The H1069Q mutation in ATP7B is associated with late and neurologic presentation in Wilson disease: results of a meta-analysis

The effect of zinc and D-penicillamine in a stable human hepatoma ATP7B knockout cell line

Mutations in the copper (Cu) transporter gene ATP7B, the primary cause of Wilson disease (WD), result in high liver Cu and death of hepatocytes. Cu chelators and zinc salts are the two most important drugs used in the treatment of WD patients; however, the molecular mechanisms of the drugs with regard to ATP7B expression have not been determined. A targeted knockout of ATP7B (KO) was established in the most widely used human hepatoma cell line, HepG2 for molecular studies of the pathogenesis and treatment of the disease. KO cells showed similar growth, Cu uptake, release, and gene expression as compared to parental cells. However, in the presence of Cu, morphological changes, oxidative stress, apoptosis, and loss of viability were observed. Induction of metallothionein (MT1X) after Cu exposure was significantly reduced in KO cells. Following zinc treatment, MT1X expression was strongly induced and a high percentage of KO cells could be rescued from Cu induced toxicity. D-penicillamine treatment had a minor effect on the viability of KO cells whereas the parental cell line showed a pronounced improvement. Combined treatment displayed a highly synergistic effect in KO cells. The data suggest that zinc has a previously unrecognized effect on the viability of hepatocytes that lack ATP7B due to a high induction of MT1X expression that compensates low gene expression after Cu exposure. A combination therapy that simultaneously targets at MT1X induction and Cu chelation improves the overall survival of hepatocytes for most efficient therapy of patients having WD.

Wilson disease: what is still unclear in pediatric patients?

Since Wilson disease (WD) may not be present with evident clinical symptoms of liver injury and neurological presentation is rare in children, establishing a diagnosis is often challenging, especially in childhood. Increased transaminases can be the only abnormality found in early course of WD. In clinical practice, high suspicion is crucial for early diagnosis and timely treatment to ensure better outcomes. Conventional diagnostic criteria established for adults are commonly agreed for children but may not always be appropriate in very young age. Currently, the best therapeutic approach for each specific presentation of the disease remains controversial and there are no clear indications about how to treat pediatric WD patients with a mild liver disease.

Genetic variants in diseases of the extrapyramidal system

Knowledge on the genetics of movement disorders has advanced significantly in recent years. It is now recognized that disorders of the basal ganglia have genetic basis and it is suggested that molecular genetic data will provide clues to the pathophysiology of normal and abnormal motor control. Progress in molecular genetic studies, leading to the detection of genetic mutations and loci, has contributed to the understanding of mechanisms of neurodegeneration and has helped clarify the pathogenesis of some neurodegenerative diseases. Molecular studies have also found application in the diagnosis of neurodegenerative diseases, increasing the range of genetic counseling and enabling a more accurate diagno-sis. It seems that understanding pathogenic processes and the significant role of genetics has led to many experiments that may in the future will result in more effective treatment of such diseases as Parkinson’s or Huntington’s. Currently used molecular diagnostics based on DNA analysis can identify 9 neurodegenerative diseases, including spinal cerebellar ataxia inherited in an autosomal dominant manner, dentate-rubro-pallido-luysian atrophy, Friedreich’s disease, ataxia with ocu-lomotorapraxia, Huntington's disease, dystonia type 1, Wilson’s disease, and some cases of Parkinson's disease.

Long term results of liver transplantation for Wilson's disease: experience in France

BACKGROUND & AIMS

Liver transplantation (LT) is the therapeutic option for severe complications of Wilson's disease (WD). We aimed to report on the long-term outcome of WD patients following LT.

METHODS

The medical records of 121 French patients transplanted for WD between 1985 and 2009 were reviewed retrospectively. Seventy-five patients were adults (median age: 29 years, (18-66)) and 46 were children (median age: 14 years, (7-17)). The indication for LT was (1) fulminant/subfulminant hepatitis (n = 64, 53%), median age = 16 years (7-53), (2) decompensated cirrhosis (n = 50, 41%), median age = 31.5 years (12-66) or (3) severe neurological disease (n = 7, 6%), median age = 21.5 years (14.5-42). Median post-transplant follow-up was 72 months (0-23.5).

RESULTS

Actuarial patient survival rates were 87% at 5, 10, and 15 years. Male gender, pre-transplant renal insufficiency, non elective procedure, and neurological indication were significantly associated with poorer survival rate. None of these factors remained statistically significant under multivariate analysis. In patients transplanted for hepatic indications, the prognosis was poorer in case of fulminant or subfulminant course, non elective procedure, pretransplant renal insufficiency and in patients transplanted before 2000. Multivariate analysis disclosed that only recent period of LT was associated with better prognosis. At last visit, the median calculated glomerular filtration rate was 93 ml/min (33-180); 11/93 patients (12%) had stage II renal insufficiency and none had stage III.

CONCLUSIONS

Liver failure associated with WD is a rare indication for LT (<1%), which achieves an excellent long-term outcome, including renal function.

