Wilson Disease (Hepatolenticular Degeneration) — Examination Question Bank

Genetics, Pathophysiology & Copper Metabolism

Question	Answer
1. What is the molecular and genetic basis of Wilson Disease?	Autosomal recessive mutation in the ATP7B gene located on chromosome $13q14.3$, encoding an intracellular copper-transporting P-type ATPase in hepatocytes. - Under normal physiology, dietary copper absorbed from the duodenum travels to the liver via portal blood, bound to albumin. - Inside the hepatocyte, ATP7B transports copper into the trans-Golgi network for incorporation into apoceruloplasmin to synthesize holoceruloplasmin ($90-95\%$ of circulating copper). - ATP7B also translocates copper into intracellular vesicles that undergo exocytosis at the canalicular membrane, excreting copper into bile (the body's sole major excretory route: $1.5-3 ext{ mg/day}$). - Mutations in ATP7B cause failure of both biliary copper excretion and ceruloplasmin incorporation. Toxic free elemental copper accumulates, produces free hydroxyl radicals via the Fenton reaction ($ ext{Cu}^+ + ext{H}_2 ext{O}_2
ightarrow ext{Cu}^{2+} + ext{OH}^ullet + ext{OH}^-$), inducing lipid peroxidation, mitochondrial DNA damage, apoptosis, hepatic fibrosis, and spillover into systemic circulation.
2. Trace the organ distribution of copper and clinical manifestations by age.	- Liver (Ages 3-10 years): First organ to accumulate copper. Manifests as asymptomatic transaminitis, acute hepatitis, chronic hepatitis, cirrhosis, portal hypertension, or fulminant hepatic failure. - Basal Ganglia & Brain (Typically $>8-12$ years): Copper deposits in the lenticular nuclei (putamen and globus pallidus), caudate, and subthalamic nuclei. Manifests as dystonia, tremors (classical wing-beating tremor), dysarthria, drooling, choreoathetosis, behavioral disturbances, and declining school performance. - Cornea (Descemet Membrane): Kayser-Fleischer rings ($>95\%$ in neurologic cases, $50-60\%$ in purely hepatic cases) and Sunflower cataracts in anterior lens capsule. - Erythrocytes: Sudden acute release of massive copper stores into circulation causes oxidative lysis of RBC membranes, presenting as Coombs-negative hemolytic anemia. - Kidneys: Proximal renal tubular acidosis (Fanconi syndrome), aminoaciduria, glycosuria, nephrolithiasis.
3. What is the clinical examination technique to detect Kayser-Fleischer (KF) rings?	- The KF ring is a golden-brown or greenish-brown granular deposition of copper in Descemet's membrane at the corneal limbus. - Gold Standard: Slit-Lamp Biomicroscopy performed by an experienced ophthalmologist. It cannot be reliably excluded by torchlight examination! - It first appears at the superior pole (12 o'clock), followed by the inferior pole (6 o'clock), and eventually becomes circumferential. - Clinical Pearl: Reversible with effective decoppering therapy (disappearance indicates copper depletion).

