A routine assay for the direct analysis of HLA-DR-related shared epitope and B27 alleles in chronic inflammatory arthritis.

Knowledge of the genetic background of patients with inflammatory arthritis may be useful for disease management. The main markers are the HLA-DR-associated Shared Epitope (SE) for Rheumatoid Arthritis (RA) and HLA-B27 for ankylosing spondylitis. We have developed a simple molecular biology-based test to provide this essential information. HLA targets are amplified by polymerase chain reaction (PCR), then simultaneously analyzed using 16 individual hybridization reactions in two 8-well ELISA strips with colorimetric detection. Concordance was evaluated using a cohort of RA patients with known genotype. Using this new assay, 100% concordance was observed with conventional genotyping in RA patients both for HLA-DR SE and B27 genotypes. Seventy-three percent of the patients with destructive RA had at least one susceptible allele within SE, compared to 38% of those patients with non-destructive disease. This new assay, which requires minute amount of blood, could be used to determine the genetic background of inflammatory arthritis, particularly in non-specialized settings and for large-scale clinical trials.