Variation in the relative copy number of the TLR7 gene in patients with systemic lupus erythematosus and healthy control subjects

Objective. To determine whether there is an increase in the number of TLR7 gene copies in patients diagnosed as having systemic lupus erythematosus (SLE) and whether gene amplification influences the autoantibody profiles in SLE patients, as has recently been reported in the BXSB/Yaa mouse model of lupus. Methods. We used a modified real-time quantitative polymerase chain reaction protocol to calculate the relative TLR7 gene copy number according to the comparative 2(-Delta Delta C) method in 99 SLE patients and 91 healthy controls matched for sex and ethnicity. Autoantibody profiles were determined by standard methods. Results. The relative number of TLR7 gene copies in SLE patients and healthy controls varied; however, no significant concordance between the number of relative gene copies and the SLE phenotype was found. There was also no difference in variation by ethnic group. Comparison of the relative gene copy numbers according to the presence or absence of antinuclear antibodies (ANAs), the ANA staining patterns, and the presence or absence of anti-RNA-associated antigen antibody showed no statistically significant difference in the SLE patients. Conclusion. We determined that although the relative gene copy number of TLR7 varied in both SLE patients and healthy controls, it was not significantly increased among our SLE patients as compared with our controls. We found no detectable trend for an association between the relative gene copy number and the autoantibody profile in SLE patients.