisms and regulatory events, including their catalytic ATPase activity, copper-induced trafficking, post-translational modifications and protein-protein interactions. This paper reviews the extensive efforts that have been undertaken over the past few years to dissect and characterise these mechanisms, and how these are affected in Menkes and Wilson disease. As both disorders are characterised by an extensive clinical heterogeneity, we will discus how the underlying genetic defects correlate with the molecular functions of ATP7A and ATP7B and with the clinical expression of these disorders.

Novel mutations of the ATP7B gene among 109 Hungarian patients with Wilson's disease

BACKGROUND/AIMS

Diagnosis of Wilson's disease may be difficult in patients presenting with liver disease and in asymptomatic siblings. The aim of the present study was to assess the impact of genetic testing for diagnosis of the disease in a large cohort (n=109) from Hungary.

PATIENTS/METHODS

One hundred and nine patients with Wilson's disease were studied (65 men and 44 women; mean age at onset of symptoms: 20+/-9 years). Diagnosis of the disease was based on typical clinical and laboratory features (all had a Wilson's disease score of >or=4). H1069Q was assessed by the semi-nested polymerase chain reaction-based restriction fragment length polymorphism assay. H1069Q heterozygotes and H1069Q negative samples were then screened for mutations (on exons 6 to 20) by denaturating high-performance liquid chromatography and than sequenced on a genetic analyser.

RESULTS

Twenty-three different mutations were found. H1069Q was the most frequent mutation in Hungary, detected in 77 patients (71%). Fourteen further known mutations were found by sequencing. We identified eight new mis-sense mutations not described before: N676I, S693Y, Y715H, M769L, W939C, P1273S, G1281D and G1341V. In 36/109 patients (33%) the diagnosis of Wilson's disease was established by adding mutational analysis. The Kayser-Fleischer ring was more frequent in H1069Q homozygous patients and their mean age at the time of diagnosis was higher than in patients heterozygous or negative for H1069Q.

CONCLUSION

Eight novel mutations in addition to the 15 that are already known were found in Hungarian patients with Wilson's disease. Our results underline the importance and usefulness of genetic testing for patients presenting with liver disease and for family screening.

Analysis of most common mutations R778G, R778L, R778W, I1102T and H1069Q in Indian Wilson disease patients: correlation between genotype/phenotype/copper ATPase activity

The present study was intended to estimate the frequencies of the most common mutations (R778L, R778W, R778G, I1102T and H1069Q) of ATP7B in Indian Wilson disease (WD) population and to explore the correlation between genotype/phenotype and copper ATPase activity. A total of 33 WD patients and their family members from North West states of India were examined. The H1069Q, R778W and R778L mutations were absent in these WD patients. R778W and I1102T mutations were present in 36% of WD patients. Family analysis for these mutations using PCR-RFLP documented 5 carriers and 2 asymptomatic WD patients. The copper ATPase activity in WD patients was significantly reduced (50%) than that of control individuals. No significant difference was observed in copper stimulated ATPase activity between homozygous (R778W/R778W, I1102T/I1102T) and compound heterozygous (R778W/unknown mutation, I1102T/unknown mutation) WD patients. Serum ceruloplasmin, serum copper levels were significantly lower in homozygous WD patients than that of compound heterozygous. However, no significant difference was observed in liver copper contents between heterozygous and homozygous patients. In conclusion, the data suggest that R778W and I1102T are most common mutations and provide the basis of genetic (PCR-RFLP) diagnostic tool for Indian WD patients as well as in siblings/parents where biochemical parameters are ambiguous.

