Spectrum of seronegative spondarthritides (SSA) with special reference to HLA profiles

The present study describes the profile of seronegative spondarthritides (SSA) in young servicemen. SSA was diagnosed in 63 patients from a prospective study on spondyloarthropathy. The SSA group consisted of ankylosing spondylitis (AS, 40 patients), Reiter's syndrome (RS, 6) and SSA undifferentiated (SSA-U, 17). The chief clinical and radiological features of the group were due to sacro-iliitis/spondylitis, peripheral arthritis and enthesopathy. Except for RS, extra-articular features were sparse. Mucosal lesions were not evident. Radiologically, sacro-iliitis varied from 24% in SSA-U to 100% in AS, and was disproportionately less when compared to its clinical extent. Dominant lower limb arthritis (poly and oligo) was seen in AS (40%), SSA-U (88.2%) and RS (100%). HLA A and B were typed in patients and controls. HLA AI had a significant negative association (p less than 0.05) with AS and the SSA group, and its relative risk (R) was consistently low (0.2-0.3). HLA B27 was present in 65.7%, 73%, 67%, 41% and 9% of the SSA group, AS, RS, SSA-U and controls respectively (p less than 0.05). Significant R values of A and B loci antigens in disease groups are presented. When compared with available Indian literature, this study highlights the variability and overlap in the disease. Disease markers currently available have limitations in defining the various subsets of SSA.