Wilson Disease

Definition And Genetics

• Autosomal recessive disorder of copper metabolism.
• Characterized by pathological copper accumulation in liver, brain, corneas, and kidneys.
• Gene involved: ATP7B located on chromosome 13 (13q14.3).
• Encodes metal-transporting P-type adenosine triphosphatase (ATPase7B), expressed predominantly in hepatocytes.
• Prevalence estimated at 1:30,000 to 1:40,000 live births.
• Heterozygous carrier rate approximates 1:90 to 1:100.
• Over 850 pathogenic variants identified (missense, nonsense, splicing, regulatory).
• H1069Q (His1069Glu) constitutes most common mutation in Europe and North America.
• Patients frequently present as compound heterozygotes.

Pathophysiology

• Dietary copper intake typically exceeds physiologic requirements (3-4 times estimated need in Western diet).
• Normal homeostasis relies on hepatic biliary excretion for excess copper elimination.
• ATP7B mutation impairs transmembrane copper transport within hepatocytes.
• Defective ATPase7B halts copper transport into trans-Golgi network.
• Results in failed incorporation of copper into apoceruloplasmin and arrested biliary copper excretion.
• Copper progressively accumulates within hepatocyte cytosol.
• Free intracellular copper induces toxicity via Fenton reaction; Cu1+ produces highly reactive hydroxyl radicals causing lipid peroxidation of macromolecules and mitochondrial damage.
• Hepatic storage capacity eventually surpassed (typically end of first or second decade).
• Free copper releases into systemic circulation.
• Secondary deposition occurs in vulnerable extrahepatic organs (central nervous system, corneas, kidneys).

Clinical Manifestations

Hepatic Features

• Represents most common initial presentation in pediatric patients (first to second decade).
• Variable spectrum ranging from asymptomatic state to fulminant failure.
• Asymptomatic transaminitis or asymptomatic hepatomegaly.
• Steatosis (fatty liver) represents early pathological feature.
• Chronic active hepatitis mimicking autoimmune hepatitis.
• Cirrhosis with portal hypertension, splenomegaly, ascites, esophageal variceal hemorrhage.
• Acute liver failure (fulminant hepatic failure) presenting with rapidly progressive coagulopathy, jaundice, and encephalopathy.
• Acute failure characteristically associated with Coombs-negative hemolytic anemia.

Neurological And Psychiatric Features

• More common presentation in older adults (third to fourth decade) but possible in childhood.
• Manifestations correlate with progressive lenticular degeneration.

Category	Specific Findings
Movement Disorders	Tremors (postural, intentional, resting), choreoathetosis, rigid dystonia, ataxia, parkinsonian syndrome (hypokinesia, rigidity).
Bulbar/Cerebellar	Dysarthria (slurred speech), excessive salivation/drooling, gait disturbances, clumsiness.
Psychiatric	Behavioral changes, depression, declining school performance, anxiety, personality changes, psychosis, obsessive-compulsive behaviors.

Extrahepatic And Systemic Features

System	Manifestations
Ophthalmologic	Kayser-Fleischer (KF) rings (copper deposition in Descemet’s membrane; rare in young children, common in neurological presentation). Sunflower cataracts.
Renal	Fanconi syndrome (aminoaciduria, glycosuria, renal tubular acidosis, impaired phosphate reabsorption), nephrocalcinosis, nephrolithiasis.
Hematologic	Coombs-negative hemolytic anemia, thrombocytopenia, leukopenia.
Skeletal/Endocrine	Rickets, osteoporosis, arthritis, delayed puberty, amenorrhea.
Dermatologic	Xerosis, keratosis pilaris, hyperpigmentation of lower legs.

