An elderly bachelor living alone presents with perifollicular hemorrhages, corkscrew hairs, bleeding gums, and a poorly healing leg wound. Biochemical analysis of his wound granulation tissue would most likely show defective synthesis of which protein?

• A Elastin with desmosine cross-links
• B Collagen with hydroxyproline residues ✓
• C Fibrillin with disulfide bonds
• D Keratin with cysteine cross-links

Explanation

This is scurvy from vitamin C deficiency. Ascorbate is a cofactor for prolyl-4-hydroxylase and lysyl hydroxylase, enzymes that hydroxylate procollagen chains inside the rough endoplasmic reticulum. Hydroxyproline stabilizes the collagen triple helix by hydrogen bonding, so deficient hydroxylation produces unstable collagen that cannot form fibrils, causing capillary fragility, hemorrhage, and poor wound healing. Elastin cross-linking depends on lysyl oxidase and copper, not ascorbate.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.