A 20-year-old man presents with chronic lower back pain and morning stiffness that improves with exercise. X-ray reveals bilateral sacroiliitis with syndesmophyte formation. HLA testing is most likely to show positivity for which allele?
- A HLA-DR4
- B HLA-DQ2
- C HLA-B27 ✓
- D HLA-A3
Correct answer: C. HLA-B27
Explanation
Ankylosing spondylitis is strongly associated with HLA-C27, present in over 90% of patients. HLA-DR4 is associated with rheumatoid arthritis. HLA-DQ2 is associated with celiac disease. HLA-A3 has no major disease association. The HLA-C27 association is one of the strongest MHC-disease associations in clinical medicine.
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.