Diagnostic Evaluation

Laboratory And Biochemical Assays

• No single diagnostic test functions as perfect gold standard.
• Serum Ceruloplasmin: Typically low (<20 mg/dL). False normals occur as ceruloplasmin acts as acute phase reactant during active hepatic inflammation.
• 24-Hour Urinary Copper: >40 µg/24h raises suspicion; >100 µg/24h highly likely indicates disease.
• Penicillamine Challenge Test: 500 mg D-penicillamine administered at onset and 12 hours into 24-hour collection. Positive result yields >1600 µg/24h (25 mcmol/24h) excretion. Highly sensitive in symptomatic patients.
• Serum Free Copper: Calculated non-ceruloplasmin-bound copper frequently elevated (>1.6 µmol/L or >15 µg/dL).

Imaging And Histology

• Slit-Lamp Examination: Required for definitive detection of KF rings and sunflower cataracts.
• Liver Biopsy: Crucial for doubtful cases.
  • Hepatic Copper Quantification: Gold standard biochemical evidence. Values ≥250 µg/g dry weight diagnostic. Lower values possible in severe cirrhosis due to variable distribution/sampling error.
  • Histology: Microvesicular and macrovesicular steatosis, glycogen-containing nuclear vacuoles, portal fibrosis, cirrhosis.
  • Ultrastructure: Pleomorphic mitochondria exhibiting increased matrix density and widened intercristal spaces.
• Genetic Testing: ATP7B mutation analysis via direct sequencing or next-generation sequencing (NGS). Identifies pathogenic variants in up to 95% of subjects.

Diagnostic Scoring (Leipzig Score)

• Evaluates clinical and biochemical parameters collectively.
• Score ≥ 4 confirms definitive diagnosis.
• Score 2-3 denotes probable disease requiring further investigation.
• Score 0-1 makes diagnosis highly improbable.

Management Protocol

Dietary Modification

• Restrict dietary copper intake strictly below 1 mg/day.
• Eliminate high-copper foods: liver/organ meats, shellfish, nuts, chocolate, mushrooms.
• Avoid copper-contaminated environmental sources (well water, copper pipes).

Pharmacotherapy

Lifelong medical compliance mandated to prevent severe organ damage or death.

Agent	Mechanism	Indication & Dosing	Adverse Effects
D-Penicillamine	Copper chelator; mobilizes intracellular copper for urinary excretion.	First-line for severe liver disease. Dose: 20 mg/kg/day divided. Requires pyridoxine (25 mg/day) co-administration.	Hypersensitivity, proteinuria, cytopenias, lupus-like syndrome, early neurological worsening.
Trientine	Copper chelator.	Alternative for penicillamine intolerance; often preferred first-line due to safer profile. Dose: 20 mg/kg/day divided.	Rare arthralgias, sideroblastic anemia, neurological worsening.
Zinc (Acetate/Sulfate)	Blocks intestinal copper absorption; induces enterocyte/hepatocyte metallothionein.	Asymptomatic patients, neurological presentations, maintenance therapy. Dose: 25-50 mg elemental zinc TID.	Gastritis, gastric/duodenal ulcers, elevated lipase/amylase.
Tetrathiomolybdate	Potent copper chelator.	Experimental; promising for neurological presentations with less neuro-deterioration.	Anemia, leukopenia, hepatotoxicity.

Surgical Intervention

• Liver Transplantation: Indicated for fulminant acute liver failure with encephalopathy, or decompensated cirrhosis unresponsive to medical chelation.
• Transplant Scoring: King’s College Criteria (score ≥ 11 indicates urgent listing) or Wilson’s disease index (Bilirubin, INR, AST, WBC, Albumin; score ≥ 11 mandates transplant).
• Transplantation curative for hepatic defect; resolves altered copper metabolism.

Surveillance And Screening

• Therapy Monitoring: 24-hour urinary copper (target 300-500 µg/day on penicillamine; <75 µg/day on zinc), serum non-ceruloplasmin bound copper (target 5-15 µg/dL), complete blood counts, and LFTs bi-annually.
• Family Screening: Mandatory for all first-degree relatives.
• Initiate screening at 3 years of age.
• Testing includes history, physical exam, LFTs, prothrombin time, slit-lamp exam, 24-hour urine copper, and ATP7B genetic testing.
• Asymptomatic patients identified via screening must initiate prophylactic zinc or chelation therapy to prevent irreversible pathology.