We chose to study four of OPN's SNPs based on previously published studies that found association between these specific SNPs and different autoimmune and Th1 related diseases, such as Systemic Lupus erythematosus, type I Diabetes Mellitus and rheumatoid arthritis, or Behcet`s Disease and Vogt-Koyanagi-Harada Disease, which are also characterized by aberrant Th1 and Th17 response. This evidence concerns the gene SPP1 and rheumatoid arthritis.