Diagnostic Scoring & Laboratory Workup

Question	Answer
4. Detail the Leipzig Diagnostic Scoring System for Wilson Disease.	Developed at the 8th International Conference on Wilson Disease (Leipzig, 2001): - Kayser-Fleischer Rings: Present = 2; Absent = 0. - Neurological Symptoms: Severe = 2; Mild = 1; Absent = 0. - Serum Ceruloplasmin: $<10 ext{ mg/dL}$ ($<0.1 ext{ g/L}$) = 2; $10-20 ext{ mg/dL}$ ($0.1-0.2 ext{ g/L}$) = 1; Normal ($>20 ext{ mg/dL}$) = 0. - Coombs-Negative Hemolytic Anemia: Present = 1; Absent = 0. - Liver Copper (if biopsy done): $>250 ext{ mcg/g}$ dry weight = 2; $50-250 ext{ mcg/g}$ = 1; Normal ($<50 ext{ mcg/g}$) = -1. - Urinary Copper (24-hour): $>2 imes ext{ ULN}$ ($>100 ext{ mcg/24h}$ or $>1.6\mu ext{mol/24h}$) = 2; $1-2 imes ext{ ULN}$ ($50-100 ext{ mcg/24h}$) = 1; Normal = 0. - ATP7B Mutation Analysis: Both alleles detected = 4; One allele detected = 1; None = 0. Interpretation: Total Score $\ge 4$ establishes a DEFINITE diagnosis of Wilson Disease; Score 3 = Probable; Score $\le 2$ = Unlikely.
5. How do you interpret Serum Ceruloplasmin, and when can it be falsely normal or low?	- Normal serum ceruloplasmin is $20-40 ext{ mg/dL}$. In Wilson disease, it is typically low ($<10-20 ext{ mg/dL}$). - False-Normal Ceruloplasmin in Wilson Disease: Ceruloplasmin is an acute-phase reactant synthesized by hepatocytes. In severe acute hepatic inflammation, sepsis, pregnancy, or estrogen exposure, ceruloplasmin can rise into the normal range despite active Wilson disease! - Falsely Low Ceruloplasmin in Non-Wilson Conditions: Severe protein-losing enteropathy, nephrotic syndrome, end-stage liver failure from any cause (failure of hepatic protein synthesis), Aceruloplasminemia, or Menkes disease.
6. Describe the 24-hour Urinary Copper Collection and D-Penicillamine Challenge Test.	- Baseline 24-hr Urinary Copper: Collected in a dedicated copper-free plastic container. Normal is $<40 ext{ mcg/24h}$ ($<0.6\mu ext{mol/24h}$). In untreated symptomatic Wilson disease, it is typically $>100 ext{ mcg/24h}$ ($>2 imes$ ULN). - D-Penicillamine Challenge Test: Indicated when baseline copper is equivocal (especially in pediatric hepatic presentations). - Administer oral D-penicillamine $500 ext{ mg}$ at the start and repeated at 12 hours ($1000 ext{ mg}$ total in 24 hr). - A post-challenge 24-hr urinary copper excretion $>25\mu ext{mol/24h}$ ($>1600 ext{ mcg/24h}$) is diagnostic of Wilson disease.

Pharmacotherapy, Acute Liver Failure & Viva Traps

Question	Answer
7. Detail the Pharmacological Management Protocol for Wilson Disease.	1) Chelation Therapy (Induction / Decoppering Phase): - D-Penicillamine: $20 ext{ mg/kg/day}$ divided 2-3 times daily, taken 1 hr before or 2 hr after meals. Start at low dose ($5-10 ext{ mg/kg/day}$) and titrate weekly to avoid paradoxical worsening of neurological symptoms. - Mandatory co-prescription: Pyridoxine (Vitamin B6) $25-50 ext{ mg/day}$ (penicillamine is an antimetabolite of B6). - Trientine (Triethylenetetramine): $20 ext{ mg/kg/day}$ divided bid-tid. Preferred first-line agent in neurological presentation or when adverse reactions to penicillamine occur (nephrotic syndrome, bone marrow suppression, Goodpasture-like syndrome, elastosis perforans serpiginosa). 2) Maintenance Therapy / Presymptomatic Siblings: - Elemental Zinc (Zinc Acetate / Sulfate / Gluconate): $50 ext{ mg}$ elemental zinc tid ($150 ext{ mg/day}$) for children $>5$ years. Administer 1 hr away from food and chelators. - Mechanism: Induces enterocyte metallothionein, which binds luminal copper with higher affinity than zinc; copper is shed into stool as enterocytes desquamate. 3) Dietary Copper Restriction: Avoid shellfish, organ meats (liver), mushrooms, nuts, dark chocolate, and dried fruits.
8. VIVA TRAP: What is the Revised King's College Wilson Index and why is chelation fatal in Wilsonian Acute Liver Failure?	In acute liver failure due to Wilson disease (presenting with severe coagulopathy, jaundice, low alkaline phosphatase, AST:ALT $>2.0$, and intravascular Coombs-negative hemolysis): - Chelators take weeks to months to lower total body copper and are completely ineffective in hyperacute necrosis; they also exacerbate renal tubular collapse. - The Revised King's College Score grades: Serum Bilirubin, INR, AST, WBC count, and Albumin (scores 0-4 each). - VIVA TRAP: A Score $\ge 11$ points predicts 100% mortality without emergency liver transplantation. Urgent referral for Living-Donor Liver Transplantation (LDLT) or deceased donor transplantation is life-saving!
9. VIVA TRAP: How do you screen asymptomatic siblings of an index Wilson patient?	Wilson disease is autosomal recessive ($25\%$ risk for each sibling). Screening must begin at 3 years of age: 1) Physical examination (hepatosplenomegaly, KF ring on slit lamp). 2) Liver function tests (AST, ALT, Bilirubin). 3) Serum ceruloplasmin and 24-hr urinary copper excretion. 4) Targeted genetic testing for family-specific ATP7B mutations (definitive gold standard). 5) Presymptomatic diagnosed siblings must be initiated immediately on oral zinc or low-dose chelator before irreversible tissue damage occurs!