Clinical Information

Antibodies to SS-A/Ro, SS-B/La, Smith (Sm), U1RNP (RNP68/A), Scl 70 and JO1 are associated with the presence of antinuclear antibodies (ANA) and useful in the evaluation of specific ANA-associated connective tissue diseases (CTD), ANA-CTD.(1) Due to their frequencies in ANA-CTD and the overlapping clinical presentations of these diseases, inclusion of these tests in a panel may be useful at initial evaluation of patients at-risk for certain CTD. The combined presence of antibodies to SS-A/Ro (Ro52 and Ro60) and anti-SS-B/La is highly suggestive of Sjogren syndrome.(2,3) Separate determination of anti-Ro52 and anti-Ro60 antibodies is preferred to combined SS-A/Ro in the evaluation of ANA-CTD as their differential presence maybe useful in risk stratification and prognosis of ANA-CTD patients.(4) The presence of anti-Sm antibodies are specific for systemic lupus erythematosus (SLE) and is included the classification criteria for disease.(5) Monospecific antibody reactivity to U1RNP may indicate a diagnosis of mixed connective tissue disease (MCTD).(6) However, anti-U1RNP antibodies may also be seen in patients with SLE, systemic sclerosis (SSc) and idiopathic inflammatory myopathies (IIM).(6,7) In addition, there exists diverse analytes for the detection U1RNP with differential correlations with MCTD, SLE, SSc, and IIM.(8) Anti-Scl 70 (topoisomerase 1) antibody is one of three autoantibodies included in the 2013 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification criteria for SSc.(9). It is generally associated with diffuse cutaneous SSc clinical manifestations including interstitial lung disease with poor prognostic outcomes.(10) Lastly, antibodies to JO1, is a member of the amino acyl-tRNA synthetase family of enzymes is suggestive of diagnosis of IIM, specifically anti-synthetase syndrome and is included in the 2017 EULAR/ACR classification for IIM.(11)

For more information, see the individual test codes.