Polymorphisms of metal transporter genes DMT1 and ATP7A in Wilson's disease

Wilson's disease (WND) is an inherited disorder of copper metabolism. Divalent metal transporter1 (DMT1) and ATP7A play important roles in metal transport in humans. The frequency of two single nucleotide polymorphisms of the DMT1 gene: DMT1 IVS4 C>A, DMT1 11245 T>C and two of the ATP7A gene: rs1062472 T>C, ATP7A rs 2227291 G>C have been evaluated in a population of 108 Wilson's disease patients and 108 sex- and age-matched healthy volunteers. The DMT1 IVS4 C(+) allele occurred more frequently in WND than in the healthy controls. The allele frequencies of other studied polymorphisms in WND group were in line with frequencies obtained for healthy volunteers. Neither of the polymorphisms had an impact on the age at onset or clinical phenotype of WND.

Concordance rates of Wilson's disease phenotype among siblings

Wilson's disease (WD) is an autosomal recessive disorder characterized by the functional disruption of adenosine triphosphatase 7B (ATP7B), which results in positive copper balance. Although the primary manifestations of the disease are hepatic or neurological in scope, the factors that cause a very diverse picture of WD are not well researched. We compared the first clinical presentation, ages of onset and diagnosis, copper metabolism parameters, and ceruloplasmin levels between index cases (ICs) and their siblings. We examined 73 ICs and 95 siblings from 73 families, including a total of 168 patients with biochemical and genetically confirmed WD diagnoses. We observed an 86% concordance rate of primary clinical symptoms among ICs with hepatic symptoms and their siblings. There was 66% concordance among ICs with neurological symptoms and their siblings. No differences regarding age at onset of symptoms or copper metabolism parameters at diagnosis were identified between hepatic ICs and their siblings. The age at symptom onset did not differ between neurological ICs and their siblings, although ICs presented lower ceruloplasmin and serum copper levels. These results demonstrate a high intra-familial concordance of the clinical and biochemical presentation of WD, suggesting that similar factors shared within the same families strongly influence the disease presentation.

A review and current perspective on Wilson disease

Wilson disease is a rare, inherited autosomal recessive disease of copper metabolism and may be more common where consanguinity is prevalent. Much has been known about the disease after it was first described by Kinnier Wilson as 'progressive lenticular degeneration in 1912. Over 500 mutations of the ATP7B gene has been identified with no clear genotype to phenotype correlation. Loss of ATP7B function leads various grades of reduced biliary excretion of copper and reduced incorporation of copper into ceruloplasmin; accumulation and toxicity of copper in the liver, brain and other tissues results in liver toxicity and other myriad manifestations of the disease. The clinical features may vary from asymptomatic state to chronic liver disease, acute liver failure, neuropsychiatric manifestations and hemolytic anemia. Diagnosis is based on the combination of clinical sign's, biochemical features, histologic findings and mutation analysis of ATP7B gene. Subtle geographical differences exist with a disproportionate proportion of children presenting with acute liver failure. A high index of suspicion is needed for an early diagnosis. Ratios of biochemical indices for early diagnosis need validation across geographical regions and may not be particularly applicable in children. Better biomarkers or the need for tests for early detection of ALF persists. Drugs used in the treatment of Wilson disease include copper chelating agents such as d-Penicillamine, trientine and zinc salt. Untreated Wilson disease uniformly leads to death from liver disease or severe neurological disability. Early recognition and treatment has excellent prognosis. Liver transplantation is indicated in acute liver failure and end stage liver disease. Family screening in order to detect the disorder in the first-degree relatives is warranted. This review provides an overview of different aspects of Wilson disease including geographical differences in presentations and clinical management and the limitations of currently available tests.

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.

Wilson disease mutation pattern with genotype-phenotype correlations from Western India: confirmation of p.C271* as a common Indian mutation and identification of 14 novel mutations

Wilson disease (WD) is an autosomal recessive disorder resulting from mutations in the ATP7B gene, with over 600 mutations described. Identification of mutations has made genetic diagnosis of WD feasible in many countries. The heterogeneity of ATP7B mutants is, however, yet to be identified in the Indian population. We analyzed the mutational pattern of WD in a large region of Western India. We studied patients (n = 52) for ATP7B gene mutations in a cohort of families with WD and also in first-degree relatives (n = 126). All 21 exon-intron boundaries of the WD gene were amplified and directly sequenced. We identified 36 different disease-causing mutations (31 exonic and five intronic splice site variants). Fourteen novel mutations were identified. Exons 2, 8, 13, 14, and 18 accounted for the majority of mutations (86.4%). A previously recognized mutation, p.C271*, and the novel mutation p.E122fs, were the most common mutations with allelic frequencies of 20.2% and 10.6%, respectively. Frequent homozygous mutations (58.9%) and disease severity assessments allowed analysis of genotype-phenotype correlations. Our study significantly adds to the emerging data from other parts of India suggesting that p.C271* may be the most frequent mutation across India, and may harbor a moderate to severely disabling phenotype with limited variability.

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.

