Many studies of human leukocyte antigen (HLA) association with juvenile idiopathic arthritis (JIA) have reported conflicting results, which were probably related to ethnic differences. Moreover, in India, studies on HLA-DR typing on JIA, particularly polyarticular JIA, is lacking.
The aim of our study was to reveal the frequency of HLA DR types in a cohort of polyarticular JIA in northern India.
Fifty-two polyarticular JIA patients were included as per the recent International League of Associations for Rheumatology classification, 2001. HLA-DR typing was performed in 21 patients (18 rheumatoid factor [RF]+ and three RF-) by a DNA-based polymerase chain reaction method for the determination of HLA alleles using sequence specific primers (SSP). The results were compared with that of 23 healthy controls of the same age and sex.
HLA-DR4 was present in five cases (23%) in the diseased group while only in one case (4.3%) in the control group with a relative risk of 5.47, but when compared with only RF+ polyarticular JIA, HLA-DR4 was found to be significantly high (27.7% vs. 4.43%; P < 0.05) with a relative risk of 6.3. Further, DR4, DR1, DR2, DR9, DR10 were also non-significantly high in these patients with relative risk of 3.2 for DR9 and 1.8 for DR10. In contrast, HLA-DR6 was seen only in 5.5% of polyarticular JIA cases, whereas it was present in 39% of controls (P < 0.05), a showing negative association.
HLA-DR4 codes for susceptibility to RF+ polyarticular JIA with a six-fold risk, whereas HLA-DR6 offers protection.