<prompt> To rule out rheumatoid arthrirtis, most important among the followings is?HLA DR8HLA DR4HLA DQ1HLA B27  <response>: Ans. is b i.e., HLA-DR4 o DR4 is strongly associated with RAalso with Type 1 DM Pemphigus vulgaris.Other optionso HLA-B27 is associated with seronegative spondyloartropathies ankylosing spondylitis, Psoriatic arthritis, Reiters syndrome, reactive arthritis and acute anterior uveitis o HLA DR8 is associated with Type 1 DM.o HLA DQ1 is associated with pemphigus vulgaris. 