We looked for an association between the MvaI polymorphism, a recently reported polymorphism on the promoter of the Apo-1/Fas gene, and rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) patients.
Two cohorts of Caucasian RA patients (total number = 185) and one cohort of SLE patients (n = 103) were studied. The MvaI polymorphism was typed by polymerase chain reaction and followed by MvaI digestion and gel electrophoresis.
A skewed distribution of MvaI genotypes was found in the first cohort of RA patients (n = 103) compared to the controls, as a result of increased MvaI*2 and decreased MvaI*1 homozygosity. This skewed distribution of genotypes was also observed in RA patients with either early onset of disease or with systemic involvement or progressive disease (assessed by the presence of erosions). The frequency of the MvaI*2 allele was significantly increased in female patients (P = 0.035), patients with extra-articular involvement (P = 0.04) and patients with early onset (P < 0.01), compared to the normals. To confirm these findings, the MvaI polymorphism was also examined in a second cohort of RA patients (n = 82). The results in this cohort did not replicate the associations shown in the first cohort of RA patients. Part of this inconsistency could be attributed to different populations and different parameters collected and analysed. In SLE patients, frequencies of MvaI alleles were not statistically different to the controls. However, MvaI*2 homozygosity was significantly higher in SLE patients with photosensitivity (P = 0.03) or oral ulcers (P = 0.01) than in SLE patients without these features.
The role of the Apo-1/Fas gene promoter MvaI polymorphism in RA and SLE is unclear and further substantiation in larger patient samples is needed.