Is there an indication for HLA-DR typing for individual patients with rheumatoid arthritis?

The clinical expression of rheumatoid arthritis (RA) varies considerably among individual patients. Genetic variations in human leucocyte antigen (HLA) may influence susceptibility to RA and the severity of the disease. The literature concerning the association of HLA-DR with the susceptibility to and the clinical expression of RA is reviewed here, taking into account the different populations studied and different typing techniques. An association between the 'shared epitope' and RA susceptibility is present on a group level and may be of some pathophysiological interest. However HLA-DR typing is not useful as a diagnostic test for individuals. The reported associations between HLA-DR and RA severity are various, which might be due to the different typing techniques used. Results from most studies using genomic techniques for HLA-DR typing show an association between HLA-DR4+, DR1+ and a more severe disease course in patient groups. However, this association is too weak to be relevant for individual patients. Therefore, with our current typing techniques, HLA-DR typing is not a useful prognostic test for individual RA patients.