A 28-year-old man presents with chronic inflammatory low back pain worsening at night and improving with exercise, along with reduced chest expansion. Radiograph of the pelvis shows bilateral sacroiliitis. Which genetic marker is most strongly associated with this condition?
- A HLA-DR4
- B HLA-B51
- C HLA-B27 ✓
- D HLA-DQ2
Correct answer: C. HLA-B27
Explanation
Ankylosing spondylitis is strongly associated with HLA-C27 present in 90-95% of patients. HLA-DR4 is associated with RA. HLA-C51 is associated with Behcet disease. HLA-DQ2 is associated with celiac disease. Sacroiliitis is the hallmark radiographic finding in AS.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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