Regional distribution of mutations of the ATP7B gene in patients with Wilson disease: impact on genetic testing

Wilson disease is an autosomal recessive inherited disorder of copper metabolism. The Wilson disease gene codes for a copper transporting P-type ATPase (ATP7B). Molecular genetic analysis reveals at least 300 distinct mutations. While most reported mutations occur in single families, a few are more common. The most common mutation in patients from Central, Eastern, and Northern Europe is the point mutation H1069Q (exon 14). About 50-80% of Wilson disease (WD) patients from these countries carry at least one allele with this mutation with an allele frequency ranging between 30 and 70%. Other common mutations in Central and Eastern Europe are located on exon 8 (2299insC, G710S), exon 15 (3400delC) and exon 13 (R969Q). The allele frequency of these mutations is lower than 10%. In Mediterranean countries there is a wide range of mutations, the frequency of each of them varies considerably from country to country. In Sardinia, a unique deletion in the 5' UTR (-441/-427 del) is very frequent. In mainland Spain the missense mutation M645R in exon 6 is particularly common. Data from non-European countries are scarce. Most data from Asia are from Far Eastern areas (China, South Korea and Japan) where the R778L missense mutation in exon 8 is found with an allele frequency of 14-49%. In summary, given the constant improvement of analytic tools genetic testing will become an integral part for the diagnosis of WD. Knowledge of the differences in the worldwide distribution of particular mutations will help to design shortcuts for genetic diagnosis of WD.

Dynamic functional and ultrastructural changes of gastric parietal cells induced by water immersion-restraint stress in rats

AIM: To investigate the dynamic functional and ultrastructural changes of gastric parietal cells induced by water immersion-restraint stress (WRS) in rats.

METHODS: WRS model of Sprague-Dawley (SD) rats was established. Fifty-six male SD rats were randomly divided into control group, stress group and post-stress group. The stress group was divided into 1, 2 and 4 h stress subgroups. The post-stress group was divided into 24, 48 and 72 h subgroups. The pH value of gastric juice, ulcer index (UI) of gastric mucosa and H⁺, K⁺-ATPase activity of gastric parietal cells were measured. Ultrastructural change of parietal cells was observed under transmission electron microscope (TEM).

RESULTS: The pH value of gastric juice decreased time-dependently in stress group and increased in post-stress group. The H⁺, K⁺-ATPase activity of gastric parietal cells and the UI of gastric mucosa increased time-dependently in stress group and decreased in post-stress group. Compared to control group, the pH value decreased remarkably (P = 0.0001), the UI and H⁺, K⁺-ATPase activity increased significantly (P = 0.0001, P = 0.0174) in 4 h stress subgroup. UI was positively related with stress time (r = 0.9876, P < 0.01) but negatively with pH value (r = -0.8724, P < 0.05). The parietal cells became active in stress group, especially in 4 h stress subgroup, in which plenty of intracellular canalicular and mitochondria were observed under TEM. In post-stress group, the parietal cells recovered to resting state.

CONCOUSION: The acid secretion of parietal cells is consistent with their ultrastructural changes during the development and healing of stress ulcer induced by WRS and the degree of gastric mucosal lesions, suggesting gastric acid play an important role in the development of stress ulcer and is closely related with the recovery of gastric mucosal lesions induced by WRS.

Molecular pathogenesis of Wilson disease: haplotype analysis, detection of prevalent mutations and genotype-phenotype correlation in Indian patients

Wilson disease (WD) is an autosomal recessive disorder caused by defects in the copper-transporting P-type ATPase gene (ATP7B) resulting in the accumulation of copper in the liver and the brain. We identified prevalent mutations in the ATP7B of Indian WD patients and attempted to correlate those with the disease phenotype. Patients from 62 unrelated families and their first-degree relatives comprising 200 individuals were enrolled in this study. Three dinucleotide repeat markers flanking WD locus and a few intragenic SNPs were used to determine the genotypes and construct haplotypes of the patients. Seven recurring haplotypes accounting for 58% of the total mutant chromosomes were identified, and four underlying defects in the ATP7B representing 37% of WD chromosomes were detected. In addition, five other rare mutations were characterized. Thus a total of nine mutations including five novel changes were identified in the ATP7B of WD patients. Interestingly, homozygotes for different mutations that would be expected to produce similar defective proteins showed significant disparity in terms of organ involvement and severity of the disease. We also observed WD patients with neurological symptoms with little or no manifestation of hepatic pathogenesis. In one WD family, the proband and a sib had remarkably different phenotypes despite sharing the same pair of mutant chromosomes. These findings suggest a potential role for yet unidentified modifying loci for the observed phenotypic heterogeneity among the WD patients.