Clinical genetics — Wilson’s disease and Menkes’ syndrome are classic disorders of which trace mineral, and do they represent deficiency or toxicity?

Introduction / Context:
Wilson’s disease and Menkes’ syndrome are paradigmatic copper metabolism disorders with opposite directions of copper balance. Recognizing which is which is a high-yield clinical nutrition and genetics fact connecting hepatology, neurology, and pediatrics.

Given Data / Assumptions:

• Wilson’s disease is due to mutations in ATP7B, causing impaired biliary copper excretion and tissue accumulation.
• Menkes’ syndrome involves ATP7A mutations, impairing intestinal copper transport and resulting in systemic deficiency.
• Clinical features reflect either toxic accumulation (Wilson’s) or deficiency (Menkes’).

Concept / Approach:
Associate the gene and phenotype: ATP7B → hepatic copper overload (toxicity); ATP7A → poor copper distribution and deficiency. Therefore, Wilson’s corresponds to toxicity, Menkes’ to deficiency.

Step-by-Step Solution:

Verification / Alternative check:
Laboratory findings support the dichotomy (low ceruloplasmin and high hepatic copper in Wilson’s; low serum copper/ceruloplasmin in Menkes’).

Why Other Options Are Wrong:

Common Pitfalls:
Confusing ATP7A (Menkes’) and ATP7B (Wilson’s) due to similar nomenclature; remembering A for absorption (deficiency) and B for biliary excretion (toxicity) can help.

Final Answer:
Wilson’s disease = copper toxicity; Menkes’ syndrome = copper deficiency.