This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
To rule out rheumatoid arthritis, most important among the followings is? 
Select and explain. 
A. HLA DR8, B. HLA DQ1, C. HLA B27, D. HLA DR4
D: HLA DR4
Answer: D: HLA DR4 
Explanation: DR4 is strongly associated with RA(also with Type 1 DM Pemphigus vulgaris).

Other options

HLA-B27 is associated with seronegative spondyloarthropathies (ankylosing spondylitis, Psoriatic arthritis, Reiter’s syndrome, reactive arthritis) and acute anterior uveitis
HLA DR8 is associated with Type 1 DM.
HLA DQ1 is associated with pemphigus vulgaris.