Clinical Use of Next-Generation Sequencing in the Diagnosis of Wilson's Disease

Navigating the CRISPR/Cas Landscape for Enhanced Diagnosis and Treatment of Wilson's Disease

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) system continues to evolve, thereby enabling more precise detection and repair of mutagenesis. The development of CRISPR/Cas-based diagnosis holds promise for high-throughput, cost-effective, and portable nucleic acid screening and genetic disease diagnosis. In addition, advancements in transportation strategies such as adeno-associated virus (AAV), lentiviral vectors, nanoparticles, and virus-like vectors (VLPs) offer synergistic insights for gene therapeutics in vivo. Wilson's disease (WD), a copper metabolism disorder, is primarily caused by mutations in the ATPase copper transporting beta (ATP7B) gene. The condition is associated with the accumulation of copper in the body, leading to irreversible damage to various organs, including the liver, nervous system, kidneys, and eyes. However, the heterogeneous nature and individualized presentation of physical and neurological symptoms in WD patients pose significant challenges to accurate diagnosis. Furthermore, patients must consume copper-chelating medication throughout their lifetime. Herein, we provide a detailed description of WD and review the application of novel CRISPR-based strategies for its diagnosis and treatment, along with the challenges that need to be overcome.

Wilson disease: the diagnostic challenge and treatment outcomes in a series of 262 cases

BACKGROUND

 Wilson disease (WD) is an autosomal recessive disorder that leads to organ toxicity due to copper overload. Early diagnosis is complicated by the rarity and diversity of manifestations.

OBJECTIVE

 To describe the diagnostic features and response to treatment in our cohort of WD patients.

METHODS

 This was a retrospective analysis of 262 WD patients stratified by clinical presentation, complementary exams, ATP7B genotyping, and response to treatment.

RESULTS

 Symptoms occurred at an average age of 17.4 (7-49) years, and patients were followed up for an average of 9.6 (0-45) years. Patients presented mainly with hepatic (36.3%), neurologic (34.7%), and neuropsychiatric (8.3%) forms. Other presentations were hematologic, renal, or musculoskeletal, and 16.8% of the patients were asymptomatic. Kayser-Fleischer rings occurred in 78.3% of the patients, hypoceruloplasminemia in 98.3%, and elevated cupruria/24h in 73.0%, with an increase after D-penicillamine in 54.0%. Mutations of the ATP7B gene were detected in 84.4% of alleles. Brain magnetic resonance imaging showed abnormalities in the basal ganglia in 77.7% of patients. D-penicillamine was the first choice in 93.6% of the 245 patients, and 21.1% of these patients were switched due to adverse effects. The second-line therapies were zinc and trientine. The therapeutic response did not differ significantly between the drugs (p = 0.2). Nine patients underwent liver transplantation and 82 died.

CONCLUSION

 Wilson disease is diagnosed at a late stage, and therapeutic options are limited. In people under 40 years of age with compatible manifestations, WD could be considered earlier in the differential diagnosis. There is a need to include ATP7B genotyping and therapeutic alternatives in clinical practice.

Missing heritability of Wilson disease: a search for the uncharacterized mutations

Wilson disease (WD), a copper metabolism disorder caused by mutations in ATP7B, manifests heterogeneous clinical features. Interestingly, in a fraction of clinically diagnosed WD patients, mutations in ATP7B appears to be missing. In this review we discuss the plausible explanations of this missing heritability and propose a workflow that can identify the hidden mutations. Mutation analyses of WD generally includes targeted sequencing of ATP7B exons, exon-intron boundaries, and rarely, the proximal promoter region. We propose that variants in the distal cis-regulatory elements and/or deep intronic variants that impact splicing might well represent the hidden mutations. Heterozygous del/ins that remain refractory to conventional PCR-sequencing method may also represent such mutations. In this review, we also hypothesize that mutations in the key copper metabolism genes, like, ATOX1, COMMD1, and SLC31A1, could possibly lead to a WD-like phenotype. In fact, WD does present overlapping symptoms with other rare genetic disorders; hence, the possibility of a misdiagnosis and thus adding to missing heritability cannot be excluded. In this regard, it seems that whole-genome analysis will provide a comprehensive and rapid molecular diagnosis of WD. However, considering the associated cost for such a strategy, we propose an alternative customized screening schema of WD which include targeted sequencing of ATP7B locus as well as other key copper metabolism genes. Success of such a schema has been tested in a pilot study.

