HLA-DRB1, DQA1, and DQB1 Alleles Associated with Giant Cell Arteritis in Northern Italy

Objective: To evaluate by molecular typing the possible associations of HLA-DRB1, DQA1, and DQB1 alleles with biopsy proven giant cell arteritis (GCA) in a Mediterranean country, and to examine possible relationships between these alleles and GCA clinical subsets.

Methods: Thirty-nine patients from the Reggio Emilia area diagnosed over a 12 year period with biopsy proven GCA were studied. The clinical findings at diagnosis and during the followup were evaluated through interviews and by reviewing the medical records. HLA-DRB1, DQA1, and DQB1 alleles were determined in the 39 patients and in 250 healthy controls from the same geographic area by polymerase chain reaction amplification using sequence-specific primers.

Results: No associations were found between GCA and the shared epitope, the DRYF epitope, or the DRB1*04 or DQA1 alleles. The only significant association was with DQB1*0302 allele (p = 0.03, RR = 2.2). However, the association was weak and the significance was lost when corrected for the number of antigens tested. The frequencies of DQB1*0301 and 0302 in DR4 patients were not significantly different from those observed in DR4 positive controls. Significant associations were found between DRB1*04 allele and the presence of systemic signs and/or symptoms (p = 0.04, RR = 1.5) and between DRB1*07 allele and the male patients (p = 0.04, RR = 2.6).

Conclusion: Our data showed no associations of biopsy proven GCA with HLA-DRB1*04 and HLA-DRB1*01 alleles, rheumatoid epitope, or DRYF epitope. Discrepancies with other studies may be related to the different ethnic backgrounds of the populations studied and to differences in the referral patterns of patients with GCA.