HLA-B27 subtypes were defined by molecular typing in 45 patients with AS and 90 controls from Marseille. We subdivided patients and controls in 2 subgroups, according to the birth place of their grandparents: 19 patients and 38 controls constituted the Spanish/North African subgroup; 26 patients and 52 controls constituted the "French" subgroup. In patients from the Spanish/North African subgroup, the frequency of B2702 was higher (74%) than in controls from the same area (21%)pc<0.01 and the frequency of B2705 was lower in patients (25%) than in controls (79%) pc<0.01. In patients from the French group, the frequency of B2702 was higher (7%) than in controls (2%)(N.S.).
Thus, in the population of Southern France, B2702 seems to carry higher risk to develop AS than B2705.