An infant boy presents with seizures, cerebral degeneration, and sparse, brittle, twisted scalp hair described as 'kinky'. Serum copper and ceruloplasmin are both very low. Which of the following best describes the underlying defect?
- A X-linked recessive mutation in ATP7A impairing copper efflux across the blood-brain barrier and intestinal absorption ✓
- B Autosomal recessive mutation in ATP7B impairing biliary copper excretion
- C Mutation in the ZIP4 transporter causing failure of dietary zinc uptake
- D Mutation in hephaestin causing defective basolateral export of iron from enterocytes
Correct answer: A. X-linked recessive mutation in ATP7A impairing copper efflux across the blood-brain barrier and intestinal absorption
Explanation
Menkes disease is an X-linked recessive disorder of the ATP7B gene, which encodes the copper transporter expressed in enterocytes and the blood-brain barrier. Defective ATP7B prevents intestinal copper absorption and copper delivery into the brain, producing low serum copper, low ceruloplasmin, and kinky hair (pili torti). Option B describes Wilson disease, which shows copper excess rather than deficiency. The contrast between ATP7B (Menkes) and ATP7A (Wilson) is the examined point.
Reference: Nelson Textbook of Pediatrics, 22nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.