Establishment of hepatic and neural differentiation platforms of Wilson's disease specific induced pluripotent stem cells

The combination of disease-specific human induced pluripotent stem cells (iPSC) and directed cell differentiation offers an ideal platform for modeling and studying many inherited human diseases. Wilson's disease (WD) is a monogenic disorder of toxic copper accumulation caused by pathologic mutations of the ATP7B gene. WD affects multiple organs with primary manifestations in the liver and central nervous system (CNS). In order to better investigate the cellular pathogenesis of WD and to develop novel therapies against various WD syndromes, we sought to establish a comprehensive platform to differentiate WD patient iPSC into both hepatic and neural lineages. Here we report the generation of patient iPSC bearing a Caucasian population hotspot mutation of ATP7B. Combining with directed cell differentiation strategies, we successfully differentiated WD iPSC into hepatocyte-like cells, neural stem cells and neurons. Gene expression analysis and cDNA sequencing confirmed the expression of the mutant ATP7B gene in all differentiated cells. Hence we established a platform for studying both hepatic and neural abnormalities of WD, which may provide a new tool for tissue-specific disease modeling and drug screening in the future.

Association of dopamine receptor gene polymorphisms with the clinical course of Wilson disease

BACKGROUND

Dopamine receptor D2 (DRD2) polymorphisms are proposed to be important factors in the presentation of neuropsychiatric symptoms in many disorders, including decreased striatum levels of dopamine D2 receptors in Wilson disease. The present study investigated the association between DRD2 gene polymorphisms and clinical manifestation of Wilson disease.

METHODS

Analyzing data from 97 symptomatic Wilson disease patients, we investigated the DRD2 gene polymorphisms rs1800497, rs1799732, and rs12364283. We assessed the polymorphisms impact on the phenotypic presentation of the disease.

RESULTS

Generally, the DRD2 gene polymorphisms had no impact on the hepatic or neuropsychiatric clinical presentation of Wilson disease. However, rs1799732 deletion allele carriers with neuropsychiatric symptoms had earlier onset of WD symptoms by almost 6 years compared with individuals without this allele (22.5 vs. 28.3 years; P < 0.05). This unfavorable effect of the rs1799732 polymorphism was even more pronounced among adenosine triphosphatase 7B gene (ATP7B) p.H1069Q homozygous patients, in whom carriership of the deletion allele was related to earlier initial neuropsychiatric manifestation by 14 years (18.4 vs. 32.2 years; P < 0.01).

CONCLUSIONS

Genetic variation of DRD2, specifically the rs1799732 polymorphism, may produce an earlier clinical presentation of Wilson disease neuropsychiatric symptoms and signs that occur in the course of dopaminergic system impairment due to copper accumulation in the brain. We speculate that this effect may be due to the impact of DRD2 polymorphism on dopamine D2 receptor density, but further studies are needed to understand the mechanisms of such phenotypic effects.

Identification of a novel Wilson disease gene mutation frequent in Upper Austria: a genetic and clinical study

Wilson disease (WD), a disorder of copper metabolism is caused by mutations in the ATP7B gene, a copper transporting ATPase. In the present study we describe a novel mutation in exon 9 of the ATP7B gene. The ATP7B gene was analyzed for mutations by denaturing HPLC and direct sequencing. DNA from 100 healthy blood donors from the same geographic area was examined as control. Sixteen (7.4%) out of the 216 patients diagnosed with WD in Austria carried the newly identified R816S(c.2448G>T) point mutation in exon 9 (4 male, age: 19 (6-30) years, median (range)). One patient was homozygous for R816S(c.2448G>T). Thirteen patients were compound heterozygotes (p.H1069Q(c.3207C>A)/R816S(c.2448G>T) (N=6), P539L/R816S(c.2448G>T) (N=3), each one G710S/R816S(c.2448G>T), P767P(2299insC)/R816S(c.2448G>T), W779G/R816S(c.2448G>T), T1220M/R816S(c.2448G>T)). In two patients no second mutation was identified. Interestingly, all but three of the patients originated within a distinct geographical area in Austria. Eleven patients presented with hepatic disease, 3 patients with neurological disease and 2 were asymptomatic sisters of an index case. A liver biopsy was available in 14 patients. Three patients showed advanced liver disease with liver transplantation for acute hepatic failure in two. The remaining patients had only mild histological changes, most commonly steatosis. Chronic hepatitis was described in five patients. Kayser-Fleischer ring was present in five patients. None of the 100 healthy controls carried the mutation. We describe a novel mutation in the ATP7B gene, occurring in patients originated from a distinct geographical area in Austria associated with a variable course of the disease.

Decreased serum antioxidant capacity in patients with Wilson disease is associated with neurological symptoms

BACKGROUND & AIMS

Wilson disease (WD) is an inherited disorder of copper disposition caused by an ATP7B transporter gene mutation, leading to copper accumulation in predisposed tissues. In addition to a genetic predisposition, other factors are likely to contribute to its clinical manifestation. The aim of the study was to assess whether oxidative stress affects the phenotypic manifestation of WD.

