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.

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).

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.

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.

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.

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).

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.

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).

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.

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.

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.