A 55-year-old man with a history of poor dental hygiene presents with swollen bleeding gums, perifollicular hemorrhages, and poor wound healing. Deficiency of which vitamin impairs the hydroxylation of proline and lysine residues required for stable collagen triple helix formation?
- A Vitamin A
- B Vitamin C ✓
- C Vitamin D
- D Vitamin K
Correct answer: B. Vitamin C
Explanation
Vitamin C is an essential cofactor for prolyl hydroxylase and lysyl hydroxylase, enzymes that hydroxylate proline and lysine residues in procollagen. Hydroxylation is required for hydrogen bonding that stabilizes the triple helix. Deficiency causes scurvy, characterized by capillary fragility, bleeding gums, and poor wound healing. Vitamin A is needed for vision and epithelial integrity. Vitamin D regulates calcium. Vitamin K enables gamma-carboxylation of clotting factors.
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.