METHODS

In 56 patients with WD (29 men; 26 with the hepatic form, 22 with the neurologic form, and eight asymptomatic; mean age 38.5 ± 12 years), total serum antioxidant capacity (TAC) and inflammatory parameters (hs-CRP, IL-1β, IL-2, IL-6, IL-10, and TNF-α) were analyzed and related to the clinical manifestation, and mutations of the ATP7B gene. The control group for the TAC and inflammatory parameters consisted of 50 age- and gender-matched healthy individuals.

RESULTS

WD patients had a significantly lower TAC (p < 0.00001), lower IL-10 levels (p = 0.039), as well as both higher IL-1β (p = 0.019) and IL-6 (p = 0.005) levels compared to the control subjects. TNF-α, hs-CRP, and IL-2 did not differ from the controls. Patients with the neurological form of WD had a significantly lower TAC than those with the hepatic form (p < 0.001). In addition, the lower TAC was associated with the severity of the neurological symptoms (p = 0.02). No relationship between the inflammatory parameters and clinical symptoms was found.

CONCLUSIONS

Data from our study suggest that the increased oxidative stress contributes significantly to the clinical manifestation of WD; as a lower TAC is associated with the neurological symptoms in WD patients.

Diverse functional properties of Wilson disease ATP7B variants

BACKGROUND & AIMS

Wilson disease is a severe disorder of copper metabolism caused by mutations in ATP7B, which encodes a copper-transporting adenosine triphosphatase. The disease presents with a variable phenotype that complicates the diagnostic process and treatment. Little is known about the mechanisms that contribute to the different phenotypes of the disease.

METHODS

We analyzed 28 variants of ATP7B from patients with Wilson disease that affected different functional domains; the gene products were expressed using the baculovirus expression system in Sf9 cells. Protein function was analyzed by measuring catalytic activity and copper ((64)Cu) transport into vesicles. We studied intracellular localization of variants of ATP7B that had measurable transport activities and were tagged with green fluorescent protein in mammalian cells using confocal laser scanning microscopy.

RESULTS

Properties of ATP7B variants with pathogenic amino-acid substitution varied greatly even if substitutions were in the same functional domain. Some variants had complete loss of catalytic and transport activity, whereas others lost transport activity but retained phosphor-intermediate formation or had partial losses of activity. In mammalian cells, transport-competent variants differed in stability and subcellular localization.

CONCLUSIONS

Variants in ATP7B associated with Wilson disease disrupt the protein's transport activity, result in its mislocalization, and reduce its stability. Single assays are insufficient to accurately predict the effects of ATP7B variants the function of its product and development of Wilson disease. These findings will contribute to our understanding of genotype-phenotype correlation and mechanisms of disease pathogenesis.

Apolipoprotein E gene (APOE) genotype in Wilson's disease: impact on clinical presentation

BACKGROUND

Wilson's disease (WD), an inherited copper metabolism disorder that leads to pathological tissue copper accumulation and secondary organ damage, is caused by mutations in the ATP-ase 7B gene (ATP7B). The apolipoprotein E gene (APOE) alleles ε2, ε3, and ε4 produce three different apoE isoforms with different biological effects, which can determine risks of many human diseases, including neurodegenerative and liver disease. This study aimed to evaluate the impact of APOE genotype on the variability of WD phenotypic expression.

METHODS

We analyzed data on 383 WD consecutive patients in the WD registry. The APOE genotypes (APOE ε3/ε3 (wild-type), APOE ε2-positive, and APOE ε4-positive) were determined and the APOE genotype effect on the phenotypic WD presentation was assessed in all symptomatic WD patients, as well as in patient subgroups divided according to sex and ATP7B genotype.

RESULTS

APOE genotype had no impact on WD presentation in the general population of symptomatic patients. However, APOE ε4-positive women tended to present WD symptoms earlier than women possessing the wild-type APOE ε3/ε3 genotype (24.2 vs. 27.9 years; p = 0.08). The effect of the APOE ε4-positive genotype was more pronounced in ATP7B p.H1069Q homozygous women, in whom disease symptoms started almost 6 years earlier (23.6 vs. 29.9 years; p < 0.05) than in APOE ε3/ε3 women.

CONCLUSIONS

In women, APOE ε4-positive genotype is associated with earlier onset of WD symptoms, particularly among ATP7B p.H1069Q homozygous patients. Further studies are needed to understand the mechanisms of these gender-dependent phenotypic effects.

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.

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.

Difference in stability of the N-domain underlies distinct intracellular properties of the E1064A and H1069Q mutants of copper-transporting ATPase ATP7B

Wilson disease (WD) is a disorder of copper metabolism caused by mutations in the Cu-transporting ATPase ATP7B. WD is characterized by significant phenotypic variability, the molecular basis of which is poorly understood. The E1064A mutation in the N-domain of ATP7B was previously shown to disrupt ATP binding. We have now determined, by NMR, the structure of the N-domain containing this mutation and compared properties of E1064A and H1069Q, another mutant with impaired ATP binding. The E1064A mutation does not change the overall fold of the N-domain. However, the position of the α1,α2-helical hairpin (α-HH) that houses Glu(1064) and His(1069) is altered. The α-HH movement produces a more open structure compared with the wild-type ATP-bound form and misaligns ATP coordinating residues, thus explaining complete loss of ATP binding. In the cell, neither the stability nor targeting of ATP7B-E1064A to the trans-Golgi network differs significantly from the wild type. This is in a contrast to the H1069Q mutation within the same α-HH, which greatly destabilizes protein both in vitro and in cells. The difference between two mutants can be linked to a lower stability of the α-HH in the H1069Q variant at the physiological temperature. We conclude that the structural stability of the N-domain rather than the loss of ATP binding plays a defining role in the ability of ATP7B to reach the trans-Golgi network, thus contributing to phenotypic variability in WD.

