In untreated polymyalgia rheumatica (PMR), high levels of circulating soluble intercellular adhesion molecule-1 (ICAM-1) have been observed. To investigate the clinical implication of ICAM-1 polymorphisms in isolated PMR, we examined their potential influence in an unselected series of patients.
We studied 72 patients with isolated PMR and 129 ethnically matched controls from Lugo, Spain. Patients and controls were genotyped for HLA-DRB1 and ICAM-1 polymorphism at codons 241 and 469 by molecular methods.
The distribution of alleles and genotypes for each ICAM-1 polymorphism did not show significant differences between patients with isolated PMR and controls. There were also no associations between ICAM-1 polymorphisms and relapses of the disease. The latter was primarily associated with carriage of an HLA-DRB1*0401 allele (OR 7.2, p = 0.01), although all relapsed patients with HLA-DRB1*0401 also carried the GG genotype of the ICAM-1 polymorphism at codon 241. The presence of both HLA-DRB1*0401 and the GG241 ICAM-1 genotype gave an OR of 15.2 (p = 0.005) after correction for age and sex.
Although ICAM-1 polymorphisms alone do not appear to be associated with disease severity in isolated PMR, the presence of both HLA-DRB1*0401 and the ICAM-1 codon 241 GG homozygosity was significantly associated with increased risk of relapses in these patients.