This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Rheumatoid Arthritis, Subject name: Medicine
HLA-DR4 is a marker of - 
Select and explain. 
A. Rheumatoid arthritis, B. Sarcoidosis, C. Sero-negative gouty arthritis, D. Psoriasis
A: Rheumatoid arthritis
Answer: A: Rheumatoid arthritis 
Explanation: Ans. is 'a' i.e., Rheumatoid arthritis DR4 is associated witho Extra-articular rheumatoid arthritiso Hydralazine-induced femal systemic lupus erythematosuso Pemphigoid gestationaliso Pemphigus foliaceuso Obstructive hypertrophic cardiomyopathyo IgA nephropathy