Major Histocompatibility Complex Class II HLA-DRB1 Allelic Epitopes in Fibromyalgia

Background: Preliminary evidence has pointed an association of the gene HLA-DRB1 with fibromyalgia. HLA-DRB1 alleles carrying the shared or susceptibility epitope encoding the five-amino acid motif QKRAA, QRRAA or RRRAA in positions 70 to 74 of the major histocompatibility complex class II DRβ chain are associated with several autoimmune diseases. Objective: The objective of this study was to test the hypothesis that susceptibility epitope-encoding HLA-DRB1 alleles are associated with fibromyalgia. Methods: Using a case-control design, the prevalence of susceptibility epitope-encoding HLADRB1 alleles in 27 white Caucasian patients fulfilling the revised diagnostic criteria for fibromyalgia of the American College of Rheumatology was compared with that in 27 white Caucasian ageand sex-matched healthy controls. Results: 13 (48%) of the fibromyalgia patients had susceptibility epitope-coding HLA-DRB1 alleles compared with 15 (56%) of the controls (P = 0.785). The DRB1*01 allele encoding the protective epitope 70-DERAA-74 motif was found in one of the control subjects; none of the fibromyalgia patients had such a protective epitope. Conclusion: While the present study does not provide evidence supporting the potential role of HLA-DRB1 in the etiology of fibromyalgia, it does not exclude the possibility that there is a polygenic component to a putative genetic causative role.