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.

Genetic analysis of BIRC4/XIAP as a putative modifier gene of Wilson disease

Wilson disease (WD) is an autosomal-recessive copper overload disorder caused by mutations in the copper-transporting adenosine triphosphatase (ATPase) ATP7B. It presents with a highly variable clinical phenotype ranging from asymptomatic to fulminant hepatic failure or progressive neurological involvement. No clear genotype-phenotype correlation has been established. Thus, variants in modifier genes could have an impact on WD manifestation and severity. Recently, the antiapoptotic protein baculoviral IAP repeat-containing protein 4 BIRC4/XIAP has been suggested as a regulator of copper-induced cell death. With the aim of investigating a putative role of BIRC4/XIAP as modifier gene in individuals with copper overload, we analyzed a WD patient cohort (n = 98) for sequence variants at the BIRC4/XIAP locus. When compared with clinical data, the previously described coding single nucleotide polymorphisms (SNPs) at the BRIC4/XIAP locus (rs28382721, rs28382722, rs28382723, rs5956583, rs28382740, rs12838858, rs28382741) did not correlate with age of onset or clinical presentation in our collective. However, three previously unreported variants in the BIRC4/XIAP gene were identified (c.1-26 T > G; c.1408A > T; p.T470S; c.1019A > G; p.N340S). The two patients with variants leading to amino acid exchanges in the BIRC4/XIAP protein showed a remarkably early disease onset at the age of 5 years. Furthermore, one of these patients was only heterozygous for disease-causing mutations in the ATP7B gene. In summary, these data emphasize the need to further elucidate a role of BIRC4/XIAP variants as putative pathogenetic factors in copper overload disorders.

High prevalence of fulminant hepatic failure among patients with mutant alleles for truncation of ATP7B in Wilson's disease

OBJECTIVE

Although many mutations of the Wilson's disease (WD) gene (ATP7B) have been reported, few data exist regarding the occurrence of fulminant hepatic failure (FHF). We sought to determine if genotypic assignment according to type of protein-product could be related to the prevalence of FHF among patients with WD.

MATERIAL AND METHODS

We performed gene analysis in Japanese patients with WD as well as genotype-phenotype analysis in 51 patients. We divided genotypes into two groups according to type of ATP7B product: truncated group [T] consisted of two truncated alleles including nonsense, insertion, deletion, or splice site mutation, and missense group [M] consisted of one or two missense alleles. We also divided phenotypes into two groups: [FHF] group and [non-FHF] group.

RESULTS

We were able to determine genotype in 42 patients. Genotypically, 11 patients were assigned to [T] group and 31 to [M] group. Phenotypically, 4 patients were [FHF] and 38 were [non-FHF]. All patients in [FHF] group belonged to [T] group. The prevalence of [FHF] in [T] group was 36.4% and was significantly higher than in [M] group (p < 0.003).

CONCLUSIONS

These results demonstrated that genotypes for truncation of ATP7B are associated with high prevalence of FHF.

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.

Neurologic Wilson's disease

Despite a long history, Wilson's disease, an autosomal recessive disease caused by mutations in the ATP7B gene, remains a commonly misdiagnosed import disease. Mutations in ATP7B result in abnormal copper metabolism and subsequent toxic accumulation of copper. Clinical manifestations of neurologic Wilson's disease include variable combinations of dysarthria, dystonia, tremor, and choreoathetosis. Among neurodegenerative diseases, it is unusual in that misdiagnosis and delay in treatment are clinically relevant because treatments can prevent and cure Wilson's disease, if they are given appropriately. If left untreated, Wilson's disease progresses to hepatic failure or severe neurologic disability and death, while those adequately treated have normal life spans. This review focuses on the neurologic features of Wilson's disease, its diagnosis, and treatment options.

Truncating mutations in the Wilson disease gene ATP7B are associated with very low serum ceruloplasmin oxidase activity and an early onset of Wilson disease

Background

Mutations in the gene ATP7B cause Wilson disease, a copper storage disorder with a high phenotypic and genetic heterogeneity. We aimed to evaluate whether 'severe' protein-truncating ATP7B mutations (SMs) are associated with low serum ceruloplasmin oxidase activities and an early age of onset when compared to missense mutations (MMs).

Methods

The clinical phenotype of 59 genetically confirmed WD patients was analyzed retrospectively. Serum ceruloplasmin was measured by its oxidase activity with o-dianisidine dihydrochloride as substrate and immunologically.

