A 6-month-old exclusively breastfed infant presents with acrodermatitis enteropathica — vesiculobullous rash around orifices, alopecia, and diarrhoea. The defect impairs absorption of which mineral via a ZIP4 transporter?
- A Zinc ✓
- B Copper
- C Iron
- D Selenium
Explanation
Acrodermatitis enteropathica is caused by autosomal recessive loss-of-function mutations in SLC39A4 (ZIP4), the major intestinal zinc importer located on the apical membrane of enterocytes. Zinc deficiency impairs zinc-dependent enzymes (>300 metalloenzymes including alkaline phosphatase, carbonic anhydrase, and DNA polymerases), transcription factor function, and immune cell development, producing the triad of acral/periorficial dermatitis, alopecia, and diarrhoea. Treatment is lifelong oral zinc supplementation. Copper malabsorption (Menkes disease) affects ATP7A, not ZIP4. Iron absorption uses DMT1/ferroportin. Selenium deficiency causes Keshan cardiomyopathy.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.