Challenges in the diagnosis of Wilson disease

The understanding and management of Wilson disease (WD) have dramatically improved since the first description of the disease by K. Wilson more than a century ago. However, the persistent long delay between the first symptoms and diagnosis emphasizes challenges in diagnosing earlier this copper overload disorder. As a treatable disease, WD should be detected early in the course of the disease by any health professionals at any care level, but the rare prevalence of the disease explains the lack of awareness of referring physicians. The most important challenge is to train physicians to recognize atypical or rare symptoms of WD that will lead to discuss the diagnosis more systematically. Atypia can come from the age of onset, the liver [non-alcoholic steatohepatitis (NASH) presentation], the central or peripheral nervous system (neuropathy, epilepsy, sleep disorders…) or may be due to lesions of other organs (renal manifestations, osteo-articular disorders or endocrine disturbances). Isolated biological anomalies, rare radiological findings or inadequate interpretation of copper test may also lead to misdiagnosis. The second challenge is to confirm the diagnosis faster and more effectively so as not to delay the initiation of treatment, and expand family screening as the genetic prevalence is higher than previously expected. Generalization of the exchangeable copper assay and the next generation sequencing (NGS) are two promising ways to overcome this ultimate challenge. By drawing attention to the earliest and rare symptoms and to new biomarkers and diagnostic tools, we hope that this article will increase diagnostic awareness and reduce delays so that patients can start their treatment earlier in the course of the illness and thus have a better disease prognosis.

Characteristics and prevalence of Wilson's disease: A 2013 observational population-based study in France

BACKGROUND AND AIMS

Only a few epidemiological studies on the incidence and prevalence of Wilson's disease (WD) have been performed to date, and the results vary widely according to the reports. The aim of the study was to investigate the prevalence, ambulatory care and treatments of patients with WD in France.

METHODS

Among the 58 million general health scheme beneficiaries (86% of the French population), people managed for WD in 2013 were identified using hospitalisation diagnosis in 2011-2013 or specific long-term disease status with a 100% reimbursement for specific healthcare in 2013. Data were derived from the Sniiram (National Health Insurance Information System database). Prevalence by age and sex were calculated.

RESULTS

In 2013, 906 prevalent cases were identified, yielding a crude prevalence of 1.5 cases per 100,000; 1.65 per 100,000 in males and 1.44 per 100,000 in females. This prevalence is comparable to that reported in other population-based studies in European countries and to a study using a similar method. Almost 40% of patients were treated by D-penicillamine and 14.3% were treated by zinc acetate. Trientine, delivered on a compassionate basis, was not available in the reimbursement database. In 2013, 1.3% of patients underwent liver transplantation and 4% had already undergone liver transplantation in previous years. Fifteen per cent of patients received antidepressants, a higher rate than in general population.

CONCLUSIONS

This is the first French population-based epidemiological study of WD in a comprehensive population based on administrative data and constitutes an important step to understand the impact of WD and to study quality of care.

Hereditary Multiple Cerebral Cavernous Malformations Associated with Wilson Disease and Multiple Lipomatosis

We report on a patient with 2 Mendelian diseases-symptomatic multiple familial cerebral cavernous malformations (FCCMs) and Wilson disease. Genetic analysis revealed single nucleotide polymorphisms in genes CCM2 and CCM3, associated with cavernous malformations, and homozygote mutation in the ATP7B gene, responsible for Wilson disease. FCCMs were symptomatic in 3 generations. The patient also had multiple lipomatosis, which is suggested to be a familial syndrome. In recent years there has been an increasing amount of publications linking FCCMs with other pathology, predominantly with extracranial and intracranial mesenchymal anomalies. The present study is the description of an unusual association between 2 independent hereditary diseases of confirmed genetic origin-a combination that has not been described previously.

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

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

Four-year follow-up of a Wilson disease pedigree complicated with epilepsy and hypopituitarism: Case report with a literature review

RATIONALE

Wilson's disease (WD) is an autosomal recessive inherited disorder of copper metabolism with excellent prognosis if treated timely. However, WD is usually prone to neglect and misdiagnosis at an early stage. We reported a rare WD pedigree, and the clinical features, laboratory tests, and gene mutations were analyzed in detail.

PATIENT CONCERNS

The patient was a 17-year-old and 136-cm-tall girl who presented with limb weakness, combined with multi-organ disorders including blind eye, epilepsy, and hypopituitarism.

DIAGNOSES

Clinical tests showed a low serum ceruloplasmin level, high urinary copper excretion and Kayser-Fleischer (K-F) rings. She carried a compound heterozygous mutations in ATP7B gene (c.2828G>A and c.3884C>T). Her younger brother, as an asymptomatic patient, manifested with elevation of transaminases but without neurological and hepatic symptoms. They were diagnosed as WD finally.

INTERVENTIONS

They were treated with sodium dimercaptosulphonate, supplemented with zinc gluconate, vitamin B6, vitamin C, as well as restriction of dietary copper.

OUTCOMES

The urinary copper excretion and serum transaminase level decreased gradually. The abnormal signals in brainstem and basal ganglia were also remarkably decreased after 4-year of de-copper treatment.

LESSONS

As to the patients with complicated clinical manifestations, the extrapyramidal symptom and basal ganglia signals should be concerned. The serum ceruloplasmin detection and ATP7B gene mutation screening are necessary.