Wilson's Disease

Wilson's Disease

Wilson's disease is an autosomal recessive genetic disorder of copper metabolism caused by mutations in the [ATP7B](/entities/atp7b) gene on chromosome 13q14.3[@bull1993]. The disease leads to progressive copper accumulation in the liver, brain, basal ganglia, and cornea, resulting in hepatic cirrhosis, neuropsychiatric symptoms, and characteristic Kayser-Fleischer rings. With early diagnosis and lifelong treatment, most patients have a normal life expectancy[@cauenburg2017].

Genetics and Pathophysiology

ATP7B Gene and Protein

The [ATP7B](/entities/atp7b) gene encodes a P-type copper-transporting ATPase (ATP7B protein) expressed primarily in hepatocytes. ATP7B has two primary functions:

Incorporation of copper into ceruloplasmin — ATP7B transfers copper to apoceruloplasmin to form holo-ceruloplasmin, the major copper-transporting protein in blood

Biliary copper excretion — ATP7B traffics to the canalicular membrane to excrete excess copper into bile[@ferenci2020]

More than 600 disease-causing mutations have been identified in [ATP7B](/entities/atp7b), including missense, nonsense, splice-site, insertion, and deletion variants. The H1069Q mutation (histidine at position 1069 replaced by glutamine) accounts for 50-70% of cases in Northern European and North American populations. Other common mutations include R778L (common in East Asian populations) and del2874 (common in Southern European populations)[@bull1993].

The pathophysiology of copper accumulation follows a staged progression:

...

Wilson's Disease

Wilson's disease is an autosomal recessive genetic disorder of copper metabolism caused by mutations in the [ATP7B](/entities/atp7b) gene on chromosome 13q14.3[@bull1993]. The disease leads to progressive copper accumulation in the liver, brain, basal ganglia, and cornea, resulting in hepatic cirrhosis, neuropsychiatric symptoms, and characteristic Kayser-Fleischer rings. With early diagnosis and lifelong treatment, most patients have a normal life expectancy[@cauenburg2017].

Genetics and Pathophysiology

ATP7B Gene and Protein

The [ATP7B](/entities/atp7b) gene encodes a P-type copper-transporting ATPase (ATP7B protein) expressed primarily in hepatocytes. ATP7B has two primary functions:

Incorporation of copper into ceruloplasmin — ATP7B transfers copper to apoceruloplasmin to form holo-ceruloplasmin, the major copper-transporting protein in blood

Biliary copper excretion — ATP7B traffics to the canalicular membrane to excrete excess copper into bile[@ferenci2020]

More than 600 disease-causing mutations have been identified in [ATP7B](/entities/atp7b), including missense, nonsense, splice-site, insertion, and deletion variants. The H1069Q mutation (histidine at position 1069 replaced by glutamine) accounts for 50-70% of cases in Northern European and North American populations. Other common mutations include R778L (common in East Asian populations) and del2874 (common in Southern European populations)[@bull1993].

The pathophysiology of copper accumulation follows a staged progression:

Copper Toxicity Mechanisms

Free copper acts as a potent catalyst in oxidative stress reactions, generating reactive oxygen species (ROS) through the Haber-Weiss reaction:

• Fenton reaction: Cu⁺ + H₂O₂ → Cu²⁺ + OH• + OH⁻
• Harber-Weiss reaction: Cu²⁺ + O₂•⁻ → Cu⁺ + O₂

The resulting hydroxyl radicals (OH•) cause lipid peroxidation, protein oxidation, DNA damage, and mitochondrial dysfunction. Key targets include:

• Mitochondrial complex IV inhibition — copper directly inhibits cytochrome c oxidase, impairing oxidative phosphorylation
• Glutathione depletion — copper binds to reduced glutathione (GSH), depleting the primary cellular antioxidant
• Alpha-synuclein aggregation — copper accelerates the misfolding and aggregation of [alpha-synuclein](/proteins/alpha-synuclein), similar to mechanisms in [Parkinson's disease](/diseases/parkinsons-disease)
• Ceruloplasmin oxidation — loss of functional ceruloplasmin reduces iron export, contributing to iron accumulation in the brain[@lorincz2010]

