Clinical and immunogenetic studies in rheumatoid arthritis from northern India.

A total of 258 patients with classic rheumatoid arthritis seen over a 7-year period were included in this study. The majority of the patients had relatively mild disease at the time of presentation. The incidence of extraarticular manifestations such as subcutaneous nodules, vasculitis, amyloidosis and pulmonary involvement was low although one or two pulmonary function test parameters were abnormal in some. Seventy patients were tested for all three subclasses of rheumatoid factors - IgM, IgG and IgA. Of these, 23 patients had all three whilst four had only IgG. The 62 patients who had most typical and severe manifestations were typed for four major HLA loci A, B, C and DR. Of these 42 (67.7%) had DR4 antigen while DR3 antigen was detected in 14 (22.6%).