This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autoimmune Diseases, Subject name: Pathology
To rule out rheumatoid arthrirtis, most important among the followings is? 
Select and explain. 
A. HLA DR8, B. HLA DR4, C. HLA DQ1, D. HLA B27
B: HLA DR4
Answer: B: HLA DR4 
Explanation: Ans. is 'b' i.e., HLA-DR4 o DR4 is strongly associated with RA(also with Type 1 DM Pemphigus vulgaris).Other optionso HLA-B27 is associated with seronegative spondyloartropathies (ankylosing spondylitis, Psoriatic arthritis, Reiter's syndrome, reactive arthritis) and acute anterior uveitis o HLA DR8 is associated with Type 1 DM.o HLA DQ1 is associated with pemphigus vulgaris.