Clinical Presentation

Wilson's disease typically presents between ages 5 and 40, with two major clinical phenotypes:

Hepatic Presentation (40-50% of patients)

Liver disease in Wilson's disease ranges from asymptomatic elevation of transaminases to fulminant hepatic failure:

• Chronic hepatitis — elevated ALT, AST, with or without symptoms
• Cirrhosis — macronodular cirrhosis, portal hypertension
• Fulminant hepatic failure — coagulopathy, hemolysis, jaundice. Occurs in 5-10% of patients, more common in females. Associated with Coombs-negative hemolytic anemia due to massive copper release[@schilsky1999]
• Hepatocellular carcinoma — risk elevated in cirrhotic patients

Neurological Presentation (40-50% of patients)

Neurological symptoms typically develop after age 15 and reflect copper deposition in the basal ganglia, particularly the putamen and globus pallidus:

Movement Disorders:

• Dystonia — the most common movement disorder, ranging from focal (blepharospasm, risus sardonicus) to generalized[@litwin2015]
• Parkinsonism — bradykinesia, rigidity, tremor (resting or postural). Tremor is often "wing-beating" (proximal)
• Chorea and athetosis — less common
• Tremor — coarse, irregular, present at rest and with posture

Neuropsychiatric Features:

• Personality changes, depression, anxiety
• Cognitive impairment (subcortical pattern)
• Psychosis (rare)
• Seizures (uncommon)[@kim2019]

Neurological Examination Findings:

• Kayser-Fleischer rings — golden-brown copper deposits in Descemet's membrane of the cornea (present in >95% of neurological cases)
• Dysarthria (scanning or hypophonic)
• Dysphagia
• Salivation (sialorrhea)
• Difficulty with fine motor tasks

Diagnosis

Key Diagnostic Criteria (Leipzig Score)

| Feature | Score |
|---------|-------|
| Kayser-Fleischer rings | 2 |
| Neuropsychiatric symptoms | 2 |
| Serum ceruloplasmin < 0.1 g/L | 1 |
| Coombs-negative hemolysis with high serum copper | 1 |
| 24-hour urinary copper > 1.6 μmol (100 μg) | 2 |
| Quantitative liver copper > 4 μmol/g (250 μg/g) | 2 |
| Mutation analysis (2 pathogenic alleles) | 4 |

A score of 4 or more confirms diagnosis. A score of 2-3 requires additional testing.

Laboratory Findings

• Serum ceruloplasmin: Low (< 0.1 g/L) in ~85% of patients
• Serum copper: Normal to elevated (free copper is increased; total copper may be normal or low)
• 24-hour urinary copper: Elevated (> 100 μg/24h, typically 200-2000 μg)
• Liver copper content: > 250 μg/g dry weight (gold standard, requires biopsy)
• Complete blood count: May show hemolytic anemia, thrombocytopenia from hypersplenism
• Liver function tests: Elevated AST/ALT with AST:ALT ratio > 2.2 (characteristic but not specific)
• Brain MRI: T2 hypointensity in putamen, globus pallidus, thalamus, and midbrain ("face of giant panda"); cerebral and cerebellar atrophy

Treatment

Treatment aims to remove accumulated copper and prevent further accumulation. Lifelong therapy is mandatory.

First-Line Medications

Chelating Agents:

| Drug | Mechanism | Dose | Side Effects |
|------|-----------|------|--------------|
| Penicillamine | Copper chelation, increases urinary excretion | 750-1500 mg/day (250 mg qid) | Pyridoxine deficiency, neurological worsening (20-50%), rash, bone marrow suppression, nephrotic syndrome[@weiss2013] |
| Trientine | Copper chelation, less pyridoxine interference | 750-1500 mg/day (250 mg tid) | Similar to penicillamine but fewer neurological side effects[@weiss2013] |

Metallothionein Inducers:

• Zinc salts (zinc acetate, zinc gluconate) — 150 mg/day in 3 divided doses. Induces metallothionein in enterocytes, blocking copper absorption. Preferred for presymptomatic patients and maintenance therapy.

