A 6-month-old boy has sparse, brittle, steel-grey hair that feels like sandpaper and breaks flush with the scalp. He has recurrent seizures, hypothermia and tortuous cerebral arteries on imaging. Serum copper and ceruloplasmin levels are low. The defective protein is:

• A ATP7B copper-transporting ATPase
• B Copper chaperone ATOX1
• C Ceruloplasmin ferroxidase
• D ATP7A copper-transporting ATPase ✓

Explanation

Menkes disease (kinky hair disease) is an X-linked recessive disorder caused by ATP7A mutations, which block copper transport across the placenta, gut and blood-brain barrier. Copper-dependent enzymes fail, including dopamine beta-hydroxylase (neurological signs) and lysyl oxidase (arterial tortuosity, subdural haematomas). Hair shows pili torti with trichorrhexis nodosa. ATP7D mutations cause Wilson disease, where copper accumulates rather than being deficient, and ceruloplasmin behaviour differs accordingly.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.