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 sing le entity but it is now evident that a range of variants exists. Among them , pure ocular cicatricial pemphigoid (OCP) and pure oral pemphigoid (OP) ap pear to be very different subsets. Previous immunogenetics studies have fou nd 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 wit h MMP predominantly affecting the oral cavity. Methods We carried out high-resolution typing of HLA-DQB1 alleles in 28 pat ients with MMP predominantly affecting the oral cavity and in 97 geographic ally matched, healthy controls. All were Italian caucasians. Results The frequency of HLA-DQB1*0301 was significantly increased in the M MP 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 evi dent 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 betwe en patients with OP and with MMP not restricted to the oral cavity. Patient s with MIT 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 predomi nantly affecting the oral cavity present the same genetic predisposition li nked to HLA-DQB1*0301 previously reported mainly in patients with OCP.