Rheumatoid arthritis and lupus are genetically distinct

Although rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) have some genes in common, including STAT4, HLA, and PTPN22, none of 9 other newly identified genes for SLE is associated with RA. This finding supports the notion that the genetic component of each disease contributes significantly to the different disease phenotypes.

Suarez-Gestal and associates studied a single-nucleotide polymorphism (SNP) in each of the 9 genetic factors in 1635 Spanish patients with RA and 1906 controls. The factors were ITGAM, C8orf13-BLK, TYK2, 1q25.1, PXK, KIAA1542, MECP2, BANK1, and LY9. They also included an evaluation of STAT4.

The investigators found no association between RA and any of the new SLE genes; like other investigators, however, they found that STAT4 is clearly associated with RA. The SNP in the C8orf13-BLK and the PXK showed a borderline association with RA. There were few significant differences between the results for subjects with and those without each of the clinical features analyzed.

The authors noted that further genetic research may provide a clearer understanding of what molecules and pathways are shared or specific in the pathogenesis of RA and SLE, possibly allowing for better management of both diseases.