Therefore, in this retrospective study, we evaluate two commercial fluoroenzymatic immunoassays (FEIA; EliATM U1-RNP and EliATM RNP70) for measuring anti-U1-RNP and anti-RNP70 antibodies in samples from four cohorts: SLE, MCTD, primary Sjögren’s syndrome (pSS) and healthy blood donors (HBDs). Here, SNRNP70 is linked to Sjogren syndrome.