Results

Thirty-nine patients had two MMs, 15 had the genotype SM/MM, and 5 patients had two SMs on their ATP7B alleles. Enzymatic and immunologic serum ceruloplasmin levels differed significantly between the three groups (P < 0.001 and P < 0.01, respectively). The lowest levels were measured in patients with two SMs (0.0 U/L; IQR, 0.0-0.0 U/L and 0.02 g/L; IQR, 0.01-0.02 g/L, respectively) and the highest in patients with two MMs (17.8 U/L; IQR, 5.8-35.1 U/L and 0.11 g/L; IQR,0.10-0.17 g/L, respectively). The age of onset was also significantly different between the three patient groups (P < 0.05), with SM/SM patients showing the earliest onset (13 years; IQR, 9-13 years) and patients with two MMs showing the latest onset (22 years; IQR, 14-27 years). By ROC curve analysis a ceruloplasmin oxidase level ≤ 5 U/L can predict the presence of at least one SM with a sensitivity of 80% and a specificity of 79.5%.

Conclusions

In our German study cohort truncating ATP7B mutations were associated with lower ceruloplasmin serum oxidase levels and an earlier age of onset when compared to MMs. Measurement of serum ceruloplasmin oxidase might help to predict presence of truncating ATP7B mutations and might facilitate the mutation analysis.

Genotype-phenotype correlation in Italian children with Wilson's disease

BACKGROUND/AIMS

Wilson's disease phenotype is very variable for clinical and laboratory features. Our aim was to assess the role of the type of ATP7B disease causing mutations on Wilson's disease phenotype.

METHODS

We retrospectively evaluated the data of children with Wilson's disease from eight pediatric departments.

RESULT

Fifty-eight patients (34 male, median age at diagnosis 7.4 years) from 47 unrelated families were studied, carrying 34 different mutations. The most common mutations were the missense p.H1069Q and p.M769V, the nonsense p.R1319X, the frameshift c.2299delC, c.2298_2299insC and c.2530delA, and the splice site mutation c.2447+5G>A. Serum ceruloplasmin and copper were lower among the patients' homozygotes for nonsense and frameshift mutations than in patients with missense mutations. A normalization of serum alanine aminotransferase after therapy was not achieved in 23.6% of patients with missense mutations versus 45.5% of patients with nonsense/frameshift mutations. A direct linear correlation was found between age at diagnosis and urinary copper excretion at diagnosis.

CONCLUSIONS

The type of mutation explains at least a part of Wilson's disease phenotype, and mutation analysis should be considered as an integrative tool for such a challenging diagnosis. Urinary copper excretion appears to be correlated to the age at diagnosis rather than genotype.

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.

Psychopathology and personality traits in patients with treated Wilson disease grouped according to gene mutations

Wilson disease (WD) is a recessively inherited copper storage disorder mainly affecting liver and brain. Genotype/phenotype correlations have been report ed but as yet not regarding psychic symptoms. Our aim was to investigate if a correlation might exist between genotype and phenotype concerning psychopathology and/or personality traits in patients with treated WD. Nine homozygous and three compound heterozygous Swedish patients were retrospectively investigated, representing four different mutation settings. Psychopathological symptoms were studied using the Comprehensive Psychopathological Rating Scale (CPRS), personality traits using the Karolinska Scales of Personality (KSP) and mutations were analyzed by manifold sequencing. Psychopathological symptoms: Patients with the Trp779Stop mutation had the lowest scores on the total CPRS, due to less pronounced reported CPRS items, as compared to the other three groups of patients. Compound heterozygotes for the His1069Gln/Arg1319Stop mutation showed the highest total CPRS scores. Personality traits: Patients homozygous for the Trp779Stop and the Thr977Met mutations had high scores on Psychopathy related scales whereas patients with His1069Gln/Arg1319Stop mutations had the lowest scores on these scales. Serum ceruloplasmin levels were undetectable in all patients with the Trp779Stop and Thr977Met mutations. The results show a trend towards a genotype/phenotype correlation regarding psychopathological symptoms and personality traits in treated patients with WD. If replicable, these results might contribute to the elucidation of the possible clinical importance of functionally deleterious gene mutations in WD psychopathology and personality traits.

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.

Neurological manifestations and ATP7B mutations in Wilson's disease

Wilson's disease (WD) is a rare inborn metabolic error characterized by deficient biliary copper excretion secondary to ATP7B gene mutations. Neurological presentations are variable in respect to both pattern and age of onset; commonly a movement disorder presents in the second or third decade. The aim of this study was to ascertain genotype correlations with distinct neurological manifestations in 41 WD patients in a Brazilian center for WD. A total of 23 distinct mutations were detected, and the frameshift 3402delC had the highest allelic frequency (31.7%). An association between 3402delC and dysphagia was detected (p=0.01) but the limited number of patients is insufficient to allow one to draw conclusions. Both clinical studies analyzing larger cohorts and basic research on ATP7B protein function could potentially shed more light on our understanding of WD.

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.

Late-onset Wilson's disease

BACKGROUND & AIMS

The clinical symptoms and age at onset of Wilson's disease (WD) are highly variable. This study investigated patients who became symptomatic at >40 years of age.

