IL6ST and rheumatoid arthritis: On the other hand, sgp130 is primarily produced through alternative splicing and exist in three isoforms, albeit we quantified solely one, sgp130-RAPS, as it is the only sgp130 isoform verified by Western blot.30 Sgp130-RAPS was originally detected in patients with rheumatoid arthritis, hence there is a risk of bias in patients with this condition, although it is relatively rare and to our knowledge none of the patients included in this study had clinically overt rheumatic disease.