Treatment Protocol

Initial phase (0-6 months): Chelation therapy (penicillamine or trientine) to remove accumulated copper

Maintenance phase: Switch to zinc or lower-dose chelator

Monitoring: 24-hour urinary copper (target < 300 μg/24h on chelator, < 100 μg/24h on zinc); liver function tests; neurological examination

Presymptomatic patients: Zinc is preferred (avoids neurological worsening)

Fulminant hepatic failure: Liver transplantation is definitive treatment

Liver Transplantation

Indications include:

• Fulminant hepatic failure with coagulopathy
• Decompensated cirrhosis unresponsive to medical therapy
• Severe neurological disease with hepatic failure[@schilsky1999]

Liver transplantation corrects the metabolic defect as [ATP7B](/entities/atp7b) is expressed in hepatocytes, and outcomes are excellent with >85% 10-year survival.

Gene Therapy and Emerging Approaches

Research is exploring gene therapy approaches to deliver functional [ATP7B](/entities/atp7b) to hepatocytes, including AAV vectors and CRISPR-Cas9 editing of patient hepatocytes ex vivo followed by autologous transplantation. These approaches remain experimental but hold promise for permanent correction[@ferenci2020].

Disease Comparison

| Feature | Wilson's Disease | Parkinson's Disease | Huntington's Disease |
|---------|-----------------|--------------------|--------------------|
| Gene | ATP7B | SNCA, LRRK2, PARKIN, PINK1, GBA | HTT (CAG repeat) |
| Protein defect | Copper transport ATPase | Alpha-synuclein aggregation | Mutant huntingtin |
| Primary site | Liver, basal ganglia | Substantia nigra | Striatum (caudate, putamen) |
| Movement disorder | Dystonia, parkinsonism | Bradykinesia, rigidity, tremor | Chorea, dystonia |
| Kayser-Fleischer rings | Present in neurological cases | Absent | Absent |
| Liver involvement | Primary and early | Not typical | Not typical |
| Inheritance | Autosomal recessive | Mostly autosomal dominant | Autosomal dominant |

Prognosis

With early diagnosis and consistent treatment:

• Life expectancy: Near normal
• Neurological symptoms: May improve significantly with chelation therapy over 2-5 years
• Liver disease: Can be arrested or reversed if treated early
• Without treatment: Fatal, usually within 5-10 years of symptom onset

Neurological worsening occurs in 20-50% of patients within the first 1-3 months of chelation therapy, thought to be due to mobilization of copper from the liver to the brain. This is not a reason to stop treatment and often resolves with continued therapy[@lorincz2010].

References

[Bull PC, et al. The Wilson disease gene is a putative copper-transporting P-type ATPase similar to the Menkes gene. Nature Genetics. 1993](https://pubmed.ncbi.nlm.nih.gov/8100725/)

[Cauenburg J, et al. Clinical Outcomes in Wilson Disease: A 21-Year Single-Center Cohort Study. Clinical Gastroenterology and Hepatology. 2018](https://pubmed.ncbi.nlm.nih.gov/29122695/)

[Ferenci P, Czlonkowski A. Wilson Disease. GeneReviews. 2020](https://pubmed.ncbi.nlm.nih.gov/20301626/)

[Schilsky ML, et al. Liver transplantation in Wilson disease. Journal of Pediatric Gastroenterology and Nutrition. 1999](https://pubmed.ncbi.nlm.nih.gov/10086534/)

[Weiss KH, et al. Efficacy and safety of oral chelators in treatment of patients with Wilson disease. Clinical Gastroenterology and Hepatology. 2013](https://pubmed.ncbi.nlm.nih.gov/23534840/)

[Lorincz MT. Neurologic Wilson's disease. Annals of the New York Academy of Sciences. 2010](https://pubmed.ncbi.nlm.nih.gov/20590505/)

[Kim JH, et al. Brain structural changes and neuropsychiatric manifestations in Wilson disease. Neurology. 2019](https://pubmed.ncbi.nlm.nih.gov/30692335/)

[Litwin T, et al. Movement disorders in Wilson disease: a prospective study of 100 patients. Journal of the Neurological Sciences. 2015](https://pubmed.ncbi.nlm.nih.gov/25442085/)