METHODS

Clinical features, laboratory data, and mutation analysis were evaluated in 46 (3.8%) of 1223 patients who were investigated in a multinational study on genotype-phenotype correlations (1053 index patients, 170 siblings) who were >40 years of age at onset of symptoms and, in 2 asymptomatic siblings, diagnosed at >40 years of age.

RESULTS

Thirty-one patients presented with neurologic symptoms (mean age, 44.5 years; range, 40-52; male/female, 14/17), 15 presented with liver disease (mean age, 47.1 years; range, 40-58; male/female, 6/9), and 2 were asymptomatic siblings. Hepatic copper content was measured in 17 patients and was above 250 microg/g dry weight in 13. One patient with hepatic presentation had "fulminant" WD, the remaining 14 abnormal liver function tests and/or hepatomegaly. Liver biopsy specimens were available in 13 patients presenting with liver disease (cirrhosis, 10; chronic hepatitis, 2; steatosis, 1; no abnormalities, 1) and in 14 neurologic patients (cirrhosis, 9; advanced fibrosis, 1; chronic hepatitis, 2; no abnormalities, 2). Twenty-seven of the 46 index cases had mutations on both chromosomes (including 13 H1069Q/H1069Q), 13 on just 1 chromosome.

CONCLUSIONS

Late-onset WD is a frequently overlooked condition. The diagnostic features and the frequency of late-onset WD gene mutations were not different than in patients with an earlier onset of disease. Factors other than ATP7B mutations may modify the phenotypic presentation of WD.

Wilson's disease

Progressive hepatolenticular degeneration, or Wilson's disease, is a genetic disorder of copper metabolism. Knowledge of the clinical presentations and treatment of the disease are important both to the generalist and to specialists in gastroenterology and hepatology, neurology, psychiatry, and paediatrics. Wilson's disease invariably results in severe disability and death if untreated. The diagnosis is easily overlooked but if discovered early, effective treatments are available that will prevent or reverse many manifestations of this disorder. Studies have identified the role of copper in disease pathogenesis and clinical, biochemical, and genetic markers that can be useful in diagnosis. There are several chelating agents and zinc salts for medical therapy. Liver transplantation corrects the underlying pathophysiology and can be lifesaving. The discovery of the Wilson's disease gene has opened up a new molecular diagnostic approach, and could form the basis of future gene therapy.

Late neurological presentations of Wilson disease patients in French population and identification of 8 novel mutations in the ATP7B gene

Wilson disease (WD) is an autosomal recessive disorder of copper biliary excretion caused by an impaired function of ATP7B, a metal-transporting P-type ATPase encoded by WD gene. It results in copper accumulation, mostly in liver and brain tissues. Mutation analysis was carried out on 11 WD French unrelated patients presenting a predominant neurological form of this illness. SSCP and dHPLC analysis followed by sequencing of the 21 exons and their flanking introns were performed. Thirteen different mutations in a total of 17, and, among them, 10 novel variants were evidenced. Two deletions (c.654_655delCC and c.1745_1746delTA), 4 missense mutations (p.F763Y, p.G843R, p.D918A and p.L979Q), 1 nonsense mutation (p.Q1200X), 1 splice site mutation (c.1947-1G>C) and 2 intronic silent substitutions (c.2448-25G>T and c.3412+13T>A) were detected. These data extend the mutational spectrum of the disease, already known to be a very heterogeneous genetic disorder. As compared to hepatic manifestations, the phenotypes associated to these mutations confirm that neurological presentations associated with other mutations than p.H1069Q are also often late in their onset. Most of these neurological forms probably correspond to an attenuated impairment of copper metabolism, as compared to hepatic forms of the disease, mostly diagnosed earlier.

p.H1069Q mutation in ATP7B and biochemical parameters of copper metabolism and clinical manifestation of Wilson's disease

We compared the effect of the p.H1069Q mutation and other non-p.H1069Q mutations in ATP7B on the phenotypic expression of Wilson's disease (WD), and assessed whether the clinical phenotype of WD in compound heterozygotes depends on the type of mutation coexisting with the p.H1069Q. One hundred forty-two patients with clinically, biochemically, and genetically diagnosed WD were studied. The mutational analysis of ATP7B was performed by direct sequencing. A total number of 26 mutations in ATP7B were identified. The p.His1069Gln was the most common mutation (allelic frequency: 72%). Seventy-three patients were homozygous for this mutation. Of compound heterozygotes, 37 had frameshift/nonsense mutation, and 20 had other missense mutation on one of their ATP7B alleles. Twelve patients had two non-p.H1069Q mutations. Patients homozygous for the p.H1069Q mutation had the less severe disturbances of copper metabolism and the latest presentation of first WD symptoms. The most severely disturbed copper metabolism and the earliest age at initial disease manifestation was noticed in non-p.H1069Q patients. In compound heterozygotes, the type of mutation coexisting with the p.H1069Q to a small extent influenced WD phenotype. The phenotype of WD varied considerably among patients with the same genotype. The p.H1069Q mutation is associated with late WD manifestation and with a mild disruption of copper metabolism. In compound heterozygotes, the phenotype of WD to a small extent depends on the type of mutation coexisting with the p.H1069Q. Besides genotype, additional modifying factors seem to determine WD manifestations.

