Association between HLA-A9 and rapidly progressive periodontitis

HLA-A, B, C, DR antigen frequencies and Properdin factor B (Bf) allotypes were studied in a group of 44 patients with rapidly progressive periodontitis. HLA-A9 (A24) was the only antigen with a frequency statistically significantly different from the control population. An increased frequency of HLA-A9 was previously reported in periodontal diseases. Our results in a well characterised group of patients adds to the evidence that HLA-A9 plays a role in the susceptibility to severe periodontitis.