[HLA DRB1 polymorphism in rhizomelic pseudo-polyarthritis and Horton disease].

Some studies have suggested that distribution of HLA DRB1 alleles in polymyalgia rheumatica (PMR) resembles that found in giant cell arteritis (GCA). However these data are controversial. OBJECTIVE--To evaluate in French native patients whether PMR immunogenetically resembles GCA in determining HLA DRB1 alleles. PATIENTS AND METHODS--Fourty-five patients were included in the study. Twenty-one patients with PMR alone (Bird's criteria) and 24 with GCA (ACR criteria). In 11 patients, GCA was associated with PMR. HLA DRB1 genotype was determined by PCR-RFLP analysis. Statistical analysis was performed by the chi 2 test and determination of the odds ratio (OR). Two hundred and thirty-three unselected normal healthy subjects served as controls. RESULTS--A significant increased prevalence of HLA DR1 was observed in patient with PMR alone and an absence of DR7 (0% vs 10.3%, p = 0.02, OR = 0.1). An increased incidence of DR4 and particularly *0401 allele was only found in patients with GCA (OR = 2.4). No patient with isolated PMR had DR7 genotype compared with 25% in GCA (p < 0.001, OR = 0.03). A comparative study between isolated PMR versus GCA showed a significant increased in DR1 and DR3 alleles in isolated PMR and a significant increased prevalence of DR4 and DRB1 *0701 allele in GCA. CONCLUSION--The present study emphasizes the absence of similarity in HLA DRB1 allele distribution between PMR and GCA. The association of DR7 in patient with GCA seems characteristic in French native patients.