HLA-DQB1 alleles in Italian patients with mucous membrane pemphigoid predominantly affecting the oral cavity

BACKGROUND: Mucous membrane pemphigoid (MMP) used to be considered as a single entity but it is now evident that a range of variants exists. Among them, pure ocular cicatricial pemphigoid (OCP) and pure oral pemphigoid (OP) appear to be very different subsets. Previous immunogenetics studies have found increased occurrence of the DQB1*0301 allele mainly in patients with OCP whereas in patients with OP the data are more open to doubt. OBJECTIVES: To analyse HLA predisposition in a group of Italian patients with MMP predominantly affecting the oral cavity. METHODS: We carried out high-resolution typing of HLA-DQB1 alleles in 28 patients with MMP predominantly affecting the oral cavity and in 97 geographically matched, healthy controls. All were Italian caucasians. RESULTS: The frequency of HLA-DQB1*0301 was significantly increased in the MMP patients compared with the controls (96% vs. 48%; corrected P, Pc = 0.001; relative risk, RR = 28.73). A strong association with DQB1*0301 was also evident in patients with OP compared with the controls (95% vs. 48%; Pc = 0.01; RR = 20.21). There was no significant difference in DQB1*0301 frequency between patients with OP and with MMP not restricted to the oral cavity. Patients with MMP were more frequently homozygous for DQB1*0301 than the controls (43% vs. 8%; Pc < 0.001; RR = 8.34). CONCLUSIONS: Our data suggest that Italian patients with MMP lesions predominantly affecting the oral cavity present the same genetic predisposition linked to HLA-DQB1*0301 previously reported mainly in patients with OCP.