Hepatitic inherited metabolic disorders

Primary metabolic disorders are a disparate group of diseases that may or may not be accompanied by hepatic manifestations. Those with liver involvement may show a range of histopathologic changes. Proper histologic diagnosis requires correlation with clinical and laboratory data, including evaluation for mutations either via serum protein electrophoresis or through formal genetic analysis. This article is a review of the three most common inherited metabolic disorders which may present with a hepatitic pattern. In alpha1-antitrypsin disorder, there is a broad range of clinical presentations, age at presentation, and histological features ranging from "neonatal hepatitis" to a chronic progressive hepatitis in later childhood and adulthood. Hence, this disorder must be in the differential diagnosis of liver disease of the very young, and in older children and adults, with or without coexistent overt pulmonary symptoms. In Wilson disease, presentation tends to be in older childhood or the adult, with a progressive chronic hepatitis. Cystic fibrosis may feature a characteristic obstructive biliary syndrome, coexisting with the many extrahepatic manifestations of this debilitating disease. Lastly, the progressive familial intrahepatic cholestasis (PFIC) syndromes are given as examples of inherited metabolic conditions in which relentlessly progressive cholestatic liver disease eventuates over years in end-stage cholestatic liver disease with cirrhosis. Distinguishing features include absence of elevated serum gamma-glutamyl transpeptidase (GGT) in PFIC-1 and PFIC-2, and elevated GGT in PFIC-3. However, molecular studies are required for a confident diagnosis of the rare PFIC syndromes.

Frameshift and nonsense mutations in the gene for ATPase7B are associated with severe impairment of copper metabolism and with an early clinical manifestation of Wilson's disease

Wilson's disease (WD) is an autosomal recessive disorder of copper metabolism. The clinical phenotype of the disease is varied. It is proposed that this variation may be a result of differential functional disruption of ATPase7B (ATP7B) resulting from mutations in the gene ATP7B. We aimed to assess the relationship between specific mutational defects in ATP7B and divergence in the phenotypic expression of WD. One hundred and forty-two patients with clinically, biochemically and genetically diagnosed WD were included in the study. The phenotypic expression of WD was compared between patients with different types of mutations in ATP7B, detected by direct sequencing of exons 1-21 of the gene. Twenty-six mutations were identified in ATP7B; eleven of them were mutations predicted to result in the absence of a full-length normal protein [frameshift/nonsense mutations; classified as 'severe' mutations (SMs)], 14 were missense mutations (MMs) and one was a splice site mutation. Patients with one or two SMs on their alleles had lower serum copper and ceruloplasmin and were younger when the first symptoms of the disease appeared, compared with individuals with two MMs. The effect of SMs on the WD phenotype was dose-dependent. It is concluded that mutations within ATP7B are very heterogeneous. Frameshift and nonsense mutations are associated with a severe phenotype of WD.

La maladie de Wilson

Wilson disease is an autosomal recessive disorder of copper overload. A principal characteristic of this disease is its wide phenotypic and genotypic variability. Its results from mutations of the ATP 7B gene located on chromosome 13, that encodes a hepatic copper transport protein. More than 300 mutations of this gene have been identified. This protein ensures the transport of copper in the hepatocyte, its incorporation with the apoceruloplasmin and its biliary excretion. The clinical manifestations are heterogeneous as well in their presentation, dominated by the neuropsychiatric and hepatic symptoms, as in the age of the first symptoms. Early recognition and initiation of therapy with chelators or zinc are essential for prognosis. Liver transplantation is indicated in cases with fulminant hepatitis, end-stage liver cirrhosis and should be considered in the therapy resistant neurological forms. A regular follow-up with monitoring of adverse effects of treatment and compliance is essential. Any discontinuation of treatments will involve, within a very variable time, but in constant manner, a reappearance or a reaggravation of the signs. Such relapses are often brutal and can be extremely serious, especially since response to subsequent treatment is often poor.

Different neurological outcome of liver transplantation for Wilson's disease in two homozygotic twins

Wilson's disease is a genetic disorder characterized by accumulation of copper in many organs and tissues. Phenotypic manifestations are wide-ranging from neuropsychiatric disorders, to severe liver disease requiring liver transplantation. Clinical presentation is not often related to the genetic defect and siblings may have different type of disease. Liver transplantation is indicated for all patients with Wilson's disease and decompensated liver cirrhosis unresponsive to medical therapy, but its efficacy in resolving the neurological symptoms is still controversial, because as far now, very different outcomes have been reported. We describe here on the exceptional case of two homozygotic twins, both with liver cirrhosis due to Wilson's disease, one of them with severe neuropsychiatric involvement, who both underwent liver transplantation and subsequently had very different outcome despite same genetic background. The presence of neurological clinical manifestations in Wilson's disease should recommend caution indicating liver transplantation, because irreversible brain damage may exist.